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WASTES
IN RELATION TO
AGRICULTURE AND FORESTRY

By Ceci H. Wap.eIcH
Director, Soil and Water Conservation Research Division

Agricultural Research Service

Miscéllaneous Publication No. 1065

UNITED STATES DEPARTMENT OF AGRICULTURE

Washington, D.C. Issued March 1968

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 60 cants

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PREFACE

In the preparation of this report, four considerations were kept in
mind: (1) How are agriculture and forestry adversely affected by wastes?
(2) What wastes are contributed by agriculture and forestry? (3) How
has research in the U.S. Department of Agriculture and the State agri-
cultural experiment stations contributed to the amelioration of waste
problems? (4) What problems in waste production and management
continue to need attention by agriculture and forestry? Commentary on
these four considerations comprises the corresponding four appendices to
the report per se.

The advice and helpfulness received from the many, many people in
the U.S. Department of Agriculture and the State agricultural experiment
stations during the compilation of this report are deeply appreciated.
The compiler accepts full responsibility for all errors of omission and
commission found herein.

Crecit H. WabLeEIGH,

Director, Soil and Water Conservation Research
Division,

Agricultural Research Service.

Beltsville, Md.

Iv

FOLLOW THE LABEL

U.S. DEPARTMENT OF AGRICULTURE

Trade names are used in this publication solely to provide specific information.
Mention of a trade name does not constitute a guarantee or warranty of the product
by the U.S. Department of Agriculture or an endorsement by the Department over
other products not mentioned.

CONTENTS

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VI CONTENTS

APPENDIX JI—Continued

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Nematocides

APPENDIX III: RESEARCH UNDERWAY IN AGRICULTURE AND FOR-
ESTRY TOWARDS AMELIORATING WASTE PRODUCTION AND WASTE
MLAS ACCUINIEEIN PROBLEMS

Chemical Air Pollutants From ‘Industrial and Metropolitan Activity mies
Smoke From Wild Forest Fires_

Airborne Dusts

CONTENTS

APPENDIX IJJJ—Continued
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Plant Disease Agents Contaminating the Environment. ______________________-
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Improved Technology for Evaluation of Damages From Airborne Toxicants____-
Effects of Airborne Toxicants on Plants, Including Interactive Effects __-

Development of Tolerant Species, Varieties, and Breeds of Plants____. eee

Evaluation of Air Cleansing of Toxicants by Foliage_. ai Peg ats ie at RRS oe

Development of Protective Chemical Treatments..___________________- a

Development of Information and Procedures to Lessen the Hazard and Intensity of
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CONTENTS

APPENDIX IV—Continued

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WASTES IN RELATION TO AGRICULTURE AND FORESTRY
INTRODUCTION

An enduring cliché proclaims that the only cer-
tainties In man’s existence are death and taxes.
Massive evidence is being accrued in our affluent
society that a third inevitable should be added—
wastes.

Wastes are ubiquitous. They occur on the farm
and in the factory, in the high-rise apartment and
on the rural estate, on the city streets and the open
highway, in murky mines and verdant forests, in
sedate offices and carefree parks, in the waters of
lakes and streams, and in the air around us.

One can take the optimistic view that these
wastes are merely resources for which we have not
found a use. This view offers hope that with under-
standing, adequate technology, and the proper
economic and legal constraints, there is a possibil-
ity that the problems inherent in the production,
management, and disposition of wastes may be re-
solved. This is a good objective. But the probabil-
ity of attainment is another matter.

We set great store by the operations of the mar-
ket place. As is proper, net profit is a key guideline
to decision. In the process, that which was previ-
ously a resource may become a waste. Waste dis-
posal problems proliferate.

Within the agricultural economy, animal ma-
nures provide a case in point. Only a few decades
ago, manure was esteemed as a prime source of
soil fertility. Much technical information was
available on proper handling to attain maximum
benefits on the land. Even today, the “Plain Peo-
ple” of the Pennsylvania Dutch region carefully
husband manure supplies toward maintaining
highly productive lands. But these people have
virtually a religious dedication to conserving and
improving their land and their farms. They are,
first of all, devoted stewards of the land, and only
secondarily participants in the marketplace. They
have no problems on how to dispose of animal

rastes.

But these conscientious Amish are exceptions to
the conventional thinking in commercial and agri-
cultural enterprises.

With the abundant availability of synthetic
nitrogen fertilizers at low cost following World
War IT, it became more economical for the farmer
to supply plant nutrients to his fields from the
fertilizer bag rather than meet the expense of haul-
ing manure from barnyard or feedlot. Further,
the general trend in mechanizing and streamlining
production was given impetus by labor shortages
during and after the war. Poultry enterprises,
cattle and hog feedlots, and dairies became enor-
mous by previous standards. Manure accumulated
in vast quantities. Disposal of the stuff became a
problem in terms of both engineering efficiency and
esthetics.

Whether wastes are looked upon as resources,
or resources as wastes, is, in the words of the
Canadian Council of Resource Ministers, “fa mat-
ter of attitudes.”

Drive along a rural road on a balmy Sunday
afternoon. Cast an eye along the roadside. All to
be seen is not natural beauty. Many a traveler has
obviously contributed to the mess of cans, bottles,
and other assorted refuse along the way. The rea-
soning, or lack of reasoning, that compels humans
to contribute to this desecration of the landscape
would make a most interesting study.

As mentioned previously, disposition of wastes
is a “matter of attitudes.” There is a venturous,
covetous streak not far below the surface of our
people; a streak that erupts now and then into
wholesale exploitation of resources. We read of
the appalling slaughter of buffalo merely for sport
or for their hides during the latter part of the
19th century. We see in the cutover areas of the
Lake States the dismal sequel to the rapacious
slashing of virgin forests in that region around
the turn of the century. We see ugly scars upon the
landscape in the form of barren and hideous spoil
banks from irresponsible strip mining of years
ago—spoil banks that even now are contributing
silt and acid to streams. There is in all of these
examples an utter disregard toward wastefulness.

1

2 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

Fortunately, there arises now and then from
the multitude a man of great stature and wisdom
who shows us the errors of our ways in exploiting
resources and creating great wastes.

Professor E. W. Hilgard, the distinguished soil
scientist and former geologist for the State of
Mississippi, gave a hard-hitting lecture on poor
farming practices, erosion, and sedimentation be-
fore the Mississippi Agricultural and Mechanical
Fair Association at Jackson on November 14, 1872.
He was gravely concerned over the poor husbandry
practices of the farmers on the brown loam soils of
the State—practices that were ruining the land,
eroding and gullying the landscape, and. silting
the streams. He told his audience frankly: “If we
do not use the heritage more rationally, well might
the Chickasaws and the Choctaws question the
moral right of the act by which their beautiful
parklike hunting grounds were turned over to
another race, on the plea that they did not put them
to the uses for which the Creator intended them.”
It was another 75 years before effective counter-
measures to land deterioration and stream silta-
tion began to be taken in Mississippi.

One of the real giants in the history of the U.S.
Department of Agriculture was Dr. Harvey W.
Wiley. During the latter part of the 19th century,
Wiley was Chief Chemist in the Department and
undertook his classic studies on food adulteration.
He found endless cases in which food processors
were not careful to distinguish between that which
was pure food and that which included an adulter-
ant or even wastes. Fortunately, Wiley was also an
excellent publicist and skilled agitator. Under his
skillful touch, Congress passed the first Food and
Drug Act in 1906.

One may not mention forest conservation—the
elimination of wastefulness in forestry—without
reference to the work of Gifford Pinchot in the
early 1900’s. Pinchot launched a crusade for sound
forest management and harvesting practices,
watershed conservation, disease control, and fire
protection. It is regrettable that so much exploi-
tation and waste in lumbering had to take place
before the need for a Pinchot was recognized.

When the drought years of the thirties depleted
the soils of cover and made vast expanses suscep-
tible to the ravages of wind and water, another
dynamic leader was at hand—Hugh Hammond
Bennett, Chief of the newly formed Soil Conser-

vation Service. He ably dramatized the tremen-
dous duststorms of 1935 as not only depleting the
soil on the Great Plains, but also creating enor-
mous pollution of the atmosphere. He dramatized
the tremendous soil losses from high runoff and
the consequent contamination of streams with silt.
The people were with him.

We have touched upon a few instances to em-
phasize the point that coping with problems in
the production, management, and control of wastes
related to agriculture and forestry is not a simple
matter. It goes beyond the development of new
and improved technology; beyond the sophisti-
cated analyses of benefits and costs in the economic
arena; beyond the police power of legislation.

One must take into account the general attitude
of people towards various wastes: their apprecia-
tion for and interest in esthetic values, their con-
cern over health hazards implicit in wastes, their
willingness to accept restrictive regulations in heu
of private privileges, and their willingness to pay
the added costs of maintaining a better quality of
their environment.

If public agencies develop active programs to
alleviate environmental contamination, the tax-
payer usually pays the bill. If industry modifies
its processing procedures to eliminate or abate
production of wastes, any added cost will even-
tually be passed on to the consumer. If agriculture
and forestry increase costs of production to re-
duce wastes, or the adverse effects of wastes, then
in due course the consumer will find an adjustment
in the price tag.

In addition to the question of how much control
of wastes we want, one must ask how much con-
trol do we want to pay for? Beyond doing that
which is economically justifiable, how far do we
go in meeting health standards and social desir-
ability? We must differentiate between the things
we would like to do, those we should do, those we
must do, and those we can do.

Compromises will need to be made among
various objectives. For example, people express
concern over pesticide residues. They want no part
of the possible ill effects from accidental or inad-
vertent ingestion of these chemicals. They are
just as adamant against biting into an apple and
finding half a worm. Both extremes are easily
avoidable.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 3

Economic and social goals may need to be abet-
ted by legal constraints.

There must be a mutuality of interplay between
the course of technology pertaining to wastes and
development of the conflux of legal-social-eco-
nomic objectives and restraints. Urban people
sometimes build homes out among dairy farms.
There are cases in which the suburbanites who did
not like the odors of dairy farming succeeded in
imposing legal constraints on the farmers, thereby
incurring the farmers’ economic and_ social
distress.

Consideration must be given to zoning laws that

protect agricultural areas from untoward en-
croachment. California has shown the way with
the passage of A.B. 2117—the California Land
Conservation Act of 1965.

There must be enlightened leadership. Those
graced with the good fortune to stand on moun-
tains and discern the bright horizons of a pristine
environment have the right—even the duty—to
help turn unawareness and indifference into un-
derstanding, concern, and action.

Nothing gets done without someone being
motivated.

APPROACH

This report provides terse consideration to 10
major categories of entities that contaminate the
air, water, and soil of our environment in relation
to agricultural and forestry endeavor (see app. I).
These categories are radioactive substances, chem-
ical air pollutants, airborne dusts, sediments, plant
nutrients, inorganic salts and minerals, organic
wastes, infectious agents and allergens, agricultur-
al and industrial chemicals, and heat. A brief dis-
cussion is also presented on economic evaluation.

A few comments are offered on each category
about the importance of the problems, the extent
to which agriculture and forestry are involved,
contributions that have been made to ameliorate
the problems by research in agriculture and for-
estry, and an indication of the need for new or
better information and technology towards meet-
ing pressing problems. More complete discussion
is presented in the four appendices.

It is imperative to recognize that different kinds
of wastes may not be completely allocated to dis-
tinct pigeonholes, such as appears to be the pro-
cedure in this report. There are many interrelated
effects.

The consequences of animal wastes moving into
a stream must be considered with reference to the
burden of oxygen-demanding organic wastes that
the stream may be carrying from sewage, mu-
nicipal garbage, processing plants, and dead or
dying algae and other aquatic life. Discussion of
animal wastes cannot be wholly discrete from that
of infectious agents of animal origin. Both may
arise from the same barnyards, feedlots, and poul-

try houses. The effects of animal wastes may not
be discussed as something quite apart from plant
nutrients. Obviously, animal wastes are a good
source of nitrogen, and there is evidence that
elevated levels of nitrate found in some ground
waters are associated with accumulations of these
wastes. Barnyard runoff may carry as much as
1,000 p-p.m. (parts per million) of phosphorus.

In discussing organic wastes as contaminants
of water, one must recognize the importance of
heat as a water pollutant. The elevated tempera-
ture of a stream that has been diverted to provide
cooling for industry can have just as adverse an
effect on poor assimilation of wastes as an increased
load of biochemical oxygen demand.

A sediment burden in the water may lower
oxygen content and thereby accentuate the adverse
effects of organic wastes bringing in biochemical
oxygen demand. Plant nutrients moving into
waters may not be fully evaluated without con-
sidering the amounts adsorbed on the sediment be-
ing carried. Sediment from surface soils carries
phosphorus into streams. Nutrient-poor sediment
from the subsoils of construction areas may deac-
tivate the soluble phosphate of a stream by tena-
cious adsorption. Sediment may be the prime
carrier of chlorinated hydrocarbon insecticides
that are occasionally detected in streams.

The interplay of these various categories of
wastes in their impairment of our environment
related to agricultural and forestry endeavor must
be evaluated. The full perspective of waste prob-
lems cannot be gained by wearing blinders.

4 MISCELLANEOUS PUBLICATION NO. 1063,

Radioactive Substances

Radioactive substances, which are possible con-
taminants of air, water, and soil, may be pro-
duced by several sources. Radioactive wastes re-
sulting from mining and refining radioactive
minerals such as uranium and thorium may wash
into streams. There may be accidental or unau-
thorized releases of radioactive isotopes from
power reactors or from research laboratories.
There is atmospheric fallout from testing nuclear
weapons. This has diminished with the existence
of the test ban treaty involving the United States,
the U.S.S.R., and Great Britain. Unfortunately,
ul nations having nuclear capability are not mem-
bers of this treaty and therefore do not adhere to
the ban. Potential for radioactive contamination
under nuclear war staggers the imagination.

Agriculture and forestry contribute but very
little to either actual or potential contamination
from radioactivity—some phosphate rocks used
for fertilizer production contain very low levels
of radioactive uranium and thorium. Agriculture
has experienced minor adverse effects from this
source of contamination. During the spring of
1966, milk was confiscated in Nevada because of
an unduly high level of iodine-131 in the area as
a result of accidental venting during and follow-
ing an underground weapons test. Potential dam-
age to agriculture from radioactive fallout could
be serious under unrestricted testing of nuclear
weapons. Under nuclear warfare, the situation
would be catastrophic.

Much information has been attained through
research on the behavior of radionuclides in soils,
plants, and animals. Attention was especially fo-
cused on the behavior of strontium-90. This iso-
tope justifies serious concern because of its rela-
tively long half-life and its chemical behavior so
analogous to that of calcium in soils, plants, bones,
and milk.

Engineering research has designed equipment
to decontaminate soil that has been surface-coated
with radioactive fallout. One procedure involves
skimming off the contaminated surface, and an-
other involves burying the surface by plowing
deeply—2 feet—and adding a chemical root in-
hibitor to the buried layer.

There is need of much better information on the
duration and effects of retained fallout particles

U.S. DEPARTMENT OF AGRICULTURE

on plants to improve validity of prediction of radi-
ation doses to plants and animals. There must be
much better techniques in terms of effectiveness,
cost, and rapidity of operation for decontami-
nating forage, food plants, and soils. Research
should ascertain the possibilities for specific ge-
netic lines of feed and food plants that have the
physiological capability to exclude radioactive
elements.

Agriculture should support a relatively modest
program of research on measures counteractive
to radioactive wastes. If ever the unfortunate time
arrives when such information is urgently needed,
it will be too late to start.

Chemical Air Pollutants

Airborne chemical contaminants include such
substances as sulfur dioxide, fluorine, carbon mo-
noxide, ozone, nitrogen oxides, peroxyacetylni-
trate, sundry hydrocarbons, and just plain smoke.
Thirty million tons of sulfur dioxide are spewed
into the atmosphere over the United States every
year from smelters, use of fossil fuels for heat and
power, and burning refuse. Seventy-five million
tons of the other chemical contaminants are emit-
ted into our atmosphere by exhausts from internal
combustion engines, industrial mills, refuse burn-
ing, home heating, forest fires, and agricultural
burning.

Crop plants, ornamentals, and trees are sub-
jected to chronic injury in and near every metro-
politan area. Livestock have been afflicted with
fluorosis near certain industries, such as steel, alu-
minum, and phosphate mills. In southern Califor-
nia acute injury is widespread. About 14,000 square
miles in that State are now afflicted with airborne
toxicants (82).1 Losses to agriculture and forestry
in the United States because of the flood of these
noxious chemicals into the atmosphere are esti-
mated as exceeding $500 million annually (88, p.
V-137).

Agricultural endeavor makes a small local con-
tribution to chemical air pollution in the form of
hydrocarbons and smoke emitted from burning
crop residues in fields. Major forest fires produce
tremendous quantities of smoke. Fires in our for-
ests produce upwards of 500,000 tons of hydro-

*Ttalic numbers in parentheses refer to Literature
Cited, p. 108.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY oO

carbons annually. In nearby areas, these hydro-
carbons can become more serious by being con-
verted to photochemical toxicants.

During the past 20 years, considerable research
has been underway on (a) evaluating the relative
sensitivity of different kinds of economic plants,
trees, and livestock to various levels of specific
air pollutants; (b) determining the actual com-
ponents in polluted air that cause damage; (c)
measuring the acute and chronic effects of given
levels of specified pollutants in different plants
and animals; (d) developing management prac-
tices that would minimize or ameliorate the ad-
verse effects of given air pollutants; and (e) de-
veloping and selecting varieties of crops and trees
with higher tolerance to air pollutants. Very prom-
ising research is underway towards prediction and
abatement of forest fires due to electrical storms.

In meeting the problems inherent in the dam-
ages of airborne toxicants to agriculture and for-
estry, it would be most advantageous if these
chemical effluvia could be eliminated at the source.
Some accomplishment has been attained on this
objective—for example, virtual discontinuance of
sulfur dioxide emanation from the smelters in
Trail, British Columbia, Canada—and more cer-
tainly will be accomplished. But there is little hope
that this approach will adequately cope with the
growing problems of air pollutants in agriculture
and forestry.

There is an urgent need to improve the validity
of the techniques available for assessing damages
from air toxicants. Information is particularly
weak for assessing chronic damages.

Little is known of the actual physiological
mechanisms by which the harmful effects of air
toxicants take place. Ignorance on these funda-
mental problems is a roadblock to valid under-
standing of damages and _ possible counter-
measures.

One of the most promising avenues for attain-
ing countermeasures to air toxicants is that of
developing and selecting species, varieties, and
genetic lines of crops, ornamentals, and trees that
are tolerant, if not immune, to the major effects
of chemical air contaminants.

There is evidence that expansive areas of vege-
tation, particularly woods, have a cleansing action
on toxic wastes in the air. Much more information
is needed on this effect.

The possibility of developing chemical protect-
ants against air pollution damage needs mucli
further exploration and study.

Even though total contribution to air contami-
nation from forest fires seems relatively small,
the total damages from these fires go far beyond
their contribution to air pollution. All possible
effort to develop better technology and better in-
formation to curb such fires should be pursued.

In view of the magnitude of the growing prob-
lems, and the paucity of research effort on air
toxicants by agriculture and forestry in the past,
it is urgent that research effort on the problems in
this general area be expanded and pursued with-
out delay.

Airborne Dusts

During the average year, 30 million tons of
natural dusts enter the atmosphere. Most of this
arises as soil blowing from inadequately pro-
tected fields under cultivation, deteriorated range-
lands, and sand dune areas. A small amount arises
from highway and industrial construction sites.
Susceptibility to wind erosion is the dominant
problem on 55 million acres of cropland in the
United States.

Industries such as cotton ginning, alfalfa mills,
lime kilns, cement plants, smelters, and mining
operations release 17 million tons of dust into the
atmosphere annually. This dust often coats the
foliage of nearby crops, ornamentals, and trees.
Growth and quality of product may be impaired.

Windblown soil not only robs the land of good
topsoil, it also becomes a serious air pollutant.
Respiratory ailments of man and animals are ac-
centuated. Eyes are afflicted. Highway and air
vision 1s impaired. Machinery is scourged by paint
removal and dirt in bearings. Offices, homes,
schoolrooms, and factories are completely perme-
ated by dust. Pesticides may be carried long dis-
tances. Farmsteads, fence rows, ditches, and roads
may be partially buried by drifts of dust.

Wind erosion research and its application has
contributed importantly to the effectiveness of
today’s conservation and other advanced farming
methods in reducing the threat of future “Dust
Bowls” in the Great Plains. Meteorological ree-
ords show that the drought in Kansas during the
mid-1950’s was just as bad as that during the
1930’s. Yet records show that soil blowing was not

6 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

nearly as serious during the fifties as it was 20 or
25 years earlier. At Dodge City, Kans., in 1936-37,
there were 120 days of blowing dust. At the same
location in 1956-57, under comparable meteoro-
logical conditions, there were only 40 days of
blowing dust.

Research has developed a wind erosion predic-
tion equation used by action agencies to provide
technical guidance in farm and ranch planning.

In expanding the research on the problems of
soil blowing in the Great Plains consideration
must be given to various concepts for describing
and delineating the influence of atmospheric wind
and turbulence on soil detachment and transport;
effect of wind and related atmospheric factors in
soul drying and creation of soil surface conditions
susceptible to high rates of detachment; modifica-
tion of tillage practices and machines to provide
effective and lasting crop residues and soil cloddi-
ness conditions to resist soil detachment ; the toler-
ance of crop plants to wind abrasion; the develop-
ment and selection of better strains and varieties
of grasses and crops to tie down soils susceptible
to blowing; design of better windbreaks; and se-
lection of better shrubs and trees to serve as wind-
breaks.

Much better information is needed on techniques
to curb dust production on large feedlots.

Research has developed greatly improved
screens to permit continuous operation of cotton
gins while reducing lint fly. But much-improved
engineering technology is needed to effectively fil-
ter the air from cotton gin operations as well as
to handle trash without contaminating the air
with dust or smoke or carrying diseases and in-
sects back to the fields.

The current emphasis by the Federal Govern-
ment to do whatever is feasible to attain clean air
over the United States must include research to
control or abate dusts from agricultural sources.

Sediment

Sediments are primarily soils and mineral par-
ticles washed into streams by storms. Although
most of the sediment comes from land, a relatively
small amount is contributed from the spoil banks
of mining operations and smelters.

Some 4 billion tons of sediment are washed into
tributary streams in the United States each year.

About one-fourth of this sediment is transported
to the sea. Water erosion is the dominant problem
on 179 million acres of cropland and a secondary
problem on an additional 50 million acres. At least
half of the sediment is coming from agricultural
lands. Some 30 percent of total sediment delivery
arises as geologic erosion such as that found on
the tributaries of the Missouri, Colorado, Rio
Grande, Red, and Arkansas Rivers. For example,
the Badlands of South Dakota are a tremendous
source of geologically eroded sediment. Five to
ten percent of the silt delivered comes from for-
ests and associated rangelands. Streambanks erode
and streambeds degrade, but aggradation may
fully compensate for sediment losses. Urban, in-
dustrial, and highway construction sites and road-
banks also contribute eroded materials. Although
such sources make but a small contribution to the
national sediment delivery, they may contribute
over half of the silt to the streams in a local
watershed undergoing intensive construction
activity.

Research conducted on many different soils vary-
ing in characteristics, slope, cover, and prevailing
climatic conditions provided a mass of empirical
data on soil loss as induced by rainstorms. The data
were subjected to complex mathematical analysis
by a digital computer which enabled the formula-
tion of a universal erosion equation. This equation
aids action agencies to predict what soil losses will
be on a given soil of specified slope, under varying
cropping conditions, with a given rainfall energy
input.

Watershed research has shown that land cover
is the major deterrent to sediment delivery into
tributary streams. Extensive empirical informa-
tion has been accrued on the entrainment, trans-
portation, and deposition of sediments in the
upstream watersheds towards making valid pre-
dictions of sediment accumulation behind flood-
detention structures.

Improved technology in logging and construc-
tion of forest roads has reduced sediment delivery
from forestry operations.

Forestry research on the abatement of wild fires
(fires not started by man) has made a major con-
tribution in diminishing sediment delivery from
forested lands. Soil loss from a burned area is
frequently tremendous.

WASTES IN RELATION TO AGRICULTURE AND FORESTR 7

Most all research in this area has been empirical.
There is an urgent need for fundamental studies
on the energetics involved in the detachment and
movement of soil particles by raindrop splash and
flowing water. Surface sealing and related phe-
nomena that result in decreased infiltration need
to be understood in order to be corrected. Water
intake and movement through soil during freezing
and thawing is especially important, but the inter-
play of forces involved is inadequately understood.
Control practices need to be developed and inte-
grated into systems that will reduce runoff a maxi-
mum amount and provide for the removal of sur-
face drainage without appreciable erosion.

There is an urgent need for new concepts and
procedures for identifying critical sediment
sources and predicting sediment delivery from
areas affected by climatic factors, soils, geology,
topography, stream channel characteristics, and
watershed protection measures. Special emphasis
must be given to developing better technology for
stabilizing and revegetating gullies, spoil banks,
roadbanks, strip mines, overgrazed rangelands,
forest burns, and badly disturbed construction
sites.

Research towards diminution of forest fires and
overgrazing of rangelands would greatly con-
tribute to reducing sediment delivery.

Criteria for engineering design of sediment
traps and debris basins could stand much improve-
ment.

There needs to be a much better understanding
of sediment transport in tortuous upstream tribu-
taries, with emphasis on better understanding of
the hydraulic forces necessary for design and
maintenance of stable stream channel systems.

Limited information is available on the role of
sediment as a transporting agent for pesticides
and other chemicals.

Since comprehensive river basin planning is
moving forward rapidly under the leadership of
the Water Resources Council, expansion of effort
to gain new or better information and technology
on sediment problems in upstream watersheds
should keep pace.

Plant Nutrients
Surface Water

Plant nutrients, as here used, are inorganic
chemicals essential for the mineral nutrition of

plants. When present in surface waters they
may become contaminants in that they pro-
vide for unwanted growth of aquatic plants.
Nitrogen and phosphorus are the two elements
principally involved, but potassium is some-
times involved.

The algae “blooms” that frequently develop
in nutrient-laden waters cause an off-taste and
an unpleasant odor to the water. When streams
and lakes reach the “green soup” stage of algae
growth, the odor of decaying plants becomes
offensive, fish are killed because of reduced
oxygen content of the water, and there is in-
terference with boating, swimming, and water
skiing.

These nutrients enter surface water by dis-
charges of raw or treated sewage, some in-
dustrial wastes, and runoff and seepage from
land. Barnyards and feedlots yield nutrients.
Use of chemical fertilizers on lands is some-
times suspected as being a significant source
of plant nutrients found in streams and lakes.
Such growths can ruin farm ponds. They harm
the usefulness of the permanent pools of up-
stream watershed structures. Along with other
water weeds, they can seriously impair the
flow in irrigation and drainage ditches.

Detergents used in households and industry pro-
vide an abundance of soluble phosphate to sewage
effluent. Evidence indicates that sewage delivery
of phosphate amounts to 2 pounds per person per
year. If the sewage effluent from 1 million people
enters a stream with an average annual flow of
5,000 cubic feet per second, the average phos-
phorus content will be 0.2 p.p.m. This level is more
than ample to enable excellent growth of algae
without the phosphorus from other sources.

Each 1,000 tons of suspended sediment can be
expected to carry about 1,000 pounds of phos-
phorus, most of which is in the adsorbed or fixed
state unavailable for plant growth. Depending on
the source, usually not more than 10 percent of the
phosphorus on sediment is available for plant nu-
trition. Sediment derived from subsoils low in
phosphate may actually deactivate much of the
soluble phosphorus in a stream.

Phosphorus is moving into streams from agri-
cultural lands. Many years of research by soil sci-
entists using lysimeters and other techniques show
that only infinitesimal amounts of phosphorus

8 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

move through the soil in the soluble state. Some of
this may be carried as complex organic molecules.
Surface runoff may well carry phosphate as part
of the suspended particles. Barnyard wastes may
earry 1,000 p.p.m. of phosphorus. Water in the
drains from fertilized fields in irrigated areas in
rare instances have been found to carry as much
as 1 p.p.m. of phosphate.

Very little modern information is available on
the phosphorus content of runoff from soils vary-
ing in geochemical characteristics, treatments with
chemical amendments and _ fertilizers, cultural
practices, and hydrologic conditions.

Far more study is needed on methods of deter-
mining phosphorus content of water in terms of
biological significance. Total phosphorus values
are meaningless. We ought to be able to distin-
guish four different states of phosphorus in water
samples: (a) That which is in true solution as or-
thophosphate; (0) that which is in solution in a
nonpolar form as an organic polyelectrolyte; (c)
that which is adsorbed on suspensoids; and (d@)
that which is a component part of the mineral of
suspensoids.

In view of the widespread concern over eutroph-
ication of surface waters, a major effort should
be launched as rapidly as possible to attain evi-
dence as to the cause and effect sequence. Even on
large bodies of water such as Lake Erie, there is
frequent accusation that use of fertilizer on farm-
ers’ fields is the causative source. The dearth of ac-
curately accrued quantitative and qualitative in-
formation on phosphorus in runoff water from the
land does little to allay argument.

Nitrate in Ground Water

Nitrate in drinking water can cause methemo-
globinemia in babies—“blue babies.” It is also toxic
to livestock. The biochemical status of a baby’s
stomach readily reduces nitrate to nitrite, as does
that of a ruminant. Thus, one hears of nitrate in
well waters causing “blue babies” or nitrate poison-
ing in ruminants. Cases of “blue babies” associated
with nitrate in well waters have been reported in
the Middle West.

When nitrate is found in ground water, the
sources may be several—sewage or septic tank
effluent, feedlots or barnyards, field fertilization,
or the natural accumulations such as found in the
caliche of semiarid regions. The Public Health
Service Standards (/25) specify that the nitrate-

nitrogen content of drinking water should not ex-
ceed 10 p.p.m.

Research evidence in Missouri indicates that vir-
tually none of the nitrate in ground water comes
from field fertilization. Evidence from a secluded
valley under concentrated study in California in-
dicates that sewage effluent and nitrification proc-
esses in the semiarid soils may be the main sources
of the rather high levels—100 p.p.m.—of nitrate
found in the ground water. Studies in Hawaii on
high nitrate levels in the aquifer indicated that
nitrogen fertilization of irrigated sugarcane fields
may be the source.

The diversity of observations and conclusions
with respect to nitrate from various sources moy-
ing into ground water indicates the need for better
information that may be gained by expanded field
studies. The degree to which nitrite may be asso-
ciated with nitrate during downward percolation
needs careful study. The very modest level of re-
search in this area needs to be increased appreci-
ably to gain reliable answers to pressing questions.

Inorganic Salts and Minerals

This category includes neutral inorganic salts,
mineral acids, and fine suspended metal or metal
compounds. These substances enter into streams or
onto soil from the effluent of various smelting,
metallurgical, and chemical industries; from
drainage from mines: and from natural sources.
Industrial sources of these chemicals are com-
paratively minor in relation to total dissolved
solids carried by the Nation’s streams.

The Public Health Service estimated in the early
1930's that 2.7 million tons of sulfuric acid were
produced annually by mines and delivered into
tributary streams. Although the amount of acid
delivery from mines has decreased, awareness of
the problem has increased. Acid mine drainage
kills fish and spoils water for domestic, livestock,
irrigation, and recreation uses. Agriculture and
forestry have an interest in the elimination of this
problem.

Salts normally present in the soils and geologic
materials of arid regions move into streams and
onto irrigated farms. Colorado River water at
Yuma, Ariz., carries about 1.2 tons of salt per
acre-foot. Average annual flow of the Colorado at
Hoover Dam is about 15 million acre-feet annually.
At this location, the river transports more than

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 9

15 million tons of salt. Three thousand freight
trains, 100 cars long, would be needed to carry
this much salt. Much of it comes from geological
deposits or accumulations in arid lands. It means
that a farmer in the Imperial Valley of California
who applies 5 acre-feet of irrigation water to his
crops, also applies 6 tons of salt per acre. Hence,
he must remove at least 6 tons of salt per acre in
the drainage water from his farm.

Salinity is a hazard on about half the irrigated
acreage in the Western States. Crop production
on one-quarter of this acreage is already impaired
by salt-affected soils. Production is threatened in
irrigated projects the world over.

Over the past couple of decades, research has
enhanced the capability of coping with salt prob-
lems affecting agriculture.

Improved procedures for evaluating water
quality for irrigation have been developed, using
electrical conductivity as the primary criterion
and sodium-absorption-ratio as the secondary
criterion.

Far better standards have been developed for
leaching procedures in the reclamation of soils and
for leaching requirements during continued man-
agement.

Much advancement has been attained in under-
standing the physico-chemical behavior of salt-
affected soils.

Since water is the vehicle by which salt moves
in soil, an understanding of the physical princi-
ples of water movement is absclutely essential.
Excellent progress has been made in measuring
the energetics of water retention and movement in
soils.

Good progress has been made in characterizing
the salt tolerance of important crop plants.

There is a real need to develop better means of
assaying salty-soil problems as related to char-
acteristics of irrigation waters. The relationships
are very complex, and oversimplification can lead
to poor technical guidance.

Recent advancements in making key measure-
ments on the physical forces involved in soil water
must be exploited towards far better appraisal of
field conditions related to water.

There is an increasing need to attain an under-
standing of the biochemical and physiological
mechanism in plants that determine their toler-
ance to various salt-affected soils. The role of cli-

matic conditions in modifying these mechanisms
also needs clarification. There is an urgent need
to develop crop varieties higher in salt tolerance.
An understanding of basic mechanisms in each
important species would obviate the present
superficial approach of cut-and-try testing.

The management practices followed in an irri-
gated field that is subject to salinization need far
better quantitative characterization.

Hard experience in the Western States has
shown that successful irrigation requires effective
drainage. Accumulating salts must be continually
leached out. Excessive leaching wastes water and
nutrients. There is an urgent need to develop and
test better mathematical expressions for the cal-
culation of leaching requirements, drainage re-
quirements, and the proper salt balance that ought
to be maintained.

One of the pressing needs for information in
irrigation agriculture is the development and
evaluation of alternative procedures for the dis-
posal or reclamation of return flow—procedures
that seek to maximize beneficial use of total water
available, while minimizing contamination for
downstream users.

The heavy salting of highways in Northern
States to facilitate traffic movement following
snowstorms has caused serious damage to right-of-
way vegetation and has increased silt damage to
streams when erosion followed killing of the vege-
tation. The consequences of highway salting need
far better evaluation.

The Federal Council of Science and Technology
has recommended that agricultural research in-
volved in this general area should increase four-
fold during the current 5-year period.

Organic Wastes

This category includes material such as sewage.
animal wastes, crop residues, forest trash, and food
and fiber processing wastes. When these substances
are carried in water, they incur a high biochemical
oxygen demand. When dry upon the land, some
are combustile, some produce odors, and some at-
tract. flies and vermin.

Sewage

About 60,000 acre-feet of water flows from
municipal sewage facilities on the average day.
Some of this could be used for irrigation even

10 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

though that which received no treatment or
only primary treatment could not be used in
the production of food crops. Such water may
be used for irrigating feed and fiber crops.
Fuither, effecting movement of such contaminated
water through soil is the best means of attaining
purification.

The State agricultural experiment stations and
the U.S. Department of Agriculture have already
developed useful information on irrigation with
sewage effluent both in terms of crop production
per se, and in terms of overirrigation to provide
ground water recharge with reclaimed water.

The good prospects of this research in sustaining
agricultural water supplies in the future, in addi-
tion to providing an effective system of water
purification, require that this line of endeavor be
supported to the fullest extent feasible.

Animal Wasies

Domestic animals produce over 1 billion tons
of fecal wastes a year. Their liquid wastes come
to over 400 million tons. Used bedding, paunch
manure from abattoirs, and dead carcasses make
the total annual production of animal wastes close
to 2 billion tons. In fact, waste production by
domestic animals in the United States is equivalent
to that of a human population of 1.9 billion.

As much as 50 percent of this waste production
may be produced in concentrated supply. Big
operations have developed rapidly in the last 20
years. An outfit with 10,000 head of cattle on
a feedlot produces 260 tons of manure a day.
Economic research reveals that it is cheaper for
the farmer to supply fertility to his fields from
the fertilizer bag than to meet the cost of hauling
manure to the field. What is to be done with this
manure ?

If it accumulates, it effuses offensive odors into
the surrounding area; it provides a spawning
ground for vermin; on drying, it is a source of
unsavory dusts; in rainstorms it produces runoff
high in biochemical oxygen demand; and it may
be the source of certain infectious agents found
in streams.

Stockmen have been subjected to lawsuits on the
grounds that such wastes were a public nuisance.
Dairy farmers have had to make expensive moves
to remote areas. Poultry enterprises have offended
and been placed under restrictive curbs.

There is a pressing need to develop basic design
criteria that are amenable to some adjustment to
meet the widely varying constraints associated
with different enterprises in different parts of the
country. Elements of the problem include char-
acteristics of manures; removal of manure from
livestock quarters; storage; transport; feasibility
of use on land; and disposal by burning, using
lagoons or similar facilities, or burying. Other
disposal problems include handling carcasses,
milkroom wastes, and silage effluents.

Much effort should be allocated to identify the
odor-producing organisms prevalent in manures,
and to develop techniques to destroy such or-
ganisms.

Treatments of manure that would lower its at-
tractiveness as a breeding ground for flies and ver-
min are especially needed.

In applying manure to cropland, more accept-
able procedures are needed for storage and dis-
tribution without emission of offending odors and
possibility of contamination of runoff water.

Use of lagoons for disposal has not been fully
satisfactory. They tend to be underdesigned, over-
loaded, and misused. Anaerobic fermentation with
the accompanying odors sometimes takes place.
Some study is underway and must be continued
to provide artificial stirring and better oxidation
of water systems used for manure disposal.

The looming urgency of disposal problems on
animal wastes, associated with a serious dearth of
needed technology on efficient and economic meth-
ods, adds up to an immediate need for major ex-
pansion of research effort to attain sound answers
to these problems.

Plant Residues

Plant residues from crops and orchards impair
the environment in two ways: (1) They act as
reservoirs of plant diseases and pests, and (2) they
emit smoke and hydrocarbons into the surround-
ing area when burned. Rice straw as well as that
of other grains is burned. Burning of residue
from grass seed production is used extensively as
a sanitation measure. Alternate methods of hand-
ling such residues are needed.

If residues are left on the soil, they can aid in
preventing wind and water erosion. However, the
soil microflora may be altered in nature and ac-
tivity, as a result of a mulch of crop residue, and

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 11

can adversely affect production of a succeeding
crop.

Although problems pertaining to the handling
of crop residues may not be regarded as top pri-
ority, new and better information is needed to
economically handle these wastes without detri-
mental side effects.

Trash in Forests and Forestry Operations

Twenty-five million tons of logging debris are
left in woods during the average year. This is a
reservoir for tree diseases and insects. It is also
an exceedingly serious fire hazard. The average
size of forest fires originating in logging waste
is more than seven times that of fires originating
in uncut areas where trash has not accumulated.
Average annual losses from forest fires are $600
million. In the average year, wild forest fires pro-
duce 160 cubic miles of smoke, 34 million tons of
particulates, and 338,000 tons of hydrocarbons.
Forest burns have excessive runoff and very high
sediment delivery. They contribute to flood
damages.

The trash and deadwood from elms killed by
Dutch elm disease and oaks killed by oak wilt
must be destroyed or treated to prevent vector
transmission of the disease to healthy trees.

At the present time, research has produced
no economically feasible technique to dispose of
forest trash en masse other than by controlled
burning. Chipping is useful in isolated instances.

Research needs to be expedited towards the im-
provement of techniques for controlled burning
that reduce atmospheric contamination. All pos-
sible effort must be allocated to research that would
aid in reducing the incidence of wild fires orig-
inating in forest trash.

Processing Wastes

Oxygen-demanding wastes from processing of
agricultural and forestry products include runoff
or effluent from sawmilling; pulp, paper, and
fiberboard manufacturing; fruit and vegetable
canning; cleaning dairies; slaughtering and proc-
essing of meat animals; tanning; manufacturing
cornstarch and soy protein; sugar refining; malt-
ing, fermenting, and distilling; scouring wool;
and wet processing in textile mills. These wastes,
on entering a stream, greatly increase the demand
for oxygen. They may make the water unsightly,
unpalatable, and malodorous.

The oxidative requirements of the effluent from
the woodpulp, paper, and paperboard industries
exceed those of the raw sewage from all of the
people in the United States.

In a year’s time, the canning industry produces
effluent with oxidative demands that are double
those of the raw sewage from Metropolitan De-
troit; the meatpacking industry, double those of
Metropolitan Chicago; and the dairy industry,
four times those of Metropolitan Boston.

Research has contributed to the abatement of
processing wastes by (a) developing a commer-
cially useful product out of that which had been
a waste—the manufacture of insulating board
out of sugarcane bagasse; (0) improving the pro-
cedure so that less wastes are produced—a new
polysulfide modification of the kraft process of
pulping results in greater pulp yields, less waste,
and reduced air and water pollution; and (c¢) de-
veloping methods of waste treatment before dis-
posal in stream—development of oxidative lagoons
for potato-processing wastes.

Because of the tremendous contribution of
processing wastes to the oxidative demands on our
streams, it is obvious that research on farm and
forest products should be enhanced by every means
possible to give much greater emphasis to (1)
developing useful products out of materials that
are now considered wastes; (2) developing and im-
proving processing procedures that lessen waste
production; and (3) improving techniques for
processing waste treatment.

Dilution of Organic Wastes in Streams

Depletion of dissolved oxygen in a stream is
conditional upon the load of oxygen-demanding
wastes added to a stream and the amount of
streamflow available to waste assimiliation. Low
flows in late summer and fall in many rivers and
streams may be only one-fifth or one-tenth the
average annual. Capacity of the stream to as-
similate organic wastes is concomitantly affected.
Hence, river basin planners must give major em-
phasis to operational plans that would minimize
low flows. This will involve both structural and
land treatment measures. Forest management and
land treatment can affect water yield and abate
low flows, but structural measures will undoubted-
ly have the major influence.

In view of the major emphasis being given to
comprehensive river basin planning at this time,

12 MISCELLANEOUS PUBLICATION NO. 1065, U.S.

it is urgent that adequate research on forested
and agricultural watersheds be directed towards
gaining new technology and better information for
determination of optimal combination of land
treatment and structural measures on upstream
watersheds to minimize the adverse effects of low
flows.

Infectious Agents and Allergens

Through history, water contaminated with in-
fectious agents has caused human disasters. It can
still happen. In late May and early June of 1965,
18,000 people in Riverside, Calif., were infected
with Salmonella typhimurium that by some un-
explained means had entered the city water
supply.

Soil, water, and air may be transmittal mediums
for numerous organisms that afflict man as well
as other animals and plants.

Those unfortunates suffering from allergies will
not be consoled by evidence that 1.7 million tons
of pollen move into the atmosphere over the
United States every year.

Animal Disease Agents

Agricultural losses caused by infectious agents
of livestock and poultry carried by air, water, and
soil have been heavy. Some of the diseases so
transmitted are leptospirosis, salmonellosis, hog
cholera, mastitis, foot-and-mouth disease, tuber-
culosis, brucellosis, histoplasmosis, ornithosis, in-
fectious bronchitis, Newcastle disease, anthrax,
blackleg, footrot, coccidiosis, blackhead of turkeys,
erysipelas, and transmissible gastroenteritis. A
number of these may afflict humans.

The presence of coliform bacteria in water has
been used as an indicator of bacteria for about 75
years. Although the coliform bacteria are not
pathological, their presence has been taken as an
indication that infectious bacteria might also be
present.

Recent evidence suggests that more definitive
information on bacterial contamination of water
may be gained by making counts of both fecal
coliform and fecal streptococcal bacteria. Empiri-
cal observations indicate that if the bacterial con-
tamination of water is coming from animals, the
f. coliform/f. streptococci ratio is less than 0.5.
If the bacterial contamination is from human
sources, this ratio usually exceeds +. On this basis,

DEPARTMENT OF AGRICULTURE

a water bacteriologist may use the following as a
general guide: If this ratio is less than 1.0, the
pollution is coming from nonhuman sources; if
the ratio exceeds 2.5, the bacterial pollution is most
probably coming from human sources. Ratios be-
tween 1.0 and 2.5 suggest that the pollution is a
mixture of human and nonhuman sources.

On the basis of the foregoing, bacterial assays
on water samples from the upper Potomac Basin
indicate that most of the bacterial pollution of this
river system is coming from nonhuman sources.

Much needs to be learned about the complete
reliability of the f. coliform/f. streptococci ratio
as an indicator of the source of infectious agents in
river water. Comparable studies need to be made
on other river systems.

Excellent progress has been made in veterinary
research in the United States over the past 85
years. Bovine tuberculosis has been reduced to a
remarkably low point. Counteractive measures in-
volving environmental sanitation have been
highly successful in curbing brucellosis and hog
cholera.

Even though much has been accomplished,
much needs to be done.

Research underway on parasitic diseases will
contribute to reduction of environmental con-
tamination in two distinct ways: First, by the de-
velopment of methods to reduce parasitism in our
livestock population which will, in turn, reduce
environmental contamination by parasite-infested
animal wastes; second, by reducing the opportu-
nity for environmental contamination by pesti-
cides through development of methods of reduc-
ing or eliminating parasitism, based on biological
control, immunization, improved management, or
more efficient use of better chemicals.

Expansion of research on developing counter-
active measures to animal diseases is warranted
fully on the basis of the huge annual losses these
diseases impose on agriculture.

In view of the key objectives for clean air
around us and clean water in our river basins, it is
essential to have (a) far better information on the
extent to which infectious agents in our surface
waters come from agricultural sources; (6) pos-
sible procedures to curb movement of infectious
agents from the farm or feedlot to the water; and
(c) continued progress in eliminating animal dis-
eases that contaminate air, water, and soil. Some
animal diseases—for example, encephalitis—are

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 13

spread by mosquitoes that are often spawned un-
der irrigation agriculture. Needed research should
be supported to the fullest extent feasible.

Plant Disease Agents

Diseases of crops, ornamentals, and trees have
caused losses in billions of dollars. Many of these
diseases are transmitted via air, water, or soil—
that is, by contamination of the environment.

Black shank of tobacco has been a very serious
disease in several tobacco-growing areas. It is
spread by contaminated water, soil, or plants. The
disease spores can contaminate ponds or streams
into which infested fields drain. The disease per-
sists for many years in some soils but not in others.
Research on this problem has developed resistant
plant varieties and a system of field sanitation.

Red stele disease of strawberry is an example
of a plant disease fungus that persists in con-
taminated soil for many years even if strawberries
are not present.

Stem rust of wheat is an example of a plant dis-
ease that is often spread, with disastrous results,
by contaminated air. This disease has cost agricul-
ture billions of dollars in losses. Countering the
broad transmission of strains of this disease by
tainted breezes has gained through development of
disease-resistant varieties of grains. Since the
disease organism mutates and attacks previously
resistant varieties, a continuous breeding program
is essential. In fact, one of the most laudable con-
tributions of research in the United States is that
of developing control measures for stem rust of
wheat—a disease that can ravage millions of acres
of a food crop by contaminated winds.

White stringy root rot of conifers is a disease
caused by the fungus /omes annosus Fr. It is pres-
ent throughout our softwood forests. Airborne
spores inoculate freshly cut stumps. Once tree roots
are infected, the fungus may survive below ground
for 50 years or more.

Although the potato blight epidemic that caused
such widespread starvation and misery in Ireland
occurred over a hundred years ago, we still know
very little about the spread of such plant disease
epidemics by a contaminated environment.

Research on the control of plant pathogens that
contaminate the soil needs particular attention,
since few are subject to control by either chemicals
or plant breeding. High priority must be given to
studies on changes in microbial populations in soils

on incorporation of specific crop residues, with
especial emphasis on the extent to which popula-
tions of plant pathogens on the soil are suppressed.

Plant disease agents carried by air, water, and
soil can be just as disastrous to man’s welfare as an
infectious agent such as Salmonella typhosa—the
cause of typhoid fever. Research towards mini-
mizing the prevalence of these agents is tanta-
mount to improving environmental quality for
man’s welfare. This is a high priority objective-

Allergens

The Public Health Service reports that in the
average year, there are 12,646,000 sufferers from
asthma or hay fever, or both. Of these, about 5
million are asthma sufferers, and about 75 percent
of the asthma cases are due to pollen. The remain-
ing 7,646,000 suffer from pollen allergies. Costs in
terms of medical treatment and workdays lost are
enormous.

There is very little research underway designed
specifically for the control of plant species that
produce allergenic pollen. In fact, there is no com-
plete catalog of allergenic pollen.

Chemical control by herbicides having high
physiological specificity offers a real possibility
for the weeds that are troublesome. Pollen is car-
ried long distances by wind, and any control
measure must significantly reduce pollen counts.

The evidence suggests that very rewarding re-
search could and should be undertaken in this area
of serious aerial contamination.

Agricultural and Industrial Chemicals

The use of synthetic organic chemicals has been
beneficial to man and his environment. But the dis-
charge of some of these chemicals into the environ-
ment has induced problems. These chemicals in-
clude such substances as household detergents and
the more recent insecticides, herbicides, fungicides,
and nematocides.

Detergents

Agriculture and forestry have interest in prob-
lems caused by detergents. The excellence of these
chemicals as cleansing agents is related to their
high capability to disperse colloidal particles.
They also disperse soil colloids. A dispersed soil
has relatively low hydraulic conductivity in either
the saturated or unsaturated state. An installation
such as a septic tank with its distributing field at a

14 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

farmhouse, in a rural community, or on a forest.
recreation area depends on reasonably good hy-
draulic conductivity of the soil around the dis-
tributing tiles. Reports of malfunctioning septic
systems are common. Design of septic systems
could be improved; they could be better adjusted
to soil characteristics and to degree and nature of
probable detergent load.

No hazard to humans or animals is apparent
from the presence of detergents in surface waters.

Detergents carry phosphate as an active com-
ponent. When sewage effluents enter rivers, lakes,
and estuaries, this phosphate becomes a key plant
nutrient promoting the development of obnoxious
algal blooms. This role of phosphate is discussed in
the section on plant nutrients. Much more factual
information is needed on the respective contribu-
tions of phosphate from detergents and sewage in
general compared to that from land runoff.

Insecticides

The potential contamination of the environment
by pesticides, particularly the chlorinated hydro-
carbons, has been a matter of public and private
discussions. Within a few years after DDT began
to be used extensively as a field and forest insecti-
cide, DDT and its metabolites were found in the
fatty tissues of fish and wildlife, both living and
dead. Newspapers carried features on fish and
wildlife losses with an implicit indictment of agri-
culture and forestry for having used insecticides.

The use of these chemical tools has made a tre-
mendous contribution to man’s health and welfare
over the past 25 years. Unfortunately, in some in-
stances, they have also been abused and misused
without due consideration to their impact on the
nontarget organisms.

In 1964. 470 million pounds of insecticides were
used on 83 million acres of land. In a few instances,
adverse effects have occurred in agriculture and
forestry. Insecticides that have broad spectrum ac-
tivity are just as effective on many nontarget in-
sects as on the target ones. For example, use of cer-
tain insecticides has resulted in losses of honeybees
and other beneficial insects.

The application of certain insecticides to cotton,
corn, or other crops may lead to insecticide residues
in soybeans or peanuts grown in the soil a year or
more later. Certain chlorinated hydrocarbons can
persist in soil for many years. In one experimental
study 50 percent of the original high-level applica-

tion of DDT was found in the soil 8 years after the
material had been applied.

The pesticide monitoring program maintained
by the U.S. Department of Agriculture on wide-
spread soils and waters is, therefore, exceedingly
important. Evidence revealed from these monitor-
ing activities does not show cause for concern on
pesticide buildup. But this does not warrant com-
placency over the diverse problems stemming from
insecticide use.

Over the long pull, research efforts towards
avoiding the adverse effects of insecticide residues
in the environment must continue to receive major
attention.

Far better information is needed on insect
population trends with the objective that emer-
gency use of chemicals may be avoided.

Research on developing insecticides with higher
biodegradability and lower persistence in the en-
vironment must move forward apace.

There needs to be far better information on
the chemical behavior of insecticides in soils vary-
ing widely in physico-chemical attributes. The
extent and level of pesticides in waters and in
soil-water systems must be better evaluated and
the significance of the findings better understood.

Certain residue problems arise as a result of
spray or dust drift beyond the target area. There
are good possibilities of developing better methods
of application or lower application rates. These
must be pursued.

The use of physical attractants to aid in non-
chemical control of economic insects needs to be
more fully explored.

All possible support should be allocated to re-
search for completely selective methods of con-
trolling major insect pests. These techniques in-
clude the use of predators and dissemination of
specific insect diseases; development of specific
insect attractants; breeding and selection of insect
diseases: breeding and selection of insect-resist-
ant crop varieties; the use of self-destruction
mechanisms such as release of sterile males; and
the development of chemical insecticides that act
on selective physiological systems peculiar to the
target insect.

Herbicides

Weed control by use of selective herbicides has
increased substantially during the past 20 years.
In 1964, 184 million pounds of herbicides were

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 15s

sold in the United States and 97 million acres of
agricultural land were treated with these unique
chemicals.

Although good progress has been made in the
technology of herbicide use, much research is
needed to refine this technology. Herbicides ap-
plied to control weeds in one crop may leave resi-
dues in the soil which prevent the growth of cer-
tain other crops planted immediately following
harvest of the treated crop. Diuron used for weed
control in irrigated cotton in the Southwest may
leave residues in the soil which could injure vege-
table crops such as lettuce, carrots, cabbage, and
cucumbers when planted in the winter following
cotton harvest.

Spray drift of 2,4,5-T and 2,4-D from applica-
tions on nearby forests, cropland, roadsides, and
rights-of-way has damaged chemically sensitive
trees such as dogwood, paper birch, box elder,
chestnut, black locust, and other shade trees,
shrubs, and herbaceous ornamentals. In some situa-
tions injury has occurred as much as 10 miles
downwind from the target area.

The aromatic solvents and other herbicides used
to control aquatic weeds in irrigation systems are
known to be toxic to fish at levels generally higher
than the amounts needed for weed control. How-
ever, judicious use of certain solvents or herbicides
will provide weed control with little or no fish
toxicity.

Limited information is available on the behavior
of some herbicides in soils. It is a complex picture.
Adsorption of a herbicide by a soil is determined
by the specific surface of the soil, organic matter
content, nature of the clay mineral, moisture status,
temperature, nature and degree of base saturation,
and structure and polarity of the herbicide
molecule.

Soil micro-organisms are important in detoxify-
ing herbicides in soils. It is largely because of these
soil micro-organisms and other dissipation mech-
anisms that most herbicide residues in soils do
not show progressive buildup.

The fact still remains that the toxicology of
residual herbicides on succeeding crops is often
unpredictable. Consequently, there is a pressing
need for far better information on the fate of
herbicides in soils, including the cultural practices
and climatic conditions that incur a modifying
influence.

There is a continuing urgency to develop su-
perior herbicides with greater specificity and fewer
adverse residual side effects.

Concentrated research effort is needed on engi-
neering principles to develop better techniques to
reduce drift.

There would appear to be tremendous economic
advantages in developing weed control chemicals
that are more specific; for example, 2 chemical
that would only inhibit pollen production on
ragweed.

The extensive use of herbicides and the problems
arising from residues in soil and water oz drifts in
the atmosphere focus on the need to emphasize in-
vestigative studies on the pertinent array of
problems.

Fungicides

Fungicides do not appear to be of major con-
cern in environmental contamination. The organic
mercury compounds are generally the most haz-
ardous to man, but these are used mostly for seed
treatment. Accidental feeding of such treated seeds
to livestock and poultry sometimes causes
poisoning.

Apple orchards and vineyards that have had a
long record of spraying with copper fungicides
may have very high levels of copper in the sur-
face soils. Zinc and manganese can accumulate
to toxic level in soils, but evidence indicates that
application of fungicides is not at fault.

In terms of residues contaminating the enciron-
ment, there are many other substances that cause
more concern than fungicides.

Heat

Heat acts as a water pollutant because the
amount of oxygen that water can hold in solution
diminishes with increasing temperature, The in-
troduction of heat in any substantial quantities
into surface water has the net effect of introducing
additional oxygen-demanding wastes.

Heat also has a detrimental environmental effect
upon fish and other aquatic life. Some fish can
stand only a very few degrees of increase in tem-
perature, and a substantial increase in tem-
perature can result in the elimination of some
forms of aquatic life.

There is little in agricultural and forestry en-
deavor that contributes heat to streams and lakes.

16 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

One example comes to mind. Water seeping from
or flowing through a recent forest burn may have
a higher temperature than if the area had been in
deep forest.

Industry may contribute serious heat pollution
of streams. The Mahoning River in Ohio provides
a good example; it is used extensively for indus-
trial and power cooling in the Youngstown area.
The temperature of the river in the summer is
raised to such an extent that fish life is com-
pletely eliminated, and the river is rendered unfit
for further use in either waste assimilation or addi-
tional cooling.

Agricultural and forestry interests wishing: to
use surface waters for recreation or fishing would
be seriously affected by water unduly heated by
industrial cooling.

Socioeconomic Evaluation

A whole array of decisions must be made among
alternative approaches posed by wastes in the
environment. How do we define quality of the
environment? Where do we draw the line between
contamination and noncontamination? How much
are we willing to pay for specific levels of quality
improvement? What level of waste treatment do
we want? Do some segments of society want differ-
ent levels of environmental quality than others?
How do we set up standards that provide flexibil-
ity? How do we attach monetary significance to
esthetic values? How do we relate these values to
quantitative aspects readily evaluated in the mar-
ketplace? Do we want to maximize economic bene-
fits, or should we seek to maximize social benefits,
or should we attain an optimal combination of the
two?

Answers must be sought to these and similar
questions 1f optimal economic and social solutions
to waste problems are to be attained.

Economic research on wastes should emphasize
the evaluation of costs and benefits associated with
waste production and waste disposal. Such evalua-
tions are needed for each of the agents that do or

may affect this quality of our environment. Such
studies would identify which areas of waste pro-
duction are most in need of correction in terms of
dollar costs and benefits.

To this end, economic studies are underway on
data from the Pesticide and General Farm Survey
for 1966. Evaluation of these data in relation to
those previously obtained will indicate trends.

Studies are underway on the economic signifi-
eance of water quality, erosion and sedimentation
processes, and the salinity of irrigation waters.

Economists maintain a continuing research pro-
gram with respect to fertilizer use.

Organic wastes present a major area for eco-
nomic studies toward arriving at sound decisions
on alternate ways of handling animal and poultry
manures and food and fiber processing wastes.

There is an immediate need for information on
the status of rural waste problems. Surveys should
be designed to provide for better knowledge on
abatement costs, economic effects, existing institu-
tional control arrangements, and other informa-
tion as specified by survey objectives.

These surveys should highlight critical problems
requiring studies in depth. Such studies should
trace the economic implications of selected prob-
lems, specify feasible alternatives for solution, and
provide information for the rational compromises
between production efficiency and waste-free
environments.

There are presently serious problems of adjust-
ment within agriculture to meet changing con-
cepts of environmental quality. Local ordinances
and court actions have caused abrupt cessation of
agricultural operations in some areas. Studies
need to be made on the role that local leadership
in county and district organizations can play in
guiding the amelioration of rural waste problems.

There is a critical need for improved techniques
for measuring secondary economic effects, and
nonmonetary benefits and costs, of waste control
programs.

The need for information thus is great in the
complex of decision-making processes.

APPENDIX |

Wastes Adversely Affecting Agriculture and Forestry

It is altogether fitting and proper that an afilu-
ent society should show mounting concern over
the deterioration of environmental quality from
an appalling effluent of wastes. The total problem
has been so well documented that little of impor-
tance can be added. Obviously, the sectors of our
National economy concerned with agriculture and
forestry are in many instances seriously afflicted
with the adverse effects of waste production. These
specific problems warrant further delineation and
evaluation.

The purpose of the discussion in this appendix
will be to comment upon those wastes that have,
or may have, an adverse effect on agricultural and
forestry endeavor, and to give some degree of ap-
praisal as to seriousness of these effects.

Committee Print No. 9 of the Senate Select Com-
mittee on National Water Resources (1/9) speci-
fies these eight general categories of water
pollutants.

(1) Sewage and other oxygen-demanding
wastes

(2) Infectious agents and allergens

(5) Plant nutrients

(4) Organic chemical exotics

(5) Salts and mineral substances

(6) Sediments

(7) Radioactive substances

(8) Heat

In discussions of air pollution, four broad cate-

gories of substances are usually delineated :
(1) Dusts
(2) Chemical contaminants
(8) Radioactive substances
(4) Biological entities (pollen, fungi,
bacteria)

For convenience, this discussion on the environ-
mental contaminants that adversely affect the qual-
ity of air, water, and soil in relation to agricul-
tural and forestry endeavor will represent the fol-
lowing amalgamation of these two sets of air and
water contaminants:

(1) Radioactive substances
(2) Chemical air pollutants

(3) Airborne dusts

(4) Sediment

(5) Plant nutrients

(6) Inorganic salts and minerals

(7) Organic wastes

(8) Infectious agents and allergens

(9) Agricultural and industrial chemicals
(10) Heat

Radioactive Substances

Radioactivity is nothing new. All living things
are constantly exposed to radiation. A smattering
of cosmic rays from outer space continually passes
through our bodies. We breathe and eat minute
amounts of radioactive materials. We are exposed
to such radiation when we have X-ray examina-
tions. X-rays of the proper intensity have been
used to destroy the abnormal cells of cancerous
growths without seriously harming healthy tissue.
But X-rays can be sufficiently strong, or applied
over sufficient duration to cause abnormalities or
death of healthy cells and tissues.

Therein lies the concern of agriculture with
radioactive substances. They emit penetrating
rays that in sufficient strength, or over sufficient
time, can bring about abnormalities or death of
cells, tissues, and organisms analagous to the ef-
fects of X-rays. Medical use of X-rays occurs
under carefully controlled conditions by a highly
trained specialist. Radioactive materials that enter
into air, water, soil, and plants are not under com-
parable supervision.

It must be emphasized, however, that the Atomic
Energy Commission and certain State agencies
exercise careful surveillance and strict controls
with respect to (1) the release of radioactive sub-
stances into our environment and (2) the handling
of soil, water, and food that may have been in-
advertently contaminated. Radioactivity cannot be
destroyed. One can only confiscate, isolate, and
restrictively dispose of materials that have be-
come dangerously contaminated.

Radioactive materials that enter, or may enter,

|
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MISCELLANEOUS PUBLICATION NO.

our environment derive from testing of nuclear
weapons; power reactors, with emphasis on acci-
dental release; mining operations involving min-
erals containing natural radioactivity; refining of
uranium and thorium; and accidental release from
medical and research centers.

Radioactivity can affect livestock either by di-
rect external radiation or by ingestion. Effects of
direct radiation from a nuclear catastrophe would
depend on the intensity and duration of the radia-
tion received. Animals that receive a lethal dose
at a slow rate may survive for weeks, whereas
deaths may occur within a few days from the same
radiation dose applied at a high intensity over a
few hours.

Detonation tests of nuclear weapons give off an
array of radioactive substances. We are particu-
larly concerned with the ones known as strontium-
90, cesium-137, and iodine-131 that enter into the
air as a result of atmospheric or surface tests, and
thereby are widely dispersed through the strato-
sphere. These radioactive particles may fali to the
earth as a downward drift known as radioactive

1065, U.S. DEPARTMENT OF AGRICULTURE

fallout. Snow and rain help bring such fallout to
earth. A nuclear detonation anywhere in the north-
ern hemisphere could produce fallout on the
United States. Fallout can contaminate food, wa-
ter, fields, and buildings.

A general diagram developed by Aleksakhin (7)
illustrates the importance of agricultural activity
as routes by which nuclear fission products may
be conveyed to man. (See diagram below.)

Chemically, strontium is similar to calcium. It
enters into and behaves in water, soil, food and
feed, plants, animal tissues, bones, and milk much
as calcium does. Strontium-90 has a half-life of
28 years, meaning that it loses half of its radio-
activity every 28 years. Because of its long half-
life and its readiness to enter into bones wherein
accumulations could cause bone cancer, it is a po-
tentially dangerous contaminant.

Radioactive iodine may accumulate in thyroid
glands and induce thyroid cancer. Fortunately,
iodine-131 has a half-life of only 8 days so the
danger period is short.

Cesium-137 behaves much like potassium. It has

Radioactive isotopes
from nuclear tests
in the atmosphere

ga.

Radioactive fallout

Ls
of,
ox.
; 2
o Bodies of So
Ss G,
ss open water } oS
c SA
@ Sok.
g “* 29
Ss tc)
a
~ I
: Root : Vegetative food
Soil 00 | Vegetation
H nutrition Zs
In Fodder “~S
A <
BSS o)
la 5
aps Lin 6

Plants and animals
of open water bodies

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 19

a long half-life of 30 years and may collect in
muscle tissue. Cesium-137 is bound very tightly by
clay particles in soil, which lowers its probability
of entering into plants providing food and feed
for livestock.

Phosphate rock used for making phosphatic fer-
tilizers sometimes contains traces of uranium-238.
Although uranium is not readily absorbed by
plants, radioactive decay of uranium-238 gives,
among other products, radium-226, radon-222,
lead-210, and polonium-210. These elements may be
absorbed by plants, or settle as dust onto plant tis-
sue. At present, radioactivity from phosphatic
fertilizers is not a significant threat, but it may
bear watching.

Tobacco leaves are reported to contain the pecu-
lar capacity to accumulate polonium-210 at an ap-
preciable level. This level varies with location,
culture, type of tobacco, and curing methods. Polo-
nium-210 volatilizes at the temperature of tobacco
combustion, and may be inhaled into the lungs by
smokers. Thus, it has been suspected of being one
of the factors causing lung cancer that is asso-
ciated with smoking. This potential effect of polo-
nium-210 in tobacco is still a debated question.
Many scientists consider its level to be too low in
tobacco to constitute a hazard to smokers.

Radioactive contaminants in farm products may
cause economic losses to farmers. During the spring
of 1966, milk was confiscated on a dairy in Nevada
because of an unduly high level of iodine-131 in
the area as a result of accidental venting during
and following an underground weapons test.
Dairymen in central Minnesota considered using
stored feed instead of pastures during the summer
of 1962, when worldwide fallout from nuclear test-
ing reached its highest level. The estimated direct
cost of this action in one small area would have
been $9,000 a day.

Knowledge of the behavior of fallout in soils is
adequate to permit a rough prediction of amounts
of fallout radionuclides that will be taken up by
plants and to recommend remedial measures.
Keeping plant uptake at a safe level will be ex-
pensive. Recent studies indicate that the fallout
must be physically separated from plant roots.
Even for shallow-rooted crops, burying contami-
nated surface soil 25 inches deep did not prevent
significant amounts of uptake by the plants. A
physical or chemical barrier was required to be

placed between the roots and the radioactive con-
taminants. However, for plants that are directly
contaminated with fallout, factors affecting the
residence time of particles on plant surfaces are
inadequately known. This seriously hampers pre-
diction of levels of forage and milk contamination
during periods with moderate-to-heavy fallout.
The adverse effects of radioactive contaminants
on the agricultural economy at the present time are
small. But if the world should resort to use of
nuclear weapons to settle international disputes,
the degree of radioactive contamination of our
soils, water, crops, and livestock that could take
place staggers the imagination. Adequate prepara-
tions for civil defense require that all possible
techniques for counteracting the adverse effects of
nuclear fallout on agriculture be developed.

Chemical Air Pollutants

People like clean air. But public concern over
polluted air is not new. During the reign of Ed-
ward II (1307-27), England put a man to the
torture ostensibly for filling the air with a “pesti-
lential odor” from the burning of sulphurous “sea”
coal. In 1661, John Evelyn, one of the founders of
the Royal Society, published the first really sci-
entific paper on sources, effects, and problems in
control of air pollution in London. The problem
has snowballed. Technical advancement which
abets air pollution outruns that which abates it.

As shown by the city of Pittsburgh, good prog-
ress can be made in stopping the emission of
appalling levels of industrial smoke. Yet, smoke
along with carbon monoxide, sulfur oxides, hydro-
carbons, nitrogen oxides, and other gases and
vapors emanating from municipal and industrial
activity continues to increasingly burden our at-
mosphere. Some of these gases react in sunlight to
produce still other toxic constituents such as ozone
and peroxyacetylnitrate. Agriculture and forestry
are adversely affected.

Internal combustion engines used in transporta-
tion in the United States pour out 75 million tons
a year of carbon monoxide, hydrocarbons, nitrogen
oxides, and lead compounds into the air.

Central-station generation of electricity belches
16 million tons of air pollutants a year, largely
made up of sulfur oxides.

Industry contributes about 23 million tons of air
pollutants per year that involve a whole array of

20 MISCELLANEOUS PUBLICATION NO. 1065, U.S.

substances including sulfur oxides, fluorine, and
hydrocarbons.

Space heating, refuse burning, and forest fires
contribute to the mucky atmosphere by emitting
10 to 12 million tons of stuff largely appearing as
smoke.

The concentration, transportation, and disper-
sion of air pollutants from the various sources are
determined by topography and meteorological
conditions. Wind is the transporting and dispers-
ing agent. In the typical American city, the air
is three times as polluted when the wind speeds
are 6 miles per hour or less than on days when the
winds are 18 miles per hour or more. Concentra-
tion of pollutant decreases with distance from the
polluting source except as modified by topography
and temperature inversion layers. Hills or moun-
tains surrounding an area can provide a pocket
for concentrating air pollutants. Such a situation
exists in the Los Angeles Basin. Although the
western part of this basin is not blocked topo-
graphically, the prevailing winds are from the
west.

Under normal atmospheric conditions, air tem-
perature decreases with altitude. Expansion of the
air under decreasing pressure with altitude in-
volves adiabatic cooling. In the presence of an
inversion layer, temperature increases with alti-
tude. The situation is well illustrated by a diagram
presented by Wanta (737). Cool air that displaces
warm air, such as air that blows from a cool ocean
onto warm land, can cause & pronounced inversion.
Similarly, warm air may flow over a cold surface
layer, especially one trapped in a valley, and cause
an inversion.

Inversions effectively suppress vertical air
movement and cause an atmospheric stagnation
in which smoke and other volatile contaminants
cannot rise from the earth’s surface. Persistent
inversions occur in Los Angeles, New York, and
other industrial and metropolitan areas. Under
such conditions, potentially lethal layers of toxi-
eants including sulfur dioxide, carbon monoxide,
ozone, and nitrogen oxides can become stati-
cally entrapped for days. Forest trees, horticul-
tural plants, field crops, and domestic animals
living in such an area can be sorely afflicted. In
tact, vegetation damage from air contamination
has been recorded in over half of the States of

DEPARTMENT OF AGRICULTURE

the Nation and no doubt occurs to some degree in
all States.

Different air contaminants have specific effects
on agricultural crops and forest trees.

Sulfur Dioxide

One of the really classic examples of the drastic
effects of sulfur dioxide (SO.) contamination still
prevails at Copper Basin in the Ducktown-
Copperhill, Tenn., area. Over a century ago, this
basin in the southern Appalachian Mountains was
covered with hardwoods and some conifers. Min-
ing was started in the basin about 1850. Open-
hearth wood-burning furnaces were later installed
directly at the mine locations, with their greatest
activity being in the years 1890-95. Soon after
1900, the sulfur dioxide fumes combined with
timber overcutting to fire the furnaces and wild
fires had killed most of the vegetation in the basin.
Even today, some 7,000 acres to the leeward of the
smelters are nude of vegetation. Erosion has been
intense. Most all of the soil and subsoil are gone.
Another 17,000 acres surrounding the nude area
are devoid of trees and produce only broomsedge
and some plantings of kudzu. White pines 30 miles
from the smelters were injured. One cannot visit
Ducktown without standing in awe at the tre-
mendous damages that airborne sulfur dioxide
ean inflict. Most smelters have now installed ab-
sorptive equipment to prevent pouring SO, into
the atmosphere. Smelters in the Ducktown-
Copperhill area for many years have converted
the SO, into a profitable byproduct, sulfuric acid,
but the scars remain on land still highly acid.

Sulfur dioxide still threatens the vegetation
around cities. Philadelphia daily releases about
850 tons of SO, into the atmosphere. New York
City air most of the time contains SO, near the
threshold level of injury to sensitive plants. Injury
to vegetation depends on concentration in the at-
mosphere, length of exposure, and tolerance of the
species. Alfalfa, cotton, wheat, and conifers are
relatively sensitive to SO., whereas potatoes, corn,
and maples are more tolerant. If the SO, content of
air is 0.8 to 0.5 part per million for several days,
sensitive vegetation will be injured. The threshold
value for alfalfa is one hour’s exposure to 1.0
p-p.m. of SO».

Since industry and metropelitan areas in the
United States are pouring 30 million tons of sulfur
oxides into the atmosphere each year, appreciable

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 21

SO, injury to forest trees, horticultural plantings,
and field crops can be expected.

Fluoride

Airborne fluorides have become a serious toxi-
cant to vegetation and animals over the last few
decades. The industries mainly responsible are
aluminum reduction, smelting of iron and nonfer-
rous metals, ceramics, and phosphate fertilizer
manufacture. Some manufacturers have been mak-
ing good progress over the last decade in installing
equipment to curb fluoride effluent.

Fluorides appear to act as cumulative poisons
to the plant. In 150 hours, corn foliage will con-
centrate 0.005 p.p.m. of atmospheric hydrogen
fluoride to 178 p.p.m. dry weight of plant. Gladio-
lus, prunes, peaches, and grapes are also sensitive
to this low level of hydrogen fluoride. More than
500 p.p.m. of fluoride can be concentrated in foli-
age during a single season from an atmospheric
iluoride level of 0.5 part per billion. Fluoride in-
jury on ponderosa pines has been detected 20 miles
from an aluminum smelting plant.

Most agricultural soils contain 100 to 150 p.p.m.
of fluoride, but most plants absorb very little of
this element from the soil because of the low solu-
bility of calcium fluoride (1.6 mg./100 ml. H.O) ;
that is, it is nearly as insoluble as calcium oxalate.
Consequently, when plant leaves contain more
than a few parts per million of fluoride,
atmospheric contamination with fluoride can be
suspected.

When one considers that air samples from a
heavily industrialized city such as Baltimore re-
veal 0.08 part per million of fluoride, the potential
for damage to vegetation by this air contaminant
is extant. In fact, legal claims for fluoride damage
to crops within three States—Utah, Florida, and
Idaho—totaled nearly $3 million in 1957.

Chronic fluorosis may develop in livestock from
ingestion of small amounts of fluoride over several
months or years. Eating contaminated forage
growth near industrial areas emitting fluorides will
induce fluorosis. If the animals receive mineral
mixture or water containing fluoride the effect of
the contaminated forage will be accentuated. All
kinds of livestock may be affected by accumulation
of fluoride in their systems, but cattle are most
sensitive followed by sheep, swine, horses, and
poultry. Cattle may ingest 1 to 2 milligrams of

fluorine per kilogram of body weight without
harmful effects if they are in good health.

Symptoms of fluorosis involve excessive wear-
ing of the teeth, staining, pitting of the enamel,
and exposure of the dentine. In severe cases, the leg
joints may become enlarged and the shaft of the
long bones may thicken.

In past years, numerous dairy herds in central
Utah have shown extensive symptoms of fluorosis.

Peroxyacetylnitrate and Ozone

Peroxyacetylnitrate (PAN) and ozone are the
two most important plant toxicants that are pro-
duced in smog that has been activated by light en-
ergy. There are many sources of compounds that
will react in the presence of sunlight to produce
PAN and ozone, but the automobile exhaust ap-
pears to be the worst offender.

PAN is extremely toxic to citrus, forage, salad
crops, ornamentals, and coniferous trees. Acute
leaf damage by PAN to sensitive species has been
observed at 0.005 p.p.m. in the air. PAN tends to
produce injury symptoms on the lower surface
of leaves, whereas ozone primarily affects the up-
per surface. PAN may also seriously retard
growth and stimulate leaf abscission. Crops of
romaine lettuce have been so badly damaged by
PAN as to be unsalable. Cigar-wrapper tobacco
grown beneath cloth shade, as in the Connecticut
Valley and Florida, has been seriously damaged
by “weather fleck” caused by ozone injury. Sensi-
tive plant species such as tomato, tobacco, radish,
and white pine may be damaged after exposure to
0.06 p.p.m. ozone for 3 to 4 hours.

Annual losses to crops in California from dam-
age caused by photochemical smog have been es-
timated at millions of dollars; the estimates also
show that these losses have been rising rapidly.
Damage of this type has been observed in 27 States
and the District of Columbia. For example, east-
ern white pine has been killed, discolored, or
stunted by photochemical smog in Tennessee and
Pennsylvania.

Oxides of Nitrogen

Nitrogen oxides are produced by high tempera-
ture combustion; thus they may be emitted by any
fuel combustion source. Nitrogen dioxide is more
injurious to living cells than nitric oxide and
causes irregular blotches of collapsed tissue near

22 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

the edges of the leaves. Pinto beans and tomatoes
will show reduced growth and leaf distortion when
exposed to 0.5 p.p.m. of nitrogen dioxide for 10
to 22 days. Most of the time, concentration of ni-
trogen dioxide in the atmosphere near sources of
effluent are below 0.3 p.p.m.

Ethylene

Cotton plants growing downwind from indus-
trial establishments making polyethylene were
found to be seriously damaged by ethylene con-
taminated air. Air samples revealed 0.04 to 3 p.p.m.
ethylene. Ethylene in the atmosphere has caused
considerable loss to orchid growers in California.
Exposure for 6 hours at 0.05 p.p.m. will cause sepal
damage to Cattleya orchids. Carnation flowers
often fail to open after a 6-hour exposure to 0.1
p-p-m. ethylene.

Lead Compounds

In the middle twenties, tetra-ethyl lead began
to be added to gasoline, enabling use of engines
with higher compression and higher efficiency
in energy conversion. Since that time, millions
of pounds of lead have been poured into the
atmosphere from motor vehicle exhausts. Most
of this was eventually deposited on soil and plants.
In Los Angeles, the average air concentration is
2.5 micrograms of lead per cubic meter of air.

Pasture grasses collected at the intersection
of two U.S. highways near Denver contained
3,000 p.p.m. lead, while grasses collected next to
a less-traveled roadway contained 700 p.p.m.
Grasses collected 50 to 100 feet away from the
latter road contained 5 to 50 p.p.m. of lead. When
the lead from auto exhausts is fortified by airborne
particulate lead from certain smelters, the lead
content of forage may become a hazard to the
health of livestock. Although there is little
evidence of iead poisoning to livestock from
combustion products up to the present time,
numerous authorities believe the situation is be-
coming critical.

Summary

Judging from past trends, the adverse effects of
air pollutants on agriculture, ornamentals, and for-
ests are going to become worse before they get bet-
ter. Recent evidence was obtained showing a syn-
ergistic (more than additive) action of low concen-
trations of ozone and sulfur dioxide. The mixed
gases caused plant injury, whereas there was no

damage from the same concentration of individual
gases. As several toxicants are usually present in
polluted air, we must be concerned about the addi-
tive effect of the various toxicants on vegetation.

Middleton (82) stated in 1964:

The industrialization of California has resulted in
an increase in air pollution which has, in turn,
caused extensive and serious damage to vegeta-
tion. About 14,000 square miles in California are
now known to be affected by oxidants, ozone. and
ethylene, which are typically emitted from com-
bustion processes and motor vehicles, and by fluo-
ride and sulfur dioxide which are typically
emitted from industrial sources.

Crop losses from air contaminants are exhibited
by suppression of yield, delay of maturity, and
reduction in quality. As the flood of these noxious
chemicals continues to pour forth into the atmos-
phere, and as capability in diagnosing their dam-
ages to plants and animals increases, we can expect
estimates of annual damages by air pollutants to
crops, ornamentals, forests, and livestock to soar.

Airborne Dusts

“May the gusty wind that blows the ladies’
skirts knee-high, also blow dust in the naughty
man’s eye.” Although this ditty penned by a
woman many years ago involves extreme bias, it
probably represents the only case wherein a benefit
was attributed to airborne dusts in day-to-day
living.

Dusts in the atmosphere derive from natural
dune-lands; inadequately protected farm and
rangelands; highway and industrial construction
sites; certain mining operations, such as strip
mines; mineral processing operations, such as
cement plants; fly ash from smelters; dust from
cotton gins, feed mills, and feed lots; and volcanic
action.

Photographs of farmsteads in the Great Plains
half buried in windblown soil as a result of the
duststorms of the thirties are stark reminders that
agriculture and agricultural people may suffer
grievously from airborne dusts. In addition to the
mess incurred on the afflicted farmsteads, the air-
borne dust threatened the health of people and
livestock, damaged buildings and machinery,
filled ditches and waterways, buried fences, dam-
aged or destroyed crops, and removed topsoil from
millions of acres of land. Finnell (36) reported
that 6,541,000 acres of land were put out of cultiva-

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 23

tion in the thirties by duststorms. In 1947, Finnell
(37) made a survey of wheat production in the
heart of the old Dust Bow] to appraise the effects
of the storms of the thirties on soil productivity.
Land severely eroded by the earlier duststorms
showed about 40 percent lower production as meas-
ured by wheat yields. During each of the drought
years of 1954-57 on the southern Great Plains, the
annual damages from windblown soil were about
as great as those during the thirties (87).

Airborne soil is indeed a resource out of place.
Windblown soil particles such as fine sand can
completely destroy a stand of seedling or young
plants by an action that is essentially sandblast-
ing. This damage frequently occurs on young
erops in the Atlantic Coastal Plain from the Con-
necticut Valley to Florida. Allen (S) reports that
in Hoke County, N.C., dust blowing caused re-
planting of 2,500 acres of cotton, 1,000 acres of
corn, and 100 acres of tobacco in 1955. Serious
damage to seedlings by sandblasting has aiso been
reported in Wisconsin, Illinois, Indiana, and
Arkansas.

Dust blowing hurts livestock. An extension serv-
ice forester made a survey of the benefits of farm
windbreaks in abating soil blowing on 200 Ne-
braska farms. Livestock feeders indicated annual
savings of $800, livestock breeders reported an an-
nual savings of $500, and dairymen estimated
their savings at $600 a year.

Dust from soil blowing or volcanic action that
settles on plants and coats the leaves has the same
stunting effect as the dust and soot from indus-
trial flues, cement plants, and lime kilns. Coating
of leaves impairs use of available sunlight in
photosynthesis and obstructs the leaf stomata that
permits gas exchange between the leaves and the
surrounding atmosphere. Hence, growth processes
are retarded. Dust accumulating on greenhouses
euts down available hght intensity and thereby
weakens the crop plants grown therein, This is
particularly serious in the wintertime.

When these airborne dusts accumulate on leafy
vegetables such as lettuce and celery, the quality
of the crop may be seriously damaged. Small fruits
and ornamentals may be harmed by dust accumu-
lations.

Dusts may carry pesticides. If 2 herbicide were
so carried, damage could oceur on crops miles
away from the area of application. Insecticides

could be carried into farm ponds and tributary
streams used by farmers or used for recreation in
forested areas.

Information that would enable a quantitative
appraisal of the adverse effects of airborne dusts
on agriculture and forestry is seriously lacking.
One can rest assured that the farmer who has ex-
perienced the duststorms of the Great Plains, ov
who has seen his young crops along the Atlantic
coast sandblasted, or who has tried to grow fruit
on the leeward side of a cement plant prolific in
its eolian effluent does not need voluble arguments
to be persuaded that the adverse effects of air-
borne dusts on agriculture are serious indeed.

Sediment

Many of us are so accustomed to seeing muddy
water in our streams, ponds, and reservoirs that
we come to look upon the situation as somewhat
like taxes—it is just part of our way of life.

Sediment is the perfect example of the defini-
tion of a waste as being a resource out of place.
Sediment has a bilateral effect. It depletes the land
resources from which it is delivered and impairs
the quality of the water resources in which it is
entrained and deposited.

Sediment carried by streams has been both a
benefit and a curse to agriculture for over 5,900
years. Sediment deposited from the annual over-
flow of the Nile River during the reigns of the
Pharaohs and their followers added a modicum of
fertility for the agriculture of that valley in
ancient Egypt. The relatively efficient crop pro-
duction so made possible enabled the release of
large forces of labor to build the massive strue-
tures of masonry that are now prime tourist
attractions.

Sediment brought down the Tigris and Eu-
phrates Rivers, following wars and destruction of
water control works, led to the eventual disappear-
ance of the fabulous civilization of ancient Su-
meria. The sediment was deposited in, and even-
tually destroyed, the brilliantly engineered canal
system built by the Sumerians in the fifth to third
millenia B.C., to provide an irrigation agriculture
that supported an astounding construction of mag-
nificent buildings in prosperous cities. Some his-
torians have indicated that the high level of civil-
ization in ancient Mesopotamia was destroyed by

| 24 MISCELLANEOUS PUBLICATION NO. 10635, U.S.

the vicious raids of Mongols led by Hulagu Khan
in A.D. 1258. But recent evidence indicates that
Hulagu and his horsemen found nothing but deso-
lation when they invaded the region. Archeologists
Jacobsen and Adams (60) found that by the 12th
century the natural phenomena delivering sedi-
ment into the irrigation waters had caused far
greater devastation to the irrigated land, and thus
to the food supply of the cities, than any invading
hordes could have inflicted.

These bits of history leave no doubt that sedi-
ment in water can adversely affect agriculture.

The sediment burden in streams may come from
many different sources through the erosion proc-
ess. It arises from forested lands that have been
devastated by fire, construction of forest roads and
other forest improvements, certain logging prac-
tices, overgrazing and trailing of animals on
rangelands, cultivated lands that are inadequately
protected, industrial construction sites, highway
construction, unprotected roadside cuts, suburban
development projects, spoil banks from strip min-
ing and other mining activities, unstabilized
stream banks, and geologic erosion of such areas
as the Badlands of South Dakota. The land is
robbed and the water despoiled.

The material is entrained by water in motion,
transported by moving water, and deposited by
relatively quiet or still waters.

Aside from filling stream channels, irrigation
canals, farm ponds, and reservoirs used for irri-
gation, recreation, fishing, and farmstead water
use, sediment in water increases the expense of
clarification of the water used on the farmstead or
in sprinkler irrigation systems. Suspended sedi-
ment impairs the dissolved oxygen balance in water
and thereby slows amelioration of other oxygen-
demanding wastes. Reduced oxygen supply hurts
fish life. Fish population is also reduced by the
sediment blanketing fish nests, spawn, and food
supplies. The thousands of farmers using farm
ponds to sell fishing rights are much concerned
with the deterioration of water quality by sedi-
ment burden.

Recreational interest in water in the ponds of
farms and ranches varies inversely with muddiness
of the water.

The useful life of many farm ponds is surpris-
ingly short because of sediment accumulation.
Surveys on 30 farm ponds in the Iowa and Mis-

DEPARTMENT OF AGRICULTURE

sourl Deep Loess Hills land resource area showed
that, on an average, they would be completely
filled with sediment in 20 years. However, the
ponds will have been rendered essentially useless,
and many will have become a nuisance, long before
their original water storage capacities have been
replaced by sediment.

The adverse effect of waterborne sediment upon
agriculture is by no means limited to losses asso-
ciated with recreational use of farm and ranch
ponds. Damage to agricultural land resources
from overwash of infertile materials, impairment
of natural drainage, and swamping and increased
flooding because of sediment accumulations in
stream channels are also aspects of the silt problem
having a direct bearing on farmers and ranchers.
Irrigation canals and waste water disposal ditches
are also subject to costly maintenance because of
silt deposited from muddy water.

Ford (43) estimated that sediment damages in
upstream watersheds come to about $87 million
annually. The damages from this particular re-
source waste are over and above those caused by
gully erosion, flood plain scour, and streambank
erosion and by impairment of water quality from
sediment in farm ponds and farm water supplies.

In the nearly 4 billion tons of sediment that are
delivered to our waterways each year, the equiva-
lent of 4 million acres of topsoil are transported.
We can validly assume that at least 75 percent of
this mass is derived from agricultural and forested
lands and that it will have an average analysis of
0.10 percent nitrogen, 0.15 percent P.O;, and 1.50
percent K,O. This means that more than 50 million
tons of primary nutrients are lost from our agri-
cultural and forested lands each year through
sediment delivery.

The adverse effects of sediment in streams on
agriculture and forestry is indeed a Texas-size
problem.

Plant Nutrients

Plant nutrients in the soil are a must for food on
the table. Volumes of benign words have been
written on the essentiality of fertile soils to meet
one of the basic needs of mankind. But when these
nutrients become resources out of place in ground
water and surface water, they are serious pollut-
ants. There are about 150 species of algae and other
aquatic plants that grow in farm ponds, woodland

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 25

lakes, canals, and tributary streams. Aquatic
plants must have mineral nutrients to flourish; and
flourish they will if the plant food is there. Lack of
phosphorus appears to be the main limiting factor
in the growth of these plants in most waters, but
nitrogen is also required.

These nutrients may enter surface waters by
way of runoff from fertilized fields; runoff from
barnyards and feedlots; municipal and rural sew-
age; sanitary facilities in recreation areas; and
industrial wastes.

Accumulations of water-loving plants on farm
ponds and similar surface waters impair use of the
water for recreation. Such plants may reduce fish
production and harvesting, impede boating and
swimming, and provide a good habitat for mos-
quitoes and snakes. When these plants die, they
become a pollutant with high oxygen demand while
deteriorating. In turn, this deterioration evolves
offensive odors, bad tastes, and seriously impairs
fish life.

As of June 30, 1965, the Department of Agricul-
ture had given technical or cost-sharing assistance,
or both, in constructing 1,420,733 farm ponds. Un-
wanted growth of water plants now limits the use-
fulness of an appreciable number of these ponds.

Canals and ditches used for irrigation and drain-
age may have their usefulness seriously impaired
by becoming clogged with growths of aquatic
weeds. Measurements have shown that ditch ca-
pacity may be reduced to one-third or one-fourth
and the reduced capacity may contribute to flood-
ing. The control of aquatic weeds in irrigation
ditches is a major item in the maintenance costs
to irrigation and drainage districts.

As of June 30, 1965, the Department of Agricul-
ture had provided technical or cost-sharing assist-
ance, or both, in establishing 37,179 miles of irriga-
tion canals and laterals, as well as 279,256 miles of
drainage mains and laterals. These figures do not
reflect the total installation of these waterways,
since the Bureau of Reclamation, State agencies,
and private concerns were also involved in ditch
construction and maintenance.

Agriculture and forestry are indeed adversely
affected when plant nutrients become wastes in
surface waters and thereby permit aquatic weeds
to luxuriate.

Concern is mounting over the presence of nitrate
and small amounts of nitrite in ground water in

many parts of the country because of the toxic
effects on livestock and rural people using wells for
drinking water.

The sources of nitrate and nitrite in ground wa-
ter are usually considered to be (a) naturally oc-
curring accumulations, (6) nitrogen fertilization,
(c) sewage, (d) corrals, and (e) industry.

Farmers must be concerned with the nitrate con-
tent of the water in their wells. Nitrate poisoning
can affect both cattle and infants. In ruminants,
such as cattle, micro-organisms in the rumen re-
duce the nitrate to nitrite. Nitrite converts the
hemoglobin in red blood cells to methemoglobin,
which cannot transport needed oxygen from the
lungs to body tissues. Thus, nitrate poison shows
the general symptoms of oxygen deficiency. Since
swine are not ruminants, they are much less sus-
ceptible to nitrate poisoning than cattle are. An
example of damage to agriculture by an industry
was recently reported in the West where a fer-
tilizer plant was put in operation slightly up-
stream from a large cattle and sheep enterprise.
Shortly thereafter, this livestock enterprise expe-
rienced abortions of 3,100 ewes and 300 cows.
Losses in lamb and calf drops from nitrate in
water or feed have long been recognized as serious.

In infants, particularly those under 6 months of
age, the pH of the stomach tends to be above 4,
permitting growth of organisms that reduce ni-
trate to nitrite. Here again, in such infants the
hemoglobin is also converted to methemoglobin,
causing an affliction known as “blue baby.” The
incidence of blue babies is largely on farms de-
pending on well water for drinking.

From 1947 to 1950, 139 cases of infant methemo-
globinemia (blue baby), including 14 deaths, from
nitrate in farm wellwater supplies were reported
in Minnesota alone. Adults drinking the same
water are not affected, but breast-fed infants of
mothers drinking such water may be poisoned. It
has been reported that cows drinking water con-
taining nitrate may produce milk sufficiently high
in nitrate to result in infant poisoning.

There are no reports of methemoglobinemia in
infants fed water from public water supplies in
the United States, although levels in nitrate in
some may be in excess of 45 mg./liter. Thus, the
evidence shows that farm people are the ones who
are adversely affected by nitrate in water supplies.

26 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

Inorganic Salts and Minerals

Farmers in the Imperial Valley of California
know about salt. This very productive valley is
entirely dependent on Colorado River water for
survival as an economic entity. About 3 million
acre-feet of Colorado River water is brought into
this valley each year through the All-American
Canal. Colorado River water at Imperial Dam
contains about 750 p.p.m. dissolved salts—a rather
moderate level. But this concentration means ap-
proximately 1.2 tons of salt per acre-foot of water.
An irrigator applying 5 feet of water over the
season, also applies 6 tons of salt per acre.

Since evapotranspiration consumes water and
leaves the salt behind in the soil, extra water over
and above consumptive use must be added to leach
the salt residue below the root zone, to avoid ex-
cessive salt accumulation. The saltier the available
water supply, the more water will be required for
leaching. Since the valley receives over 3 million
tons of salt in the irrigation water each year, 3
million tons of salt must be removed annually from
the irrigated soils into the elaborate drainage
system in order to maintain a favorable salt bal-
ance. Fields that are improperly managed with re-
spect to leaching and drainage produce only one
crop—‘Imperial Valley snow’—a white crust of
sodium sulfate. When this happens, agriculture is
not only hurt, it is virtually eliminated. Adverse
effects on production take place at even modest
levels of salinization because of stunted crop
growth.

Inorganic salts and minerals that impair the
quality of soils and waters derive from natural
deposits, acid mine drainage, industrial proc-
esses, and return flow from irrigated areas. The
main losses to agriculture occur through salt ac-
cumulation on irrigated soils with its consequent
effect on crop production.

There are about 30 million acres of irrigated
land in the 17 Western States. Salinity is a poten-
tial hazard on about half of this acreage, and crop
production has been affected adversely by salt in
the soil on about 8 million acres.

Rainfall generally contains negligible quanti-
ties of salt, but as the water flows over and through
the land, its salt content increases. Salts are formed
in the soil by solubilization of soil minerals, or
they may be present in geologic deposits such as

saline shales. In arid climates, soils may contain
appreciable quantities of salts because rainfall and
drainage are often inadequate to leach out the salt.
Thus, surface and ground waters in arid regions
may contain moderate, and even high, concentra-
tions of salt as a result of normal or natural proc-
esses. When such natural waters are used by man,
the salt content may be increased by the addition
of salts not originally present in the water. Thus,
metropolitan and industrial wastes can increase
the salt burden of the water system. Such salt
additions are usually minor in importance, al-
though in certain cases, such as in the contamina-
tion of surface and ground waters by brines from
oil well fields, the additions can be critical to the
further use of the water for agriculture.

The salt concentration of the water system may
also be increased by evaporation of the water. In-
dustrial and municipal use of water contributes
relatively little to this effect, since only about 7
percent of water diverted for these uses is evapo-
rated. Agricultural use, on the other hand, results
in evaporation of 60 percent of the diverted water.
Thus, agricultural use tends to concentrate the
salt in the water, whereas industrial and municipal
use largely adds exogenous salts.

In addition to total salt content, the salt com-
ponents may be altered by the use of the water.
For municipal and some industrial uses (boiler
water), it is necessary to soften the incoming water
supply by replacing calcium and magnesium with
sodium. The effluent water will, therefore, be en-
riched in sodium at the expense of calcium and
magnesium, and its quality for agricultural use
thereby impaired. Reclamation of sodic soils effects
similar changes in the quality of the water used
in leaching, although total salt content as well as
the proportion of sodium may be greatly increased
in the efiluent.

Initial use of water for irrigation also results
in changes in composition, as well as concentration,
of dissolved salts. Some precipitation of lime and
calcium sulfate may occur as the volume of the
water is reduced by evaporation, whereas the more
soluble sodium salts do not precipitate. The effluent
water, therefore, is often relatively more en-
riched in sodium chloride than in the sulfates
or bicarbonates of calcium. Both increasing salt
concentration and altered ionic compositions of

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 20

once-used waters have great significance in their
reuse potential for agriculture.

Although all crops tend to exhibit decreased
growth and yield with increasing salinity of the
water supply, the differential salt tolerance of
crops and the specific sensitivity of some crops to
some ions make a single-scale set of values for
irrigation water quality quite unrealistic. Soil,
climatic, and management factors also influence
how damaging an increase in salinity of the irri-
gation water supply will be. When all conditions
are favorable, an increase in total salt content of
the water supply from a few hundred parts per
million to even a few thousand parts per million
may not affect agriculture adversely. Under less
favorable conditions, such an increase of salinity
may render the water totally unfit for further use.

A high proportion of sodium in the irrigation
water supply will affect soils and plants adversely
because sodium causes soil aggregates to disperse
and renders soil highly impermeable. Thus, water
softened for metropolitan use is usually unsatis-
factory for irrigation. The sodium may also be
directly toxic to woody plants (fruit crops) at
levels well below those that cause deterioration of
soil properties.

Other specific salts or ions may be highly in-
jurious to plants. Boron, although essential for
plant growth in concentrations of a fraction of a
part per million, rapidly becomes toxic as concen-
trations in the water increase above 1 part per
million. Municipal use and some industrial proc-
esses involving borax or other boron compounds
may add enough boron to the water to preclude
its further use for agriculture or for supporting
growth of native or ornamental plants.

It has been estimated that about 25 percent of
the irrigated lands of the United States are now
affected to some degree by salinity. As available
water resources are used more intensively, the
incidence of salinity problems will increase because
saline return flows usually mix with the river or
ground water supplies, thereby salinizing the water
available for further use.

The use of salt on highways to melt snow and
ice from winter storms is creating very serious
problems to rural areas in many States. Salt run-
ning off the highways has killed trees and shrub-
beries along the frontage of farmsteads. Worse yet,
the salt has penetrated into the ground water, and

rural wells have been condemned because the water
was polluted with excessive levels of chloride.

Salinity from return flow in the lower Colorado
River has caused an international problem with
Mexico. This was solved by building a bypass con-
erete-lined conveyance which returns the drainage
water to the Colorado River below the point at
which Mexico diverts its water for irrigation.

Agricultural and forestry endeavors using trib-
utary streams for recreational benefits are con-
cerned with acid mine drainage. In Pennsylvania
alone, about 2,000 miles of streams are ruined by
acid mine drainage. The acidity of mine drainage
is usually due to the oxidation of iron pyrites to
ferrous sulfate and sulfuric acid. Estimates of the
amount of sulfuric acid reaching streams in the
United States run into about 3 million tons an-
nually. At present there is no satisfactory way of
reducing this acid load. The problem is serious in
the coal mining areas of the Ohio River Basin,
but the adverse effects on agriculture and forestry
are minor in relation to the effects of other wastes.

Organic Wastes

Sir Albert Howard (56) had an answer for the
problem of coping with vast accumulations of
vegetable, animal, and human wastes: Make
humus out of the stuff by his Indore Process. The
humus so produced would benefit many soils. For
the product to have economic feasibility, someone
would have to provide large masses of very cheap
labor for all the collection, piling, stirring, repil-
ing, and distribution activities.

We lack economical procedures for effectively
handling all the mountainous quantities of putres-
cible organic substances coming from domestic
sewage, garbage, food processing industries, lum-
bering operations, pulp mills, crop residues, and
animal and poultry enterprises. This group of
wastes is rather readily attacked by aerobic bac-
teria to reduce them to more stable compounds.
Thus, when these wastes are dispersed in water,
the oxygen content of the water may be seriously
or completely depleted by the action of decompo-
sition processes. When the oxygen in the water is
reduced to zero by the demands of aerobic decom-
position, a different type of bacterial action oc-
curs—nonoxygen-demanding, or anaerobic, bac-
teria take over the processes of reducing these

28 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

organic wastes to inert materials. This latter situ-
ation produces what is called a septic condition,
and the water takes on the dark-colored, evil-
appearing, vile-smelling character of grossly pol-
luted water.

Agricultural and forestry activities involving
use of water for fishing or recreation cannot tol-
erate waters having organic wastes that have not
been fully assimilated by action of aerobic bac-
teria. Since recreational use of water in association
with agriculture and forestry has become an ac-
tivity involving expenditures of hundreds of
millions of dollars, water polluted from anaerobic
decompositions of organic wastes may have seri-
ous economic consequences on such activities.

Water that is polluted in any way or shows the
effects of additions of organic wastes that have
not been fully assimilated by aerobic decompo-
sition cannot be used on the farmstead. Agricul-
ture faces serious limitations on use of water for
irrigation on crops used for food, if that water is
polluted with unassimilated wastes.

Accumulations of putrescible wastes may hurt
agriculture in other ways than by entering into
water supplies. Manure heaps, piles of crop resi-
dues, and accumulations of food-processing wastes
usually emit pungent aromas that are offensive.
Along with the stench, piles of animal wastes can
be tremendous spawning grounds for flies and
other vermin that pester livestock as well as
people. Large sums are spent each year on insecti-
cides to control pest production around manure
piles.

As suburban people move into agricultural
areas, they protest against accumulations that give
off foul odors. When the protests are legally sus-
tained, agricultural people may have to pay a high
price to meet imposed restrictions.

Within the last 6 years, 43 California dairy
farms having a total of about 12,000 cows have
had to relocate from the Los Angeles area to the
Bakersfield area, a distance of about 80 to 100
miles, because of their “noncompatibility” with
activities of the expanding Los Angeles metro-
politan area. Provision of new facilities for these
dairies averaged about $112,000 each, of which
$35,000 to $42,000 was for constructing milking
facilities. The total relocation cost within this one
county for the milking facility portion of these
enterprises alone is over $1.6 million. Such reloca-

tions have occurred in several other areas and
States and the problem will probably increase.
These relocations apply to all classes of livestock.
The costs to agriculture are high.

Lawsuits are pending in Milford, Tex., pertain-
ing to a 27,000-head beef cattle feedlot located
well out in the country. The owners had purchased
land to provide what they thought to be an ade-
quate buffer zone between themselves and the other
rural residents. The feedlot operators recently had
11 damage suits, averaging about $15,000 each,
filed against them. Four have been settled, with
the court allowing claims ranging from $2,500 to
$7,500. One claim, for death of cattle, was denied
primarily because the claimant had failed to have
a veterinarian determine the cause of death of
cattle downstream from the feedlot. The other
claims are still in litigation. Odor nuisance, dust,
insects, water pollution, and noise are among the
grievances alleged.

Coping with manure accumulations can cost
money. Farmers are suffering from damage suits
and are having to make costly changes.

In Sullivan County, N.Y., poultry and tourist
industries have conflicting interests. In one in-
stance, the State supreme court issued a temporary
injunction against a large poultry producer re-
straining him from allowing noxious odors to per-
meate the air of two adjoining resorts pending the
outcome of a $125,000 lawsuit against the producer.
The injunction was issued in spite of the fact
that the poultry industry represents a large part of
the county’s income. These poultrymen have re-
ceived a rough blow. Other damage actions have
been filed, but it may take years for courts to de-
cide and the decision will not solve the problem.

Removal from animal quarters, transport, and,
where feasible, spreading of animal waste on land
represent a significant item in the cost of produc-
tion. A 1961 Michigan study indicated that beef
feedlot operators spend $3.48 per head marketed
and dairymen $9.29 per head for waste removal
and spreading. An Illinois study indicated that
annual operating costs were $0.62 to $1.28 per hog.
A million-bird laying operation in Mississippi es-
timates the annual waste handling costs at $100,-
000, or $0.10 per bird. A Maryland egg farm with
automated cage operations spends about $0.12 per
dozen of eggs. Other operators of egg farms have
reported costs more than double this amount. East-

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 29

ern Shore (Delmarva) broiler producers are pay-
ing about $9 per 1,000 birds ($0.09 per bird) to
contract removal companies for each cleaning,
which may be as frequent as four times a year.

These studies emphasize that in earlier times
manure was highly prized as a source of soil fertil-
ity, whereas now it has become a costly burden to
many livestock operators. Furthermore, costs in
the future probably will rise as better pollution
abatement procedures become mandatory. These
procedures will not increase either the quality of
the product produced or the efficiency of produc-
tion. The economic value of manure as a fertilizer
or a gas does not compensate for the processing
required to modify the manure. Hence, manure
disposal systems can only add to the cost of pro-
duction.

The adverse effects of accumulations of putres-
cible wastes on agriculture and forestry are grow-
ing to major proportions. Surface waters asso-
ciated with the farm, the ranch, or the forest are
a great source of potential revenue for fishing and
recreation if they can be kept free of oxygen-de-
manding wastes. On the other hand, the financial
burden to farmers for coping with wastes that are
offensive is becoming tremendous.

Infectious Agents and Allergens

Man’s hard march down through the ages is
largely a record of calamities induced by three
grave adversities: Famine, pestilence, and war.
One can argue that the ravages of pestilence kept
famine from being more extensive than that re-
corded. However, an infectious agent attacking a
food crop caused one of the most serious famines
in history. Late blight of potatoes almost totally
destroyed this main food crop in Ireland in the
middle 1840’s. Records indicate that the physical
misery and spiritual anguish because of the famine
caused by this one crop disease go far beyond any-
thing that ordinary experience equips one to
understand. The farmers suffered along with
everyone else.

Phytopathogens

The infectious agents of bacterial and fungus
diseases of field crops, fruits, and forest trees are
almost entirely carried by wind, water, or soil.
Many of the most serious virus diseases of plants
are carried by insects, and such insects cannot be

ignored in evaluating the effects of infectious
agents on environmental quality. The destructive-
ness of these plant diseases merits a few illustra-
tions.

In the 50 years or so since chestnut blight was
first discovered in this country, this disease has
killed virtually all of the American chestnuts, one
of our finest hardwoods, in its native range.

Fifty years ago, white pine blister rust was mak-
ing extensive ravages in one of our finest conifers.
Our white pines would have been doomed within
a few years except that the fungus had to be trans-
mitted back and forth under proper aerial environ-
ment with the alternate hosts, currants and goose-
berries. An extensive campaign of eliminating
these alternate hosts saved our white pines.

A wheat stem rust epidemic destroyed almost
300 million bushels of wheat in the United States
and Canada in 1916.

In the epidemic year of 1935, stem rust caused a
60-percent loss to the wheat crop in Minnesota and
some of the neighboring States, and the loss for the
whole country was almost a quarter of the crop.

As recently as the 1950’s, losses to the Nation’s
wheat crops from the highly destructive stem rust
race, 15B, were estimated at over 8.5 million
bushels annually in 1953 and 1954. A large part of
the spring wheat crop was virtually eliminated in
those years.

In 1946, airborne spores of the late blight dis-
ease of tomatoes caused an estimated reduction of
50 percent of the national tomato crop.

Thirty to forty years ago, Granville wilt of to-
bacco was taking 20 to 50 percent of that crop in
Granville County, N.C. The physical and mental
sufferings of the farmers because of economic
losses incurred by this bacterial disease were
enormous.

Crop diseases may be spread by agricultural
machines that move contaminated soil on wheels
or carry disease organisms on the blades of
mowers. Thus, diseases are spread most rapidly in
the direction of cultivation. Contact of plants
often is necessary in the spread of disease fungi
which produce no spores but spread by slow my-
celial growth from one plant to the next. Texas
root rot and Rhizoctonia root rot exemplify such
cases.

In picking beans when the vines are wet, the
hands distribute the bacteria of bean blight so

30 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

effectively that the greater part of the crop may
be lost.

Handling of tobacco or tomato plants in trans-
planting, pruning, and staking may be followed
by 100-percent infestation of tobacco mosaic.

Weed Seeds

Farmers’ fields can be infested by weed seeds
that are transmitted by wind, soil, birds, and
animals. In a sense, these seeds become infectious
agents, since weed pests can be just as harmful
to a crop as insects or diseases. Wind is the natural
disseminator of many weed seeds to millions of
acres of cropland. Use of irrigation water con-
taminated with weed seed reinfests thousands of
acres of irrigated land each year. Spreading ma-
nure, especially that with an abundance of bedding,
spreads weed seeds.

Witchweed, a parasitic plant, produces thou-
sands of microscopic seeds that are easily dissemi-
nated by wind, water, or soil. The spread of these
seeds increases the cost of quarantine and eradica-
tion programs.

Seeds of many weed species are poisonous to
livestock, birds, and wildlife. A number of
Crotalaria species have poisonous seeds (7/4).

These natural mechanisms of weed seed dissemi-
nation provide for continual replenishments of
these weeds in soils. Some degree of weed control
is needed on 365 million acres of cropland each
year. Weed and brush control are urgently needed
on several hundred million acres of rangeland.

Farmers spend about $214 billion annually to
control weeds. Yet during the period 1951-60, the
estimated annual loss due to reduced crop yields
and quality caused by weeds varied from 3 to 25
percent, depending on the crop.

The winds that transport infectious agents to
soil, water, crops, and trees can be just as devas-
tating in terms of financial loss and human suffer-
ing as the waters that transmit scarlet fever.

Nematodes

Nematodes move from one infested area to the
next on plants and soil and in water. Irrigation
water is suspected to be a principal means of dis-
tributing nematodes affecting alfalfa in the North-
west. Direct examination and bioassay of irriga-
tion water from a farm pond in south Georgia
indicated several species of plant-parasitic nema-
todes can be spread by irrigation water.

Animal Disease Agents

Agricultural losses caused by infectious agents
of livestock and poultry carried by air, water, and
soil have also been great. Some of the animal
diseases that may be so transmitted are leptospiro-
sis, salmonellosis, hog cholera, mastitis, foot and
mouth disease, tuberculosis, brucellosis, histoplas-
mosis, ornithosis, infectious bronchitis, Newcastle
disease, anthrax, blackleg, foot rot, coccidiosis,
blackhead of turkeys, erysipelas, and transmissible
gastroenteritis.

Hog cholera was first noted in this country in
the 1880’s, but it spread rapidly. The virus causing
the disease may be picked up from polluted water,
polluted soil, or polluted feed. Over the years, the
ravages of this disease have caused losses of hun-
dreds of millions of dollars to hog farmers.

Brucellosis of cattle, swine, and goats can be
spread by water, feed, or soil polluted with the
causal bacteria.

In the summer of 1966, approximately 130 clini-
cal cases of encephalitis in horses were reported in
southern Louisiana. Mosquitoes developing in the
waste waters of marshlands carried the infectious
agent. This example well illustrates how stagnant
water may provide the vectors for a serious infec-
tion afflicting agricultural endeavor.

Costs

Infectious agents transported by the en-
vironment are causing heavy annual losses to agri-
culture and forestry. In fact, each crop and do-
mestic animal grown on a large scale in the United
States is susceptible to one or more highly infec-
tious diseases that may be transported by air, water,
or soil.

During the 1950’s, estimates of losses in potential
production of domestic food animals because of
diseases ranged from an average of 3 to 28 percent
annually. During 1966, there were over 100 mil-
lion cattle on U.S. farms valued at more than $14
billion. The value of all meat animals exceeded $17
billion. Thus, losses on the order of 10 percent are
staggering. The infectious agents of most all of
these diseases were carried in wind, water, or soil.

Estimat:s of losses in production potential
owing to diseases of pasture and range plants
varied from 3 to 9 percent for the same period.
Comparable figures for fruit and nut crops and
for vegetables are 2 to 38 percent and 2 to 23 per-
cent, respectively.

|

WASTES IN RELATION TO AGRICULTURE AND FORESTRY ol

In 1965, losses from forest diseases amounted to
1.2 billion board feet; equal losses were suffered
from forest insects (124, p. 101). This would have
been enough lumber to build 100,000 five-room
frame houses.

Agricultural and Industrial Chemicals

In 1828, Friedrich Wohler achieved the first
synthesis of an organic compound; that is, he pro-
duced urea from ammonium cyanate. Hundreds of
thousands of organic chemicals have since been
synthesized: many with powerful physiologic ac-
tion; many that sometimes seem to be a curse.

The organic chemicals under discussion are
largely detergents, insecticides, herbicides, fun-
gicides, nematocides, rodenticides, growth regu-
lators, defoliants, and miscellaneous industrial by-
products that may impair quality of air, water, and
soils. Proper use of many of these chemicals has
made tremendous contributions to human conven-
lence (use of detergents), human health (control-
ling disease-carrying pests), and human welfare
(greatly augmenting needed food production).

Just as ordinary aspirin may be misused and
cause human deaths each year, the kinds of chem-
icals aforementioned may be misused. Agricultural
endeavor may suffer from unwise, inadvertent, or
careless use of these organic chemicals.

Detergents

Detergents entering into sewage effluent from
rural homes, rural communities, or camping areas
in National Forests adversely affect the operation
of septic tanks. These chemicals effectively disperse
the soil particles as part of their cleansing action.
They retain this capacity in moving through a
sewage disposal system such as a septic tank into a
tile system dispensing the effluent. Clay particles
adjacent to the tiles become dispersed and seriously
lower soil permeability to water near the tile line.
Thousands of septic sewage disposal systems have
become inoperative or malfunctioning, depending
on the nature of the soil. Adverse effects of de-
tergents on the tile dispensing system may be
especially serious in soils containing appreciable
amounts of clay.

If treated sewage effluent is used for irrigation,
and if detergents in the sewage are not biode-
graded, use of such water would impair rate of
infiltration of water into the soil and possibly lower

irrigation efficiency. This possible adverse effect of
detergents on agriculture has not been fully
explored.

Concern has been expressed from time to time
that detergents in water used for livestock may be
adverse to their health, but this has not been
demonstrated.

Insecticides

Along with their many benefits to agriculture,
insecticides can adversely affect agriculture in
many ways.

The application of insecticides to protect cotton
led to drift that destroyed the beneficial insect com-
plex in citrus groves, necessitating the use of in-
secticides to control certain pests of citrus that
were ordinarily controlled by beneficial insects.

The use of malathion to control and eradicate a
cereal, forage, or forest insect pest has destroyed
honey bees and other insects necessary for crop pol-
lination.

The application of persistent insecticides to po-
tato lands has led to residues in sugarbeets grown
in the same soil the following year, for which there
are no tolerances.

Residues may occur on agricultural commodities
as a result of accidental contamination, inad-
vertent use, or even recommended use of pesticides.
Losses from condemnation may be serious. Con-
gress authorized an appropriation of $10 million
to reimburse cranberry growers following confisca-
tion of certain lots of cranberries found to contain
illegal residues of a herbicide. This herbicide had
been applied by some growers at the wrong time
of the growing season in spite of warnings from
recognized authorities. Dairymen whose milk was
confiscated because of pesticide residues were com-
pensated in the amount of $350,000.

Fish in farm ponds have been killed because of
the drainage of insecticide wastes from nearby
lands into these ponds following heavy rains.

Pesticides such as heptachlor and aldrin for-
merly were applied on rangelands to control grass-
hoppers, but their use was discontinued. Residues
of these pesticides in meat of beef animals are not
permitted. Such uses are no longer registered.

The use of heptachlor in the past for the control
of alfalfa weevil has led to soil contamination, and
through translocation or external contamination
of the hay during harvest has caused nonpermitted

32 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

residues in milk of dairy cows consuming such hay.
This use is no longer registered or recommended.

The application of persistent insecticides, such
as dieldrin for the eradication of the Japanese
beetle, led to low-level but significant residues in
livestock grazing in the eradication area.

The careless disposition of insecticide and in-
secticide containers has caused injury to livestock
through contamination of drinking water and feed.

Improper use of insecticides and so-called empty
containers have caused injuries, and in a few cases
even death, to farmers and farm labor applying
the materials, and has created hazards to workers
in the treated fields.

Herbicides

Use of selective herbicides has made a tremen-
dous contribution to agricultural and forestry
production. But these chemicals can be misused or
used without proper precautions. The adverse
effects arising from the use of these chemicals fall
predominantly on agriculture and forestry.

Spray drift and vapors from aerial and ground
applications of herbicides for the control of weeds
and brush on nonagricultural lands, such as utility
rights-of-way, roadsides, railroads, ditchbanks.
and industrial and aquatic sites, often cause dam-
age to nontarget crops—flowers, ornamentals, and
trees. The volatile ester formulations of the phe-
noxy herbicides cause the greatest number of dam-

age claims, but other herbicides also may cause

damage.

Drift from aerial application of a herbicide on
a crop such as rice may seriously damage a sensi-
tive crop such as cotton, even miles away. In years
past, there were serious incidents of this sort, but
adherence to careful field application procedures
has largely eliminated this source of damage. In
addition, many States now control the application
of herbicides by aircraft.

A herbicide may be carefully tested under cer-
tain enviromental conditions for a specific cror
and deemed to be completely safe: but under a
changed environment, identical use on the same

crop may cause serious damage. For example,

prometryne was found to be completely safe for
use as a selective herbicide on potato fields at many
locations in the Northern States. However, in the
San Joaquin Valley of California, residual effects

caused serious damage to potatoes in the spring of
1966.

Herbicide wastes from sprayer-loading areas
and storage areas, improper disposal of empty con-
tainers, and excess herbicides may damage nearby
crops. Herbicide wastes may enter drainage and
irrigation ditches and cause damage far removed
from the source of contamination.

Fungicides, Rodenticides, Industrial Chemicals

Occasional incidents occur wherein careless han-
dling or misuse of these substances cause damage
to agriculture or forestry, but adverse effects from
these entities are much less than those experienced
from insecticides and herbicides.

Seriousness of the Problem

The presence of residues in agricultural com-
modities, resulting from accidental contamination
or inadvertent use of pesticides could constitute a
significant economic problem. Small quantities of
potatoes, sugarbeet pulp, and soybean oil have been
seized because of pesticide residues. Such events
can adversely affect consumer acceptance and con-
sumption of agricultural products once these
incidents are brought to public attention.

The economic impact from the loss of honey bees
and other beneficial insects, due to pesticides, has
not been determined. In areas highly dependent on
pollinating insects the losses could be substantial.

The economic losses incurred by damages from
herbicide vapors and spray drift are unknown.
However, the litigation and damage claims were
sufficiently serious during the past 20 years to cause
passage of laws and establishment of regulations
in 45 States which authorize certain restrictions on
the use of herbicides.

Damages to agriculture have occurred from use
of pesticides, but the benefits far outweigh the
damages. Whitten (133) has provided a penetrat-
ing review of the evidence concerning adverse ef-
fects from using pesticides. Mistakes have been
made. Decisions and recommendations have in the
past proceeded from inadequate information. We
must exercise every caution. But when one con-
siders all the evidence relating to the use of these
chemicals, their great assistance in man’s eternal
fight against insects, diseases, and weeds dwarfs
the damages incurred by inadvertent use.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 33

Heat

Tremendous quantities of water are withdrawn
daily from streams and lakes for cooling in indus-
trial and processing plants. After use, these waters
are usually returned to the stream or lake from
which they were withdrawn. Large quantities of
heat are thus transferred to these water bodies.
Since the amount of oxygen that water can hold
decreases with increasing temperature, the intro-
duction of heat into water has the net effect of in-
troducing additional oxygen-demanding pol-
lutants.

Added heat to streams and other water bodies is
adverse to fish life in terms of oxygen supply. Heat
also has a direct detrimental effect upon fish and

other aquatic life because it changes their physical
environment. Some fish can stand only a few de-
grees increase in temperature.

Forests providing recreational and fishing rights
on associated lakes and streams, rural area develop-
ment programs providing fishing opportunities,
and farmers and ranchers providing fishing oppor-
tunities in their ponds, lakes, and streams can be
and frequently are hurt by loss of fish life as a re-
sult of heat added to these waters.

Although heat as a water pollutant is not a
waste having a major adverse effect on agriculture
and forestry, the growing interest in providing
recreational opportunities in rural and forested
areas indicates that the effect of added heat on fish
life will arouse mounting concern.

APPENDIX Il

Wastes From Agriculture and Forestry

Of the total wastes produced in the United
States, agriculture and forestry contribute a share,
but not an inordinate share. In fact, agriculture
provides a prime means for amelioration or dis-
posal of many wastes that might otherwise pollute
the environment.

A grouping of substances that impair the quality
of the environment was set forth in appendix I.
Where applicable, this list will be followed in ap-
pendix IT. The discussion will cover—

. Chemical air pollutants

. Dusts

. Sediment

. Plant nutrients

Inorganic salts and minerals

. Organic wastes

Infectious agents and allergens
. Agricultural chemicals

_

H CO bo

OIA

Chemical Air Pollutants

The burning of plant residues in fields produces
a small amount of photochemical air pollutant.
Trash and residues in forests that burn produce
a significant amount of hydrocarbons that may be-
come photochemical air pollutants to the leeward
of a forest fire.

These possible sources of photochemical air pol-
lutants from agricultural and forestry activities
are mentioned in the discussion of organic wastes.

Dusts

Thirty million tons of natural dusts are emitted
into the atmosphere of the United States during
the average year. This is equivalent to the topsoil
from 30,000 acres of land. Agriculture makes no
claim to being the source of all of this dust, but
windblown soil is by no means a minor contributor.

Agricultural dusts arise from processing opera-
tions such as cotton gins and alfalfa mills, as well
as from the soil of unprotected fields.

Cotton Ginning

Dust and lint particles emitted from cotton gins
create a distinct nuisance to everyone in the

34

vicinity of a cotton gin during operation. The
smaller particles are reported to be the most
injurious to health and the most widely dispersed
by wind currents. The bulk of the dusts settles
within 300 feet of the gin, but smaller particles are
carried a half mile or more.

Medical authorities report a noticeable increase
in human respiratory ailments in the vicinity of
cotton gins when they are operating.

Throughout the 14 major cotton-producing
States there are about 5,000 gins, which process an
average of 3,000 bales each season. The foreign
matter to be discarded ranges from 50 pounds per
bale for handpicked cotton (of which there is now
very little) to more than 2,000 pounds per bale for
machine-stripped or machine-scrapped cotton.
Gins must dispose of up to 3,000 pounds of waste
per hour. The dust includes soil particles, pollen,
fungi, fibers, pesticide residues, and various types
and sizes of vegetative matter.

Over 50 percent of this trash is burned at the
gin. With cotton production at 15 million bales and
a thousand pounds of trash per bale, some 3,750,000
tons of residues are burned, giving rise to 375,000
tons of particulates in smoke.

Years ago the gins were established in open
country. In many instances, residences and busi-
nesses have now moved into the immediate vicinity
of the gin. Often, the city limits have extended to
include gin property. Lawsuits have been insti-
tuted as a result of the various nuisances and some
gins have had to be moved.

As mechanical cotton harvesting brings more
trash from the field to the gin, the production of
dust at the gin will increase.

Alfalfa Dehydrators

Alfalfa processing plants discharge dust and
small vegetative particles into the atmosphere.
Since the plants are located near the source of raw
materials and remote from centers of population,
they are more serious contributors to pollution in
rural areas than in suburban areas.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 35

Airborne Soil

Airborne soil can depress visibility; act as an ir-
ritant and health depressant to people; impair
machinery; cover up highways and railroad
tracks; fill ditches, fences, and waterways; cause
dirtiness in homes, offices, schools, stores, and fac-
tories; and exasperate people.

Measurements in western Kansas and eastern
Colorado in 1954-55 during a period of relatively
severe blowing indicated visibilities as low as %o
of a mile associated with dust loads of 1,290 tons
per cubic mile (8 mg. per cu. ft.). The reduced
visibility is often a cause of serious automobile
accidents on the highways of the Great Plains.

The local newspaper in Dodge City, Kans., car-
ried this item on April 6, 1893:

The dust was blinding and was deposited so

thickly on the office furniture that everything

looked as though it were covered with a layer

of dirt prepared for a hotbed.
The same situation prevailed in many, many
homes, offices, schools, and factories during the
1930’s and mid-1950’s in the Great Plains. This
situation occurs nearly every year at some loca-
tions in the Plains. Such duststorms have a pro-
nounced effect on the health and morbidity of the
population. In addition, the general atmospheric
conditions are very irritating to those who live or
travel in the area.

Airborne dusts can be carriers for other entities.
Dusts arising from cattle corrals may be astrin-
gently aromatic, but this does not improve their
acceptability. Significant amounts of pesticides
may be carried on the dust, and awareness of this
does little to placate the recipients.

One does not need to be a mechanical engineer
to appreciate what such heavy burdens of airborne
soil do to machinery bearings or the innards of
internal combustion engines.

The main cause of soil blowing is devegetation of
the land. Drought is an ancillary cause by its ef-
fect on vegetation. Any trend in agricultural pro-
duction that would increase land under the plow
in the Great Plains would increase the potential
for wind erosion and duststorms. This possibility
bears watching. Sound conservation practices on
the Jand will be the main countervailing force.

The nasty effects of airborne soil are not con-
fined to the Great Plains. During the severe dust-
storms of April 1934, the sun was beclouded by the

dust as far east as Washington, D.C. The irita-
tions of windblown soil on people, their habita-
tions, and their work are found in many parts of
the country, including the Columbia Basin, the
Coachella Valley of California, the Connecticut
Valley of New England, and around many of the
cultivated areas along the Atlantic Coastal Plain.

At noon on January 26, 1965, a weird red cloud
appeared over Cincinnati, Ohio. Soon thereafter,
people, houses, cars, and sidewalks were covered
with a cloak of red dust. Officials in Cincinnati
measured this fallout dust and found that it
amounted to 9 tons per square mile. They calen-
lated that 140 tons were deposited in the city
proper, and 1,800 tons in the four-county metro-
politan area. The deposit took place within an
hour. The dust had traveled by wind more than a
thousand miles from the plains of Texas and Okla-
homa. Tests by scientists at the Robert E. Taft En-
gineering Center in Cincinnati indicated that the
dust contained pesticides.

Seriousness of the Problem

The adverse effects of airborne dusts arising
from agricultural endeavor include illness, irrita-
tion, morbidity, and exasperation of afflicted peo-
ple; all-pervading silt within their homes; and
filth and depredation upon their work-a-day loca-
tions and equipment. The problem is not of minor
concern.

Sediment

Sediment derived from land erosion constitutes
by far the greatest mass of all the waste materials
arising from agricultural and forestry operations.
Committee Print No. 9 of the Senate Select Com-
mittee on National Water Resources (779) states:

Rough estimates of the suspended solids load-
ings reaching the Nation’s streams from surface
runoff show these to be at least 700 times the
loadings caused by sewage discharge.
Wolman and others (737) emphasized that pol-
lution of the Potomac River by sediment is so
great it dwarfs the effects of all other pollutants.

The Mississippi River dumps more than 500
million tons of sediment into the Gulf of Mexico
during the average year. This amount constitutes
about half of the average annual sediment delivery
to the oceans by the rivers of the conterminous
United States. Brown (20) estimated that only
one-fourth of the silt produced by erosion from our

36 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

watersheds ever reaches the ocean. Thus, total sedi-
ment production in the United States runs about
4 billion tons a year.

Sediment production from representative basins
in the United States varies from 51 to 10,000 tons
per square mile (79). Sediment delivery varies
widely according to soils, geology, topography,
precipitation, vegetative cover, and applied soil
conservation practices.

Measurements of soil erosion from field plots
leave no doubt that cultivated fields can be major
contributors to the sediment burden. Forested
cover provides excellent protection against sedi-
ment delivery, but burned out forest land can be a
tremendous contributor of sediment. Logging
roads also become sites of erosion and sediment de-
livery.

Highway construction sites, barren roadbanks,
mining operations, construction sites for industrial
and suburban development, and eroding stream-
banks are also conspicuous sources of sediment.

Sediment suspended in flowing or impounded
water may havea harmful effect on (a) water sup-
ply, (0) recreation, and (¢) power generation.

Potable water must be free of sediment. Many
industrial uses, for example, food processing, re-
quire sediment-free water. Sediment deposited in
condenser tubes used in industrial cooling may
cause costly incrustations. Cost of clarifying water
increases with degree of turbidity. High turbidity
of water adds costs through the need for greater
use of chemicals as flocculants, and more frequent
cleaning and disposition of silt from settling
basins.

People like clean water for swimming and other
recreational activities.

Fine suspended sediment has caused heavy losses
of commercial fish and shellfish yield from both in-
land and tidal waters (178).

Coarse sediment passing through power plants
has caused serious abrasion of turbine blades.

Deposition of sediment in stream channels or
aggradation of flood-plain lands may impair
drainage and cause channels to overflow more fre-
quently. Floodflows carrying high sediment loads
inundate a much larger area than comparable flows
free of sediment (79). Floodborne sediment may
damage growing crops; and sands, gravel, and

such coarse debris when deposited on fertile al-
luvial soils may reduce their productivity.

Reduction of reservoir storage capacity is an-
other devastating consequence of sediment. About
1 million acre-feet of sediment is deposited in arti-
ficial reservoirs of the United States each year.
Loss of reservoir capacity to sediment has partic-
ular implications for programs of water resources
development. Indeed, prevention of such losses is
a primary justification for land treatment meas-
ures and watershed protection programs in many
upstream tributary areas of the country.

Estuaries, bays, and coastal harbors tend to be-
come vast sediment traps where continuous dredg-
ing and other operations are required for handling
sediment. Commingling of fresh sediment-laden
water and saline water, plus the influence of tides,
waves, currents, and shipping traffic, complicate
the depositional processes in such coastal areas, and
we should recognize that sediment is a major con-
taminant of these areas.

We have become accustomed to thinking of the
consequences of sediment in engineering terms;
that is, as rates of reservoir silting, dredging of
harbors, or channel systems. But we are now be-
ginning to recognize other possible influences of
sediment on our environment. We are concerned,
for instance, about sediment as a carrier of pesti-
cide residues and the significance of phosphorus
adsorbed on sediment in the eutrophication of lakes
and estuaries. There are few complete and definite
answers to these questions.

Studies in various parts of the country have
shown that erosion control practices in the forest,
on the range, and on the farm can and do reduce
the sediment delivery. The amount of sediment
coming from watersheds having good conservation
treatment at the Blacklands Experimental Water-
shed, near Riesel, Tex., is only 12 percent of that
from watersheds farmed without soil conserving
practices. Sediment yield from a 400-acre water-
shed receiving good conservation practices at the
Central Great Plains Experimental Watershed,
near Hastings, Nebr., was only 5 percent of that
from a comparable 400-acre watershed that did not
receive soil conservation treatment. Application of
streambank crosion control measures on the 145-
square-mile Buffalo Creek Watershed, near Buf-
falo, N.Y., reduced sediment delivery from that
watershed to Buffalo Harbor by 40 percent. The

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 37

average turbidity of the Chattahoochee River in
Georgia was decreased to 82 percent by applying
improved forestry and conservation practices to
lands of the river basin (6).

Plant Nutrients

High crop production to meet ever-increasing
food demands requires an adequate supply of plant
nutrients in the soil. Americans applied 32 million
tons of chemical fertilizers on their lawns, gardens,
fields, and pastures in 1966. Those who are con-
cerned with the adverse effects of plant nutrients
in surface water sometimes find this seemingly
large tonnage a convenient culprit.

The following table reveals the rather low level
of chemical fertilizers being applied to arable soils
in the United States compared with the Nether-
lands—a nation that has responded to the economic
need of making highly efficient use of its available
cropland.

Plant Nutrients Applied in 1965

{In pounds per acre]

Nutrient United States Netherlands
Nitro pene eee ee eee Ree 22 244
IP2O; Steer PROT BED ty 8 17 93

Ker Lecas. Visteon: oe 13 116

Plant nutrients in water give rise to two prob-
lems of mounting concern: (1) eutrophication of
lakes and streams and (2) nitrate in well water
used for drinking.

Eutrerication

Complaints abound that many rivers, estuaries,
ponds, lakes, and reservoirs are being ruined by a
tremendous growth of algae and other water
plants, forming what is known as “algal blooms.”
These blooms are not pretty, and on death and
deterioration of the plants unpleasant odors are
emitted. The decaying plantlife robs the water of
the little dissolved oxygen that may have been
present. The water becomes uninhabitable for fish
and unsavory for recreation. These excessive
growths of water plants constitute the eutrophica-
tion of surface waters. The process is an important
stage in the death of a lake.

These algae, like all plants, must have mineral
nutrients in order to grow. In most waters the main
limiting factor for algal growth is phosphorus,

since other elements, such as nitrogen, potassium,
calcium, and magnesium, are present in much more
abundant supply. Accordingly, the phosphorus
level in river and lake waters becomes a matter of
prime concern.

Available evidence indicates that these algae will
grow vigorously if the water contains only 0.1
p.p.m. of phosphorus. It is also evident that the
level of phosphorus in the water must be below
0.02 p.p.m., if the growth of algae is to be com-
pletely inhibited. The phosphorus content of the
water in some streams and lakes may reach 1 p.p.m.
Obviously, this water provides a good medium
for the growth of algae.

About 1 million tons of elemental phosphorus is
applied to the land as fertilizer each year in the
United States. Average annual runoff of precipita-
tion into the streams of the conterminous United
States is 1,380 million acre-feet, or 1,875 billion
tons. If only 10 percent of the applied phosphorus
reached the streams as soluble phosphate, the
average phosphorus content of our streams would
be 0.05 p.p.m. On the basis of these figures, one
could erroneously conclude that the phosphorus
in surface waters is all coming from land runoff.

Considerable phosphorus is present in domestic
sewage, largely arising from use of household
detergents. On the average, about 2 pounds of
phosphorus per person per year is delivered in
metropolitan sewage effluent, but the Public Health
Service reports that Lake Washington near
Seattle, Wash., receives 3.4 pounds of phosphorus
per capita. per year from the treated sewage of
76,300 people (70). Thus, effluent from a city com-
prising 1 million people will contain 1,000 tons of
phosphorus a year. If this amount of phosphorus
enters a stream with an average annual flow of
10,000 cubic feet per second, the average phos-
phorus content of the water will be 0.1 p.p.m.—an
adequate level for growth of alore. The Potomac
River has an average annual flow of nearly 10,000
cafis.

In a situation like the one just cited, even if the
total contribution of phosphorus to the stream by
agriculture were eliminated, there would be little
effect on growth of algae since the 0.1 p.p.m. of
phosphorus in the sewage effluent would be
sufficient.

Although some reports have implied that phos-
phorus in surface waters was a result of fertilizer

38 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

applied to farms, Verduin? has carefully exam-
ined the evidence and finds that most of the phos-
phorus enrichment in surface waters is coming
from sewage treatment plants and only second-
arily from agricultural] fertilizers.

The sediment delivered into farm ponds by soil
erosion is usually insufficient to provide enough
nutrients to support aquatic plant growth for
fish food. Most recommendations (76, 89) on the
management of ponds specify the addition of 100
pounds of 8-8-2 fertilizer per acre of pond sur-
face to permit the growth of an adequate supply
of miscroscopic plants for fish food. If the pond
averaged 13 feet deep, the fertilizer would supply
0.1 p.p.m. of elemental phosphorus in the water,
assuming the phosphorus was entirely soluble.

The extensive use of fertilizers in farm ponds
for fish production is an indication that land run-
off is a poor source of the needed phosphorus.

Phosphorus is getting into streams from farm-
land; however, it mainly gets into surface water
through runoff and erosion of topsoil. Water seep-
ing down through the subsoil or moving laterally
through the soil carries virtually no phosphorus
because of the high capacity of soil particles to
adsorb phosphate. Topsoil contains on the average
about 200 p.p.m. of phosphorus adsorbed on soil
particles. The clay fraction of a soil usually con-
tains about 1,000 p.p.m. of adsorbed phosphorus.
Thus, the richer a particular soil happens to be in
clay, the more adsorbed phosphorus that can be
carried into the stream by soil erosion.

Soil particles have a tremendous affinity for
holding onto phosphate molecules. Even when the
fine suspended particles in a river water contain
1,000 p.p.m. of phosphorus adsorbed on their
surfaces, the phosphorus in true solution may be
only 0.005 to 0.0005 p.p.m. Water samples, there-
fore, should be analyzed in a way that distin-
guishes between phosphorus in true solution and
phosphorus adsorbed on suspended sediment.

Barnyard waste carries around 1,000 p.p.m. of
phosphorus. Runoff that flows directly from feed-
lots and barnyards into stream channels may be
an untoward source of phosphorus.

The conclusion is obvious that the best way to
control the phosphorus content of surface water

*Verduin, J. Eutrophication and Agriculture. Pre-
sented at Amer. Assoc. Adv. Sci. Symposium, Dec. 27, 1966,
Washington, D.C.

that might arise from agricultural practices is to
use soil conservation practices and structures that
minimize runoff and sediment delivery from farms
and farmsteads.

Certain aquatic plants such as cattails and sedges
that have their roots in bottom sediments offer a
more difficult problem. These plants may be a
serlous nuisance in canals and waterways, and on
the edges of ponds and lakes. They can obtain their
phosphorus supply by their roots permeating the
bottom sediment. They appear to flourish best
when this furnishes some adsorbed phosphorus and
the water of submersion also contains a trace of
phosphorus.®

Nitrate in Well Water
The Public Health Service (725) states:

Serious and occasionally fatal poisonings in in-
fants have occurred following ingestion of well
waters shown to contain nitrate (NO3;). This has
occurred with sufficient frequency and widespread
geographic distribution to compel recognition of
the hazard by assigning a limit to the concentra-
tion of nitrate in drinking water.

From 1947 to 1950, 189 cases of methemoglc-
binemia (blue babies), including 14 deaths due
to nitrate in farm wellwater supplies, have been
reported in Minnesota alone. Wastes from chemi-
cal fertilizer plants and field fertilization may be
sources of pollution.

The observation that nitrate moves into ground
water is not new. As early as 1910, W. P. Headden
published extensively on nitrate (63). He found
high quantities of nitrate in ground water 80 feet
below the surface at a time when chemical fer-
tilizers had not been used in Colorado. He reasoned
that the nitrate was formed in the surface soil by
natural processes and leached to deep horizons.

Vernon Michael (80) District Health Officer,
Franklin County, Wash., 1mphed that heavy use
of nitrogen fertilizer in that county resulted in
relatively high concentrations of nitrate in drink-
ing water.

De Laguna (37) found high nitrate (about 10
p-p-m.) in wells in the vicinity of Suffolk County,
N.Y. He concluded that the nitrate in the wells was
obviously caused by high applications of fertilizer
to the potato fields in the area.

3 Martin, J. B., and Clements, L. B. National Fert. Devel.
Cent., Tennessee Valley Authority, Muscle Shoals, Ala.

WASTES IN RELATION TO

Stout and Burau ‘ studied nitrate accumulation
in ground water within the 10-square-mile basin
occupied by Grover City and Arroyo Grande,
Calif. Concentrations of nitrate at 90 to 130 p.p.m.
in water percolating to the underground reservoir
were not uncommon. The sources appeared to be
nitrification of sewage effluent and natural] nitri-
fication processes in the surface soils that are fos-
tered by the climate and the nature of the soil.

The Soils Department (59) at Washington State
University studied nitrate content of well water
in areas where various amounts of fertilizer had
been used, and found that high nitrate in the well
water was not a direct consequence of heavy fer-
tilizer use.

At a recent American Association for the Ad-
vancement of Science symposium, Smith® re-
ported on his extensive studies of the nitrate
content of 6,000 rural water supplies. He
found that animal wastes, improperly con-
structed shallow wells, and septic tank drainage
were the main sources of water contamination. His
evidence showed that leaching of fertilizer nitro-
gen was an insignificant source of nitrate in the
well waters of Missouri.

The foregoing presents conflicting evidence.
Conclusive evidence is lacking that chemical fer-
tilization of fields results in high nitrate levels
in well water. Natural nitrification processes in
soils and nitrification of sewage effluent and animal
wastes do seem to be major contributors when
nitrate is found in ground water. The general
problem is one of growing importance and much
more definitive information is needed.

Inorganic Salts and Minerals

Of the water diverted from massed supply and
consumptively used, 90 percent is used in irriga-
tion. Thus it is that agriculture is sometimes
referred to as “the greatest water hog of all” (26).

Because of this high consumptive use through
the processes of evapotranspiration, salts present
in the irrigation water supply become more con-
centrated in the drainage effluent. Consequently,

‘Stout, P. R., and Burau, R. Extent and Significance of
Fertilizer Buildup in Soils. Presented at Amer. Assoc. Ady.
Sci. Symposium, Washington, D.C., Dee. 28, 1966.

*Smith, G. E. Fertilizer Nutrients as Contaminants in
Water Supplies. Presented at Amer. Assoc. Ady. Sci. Sym-
posium, Washington, D.C., Dee. 27, 1966.

AGRICULTURE AND FORESTRY 39

frequent claims are made that irrigation agricul-
ture seriously impairs the quality of water.

Irrigation agriculture provided the very spawn-
ing ground for the beginnings of civilization in
the valleys of the Nile, the Indus, and the Tigris-
Euphrates. The benefits that have arisen from ir-
rigated farming have not been fully appreciated.

The irrigation water brought onto a field always
carries some dissolved salt—usually within the
range of 25 to 8,000 p.p.m. Plants extract water
from the irrigated field for transpiration, but most
of the salt is excluded by the roots. Water evapo-
rating from the soil surface is pure water. The
residual salt accumulates in the soil. In arid cli-
mates where Nature has left an accumulation of
salt in the soil, the application of irrigation water
will fortify this salt concentration.

For irrigation agriculture to survive, this proc-
ess of salt accumulation in the soil must contin-
ually be countered by leaching with excess
applications of water. The salt moves to deep hori-
zons, the ground water, or the drainage system.
Thus, the salt appearing in drains is that brought
in by the irrigation water plus that which may
have been naturally present in the soil. The irriga-
tion farmer adds but little to this salt burden by
lis application of chemical fertilizers. These fer-
tilizer salts barely meet crop needs. Under the
natural conditions of crop production, evapotran-
spiration depletes the vehicle-water that trans-
ports salt to the drainage system. This natural sys-
tem imposes an increase in salt burden in the
drainage water from an irrigated field compared
with that in the water supply.

In arid regions, it is a first criterion for the sur-
vival of an irrigated area that there be favorable
salt balance; salt leaving the project by drainage
or deep percolation must equal or exceed that re-
ceived in the water supply. In the initial years of
a project, when there is residual salt in the soil,
more salt will have to be removed than is brought
in.

Thus, the irrigation farmer does not actually
produce a waste in the form of dissolved salts, he
merely transfers the waste in a more concentrated
form. Nevertheless, drainage water frequently
warrants the label of “impaired quality” because
of its burden of dissolved solids.

The quality of the return flow from irrigation
projects may also be impaired by partial precipi-

40 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

tation of the salts, even though precipitation de-
creases the total salt concentration. The slightly
soluble carbonate and sulfate of calcium precipi-
tate as the water volume is reduced by evapotran-
spiration, thus increasing the proportion of
sodum in the effluent. High proportions of sodium
in the irrigation waters are generally damaging
because they cause deterioration of soil properties
and specific toxic effects of sodium in some fruit
crops and other woody plants. For municipal and
many industrial uses, an increased proportion of
sodium is, however, not harmful.

The increase in total salinity of return flows
from irrigation projects will generally render the
water unpalatable even before its utility for agri-
culture is completely lost. Thus, public health
standards for potable water have been set at -250
mg./liter of chloride, a level which may damage
only some sensitive fruit crops. In fact, waters
containing several thousand mg./liter of total salts
may still be of value for agriculture, especially
when favorable soil conditions prevail and tolerant
crops are grown, but such waters cannot be used
for municipalities or for many industrial processes.
The upper recommended limit of total salts for
potable water is 500 mg./liter, although waters
with twice this salt content are actually being used.
Highly saline waters also have considerable reuse
potential for recreational purposes. The drainage
waters of the Imperial and Coachella Valleys, con-
taining about 2,000 mg./liter of total salts, flow
into the Salton Sea, which affords fishing, boating,
and other water sports for many hundreds of peo-
ple. However, since the Salton Sea has no outlet,
continued evaporation will ultimately render the
sea so saline that the recreational use pattern will
undoubtedly have to be adjusted.

The trend toward intensified use of limited ir-
rigation water resources foreshadows more severe
problems in the future. Irrigation projects must
generally maintain salt balance. Salt cannot ac-
cumulate in the soil without damaging crops, so as
much salt must be carried out in drainage water as
is applied in irrigation water. The decrease in vol-
ume of water with each use results in a propor-
tional increase in salt concentration. Thus, if 20
percent of the total water flow in a river is con-
sumptively used by each of four successive projects
along the river, the relative salt concentration of
the river will increase from 1.0 to 1.25, 1.67, 2.50,

and 5.00 following each stage of use and return
flow. It is obvious that as the river flow is depleted,
the salt concentration of the remaining flow must
increase inversely with the volume of water if salt
balance in all projects is to be maintained. It is
further obvious that, under salt balance conditions
and with return flow of drainage water, complete
allocation of the river flow may give the last proj-
ect a water with prohibitively high salt content.

Alternative procedures for handling return
drainage flow along some rivers may have to be
devised, especially if downstream users are to have
potable water as well as irrigation water. One solu-
tion may be to purify the drainage flow by suitable
desalination process, returning the purified frac-
tion to the river and disposing of the concentrated
salines in other ways, such as outfall drains to the
sea, collection in evaporation ponds, or percolation
into the ground where usable ground water would
not be affected. Such solutions would be practical
only when return flows are readily recoverable, as
from tile drains or pumped wells, or can be readily
intercepted before the underground flow returns
to the river.

Organic Wastes

It is in the nature of things that man’s domesti-
cated animals produce wastes; that his fields and
forests produce residues and trash; and that his
food- and fiber-processing plants produce useless
byproducts.

There are instances wherein wastes of this cate-
gory have emitted odors into the atmosphere;
have contaminated the water of streams, ponds,
lakes, and reservoirs; have provided dangerous
fire hazards; have disseminated infectious agents;
and have been the very spawning ground of a
whole array of vermin.

Animal Wastes

Time was when animal wastes were considered a
tremendous asset in providing fertility to the Na-
tion’s soils. The 1988 Yearbook of Agriculture
(121, p. 445) carries this statement :

One billion tons of manure, the annual product
of livestock on American farms, is capable of
producing $3,000,000,000 worth of increase in
crops. The potential value of this agricultural
resource is three times that of the Nation’s wheat
crop and equivalent to $440 for each of the coun-
try’s 6,800,000 farm operators. The crop nutrients

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 4]

it contains would cost more than six times as

much as was expended for commercial fertilizers

in 1936. Its organic matter content is double

the amount of soil humus annually destroyed in

growing the Nation’s grain and cotton crops.
How times do change!

In 1966, animal excrement was considered by
some to be the béte noire of agricultural wastes.
Waste production by our domestic animals is
equivalent to that of a human population of 1.9
billion. Sewage treatment facilities for this live-
stock are infinitesimal.

The change in view towards manure has oc-
curred because livestock and poultry production
in the United States is becoming concentrated in
large scale, confinement-type enterprises. These in-
clude multihundred-cow dairy operations, multi-
thousand-head beef or hog feedlots, and enterprises
with many hundreds of thousands of birds. Such
large concentrations of animals or birds have
greatly magnified the problems of handling wastes,
including health hazards and esthetic nuisances.
Economic studies indicate that the costs of han-
dling manures make them no longer competitive in
price with chemical fertilizers. Table 1 provides
an indication of the amount of solid wastes pro-
duced by livestock in the United States. Domestic
animals produce over a billion tons of fecal wastes
a year. Liquid effluent amounts to over 400 million
tons. Used bedding, paunch manure from ab-
batoirs, and dead carcasses make the total annual
production of animal wastes close to 2 billion tons.

Possibly half of this waste is produced under
concentrated conditions. Cattle in a feedlot for
fattening, or dairy cows maintained for high milk

TABLE 1.—Production of wastes by livestock in the
United States

U.S. Total pro- Total pro-
Livestock popu- Solid duction of Liquid duction of
lation wastes! solid waste wastes liquid
1965 wastes
Mil- G./cap./ Million G./cap./ Million
lions day tons/yr. day tons/ur.
Cattle_____ 107 23,600 1, 004.0 9, 000 390.0
Horses ?___ 3 16,100 Wile & 3, 600 4.4
Hoge == = 53 2,700 57.3 1, 600 33.9
Sheep-_-__-_ 26 =: 17, 180 11.8 680 Liss!
Chickens_. 375 182 Diag pels peed a Ty py beer Sh
Turkeys___ 104 448 Ih Se aoe oe
Dueckss 2s" ilal 336 Or eer eee eee ee
Motaline oe ee ge ee SS Grim pe 435. 4

1 Geldreich and others (47).
* Horses and mules on farms as work stock.

production, may produce double the daily amount
of wastes shown in the table.

Table 2 shows the population equivalent of the
fecal production by various kinds of livestock in
terms of biochemical oxygen demand (BOD). For
example, a feedlot carrying 10,000 head of cattle
has about the same sewage disposal problem as a
city of 164,000 people. The city will be using 8,200,-
000 gallons of water a day to carry off the sewage.
Such amounts of water are never used and are
seldom even available at the feedlot.

BOD is an important measurement in determin-
ing the quality of water. BOD indicates the amount
of oxygen required for the oxidation of the organic
matter present in a sample of water. It is ex-
pressed by the amount of oxygen the water will
absorb when it is incubated for a 5-day period at
68° F.

In such tests, water absorbing not more than 1
p-p-m. of oxygen in 5 days can generally be con-
sidered very pure; 3 p.p.m. suggests fairly clean
water; but water absorbing 5 p.p.m. or more of
oxygen is of doubtful purity.

BOD demand of a waste acts to deplete dis-
solved oxygen in water. Fish depend upon this
dissolved oxygen in order to breathe. Most fish
should have 5 p.p.m. of dissolved oxygen—brook
trout should have 6 p.p.m. or more. However, a
sluggish stream during the summer may have its
dissolved oxygen lowered to 1 to3 p.p.m.

A primary problem in handling animal waste
involves coping with its high BOD. A sample of
concentrated liquid waste from a pigpen has been
reported as having a BOD as high as 50,000. This
undoubtedly is an unusually high value.

Untreated municipal sewage has a BOD of about
100 to 400 p.p.m. This means that such sewage
entering a stream already low in dissolved oxygen

TaBLE 2.—Population equivalent of the fecal pro-
duction by animals, in terms of biochemical
oxygen demand (BOD)

Relative Population

Biotype Fecal BOD per equivalent
unit of waste
G./cap./day Lb.

Nana ae? Hares ee 150 1.0 1.0
nO) ae ae ne 16, 100 0. 105 11.3
COE eae cere eee 23, 600 - 105 16.4
Sheep see, Bete 1, 180 . 325 2.45
Lalo) 2 ee oe See ee 2, 700 . 105 1. 90
Men tecesot ae 182 ~115 .14

42 MISCELLANEOUS PUBLICATION NO. 1065

must be highly diluted if it is not to completely
exhaust the dissolved oxygen of the stream.

Wastes carried in runoff from barnyards and
feedlots may vary in BOD from 100 to 10,000
p-p-m. depending on dilution and degree of deteri-
oration of wastes. Public health authorities object
to runoff entering a stream if it exceeds 20 p.p.m.
in BOD. Hence, the problem is obvious.

Many installations using lagoons for oxidation
of animal wastes have been tried (2). Success has
not been complete. The South Dakota agricultural
experiment station reports that they are essentially
a failure in that State. These lagoons are plagued
by problems, such as overloading, floating litter,
intermittent loading, aquatic weeds, and sludge
buildup.

When a lagoon becomes overloaded, bacteriologi-
cal decomposition changes from aerobic to anaero-
bic. During anaerobic decomposition, noxious
gases and vile odors emanate. Under such condi-
tions, the lagoon becomes more unacceptable than
the ordinary manure pile.

The Pasveer Ditch was developed in Holland to
handle municipal sewage. It accentuates natural
oxidation by a motor-driven paddle wheel that
both aerates and stirs. Modifications of the Pasveer
Ditch for handling animal wastes are being tried in
the United States. Animal wastes pose a much
greater problem since they are not nearly as diluted
as metropolitan sewage.

Even though the concern over animal wastes is
great in terms of their high BOD, their use as
spawning grounds for vermin, and their role as
vehicles for infectious agents, public objections
mostly arise through olfactory awareness.

Odors and water-polluting wastes from the con-
centrated egg production industry in Sullivan
County, N.Y., is posing a serious threat to the
resort industry that has flourished in the favorable
climate and scenic attractions of this county. Re-
ports have been made of serious losses in recrea-
tional enterprises because of offensive odors and
other nuisances arising from the poultry.

The communities of Gardena and Torrance in
Los Angeles County, Calif., have enacted ordi-
nances requiring all dairy farmers to move out
because of odors and other nuisances. Within the
last 6 years, 43 dairy operations have had to move
out of Los Angeles County because odors and

U.S. DEPARTMENT OF AGRICULTURE

other nuisances made these dairy cows “noncom-
patible” with Metropolitan Los Angeles.

People in Milford, Tex., have brought numerous
damage suits against a large feedlot separated
from the community by a mile-wide buffer zone
because of odors, flies, dust, and water pollution.

In 1963, the State of Kansas enacted a feedlot
licensing law to provide State inspection and con-
trol over the handling of wastes from feedlots
1,000 head and greater in capacity. The law was
enacted because of complaints regarding odors,
vermin, and water pollutants.

In early 1966, the Interstate Commission on the

Potomac River Basin (45) reported:

Every time its rains .... enormous amounts of

animal wastes are washed from farmyards into

the River, rendering it unsafe for swimming ....

Although only a quarter-of-a-million people live in

the river basin above Great Falls, it has been esti-

mated that the number of farmyard animals—

cows, sheep, pigs, chickens, turkeys—is the equi-

valent of a human population of 3.5 million.

While most of the human population is served

by some sort of sewage treatment plant, there is

no comparable treatment for the animal wastes.
It can be stated without fear of successful contra-
diction that domestic livestock are producing
wastes that are in some degree offensive to the
general public.

Plant Residues on Farms and Ranches

Plant residues from crops and orchards contrib-
ute to pollution in two ways; namely, as a source
of smoke and other air pollutants when burned,
and as reservoirs of plant diseases and other pests.

Agricultural wastes from orchards, grainfields,
and rangelands, especially in the Western United
States, are burned as the practical means of ridding
the land of the wastes. In one California county in
1960, an estimated 41,000 tons of orchard wastes
were burned. From 30 to 80 percent of approxi-
mately 240,000 acres of rice in 8 California counties
are burned annually. The smoke may be seen for
miles.

Around 900,000 acres of grass are grown for
grass seed each year, with the production of about
2 tons of residue per acre. Estimates indicate that
about one-third of this acreage is burned each year
as a sanitation measure. Such burning emits
around 50,000 tons of particulate matter as carbon
and ash into the atmosphere.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 43

Evaluations of the relative contribution of burn-
ing agricultural wastes to photochemical air pol-
lution have been attempted. The studies indicated
concentrations of photochemically active hydro-
carbons were negligible at a mile and a half from
the fire when more than 1,000 acres of wastes were
burned. The emissions of hydrocarbons and oxides
of nitrogen from burning of agricultural wastes
were considerably less per ton of fuel consumed
than those in auto exhaust. The burning of fruit
tree prunings, rice straw, barley straw, and dry
native range brush produced approximately 14, 9,
18, and 7 pounds, respectively, of hydrocarbons
compared with 130 pounds of the same hydrocar-
bons in auto exhaust per ton of fuel consumed. It
appears from limited study that the burning of
agricultural wastes does not add significantly to
the burden of pollutants in community air. The ef-
fects of smoke on visibility from burning the agri-
cultural wastes, however, may be a significant
esthetic factor.

As agricultural land in the United States be-
comes more limited and agriculture becomes more
intensive, the danger of plant debris carrying dis-
eases and other pests to the succeeding crops
becomes greater. Control of the plant diseases,
preferably by disease resistance or nonchemical
means, could solve the problem. But until such con-
tro] becomes a reality, destruction of the plant
debris by burning will be a common practice.

A case in point here is the destruction of plant
residues of grass seed crops in western Oregon by
burning, which is the only practical control for the
blind seed disease, but which has led to an air pol-
lution problem. Alternative methods of control
must be found if the pollution problem is to be
abated while enabling the multimillion-dollar
grass seed industry to remain prosperous.

Many plant diseases are transmitted through
plant residue, including late blight of potato, cot-
ton verticillium wilt and bacterial blight, apple
scab, brown rot of stone fruits, and leaf spot of
tung, to name but a few. The extent of the plant
disease problem associated with plant residues is
not known for many crops. Some estimates have
been made, however. For example, observations in
Maine and other States indicate that culled piles of
potatoes outside potato storage houses, along rail-
way tracks, and on farms are primary sources of
infection for late blight, a disease that causes an

estimated average 4-percent loss of the potato crop
each year.

In the southeastern United States piles of litter
left in peanut fields are often an important source
of stable fly breeding. Similarly, in other areas of
the United States, rotting hay and straw provide
suitable breeding places for the stable fly and house
fly. Volunteer wheat, resulting from grain waste in
inefficient harvesting practices, provides a breed-
ing ground for the wheat curl mite, the vector of
wheat streak mosaic. Volunteer beets are a source
of beet yellow virus for reinfection of subsequent
beet crops In the western and northwestern United
States. Pink bollworms overwinter in waste cotton
bolls and cottonseed left in fields. The European
corn borer and sugarcane borer overwinter in the
stalks remaining in the fields.

The European corn borer is one of the most de-
structive pests to sweetcorn in the United States.
It causes coarse, broken stalks, poor ear develop-
ment, and dropped ears, resulting in reduced yield
and increased cost of harvesting. The average an-
nual crop loss is estimated at 3.5 percent of the
total production. The sugarcane borer is the most
injurious insect attacking sugarcane in the United
States and is responsible for an annual estimated
loss of 12.1 percent. This insect also attacks corn,
rice, and sorghums. The pink bollworm constitutes
a threat to cotton comparable to the boll weevil.
The stable fly is a serious pest of domestic animals
and man throughout the United States, especially
in North Central, Eastern, and Southeastern
States. Reliable estimates from Illinois indicate
that heavy stable fly outbreaks can reduce milk
production by as much as 25 percent and reduce
beef gains materially. In the Hard Red Winter
wheat areas of Kansas and Nebraska, wheat streak
mosaic caused an estimated loss of 15 million
bushels in 1949 alone. The average annual loss from
this disease is estimated at 1 percent of the total
wheat production in the United States. The an-
nual loss of beets from yellows disease is estimated
at 6 percent; potato losses from aphid-transmitted
virus diseases are estimated to be in excess of 3 per-
cent annually.

Residues and Trash in Forests and Forestry
Operations

Twenty-five million tons of logging debris are
left in woods during the average year. This ma-
terial is a fire hazard. Some of the most disastrous

44 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

forest fires in North American history started in
slash left from logging and land clearing. The
average size of fires originating in logging waste
is more than seven times that of fires originating
in uncut areas or areas where slash has been
disposed of.

Forest fires are a major concern in the United
States. During a typical vear, there are about
150,000 forest fires in this country, which ravage
5 to 7 million acres. Of these fires, between 7,000
and 8,000 occur in the National forests, between
3,000 and 4,000 on other Federal lands, and the
rest on State and privately owned lands.

Prescribed burning in forests each year pro-
duces about 82 cubic miles of smoke in the con-
vection column, while generating 6,500,000 tons of
particulate matter and 68,000 tons of hydro-
carbons.

Wild forest fires in the average year produce an
estimated 160 cubic miles of smoke in the convec-
tion column. Such fires generate about 34 million
tons of particulate matter each year, largely as car-
bon and ash; and about 338,000 tons of hydro-
carbons are vaporized and condensed.

Wild fire yields more smoke and hydrocarbon
per ton of fuel than prescribed burning because the
oxygen deficiency is usually greater during wild
fire burns.

The conclusion is obvious that a way should be
found to dispose of logging debris so that it does
not become a fire hazard. The cost per ton of elimi-
nating this material by burning is about $1 per ton,
whereas disposal by chipping costs about $12 per
ton.

Even prescribed burning causes problems. Ore-
gon-Washington applegrowers have filed suit
against the U.S. Forest Service because they claim
smoke from prescribed fires prevents proper ap-
ple coloration. Police in several Southern States
have complained that smoke from prescribed fires
has been a significant cause of automobile acci-
dents. Smoke from forest fires closes a number of
airports each year. Recreation activities are dis-
couraged.

Tf trash from trees is not burned, it may become
a serious source of disease organisms. Elm logs
killed by Dutch elm disease and oak logs killed by
oak wilt must be destroyed or treated to prevent
vector transmission of the disease to healthy trees.
The log disposal problem from trees killed by
Dutch elm disease is monumental. In Nassau

County, N.Y., 3,000 trees die per year and must
be burned, buried, or treated with insecticides.
Similar conditions exist in all Eastern and Mid-
western States.

Roots of conifers killed by Fomes annosus and
Poria weirii root rots are sources of new infections
for many years.

Felled oaks with Strumella cankers must be de-
stroyed to prevent fruiting and spread of the path-
ogen.

The need to dispose of logging debris and dead
trees is urgent. It would be desirable to have meth-
ods for disposal alternative to burning, but the
probability of discovering such alternatives that
have economic feasibility appears to be low.

Processing Wastes

Wastes from food- and fiber-processing plants
can vary tremendously in potential for pollution.
Research at Louisiana State University (22)
showed that liquid wastes from asparagus canning
have a BOD of not more than 100 p.p.m. whereas
the BOD for waste from squash canning would
run as high as 4,000 to 11,000 p.p.m. A sample from
concentrated pea vine ensilage Juice was reported
to have a BOD of 75,000. These figures must be
evaluated in terms of water quality standards to
the effect that stream water with a BOD of 5
p-p.m. is looked upon as being of doubtful purity.

Oxygen-demanding wastes from processing of
agricultural and forestry products include runoff
or effluent from sawmilling; pulp, paper, and
fiberboard manufacturing; fruit and vegetable
canning; cleaning of dairies; slaughtering and
processing of meat animals; tanning; manufactur-
ing of cornstarch and soy protein; sugar refining;
malting, fermenting, and distilling; scouring of
wool; and wet processing in textile mills. These
wastes on entering a stream may be of such con-
centration in terms of BOD as to make the water
unattractive, unpleasant, unesthetic, anaerobic,
and reeking with the redolence of fetid putrescence.

There are difficulties in appraising the signifi-
cance of processing wastes in terms of p.p.m. BOD
in the effluent since degree of dilution by water
used during processing will be a primary deter-
minant. It is preferable to evaluate water pollution
potential of these wastes in terms of pounds of
BOD required for wastes produced from a given
amount of product processed.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 45

An excellent summary of available information
on processing wastes has recently been prepared.°
The key data are shown in table 3.

The second column in this table presents data
on the amount of product from farm and forest
that is processed annually.

The fourth column lists the pounds of BOD re-
quired per 1,000 pounds of product processed.

The fifth column lists the potential daily load
of BOD from the processing of a given product
based on a 365-day year. For example, the waste
from corn canneries requires 9.8 pounds of BOD
for each 1,000 pounds of the 2,364 million pounds
of corn processed. Thus, 23 million pounds of BOD
are produced a year or 63,000 pounds per day. But
the corn canning season does not last 60 days, so
that potential daily load of BOD from corn can-
ning during the season may approach 10 times the
63,000 pounds shown in the table.

The sixth column presents the population equiv-
alent (PE) of the BOD load shown in column 5.
One PE of a processing waste is an amount of
liquid waste equivalent in BOD to the normal
sewage contributed by 1 person. The base value of
0.167 pound of BOD per capita per day is used.

Certain comparisons may offer additional clari-
fication. A population of 1 million people will use
about 50 million gallons of water a day to carry
their sewage effluent. Thus, 417 million pounds of
water carry 167,000 pounds of BOD, and the
average BOD of raw sewage would be 885 p.p.m.
Records of BOD of raw sewage indicate that it
ranges from 200 to 400 p.p.m. If the corn canning
industry used 1 gallon of water for each pound of
corn processed, the average BOD of the effluent
would be 1,200 p.p.m. This is well within the
range of values given for effluent of many process-
ing industries (4).

Table 3 shows that the pollution potential in
terms of BOD from the woodpulp industry over-
shadows all other industries listed. The potential
oxidative requirements of the effluent from the
woodpulp, paper, and paperboard industries are
greater than those of the raw sewage from all of
the people in the United States.

Progress in pulp and paper manufacturing
processes to reduce water pollution has been good.

° Hoover, S. R., and Jasewitz, L. B. Agricultural Proc-
essing Wastes. Presented at Amer. Assoc. Ady. Sci.
Symposium, Washington, D.C., Dee. 27, 1966.

In krait pulping, chemicals are now recovered and
oxygen-depleting substances are removed by sedi-
mentation to minimize stream pollution. Better
utilization of byproducts reduces the amount of
material discharged into streams.

In a year’s time, the canning industry produces
potential efluent with oxidative demands that are
double those of the raw sewage from Metropolitan
Detroit; the meatpacking industry, double those
of Metropolitan Chicago; and the dairy industry,
four times those of Metropolitan Boston.

Industry has made progress in efficiently utiliz-
ing many of its wastes as byproducts and new tech-
niques and processes are constantly being devel-
oped. For instance, the sugar industry has found
uses for filter press mud and bagasse; effluents
from food-processing plants are being used as a
source of much-needed irrigation water; a tech-
nique for recovering sugar from pear processing
wastes has been developed; and a process for re-
covery of feed and fertilizer values from chicken
feathers was developed and is in general use.

Infectious Agents and Allergens

Infectious agents from agriculture and forestry
that may be of concern to the general public could
comprise a long list. Such a list would include
brucellosis, which is transferable from diseased
cattle to man; diseases transmitted by mosquitoes
and flies from farm ponds and barnyards, respec-
tively; walnut or ragweed pollen to harass people
with these specific allergies; and a wide array of
insects and plant diseases that may arise on the
farm or from the forest and infest the herbage in
city parks or suburban backyards.

Animal Disease Agents

A study on the Potomac River Basin indicated
the possibility of transmission and dissemination
of such organisms. A number of reports have in-
dicated that the lower Potomac could never be
made safe for swimming because of the prevalence
of pathogenic bacteria. Evidence has been pre-
sented alleging to show that most all of the bac-
terial pollution in the Potomac is coming from
farm runoff.

The presence of coliform bacteria in water has
been used as an indicator of bacterial pollution for
about 75 years. Although coliform bacteria are
rarely capable of inducing disease, their presence

46

TABLE 3.—Estimated pollution loadings of selected agricultural processing industries }

MISCELLANEOUS

PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

5-day BOD
— Potential
Lb. BOD Potential daily
Processing industry Annual per 1,000 lb. daily population
production Data in literature 2 processed load equivalent
(1) (2) (3) (4) (5) (6)
Million pounds 1,000 pounds Millions
CANNERIES:
Apples. Se eee LQ See ee 32 gal. 3,600 p.p.m. BOD per case (24 13.3 44 0. 26
No. 2% cans).
Reachest=o== tee eee 29 Ona eee 50 gal. 2,000 p.p.m. BOD per ease (as 20. 8 169 1. 02
above).
Cornea Se aia eae Co tO OL Mae eee 19.5 lb. BOD per ton corn processed _- _- 9. 8 63 . 38
Momiatoes! aN e Lees OS PASO ee 8.4 lb. BOD per ton tomatoes processed_ 4,2 113 . 68
arama gs (CO GEL) oie se Ve eS cL AEE CUR a eg aT ne ee ay 1, 370 8
CORNAWAE TOME TEN Gia see eel OES (0,0) easter td Uae =e NA opt pe ee 4.5 133 . 80
PE
coTToN (processed through 4, 600____- Sizing? Se 22 ee ee en ee 2
basic dyeing step). Desizingsiey® |. Sees eae es eee 96
yigning Saerege ae ete 2 Bi a ie ae re 108
leaching 2. 2 ets eee ee anaes LG =
SCouringwe te ye ue ae eee 12 68 857 Bt:
Mercenizings 2.06 fee ai ee see 83
Basicidyeings 52552 ie nee eee 90
(per 1,000 lb. goods).
DAIRY:
Eluidemild 22 ek = TOON OO OM ae OSes Ree eee he rae 2 Seal epee ere nena 0 162 1.0
Evaporated milk______ I 1K ees a a eR Mh re tae lps te. Lge dodge 3 49°25 11.6 OM
IN EVD MIS 2s Nae PAI PASS (enna Contest Cle ie cee a) OO 426, 4 157 945
Cheddar cheese_-_-_ ~~ _- NEY Ge DAS Sha ab ame tO CSC) 0 See OE NL SN 424.5 Ue . 465
Cheddari whey, (dried) 22. ~ 20 moercenitiin li7 Oyster to eae epee ase epee eR eee ae 9.7 . 06
of total.
Cheddar whey_-_-_-__-_-_- Nico sees 2 el ees Rea ape a a a I ele 500 3.0
of total.
Cottage cheese________ 1 ADA eee S35 (D3 RUPERT)! 20 ole re a ope eta ay 9h ee 402655 64.5 . 38
Cottage cheese whey_-. 7,500_____ Bay OCS Pyne ite ve Mtr Cares wf LAS Te ea Richa 3 4165 1, 000 6.0
HIDES AND LEATHER ______ 13002 eae 650 gal. 1,500 p.p.m. per 100 lb. hides__- 81 300 @ ils}
MEAT:
Slaughtering and 59,400__--- 14 lb. BOD per 1,000 Ib. live weight _ --- 14.0 2, 300 NBS 7
packing.
PAPER AND PULP:
Wiood) pulps 2s see= == 66:000-2 22% 300i by BOD) per toniof pulpee seas oe 150.0 27, 000 162.0
Paper and paperboard__ 96,600____ 68 lb. BOD per ton of paper___________ 34.0 9, 000 54
POTATOES:
Chips ee Saas 5 aoe fl po 29.3 lb. BOD per ton raw potatoes_____ 14.6 106 . 64
Deby dratedaanaseanes 2 Adee oa 71.1 lb. BOD per ton raw potatoes _____ 35. 6 93 . 58
Flour and starch-_-__--_- 3.2___.... 57 1b. BOD per ton raw potatoes__-__-__- 28.5 91 .55
Frozen french fries____ 5.4______- 22 Ib. BOD per ton raw potatoes__-__-__- 11.0 57 . 34
POULTRY 2 aaa a Su2 002 mane 33ilbsBODEpenadl-000; birdsae ss 10.0 225 1.3
SOAP AND FATTY ACIDS_____ Cgea ee 1.75 lb. BOD per lb. soap made____-___-_ 1, 750. 0 Sr OOks aes eee
SOMBPAIN ey ee alent se Pl, PAO, Seen Nar soy, 1EXOND) joyere OO) lob g ee ee .19 14 . 085
SUGAR REFINING:
Can ee ee nig.) pie Reet 48°. 000E2= = 25:31 ba BOD iperston saa! sae a eeeee
Becton 4 Poa iE ATAGO0D AE WELGLID BOD per tena ual il lute anne hay. 3.0 800 ol
WOOL), SCOURING... 42-2 -_— IOs sees reall, ZO) joy opedle ae ee 267 100 .6

——

1 Hoover, 8. R., and Jasewitz, Leonore B. Agricultural
Processing Wastes. Presented at Amer. Assoc. Adv. Sci.
Symposium, Washington, D.C., Dec. 27, 1966.

2 PE= Population equivalent.
3 Pounds BOD/10,000 lb. milk equivalent.
‘Milk equivalent.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 47

has been taken as an indication that infectious
bacteria might also be present. Coliform counts are
considered to be prime criteria of bacterial pollu-
tion of water.

Coliform bacteria can enter streams by means
of sewage, animal wastes, or runoff from soils since
some coliforms persist in soil. A trained technician
using appropriate laboratory methods can dis-
tinguish between the form of bacteria coming from
animal effluent and those from soil. The former
are designated as fecal coliform bacteria.

Streptococcal bacteria are also normally present
in fecal effluent of both animals and humans.

Kenner, Clark, and Kabler (67) established
ratios between fecal coliform and fecal streptococci
for different pollution sources, as shown in table
4.

Based on such information, water bacteriologists
used as a general guide that if this ratio is less
than one, the pollution is coming from nonhuman
sources; if the ratio exceeds 2.5, the bacterial
pollution is most probably coming from human
sources. Ratios between 1.0 and 2.5 suggest that
pollution is a mixture of human and nonhuman
sources.

Fry (45) has conducted a number of bacterio-
logical examinations at various points on the
Potomac River system. He found that the Potomac
River at Shepherdstown, W. Va., has an average
f. coliform/f. streptococci ratio of 0.072: the
Shenandoah River at Charles Town, W. Va., had
an average ratio of 0.24; and the Potomac River
at Point of Rocks, Md., averaged 0.25. The Monoc-
acy River (Potomac tributary in Maryland) at
a point just below the city of Frederick, Md., had
an average ratio of 4.36, showing that the pollution
was definitely from human sources. However, at
Great Falls on the Potomac (below Monocacy con-
fluence but just above Washington, D.C.) the aver-
age for the ratio was 0.042. Fry concluded from
these observations that most of the bacterial pol-
lution of the Potomac was coming from barnyards
and land runoff.

Although fecal coliform and fecal streptococci
bacteria are rarely pathogenic, they do serve as
indicators that contamination has occurred and
that infectious organisms may be present. It is also
important to keep in mind that a variety of wild
animal species may contaminate streams with lep-
tospira and other organisms.

TaBLE 4.—Average contents of f. coliform and
f. streptococci in fecal wastes of various animals,
and ratio of f. coliform to f. streptococci

F. strepto- F. coliform-
Vertebrate F. coliform cocci {. strep-
tococci ratio
Millions Millions

Cow Sees eee _ 0. 23 Mee 0.18
Biggs. Se ek 2 a= 350 84.0 . 04
DHeept sete ees 16.0 38. 0 . 43
Poultrya meen wabiwe 133 3.4 . 38
AUT ey eee = te) Se . 29 2.8 - 10
IDuCke aE ase eee eee 33.0 54.0 . 61
Mant sey et es as! 13.0 3.10 4.33

Other infectious agents of animals that may pol-
lute streams are as follows: Anthrax, brucellosis,
coccidiosis, encephalitis, erysipelas, foot rot, histo-
plasmosis, hog cholera, infectious bronchitis, mas-
titis, Newcastle disease, ornithosis, transmissible
gastroenteritis, and salmonellosis. Such agents may
subsequently infect other animals, or in the case of
some disease producing agents, even humans.

In late May and early June 1965, 18,000 people
in Riverside, Calif., were infected with Salmonella
typhimurium that had entered into the city’s water
supply. Drinking water for Riverside comes from
deep wells, a source presumed to be beyond bac-
terial contamination. No one has satisfactorily ex-
plained how salmonella got into this water supply.

In view of our large livestock population and
the number of livestock diseases that could afilict
man, the actual number of infections from drink-
ing water is exceedingly low. During the 15-year
period, 1946-60, there were only 16 human deaths
attributable to waterborne agents—eight from ty-
phoid fever, four from chemical poisoning, and
four from infections other than typhoid. This ex-
cellent record is due to the high level of activity
in protecting animal health and curbing dissemina-
tion of animal diseases; and intense vigilance in
monitoring drinking water supplies.

Encephalitis is the most serious mosquito-borne
disease in the United States. It is endemic in virtu-
ally all irrigated regions, but certainly not re-
stricted to these. Epidemics occur in scattered
irrigated areas every year. Such outbreaks can re-
sult in hundreds of cases and scores of human
deaths. Serious epidemics frequently kill hundreds
of horses.

In recent years, encephalitis outbreaks have oe-
curred in irrigated areas in the Texas High Plains,

48 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

the Intermountain States, the Lower Rio Grande
Valley, and the Central Valley of California. In
addition to their avid and pestiferous hunger for
human and animal blood, a few species of mosqui-
toes transmit human and avian malaria, fowl pox,
infectious anemia, as well as encephalitis.

In an irrigated region, the storage reservoirs,
water conveyance systems, farm distribution sys-
tems, and drainage systems provide favorable con-
ditions for the production of mosquitoes, horse
flies, and deer flies. Similarly favorable conditions
are often found in coastal areas and near lakes.
These insect pests give the word “pests” a really
distressful meaning even without transmittal of a
primary infectious agent. Some individuals, espe-
cially children, often require medical attention for
treatment of secondary infection and serious aller-
gic reactions to mosquito bites. These problems,
present in all irrigated areas and in many areas
without irrigation, have resulted in the formation
of organized mosquito control districts and the ex-
penditure of large sums of money. For example, in
California mosquito control districts operate in
over 40 counties. About 75 such districts now oper-
ate in the Western States alone, involving the esti-
mated expenditure of about $9 million annually.

Histoplasmosis is a lung disease of humans. It
is caused by a fungus that thrives on collected
poultry and other bird droppings. Dusts emanat-
ing from such droppings carry the fungus through
the atmosphere. Incidence of human infections are
relatively high in the Middle West and the Middle
Atlantic States (700).

The potential for disastrous outbreaks of com-
municable diseases from livestock is recognized
and a high level of vigilance in disease control is
maintained and consistently improved.

Plant Disease Organisms

The serious impact on agriculture and forestry
of such infectious agents as plant disease orga-
nisms and their vectors is briefly discussed in ap-
pendix I. These organisms have no restrictions in
moving from field and forest to the flora of parks,
streets, highways, and suburban lawns and gar-
dens, and vice versa. About one-fourth of the
dollar sales of pesticides in the United States
comes from small packages sold for use by com-
munity and suburban dwellers. Certainly one can-
not say that plant and tree diseases in nonrural
America arise from agricultural crops and forest

trees, but coping with these infectious agents must
involve all facets of the environment.

Allergens and Poisonous Weeds

Ragweed, goldenrod, bermudagrass, walnut
trees, and a host of other weeds, economic plants,
and trees produce pollens and toxins that cause
serious human allergies even in most of our heavily
populated areas. Allergies reduce working effi-
ciency, impair health, and increase medical costs
of our people.

Allergies from pollen are indeed costly. The
Public Health Service reports that in the average
year, there are 12,646,000 sufferers from asthma or
hay fever, or both. Of these, about 5 million are
asthma sufferers, with about 75 percent of the
asthma cases caused by pollen. The remaining ‘,-
646,000 suffer from pollen allergies. About 10,483,-
000 workdays are lost each year with a loss in
wages—assuming an average daily wage of $12—
of at least $125 million. Loss of production capac-
ity by industry would add to this figure.

Little pollen grains can run up big figures in
human misery.

Poison ivy, poison oak, and other poisonous
weeds cause nearly 2 million cases of skin poison-
ing each year. The resulting 330,000 lost workdays
represent a more than $4 million cost in wages
alone. The loss due to restricted activity would in-
crease this amount.

Fungus spores produced on stored pulpwood
cause sarcoidosis in man. Such spores from stored
maple logs cause human allergies. These fungus
spores are also spread to healthy trees.

Allergies caused by pollen and toxins affect the
use of parks and recreation areas. Health problems
caused by allergens are becoming more widespread
as more people use naturalized parks, campsites,
and other rural recreation areas.

Insect Vectors

During man’s long struggles with a hostile
Nature, the host of human diseases carried by in-
sects and other arthropods has been a veritable
scourge to man’s survival. Livestock, birds, wild
animals, and vermin may also be sources.

Simmons (705) lists a number of diseases, in-
cluding some of the most important diseases in the
world, that can be completely or partially con-
trolled by exterminating the appropriate arthro-
pod vector by a powerful insecticide:

WASTES IN RELATION TO

Malaria Dysentery and diarrhea
Filariasis Amebiasis

Urban yellow fever Leishmaniasis

Dengue Zartonellosis

Onchocerciasis
Sandfly fever
Trypanosomiasis

Virus encephalitis
Louse-borne typhus
Louse-borne relapsing

fever yaws
Trench fever Infectious conjunctivitis
Plague Chagas’ disease
Murine typhus Scabies
Cholera Yick-borne diseases:
Scrub typhus (tsutsuga- Relapsing fever

mushi) Rocky Mountain spotted
Rickettsialpox fever

Knipling (77) estimated that on a worldwide
basis over the first 10 years of use of the insecticide
DDT, 5 million lives were saved and 100 miliion
illnesses prevented. Flies, mosquitoes, lice, fleas,
and ticks constitute most of the vermin involved.
If only a fraction of the pests involved had their
spawning ground in rural areas, one cannot dis-
miss this class of infectious agents as being of sec-
ondary importance.

Insects are also vectors of diseases afflicting trees
and shrubbery, lawns and gardens, and even pets of
urban and suburban residents. The source of the

~ Vector or the infectious agents is often from agri-

cultural, forested, or rural areas.

Agricultural Chemicals

Pesticides, when used properly, have resulted
in great benefits to man and his surroundings. Con-
versely, when misused or used carelessly, they have
caused harm. On balance, the adverse effects have
been relatively minor in relation to the great bene-
fits from pest control.

Use of pesticides continues to increase. In 1964,
693 million pounds of these chemicals were sold
in the United States; 65 percent was used in for-
esiry and agriculture. A study was made based on
a survey of farmers whose sales represented 90
percent of total agricultural sales in the United
States in 1964 (77). Of the farmers surveyed, 94
percent used pesticides to some degree. These farm-
ers spent $456 million on pesticides in 196-4. Sup-
plementary information indicates that farmers
who operated small farms but were not included
in the survey spent about $58 million on pesticides.
Thus expenditures for pesticides by all farmers in
1964 amounted to $514 million.

Insecticides

Insecticides were applied to about 83 million
acres of Jand in 1964. When these chemicals are

AGRICULTURE AND FORESTRY 495

applied directly to the environment, it is obviously
impossible to avoid exposing most, if not all, of
the organisms in that environment to the insecti-
cide applied. Therefore, it is not always possible
to avoid hazards to many nontarget organisms liv-
ing in the same part of the environment treated for
insect control. These chemicals may then move to
other parts of the environment not actually
treated.

Organizations and individuals associated with
conservation and the preservation of wildlife have
alleged that nontarget organisms are unduly jeop-
ardized by the insecticide treatment. Obviously.
most insect problems are now being met by insecti-
cides; and many insecticides currently in use have
a broad spectrum of biological activity. It is not
surprising that a chemical agent that will kill a
harmful insect may also pose hazards to other
animal life.

It is not possible with some current materials
to avoid the destruction of many kinds of beneficial]
insects—and there are far more kinds of beneficial
than of destructive insects. Insect parasites and
predators are helpful in maintaining reasonable
population levels of some destructive insects.

It is hikewise not always possible to avoid expos-
ing many other organisms such as fish, birds, mam-
mals, and other animals that may exist in culti-
vated fields, forests, orchards, rangelands, marshes,
lakes, or streams. While these animals generally
are less likely to be adversely affected by insecti-
cides than beneficial or destructive insects are, sig-
nificant adverse effects have been noted under cer-
tain situations.

The most complex and serious consequences of
environmental contamination with insecticides in-
volve the phenomenon of biological magnification
of residues in tissues of animals. This phenomenon
appears to be limited to the fat soluble pesticides.
Certain organisms may be exposed for long periods
to low-level, persistent insecticides that accwnu-
late in body tissues. These accumulations may not
cause measurable acute effects in these organisms.
However, through food chains the residues may
accumulate to higher and higher levels in tissues
of the succession of animals involved in the food
chain.

In some instances, animals near the top of such
food chains, such as fish-eating birds, appear to
have been killed through such insecticide residue

00 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

magnification. Robins feeding on earthworms liv-
ing in DDT-contaminated soil have been killed.
Wildlife conservationists and others are concerned
over this problem.

An adequate explanation is lacking of how and
why certain insecticides such as DDT become so
widely distributed in organisms throughout the
environment. Conservationists are concerned over
the direct kill of animals that occasionally occurs
because of accumulation of residues, but they are
even more concerned over the possible adverse
effects on reproduction in animals because of a low
level of residues in tissues. The chief culprits in
this problem are the persistent chlorinated hydro-
carbon insecticides that accumulate in animal
tissues.

These persistent insecticides are being replaced
by insecticides that degrade more rapidly in the
environment and that do not accumulate in animal
tissues. However, use of the more persistent types
is still substantial in agricultural and public health
programs.

Pesticide monitoring programs conducted by
Federal and State agencies show that residues of
certain insecticides, particularly DDT, are wide-
spread, not only in soils, but also in the tissues of
fish, wild animals, birds, and man himself. The
significance of these residue levels has not been
established.

DDT residues were detected in the soils of In-
diana orchards at levels exceeding 100 pounds per
acre when 50 to 75 pounds per acre per year were
applied to the trees for 8 to 10 vears. Residues of
endrin or dieldrin have been found in grass, soy-
beans, peanuts, carrots, and other crops. These
residues are generally associated with correspond-
ing residues found in the soil.

The average human in the United States carries
approximately 270 milligrams of DDT or 900 mil-
ligrams of DDT-derived materials, expressed as
DDT, in body fat (52). The human body burden
of these pesticides appears to have remained fairly
constant for several years. Most toxicologists con-
sider these levels to be of no health significance.

The significance of residue levels of DDT and
other insecticides found in fish and wildlife is not
known. In some instances the levels are substan-
tially higher in game animals than the maximum
tolerance set for meat of livestock.

Because of its potential effect on fish and wild-

life, the U.S. Forest Service is restricting the use
of DDT for the control of spruce budworm, pine
tip moth, tussock moth, and other destructive for-
est pests, and substitute materials are used wher-
ever possible.

Some conservationists believe that certain ma-
rine fisheries’ resources, such as shrimp, salmon,
and oysters, may be adversely affected in river
estuaries.

Entomologists are deeply concerned over the
adverse effects of insecticides on insect parasites
and predators. Beekeepers sometimes take heavy
losses in destroyed or weakened colonies because
of insecticide exposure.

The upset in balance of insect parasites and de-
structive insects gives rise to new problems. For ex-
ample, it is generally conceded that mites in apple
orchards now constitute an important pest prob-
lem because the mite predators have been destroyed.
Bollworms have become major pests of cotton.
Their growing importance is due, at least in part,
to the destruction of their natural enemies when
insecticides are applied to control boll weevils and
fleahoppers.

Fungicides

Air, soil, water, and plant contamination by all
types of fungicides does not appear to be significant
even though they are used in large quantities on
certain crops.

The organic mercury fungicides are generally
the most hazardous to man. These compounds are
widely used as seed treatments, but the amounts
per acre are relatively small compared with those
of most other fungicides.

Trace amounts of tetrachloro nitrobenzene
(TCNB) and several of the dithiocarbamate
fungicides have been detected in the total diet
studies conducted by the Food and Drug Adminis-
tration. The levels detected did not appear to
present a problem.

Tolerances set for most currently used fungicides
allow applications at rates needed to control or pre-
vent diseases. However, for the antibiotic, strep-
tomycin sulfate, which is used to control fire blight
of apples and pears, the Food and Drug Adminis-
tration permits no fruit residue. Thus, application
of this antibiotic is restricted to the bloom season,
but this does not allow effective control of this
disease and copper-bearing summer sprays are
necessary.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 51

Treated seed in excess of current seeding needs
may be inadvertently fed to stock by farmers.
Poultry and livestock sometimes are poisoned
from eating seed treated with mercury or other
fungicides. When fungicide-treated seed is de-
tected in shipments of food or feed grain, the
entire shipment is subject to seizure and destruc-
tion. Label directions on fungicides caution
against feeding fungicide-treated grain or inter-
mingling it with untreated grain.

Nickel-maneb fungicides are being used to con-
trol rusts in grass seed fields. A significant amount
of nickel may accumulate in the soil following
repeated applications. This in turn can be taken
up by subsequently grown crop plants. Presently
available information shows no toxic effects on
sensitive plants from 200 pounds of nickel per acre.

Herbicides

In 1964, 97 million acres of agricultural land
were treated with herbicidal chemicals. They have
been tremendously effective in combating weeds.

Herbicides applied to control weeds in one crop
may leave residues in the soil that prevent the
growing of certain crops immediately following
harvest of the treated crop. Losses are minimized
only by restricting subsequent crops to those that
are tolerant to the herbicides used.

Diuron applied for weed control in irrigated
cotton in the western region leaves residues in the
soil which injure vegetable crops such as lettuce,
carrots, cabbage, and cucumbers when planted in
the winter following cotton harvest. Research in
Wyoming showed that residues from an applica-
tion of 2 pounds per acre of diuron persisted in the
soil for 2 years in amounts toxic to oats.

Research in the Mississippi Delta shows that an-
nual applications of diuron for late season con-
trol of weeds can build up residues that would
damage soybeans and oats, but not subsequent cot-
ton crops.

Atrazine, applied to control weeds in corn, re-
mains as a residue in the heavy soils of the north-
central region and often causes severe injury or
prevents the growth of fall-seeded grain crops,
causes damage to spring-seeded cereal crops, and
may prevent the establishment of small-seeded
forage grasses and legumes.

Phenoxy herbicides used to control weeds in tol-
erant crops such as corn, wheat, and rice and on
grazing lands are volatile and they drift. Damage

may occur to nearby susceptible crops, such as cot-
ton, grapes, tobacco, and vegetables. The yield of
cotton can be reduced more than 50 percent by as
little as 0.01 pound of 2,4-D per acre.

Spray drift of 2,4-D, and 2, 4, 5-T from applica-
tions on nearby forests, cropland, roadsides and
rights-of-way has damaged chemically sensitive
trees such as dogwood, paper birch, box elder,
chestnut, black locust, and other shade trees,
shrubs, and herbaceous ornamentals. Damaged
trees and shrubbery create long-lasting, unsightly
conditions on travel routes and in recreation areas.

There are documentable instances in which spray
drift from aerial applications of the phenoxy her-
bicides without adequate precautions have caused
crop injury 10 miles or more downwind from tar-
get areas. In addition to major problems, smaller
incidents occur. For example, when a sprayer that
had previously been used to apply phenoxy herbi-
cides was used for insect control in cotton, more
than 200 acres of cotton in Washington County,
Miss., were damaged before the contamination of
the sprayer was detected. In another instance, a
formulation of the herbicide DNBP, applied as a
preemergence treatment for weed control in cotton,
volatilized and killed an extensive acreage of cot-
ton in the Mississippi Delta. DNBP is no longer
registered for this use on cotton.

The use of herbicides for aquatic weed control
is subject to regulation and restrictions. No organic
herbicides are registered for use in potable water.
Certain herbicides are registered for use in water
that is to be used for irrigation purposes.

The control of aquatic weeds in irrigation sys-
tems improves water conveyance. Many herbicides,
such as diquat, potassium and sodium salts of
endothall, simazine, sodium arsenite, silvex, 2,4-D,
an dichlobenil, do not injure fish at the concentra-
tions required to control most submersed aquatic
weeds. At higher rates they may become toxic to
fish, humans, livestock, wildlife, and crops.

Dalapon and fenac do not harm fish even at
concentration levels far above those required for
aquatic weed control.

Acrolein, chlorinated benzenes, xylene, and
amine salts of endothall are deadly or injurious to
fish at concentrations necessary to control aquatic
weeds and are not registered or recommended for
use in areas where protection of fish is required.

02 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

Sodium arsenite at rates required to control
many aquatic weeds is not toxic to fish. But sodium
arsenite is highly poisonous to humans and all
warm-blooded animals, and extreme caution and
attention to details of application are absolutely
essential when it is used. It has been used exten-
sively since 1930 under rigid State and local regu-
lations with few human fatalities or injuries, or
serious losses of livestock or wildlife. However, its
use is now being generally discouraged in many
localities and States.

Concentrations of ortho dichlorobenzene-xylene
mixtures required to control aquatic weeds in ir-
rigation ditches will damage corn irrigated with
treated water. However, under proper manage-
ment, water so treated can be safely used for irri-
gation purposes. Copper sulfate usually does not
injure bass, bluegill, and certain other fish, but kills
trout at concentrations necessary to control algae.

Copper sulfate is considered safe in drinking water
at concentrations up to 3 p.p.m.

Nematocides

The principal nematocides in use are halogen-
ated hydrocarbons, carbamates, and organophos-
phates. Chlorine and bromine residues persist 1
soil, are taken up by crops, and are a potential
hazard to man via foodstuffs and animal products.
To date no evidence of injury to man or animals
from such residues is known to exist. Although no
immediate health hazards are apparent, chlorine
accumulation is a factor in tobacco production,
and bromine levels above normal are reported in
milk from cows fed fodder grown on nematocide-
treated land. Runoff from fields treated with nema-
tocides and irrigation water to which nematocides
have been added are potential hazards as pollut-
ants.

APPENDIX Ill

Research Underway in Agriculture and Forestry Towards Amelicrating Waste

Production and Waste Managemeni Problems

The current terse review will not permit a listing
of all the research projects active in the U.S. De-
partment of Agriculture and the land-grant uni-
versities pertaining to wastes in relation to agricul-
ture and forestry. Rather, only a few research
activities will be mentioned to illustrate the kinds
of studies that are underway, or have been recently
completed, that are providing needed and useful
information on the subject.

As in the foregoing appendices, the discussion
will be delineated among nine major groups of
entities with one important addition—a section on
socioeconomic studies that pertain to wastes re-
lated to agriculture and forestry.

The subjects touched upon are—

. Radioactive substances

. Chemical air pollutants

. Airborne dusts

. Sediment

. Plant nutrients

. Inorganic salts and minerals

. Organic wastes

. Infectious agents and allergens
. Agricultural chemicals

10. Socioeconomic evaluation

CTS ob ew bob

Radioactive Substances

Concern over radioactive wastes received its
major impetus when the aftermath of Hiroshima
became known. Subsequent emphasis on nuclear
arms as possible instruments in international pol-
icy aroused shock at the possibilities of nuclear at-
tack. The public became anxious to know what
effect radioactivity would have on people, food,
crops, livestock, soils, and water supplies.

Research on the problems of radioactive wastes
in agriculture was initiated in the U.S. Department
of Agriculture and at many State agricultural ex-
periment stations under the auspices of the Atomic
Energy Commission in the late forties. The Atomic
Energy Commission is still the main supporter of

this research, but some financial assistance is de-
rived from the U.S. Public Health Service and
the Office of Civil Defense. The current areas of
research may be divided into reducing the levels
of radioactive contamination in soils or in plant or
animal products and defining more closely the ef-
fects of radiation on plants or animals.

The direct removal of surface contamination
from agricultural land is under study in the U.S.
Department of Agriculture. If radioactive fallout
occurs on crops, part of it may be removed by re-
moving the crop from the land. The larger part,
however, falls to the soil surface and can be re-
moved only by scraping or otherwise cleaning the
soil surface. Cost-effectiveness studies of various
methods are continuing. Any method requires dis-
posal of large volumes of surface soil and, there-
fore, much attention is given to reducing the
thickness of soil removal required for effective
decontamination.

Methods for reducing plant uptake of hazardous
radioactive elements, particularly radioactive
strontium, from soils are being studied by many
groups. Presently, the most active areas of research
are on deep plowing and fixation of strontium in
less soluble forms. Deep plowing, with additions
of various chemicals to inhibit root growth in the
contaminated soil, is under study in the U.S. De-
partment of Agriculture. Various conditions lead-
ing to the fixation of strontium are under study at
different locations: (1) In calcareous soils at the
University of Arizona; (2) with silicone treat-
ments at the University of California at Berkeley ;
and (3) with aluminum phosphates and silicon-
phosphates in the Department of Agriculture at
Beltsville, Md. Soil scientists from Ohio State Uni-
versity are studying the long-term behavior and
movement of strontium-90 in field plots at
Wooster.

Methods for removing radioactive contamina-
tion from plant or animal products have recently

=o
vo

54 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

been studied by several groups. The removal of
such contamination from fruits and vegetables
during processing is being studied at Berkeley,
Calif. Studies have recently been completed toward
improving the separation of strontium-90 from
wheat flour during milling. The commercial re-
moval of radioactive fission products from milk
by an ion-exchange process has been evaluated.

Further studies of radiation effects on plants
and animals are being conducted by many groups.
The U.S. Department of Agriculture is cooperat-
ing with the Office of Civil Defense, Public Health
Service, and the University of Tennessee-Atomic
Energy Commission Agricultural Research Labo-
ratory at Oak Ridge, Tenn., in a study of the
problem of beta radiation dose to plants. This
may be the most important source of radiation to
plants early after fallout, while many of the radio-
active particles remain on the plant surfaces. How-
ever, the problem has been largely neglected to
date. The University of Tennessee-Atomic Energy
Commission Agricultural Research Laboratory
and the New York State Veterinary College at
Ithaca, N.Y., have the most comprehensive studies
of radiation effects on farm animals.

In research that has taken place and is under-
way on techniques for coping with radioactive con-
tamination, we are seeking information we ear-
nestly hope we will never need. But we cannot feel
complacent. We probably will never be able to
feel secure in the adequacy of our knowledge in
this area. If we should ever be lulled into a sense
of security, we could harshly learn the meaning of
the words by old Hecate, the Witch, in Shake-
speare’s Macbeth: “And ye all know security is
mortals’ chiefest enemy.”

Chemical Air Pollutants

As to the vast production of air-polluting chemi-
cals by automobiles, industry, and metropolitan
activity, agriculture and forestry can do little.
Nevertheless, much work has been underway on
the sensitivity of plants and livestock to air pollu-
tants, the injurious components in polluted air,
the effects of pollutants in different plants and
animals, management practices to reduce the ad-
verse effects of air pollutants, and varieties of
plants with higher tolerance of air pollutants. Most
of the research with animals has been concerned

with fluoride injury to cattle and sheep from eat-
ing forage with high levels of fluoride.

The complexity of chemical air pollution prob-

- Jems is indicated by recent studies in the U.S. De-

partment of Agriculture. For example, the dis-
covery has been made that sulfur dioxide and ozone
act synergistically in mixed air to produce injury
to tobacco leaves when levels of the individual
gases used alone are too low to cause injury. The
effects of the combined gases are more than addi-
tive. There is an increasing amount of evidence, as
well, to show that the greatest loss from chemical
air pollutants is from chronic rather than acute
injury; that is, the continued exposure of plants,
such as citrus, for long intervals to toxicants in
photochemical smog significantly reduces growth
of the trees and yields of fruit.

Tremendous quantities of hydrocarbons and
particulates enter the air each year from wild
forest fires so that research information that
enables better forest fire control is exceedingly
important.

Chemical Air Pollutants From Industrial and
Metropolitan Activity

The California Agricultural Experiment Sta-
tion began studies on smog damage to crops in the
Los Angeles area back in the forties. Also at this
time, the New Jersey and Washington stations
began research on fluorine injury to plants. About
this same time, several State agricultural experi-
ment stations (Michigan, Tennessee, Utah, Wash-
ington, and Wisconsin) started work on fluorine
injury to cattle. The U.S. Department of Agricul-
ture began investigations on sulfur dioxide injury
to forest trees and other vegetation at about the
turn of the century. U.S. Department of Agricul-
ture studies on SO. injury to plant life were re-
ported as early as 1905, and to animal life in 1910.
The U.S. Department of Agriculture began its in-
vestigations on fluorine damage to crops in the
early forties.

Plant breeding offers the most promising route
towards minimizing air pollution injury to eco-
nomic crops. Because plant breeders select the most
vigorous plants to maintain a line or variety, they
have inadvertently selected plants within sensitive
species which are most tolerant to prevailing air
pollution. Thus, breeders of cigar-wrapper tobacco
selected plants that were weather fleck resistant for

WASTES IN RELATION TO AGRICULTURE AND FORESTRY r9y9)

at least 5 years before the cause of the injury was
attributed to ozone in the ambient atmosphere.

Spinach is exceedingly susceptible to photo-
chemical air pollutants. Current observations in-
dicate that several spinach lines are tolerant to
certain air pollutants. Crosses have been made to
develop lines and hybrids having a high level of
tolerance to airborne contaminants as well as hav-
ing a resistance to major spinach diseases.

Forestry researchers have made selections of
ponderosa and eastern white pines that are nearly
immune or highly tolerant to specific air pol-
lutants such as SO., F., ozone, and PAN. Genetic
variation in susceptibility has been established.
Clonal lines with high tolerance have been selected
for reforestation in high-hazard areas, and lines
with low tolerance for use as monitors of air pol-
lution. The demand for such clonal materials im-
pelled the research on expediting reproduction of
elite clonal materials. To illustrate the urgency of
this research, trees along highways and in metro-
politan areas may all need to be from resistant
clones.

Some corn varieties are susceptible to fluorine
injury; however, ever-increasing air pollution
show good potential for breeding research in this
species.

Even though relatively tolerant strains are de-
veloped, plant breeders must continue their re-
search. In 1963, cigar-wrapper tobacco growers
around South Hartford, Conn., found that a vari-
ety considered resistant was significantly damaged
by fleck. The point illustrated is that varieties with
higher resistance have high threshold values for
injury; however, ever-increasing air pollution
around metropolitan areas can overtake the thres-
hold values of injury of even the more resistant
varieties.

Air pollution injury has been reduced by appli-
eation of chemicals to foliage. Field and fumiga-
tion tests in California disclosed that a number
of fungicides and antioxidants reduced damage to
beans, lettuce, and endive. Numerous compounds
will reduce ozone injury or weather fleck on
tobacco. Various fungicides and such materials as
ascorbic acid, powdered clay, kaolin, and diato-
maceous earth have been evaluated. It was recently
shown by the U.S. Department of Agriculture that
the application of W,WV’-diphenyl-p-phenylene-
diamine protected tobacco from ozone fleck with-
out evidence of injury to the plant by the applied
chemical.

Research is revealing many difficulties in using
chemical treatments to prevent air pollution in-
jury. For example, treatments may be washed off
by rains or sprinkler irrigation and thereby require
frequent application. The chemical residues from
the treatment may be hazardous to consumers.
Because of this concern over residues, research has
not yet produced a satisfactory chemical treatment
to prevent air pollution injury to crop plants.

Applied research has developed a practical
method of reducing or preventing certain types of
air pollution injury to plants in greenhouses. A
number of greenhouses in California are equipped
with carbon filters to remove ozone and other oxi-
dants. At present, the method is expensive to in-
stall and the filters may need to be replaced after
a few years, or even a few months, of operation.
Evidence of air pollution damage in greenhouses
in the eastern United States is increasing.

Preliminary studies show that cultural pro-
cedures may affect the extent of air pollution in-
jury. Irrigation tends to accentuate the damage.
Levels of mineral nutrients appear to modify the
adverse effects of air pollution. The complexity of
current observations, however, offers no clear-cut
conclusions.

Research underway pertaining to the injury,
and the abatement of injury, of these airborne
chemicals on crops, trees, and animals obviously is
inadequate.

Smoke From Wild Forest Fires

As indicated in appendix II (Organic Wastes),
wild forest fires during the average year emit
hundreds of thousands of tons of hydrocarbons
and millions of tons of particulates into the atmos-
phere. Abatement of this smoke production has
importance in air pollution control besides the
urgent need to minimize decimation of our forests.

The Forest Service began research on forest fire
control in 1923. The three Forest Fire Laboratories
conduct research on the development of (a) fire
danger prediction systems; (6) aerial fire control
methods; (¢) low-cost fire-retardant chemicals:
and (d) infrared fire detection and mapping
techniques.

The importance of the application of these re-
search findings is indicated by the reductions in
fire damage in the National forests from 602,000
acres in 1924 to 92,000 acres in 1963. In 1964, the
average expenditure for fire protection on Federal,

56 MISCELLANEOUS PUBLICATION NO. 1065,

State, and private forest lands was $10,800 per
fire. This figure represents only the cost per acre
of fire protection and does not include any of the
losses inherent in forest fires, such as timber value,
erosion and sediment control, recreation, and
esthetic values. ‘

Research is also underway to develop alterna-
tives to prescribed burning of slash. Various
mechanical, chemical, and biological methods have
been evaluated. Chipping has been used near
urban areas, but it is prohibitively expensive for
most forestry operations. A. more feasible proce-
dure for eliminating slash than by prescribed
burning is highly desirable.

Airborne Dusts

The duststorms of the 1930’s stimulated serious
attention to research on basic causes and effects of
wind erosion and development of conservation
practices to avoid soil blowing. Between 1935 and
1941, soil surveys and serious research on wind ero-
sion were undertaken at Swift Current, Canada,
and at the California Institute of Technology.
Wind tunnels were constructed at Swift Current,
at the California Institute of Technology, at
Brookings, S. Dak., and at Amarillo, Tex., to study
wind erosion problems continually, not just when
they occurred in the field.

Following World War II, special funds were
appropriated under the Research and Marketing
Act of 1946 to establish a cooperative wind ero-
sion research project at Kansas State University.
The most significant research finding thus far em-
anating from this project has been the computer
analysis of a large mass of field and laboratory
data that enables a delineation of the factors hay-
ing major influence on soil blowing. The incor-
poration of these factors into a wind erosion equa-
tion provided an extremely useful management
tool in planning and installing conservation prac-
tices to control wind erosion. Current research is
providing information on basic wind erosion me-
chanics and processes, soil physical properties that
influence erosion, wind erosion climatic factors,
prevailing wind erosion directions, effectivness of
shelterbelts and strip crops, performance charac-
teristics of tillage machines, and effectiveness of
a number of vegetative and nonvegetative surface
films in controlling wind erosion.

U.S. DEPARTMENT OF AGRICULTURE

Research is underway on seeding methods, spe-
cies and varieties of plants adapted to soil stabili-
zation, and management practices and forage sys-
tems designed to maintain satisfactory cover on
range and pasture sites.

Many species of trees and shrubs have been and
are being tested for persistence and suitability
as windbreaks at several locations in the Great
Plains.

From these studies, the species rated the highest
for windbreaks include juniper, ponderosa pine,
honeylocust, Russian olive, Siberian elm, Ameri-
ean plum, common chokecherry, and Siberian
peashrub. Research in the Northern Great Plains
has shown that use of windbreak plantings has
conserved both soil and water. Under experi-
mental conditions, wheat yields have been in-
creased from 18.9 to 27.2 bushels per acre.

Results of research related to soil blowing have
been extensively used by action agencies such as
the Soil Conservation Service and the Federal Ex-
tension Service. For example, the wind erosion
equation is used by the Soil Conservation Service
to provide technical guidance on ranch planning in
the Great Plains and on the vegetable-growing
areas of the Great Lakes and along the Atlantic
seaboard.

Wind erosion research has contributed impor-
tantly to the effectiveness of today’s conservation
and other advanced farming methods in reducing
the threat of future “Dust Bowls” in the Great
Plains. One of the best testimonials to this point
was the experience of farmers in Kansas during
the drought of the mid-1950’s, which records show
was as bad as that of the 1930's. Erosion was not
nearly as serious as it was 20 or 25 years earlier.
Esthetic impact is difficult to measure.

If world food demands impose the need for ex-
panded wheat production under intensive opera-
tions in the Great Plains, the recurrence of another
drought period such as the ones in the thirties and
fifties may well reveal inadequacies in our present
technology to cope with soil blowing. If these con-
tingencies come to pass, research on wind erosion
control will have difficulty just keeping technical
effectiveness from going backwards. Current re-
search is directed toward meeting problems that
are expected to become more serious.

Airborne dust, other than that from soil blowing,
emanates from processing of farm products, such

WASTES IN RELATION TO AGRICULTURE AND FORESTRY

as cotton ginning, feed grinding and mixing, and
most harvesting operations. The dust varies from
small particulates of the product being processed
to fine powders of organic material including
spores and soil that may be attached to or inter-
mingled with the product. Depending on circum-
stances, the dust may fall out quickly or may be
carried long distances by wind.

Research has led to relatively efficient collecting
devices for larger particles. Cyclones—mechanical
dust removers—are widely used on feed grinding
and mixing equipment; when properly designed
and used they will collect all but very fine dusts. If
more stringent requirements for dust removal are
imposed in the future, new techniques will need to
be developed.

Cotton ginning presents a special problem in
that the lint fly is mingled with other dust and both
are exhausted with air used to transport cotton
through the gin. Research to date has greatly im-

roved screens for collecting the lint fly. One major
accomplishment was the development of a self-
cleaning screen to permit continuous operation and
to permit maximum effectiveness of the screen.
Current studies are investigating wet and dry
imertial separators, electrostatic collectors, special
screens to collect very fine particles, and methods
to measure air pollution quantities and distribu-
tions from cotton gins.

The general problem of control of fine particles
suspended in turbulent conveying media, such as
air, is being studied by the U.S. Department of
Agriculture in one of its pioneering laboratories.
Research emphasis is directed toward developing
a mathematical formula to characterize the com-
plex system of fine particles. This would aid in
their measurement, classification, and control.

Sediment

Conservationists in the United States have been
concerned over excessive delivery of sediment from
cultivated land to streams for over 200 years.
Around 1750 Jared Eliot of Connecticut was writ-
ing on the seriousness of soil erosion and stream
sedimentation. John Taylor of Virginia published
a vigorous essay in 1813 on ways to reduce soil
erosion, to control gullies, and to prevent stream-
bank erosion and stream sedimentation. Many
leading agriculturists made a contribution, but let
us especially consider the work of E. W. Hilgard.

eS)
a |

Sediment Delivery

Hilgard must be regarded as the most distin-
guished soil scientist the United States has pro-
duced. From 1855 to 1873, he was State Geologist
of Mississippi. In 1860, he published a book en-
titled “A Report on the Geology and Agriculture
of the State of Mississippi”—a contribution that
is now regarded as one of the “classics” in history
of American agriculture.

Hilgard noted in this book that the brown loam
soils in north-central Mississippi were some of the
most fertile cotton-producing soils in the South.
But he warned that these soils were prone to what
he called “running,” and that unless proper “hus-
bandry” practices were followed, the soil would
run off the fields into the streams filling up the
channels.

Soon after Hilgard’s report was published, the
Nation erupted into a violent holocaust. During
the war years and the turbulent years of the Re-
construction, little, if any, thought was given to
the problems of soil erosion and attendant sedimen-
tation.

That which Hilgard warned might come to pass,
did come to pass.

By the turn of the century, the U.S. Depart-
ment of Agriculture and several State agricul-
tural experiment stations were providing technical
advice on field management practices to reduce
soil erosion and the movement of sediment from
fields to streams. Several States began measuring
soil and water losses from different kinds of lands
in the early 1900’s.

But the decade beginning in 1928 stands out as
the period when the soil and water conservation
movement began to flourish in this country. This
era saw the establishment of soil and water con-
servation programs within the U.S. Department of
Agriculture in both research and operations,
which have evolved as major bulwarks in the con-
servation development of the Nation’s land and
related water resources.

Research was begun and has continued on the
mechanics of erosion and factors influencing ero-
sion processes; mechanics of sediment transport:
principles of sediment deposition in stream chan-
nels and on flood plains; rates and processes of
reservoir silting; sediment burden of streams in
relation to erosion processes in contributing water-

58 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

sheds; and development of methods and systems
for control of erosion and sediment problems.

It has been clearly shown that rates of erosion
and resulting sediment delivery have been greatly
accelerated by man’s use and management of
lands, vegetation, and stream channel systems. It
is also a well-accepted fact that stabilization of the
sediment source by proper erosion control meas-
ures is the most direct approach to solving most
sediment problems. Where the sediment is derived
from sheet and rill erosion on agricultural, forest,
or rangelands, certain agronomic and silvicultural
practices are known to effectively reduce sediment
yields. For instance, changing cultivated fields
from row crops to small grain may reduce soil loss
to sheet erosion by from 60 to 90 percent, depend-
ing on cover conditions, soils, and seasonal distri-
bution of rainfall.

Rotation of crops to include meadow in the crop-
ping sequence may reduce average soil Joss from
fields by 75 percent. Such practices as mulching
stripecropping, and contour cultivation have been
shown to be highly effective in reducing soil ero-
sion on farmlands.

Graded cropland terraces may reduce erosion on
fields by 75 percent, and in combination with crop
rotations, mulching, minimum tillage, etc., can re-
duce to practically nothing soil loss from culti-
vated cropland fields. Converting croplands to
good grasslands, pasture, or woodlands can reduce
soll erosion by 90 percent or more.

At Riesel, Tex., sediment yield from a 132-acre
watershed with good conservation practices (in-
cluding improved rotations, increase in acreage of
permanent grass, and graded cropland terraces) is
only 12 percent of that from an adjacent 176-acre
watershed without conservation practices. On
paired watersheds of 400 acres at Rosemont, Nebr.,
land treatment measures started in 1957 have re-
duced sediment yield by about 50 percent.

The effectiveness of watershed management
practices on National forest lands as stabilizers of
erosion and for control of floodborne sediment has
been clearly demonstrated. Improved grazing
practices, fire protection, contour trenches, and
seeding of perennial grasses have successfully pre-
vented debris-laden flows from the Wasatch Front
north of Salt Lake City, Utah. Adoption of re-
search-derived criteria for location and construc-
tion of logging roads and skid trails has mini-

mized soil disturbance and sediment delivery from
timber harvest operations. Forestry research on
the abatement of wild fires has made a major con-
tribution in diminishing sediment delivery from
forested lands.

Where the primary source of sediment is erosion
from gullies or stream channels, various types of
engineering works can effectively reduce the
amount of sediment delivery to downstream points.
On the 145-square-mile Buffalo Creek Watershed,
for instance, streambank erosion control measures
reduced sediment delivery by 40 percent. During
the same period, sediment delivery by other
streams tributary to the City Harbor of Buffalo,
N.Y., but without stream channel erosion control
practices, increased by about 10 percent.

Mathematical equations of sediment-streamfiow
relations, criteria for designing vegetation-lined
waterways and for streambank erosion control
measures, ratios between sediment delivery and
watershed erosion, and information about the
properties and distribution of sediment in reser-
voirs are also products of this research in the U.S.
Department of Agriculture.

About 10 years ago, data from all of the coop-
erative soil erosion studies were brough? together
at the Indiana Agricultural Experiment Station
where further cooperative research using 2 digital
computer reduced the data to a state permitting
meaningful evaluation of the key determinants in
soil loss, or sediment delivery. A “Soil Loss Equa-
tion” evolved from this comprehensive analysis of
the accrued data.

The findings showed that erosion can be related
to the energy available for dislodgment and trans-
port of soil particles. The energy sources are (1)
falling raindrops and (2) the elevation differences
of sloping topography, which impart energy to
runoit water. Effective contro] measures include
using crop or residue covers to intercept the fall-
ing raindrops and promote water intake, planting
sod crops and crop row barriers to reduce runoff
velocity, and modifying the topography te reduce
slope steepness and length.

The soil loss prediction handbook (136), based
on the results from 35 locations in the United
States, has been used widely by the Soil Conserva-
tion Service and educational institutions in their
programs.

WASTES IN RELATION TO-AGRICULTURE AND FORESTRY 59

‘The data from these studies are used effectively
by educational institutions in teaching conserva-
tion courses and by action agencies in explaining
to potential cooperators the need for and the ad-
vantages from application of the practices to these
lands.

These findings point out the need for application
of effective conservation practices to land areas
and show the tremendous reductions that can be
made in sediment yield. In addition to preserva-
tion of the soil resource for food production, such
measures are necessary to preserve the storage ca-
pacity in water reservoirs; to protect the beauty
and utility of recreational areas, particularly those
that are water based; to reduce highway mainte-
nance costs: and to mitigate the damage inflicted
during urban and industrial expansion.

Slopes once scarred by gullies have been healed
by establishment of grasses and legumes. Contour
striperopped fields have added to the beauty of the
rural landscape.

Clarifying Silted Water

Investigations of the ground water acquifer of
western Texas and Oklahoma and eastern New
Mexico have shown that natural recharge is so
small that pumping is essentially a mining opera-
tion. Depletion of this aquifer exceeds 4 million
acre-feet annually. Natural recharge is about 75,-
000 acre-feet a year. Simple arithmetic reveals the
future of the aquifer. During the average year,
about 1.5 million acre-feet of runoff water is col-
lected in shallow playa lakes that have almost im-
permeable Jake bottoms. This water, which is
almost always wasted by evaporation, is a potential
source for recharge through reverse operation of
irrigation wells.

A study of recharge through multiple-purpose
wells showed a drastic reduction of well pumping
rates caused by clogging of the acquifer pore space
by the clay and silt in the playa lake water. Pump-
ing of the wells removed little of the sediments.
The need to clarify the water before recharge
thereby became urgent. Numerous chemical floceu-
lants have been studied in an effort to develop an
economical clarification system. The flocculation
potential of polyelectrolytes has been intensively
investigated for several years under cooperative
research with the Government of Israel through
authorization in P.L. 83-480 (776) in Israel. From
these studies a model clarification system has been

developed and tests made on the Texas High
Plains. Early results indicate 90 percent of sedi-
ments can be removed; however, considerable re-
search remains to be done before commercial
operation is warranted.

Résumé

The vast magnitude of sedimentation problems
is mitigated by their subtle nature. Many people
are so accustomed to seeing muddy water that they
become indifferent to its presence.

Sediment in the waters of many of our streams
and their associated reservoirs can never be elimi-
nated, but abatement of this water pollutant
should go forward to the full extent practical.
There must be ever-continuing improvement in
technology that will warrant economically feasible
plans and procedures for curbing and controlling
the sediment burden entering and being trans-
ported by our streams.

Plant Nutrients

Major concern over the effects of plant nutrients
in surface waters as a precondition to eutrophica-
tion is rather recent. Research on the behavior of
such nutrients as phosphorus and nitrogen in soils
and soil solutions has been underway for over a
century.

In 1834, at the age of 20, John Bennett Lawes
was given the management of the family estate.
This family farm was called Rothamsted. It cov-
ered 250 acres near the village of Harpenden,
England. While at Eton and Oxford, Lawes be-
came interested in the new science of chemistry.
Working in his home laboratory, he discovered
that treating bone black with sulfuric acid made
the product more effective as a phosphatic fertil-
izer. This suggested using the same treatment on
apatite and other mineral phosphates. In 1842, he
obtained a patent for, and began manufacturing,
superphosphate.

In 1843, Joseph Henry Gilbert, a chemist, joined
Lawes at Rothamsted. They started their histori-
cally famous soil fertility experiment that is still
underway. The effects on crop yields of chemical
fertilizers providing nitrogen, phosphorus, and
potassium were evaluated with comparable levels
of plant nutrients provided in barnyard manures.
The tremendous value of chemicals as sources of
soil fertility soon became apparent.

60 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

Phosphorus

Research on the field application of phosphatic
fertilizers has been underway in the United States
for over 80 years. A number of the State agricul-
tural experiment stations—Illinois, Pennsylvania,
Ohio, and New Jersey, for example—initiated this
early research. As time went on, there also de-
veloped an extensive program of laboratory studies
towards understanding the chemical behavior of
phosphate in soils.

Research showed that some phosphorus is pres-
ent as a natural component of soil-forming min-
erals in all soils. The amount in the 7-inch plow
layer ranges from less than 100 to as much as
4,000 pounds per acre (of soil to the plowed depth).
The average content runs about 1,000 pounds per
acre or about 0.05 percent of the 2 million pounds
of soil in an acre to plow depth. To illustrate, the
Clyde, Brookston, and Claremont soils of Indiana
and Ohio averaged 2,540 pounds per acre, whereas
the Norfolk and Tifton soils of the Atlantic
Coastal Plain averaged only 340 pounds per acre.

Much of the mineral phosphorus content in soils
is not only insoluble in water, but unavailable to
plants. The part of the phosphorus that is not ac-
tually present as crystals of insoluble phosphates
or occluded within grains of other minerals is ad-
sorbed very tenaciously on the surface of the soil
colloids. Phosphate derived from water-soluble
fertilizers is rapidly converted to insoluble forms.

Much research has been done on thousands of
soils as to the soil chemical factors that control
phosphorus availability. In acid soils, freshly ap-
plied fertilizer phosphate is rapidly converted to
various forms of aluminum phosphates, some of
which are crystalline. With the passage of time
these compounds disappear, as the phosphate is
converted to forms of iron phosphate by reaction
with the iron oxides that are an almost universal
component of the soil. In virgin (undisturbed)
soils most of the mineral phosphate is present as
poorly defined but highly insoluble iron phos-
phates.

In neutral and alkaline soils the principal forms
present are basic calcium phosphates. At pH values
above 6 these are very stable and highly insoluble.
Tn addition to the mineral forms, significant quan-
tities of phosphorus can be present in organic
forms, in amounts ranging from 5 to 75 percent of
the total depending upon the character of the soil.

These are also very stable compounds; the availa-
bility of this kind of phosphorus depends mainly
on its rate of conversion to mineral forms.

A marked step forward was made possible in
studying the phosphate chemistry of soils in the
middle twenties by discovery of the ceruleo-
molybdate reaction in which traces of phosphate
reacting with molybdenum in the presence of a tin
catalyst produce a bright blue color that is propor-
tional to the concentration of phosphate. This
colorimetric technique made possible assay of phos-
phorus in soil solutions that contained only 0.1
p-p.m.

A tremendous step forward in research and un-
derstanding of the behavior of phosphate in soil
solutions was made in the midforties when a radio-
active isotope of phosphorus, P*?, became availa-
ble from atomic research. Use of this isotope ena-
bled the researcher to distinguish between the
phosphorus that was inherent in the soil and that
which was applied as a fertilizer. Phosphate ions
that entered into crop plants, into drainage waters,
or became residual in the soil itself could be traced.
The great mass of chemical evidence that has been
attained from research on soil phosphorus shows
very conclusively that phosphate applied to soils
does not move downward into the ground water
or drainage water except in very minute amounts.
Studies of soils in lysimeters have shown this very
clearly. For example, in lysimeter studies at the
Illinois and Wisconsin agricultural experiment
stations (68, 107) phosphate content of the per-
colate was not even measured because there was
such a minute trace.

Cooperative research by the U.S. Department of
Agriculture and the South Carolina Agricultural
Experiment Station (9) involving lysimetric
studies of a Lakeland sand is of special interest.
If phosphorus would percolate downward through
the soil and into the effluent from any soil, it would
do so in Lakeland sand. Phosphate was added to
the soil in the lysimeters at rates varying from
zero to 288 pounds of P.O; per acre. A number of
different crops were grown on the soils so treated.
The amount of phosphate that accumulated in the
leachate was measured over a 5-year period follow-
ing fertilizer application. In the lysimeter that re-
ceived no phosphate fertilizer, the total loss of
P.O; over the 5-year period was 1.48 pounds per
acre. The four lysimeters that had received 288

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 61

pounds per acre of P.O; at the beginning of the
study, lost an average of 1.42 pounds of P.O; per
acre for the 5-year period. This study on a soil
which was amenable to maximum leaching pro-
vides little evidence that phosphorus enters into
drainage water as a result of field application of
phosphate fertilizer.

The excellent experiments on soil loss from ero-
sion carried on by the Missouri agricultural ex-
periment station (84) were very significant in re-
vealing the large losses in phosphorus that would
take place from fields by soil erosion. An experi-
ment was carried out on a Shelby loam soil with
plots 90 feet long, having a 3.86-percent slope.
Where corn was grown continuously, the loss of
phosphorus by erosion was 18 pounds a year. That
is, more phosphorus was lost by erosion in 1 year
than would be absorbed by corn plants producing a
75-bushel crop. Even where a good rotation was
practiced, the loss of phosphorus by erosion was
found to be 6.2 pounds per acre. However, under
continuous bluegrass, only 0.1 pound of phos-
phorus per acre was lost by erosion simply because
grass cover provides such excellent protection
against soil losses. This early research presented
clear evidence that if phosphate is getting into
streams from farmers’ fields, it is getting there by
soil erosion. However, such phosphorus riding on
soil particles is highly insoluble in the water of
the stream.

Other studies have shown similar results. Studies
(98) at the Alabama agricultural experiment sta-
tion indicated that 82 percent of the phosphate
applied to a fine sandy loam soil in Alabama over
a period of 26 years was lost by erosion, amount-
ing to a total loss of 1,430 pounds per acre. Re-
search at the Virginia agricultural experiment sta-
tion measured nutrient losses by erosion from a silt
loam soil on different slopes (94). During a 5-year
rotation of corn, wheat, and clover, 610 pounds of
phosphorus per acre were lost from a 5-percent
slope. The loss of phosphorus was twice as great
on a 15-percent slope. Direct measurement of the
amount of soil eroded showed that most of this
loss took place during the growth of the corn.

The U.S. Department of Agriculture has long-
term studies underway to measure the soluble
unadsorbed phosphate in water from the runoff of
variously treated watersheds in the Appalachian
foothills. This study will provide some information

that is urgently needed on the sources of phos-
phorus in the streams of a watershed.

Nitrate

Research in the U.S. Department of Agricul-
ture has not ignored the movement of nitrate from
fields into surface and ground waters. Nitrate salts
are extremely soluble, and are readily transferred
by water movement. However, this simple rational-
ization by no means implies that the nitrogenous
fertilizers applied to farmers’ fields are the source
of nitrate found in surface and ground waters.

Nitrate salts have accumulated to high ievels
under natural conditions. The high level of ni-
trate salts in the vast accumulation of “caliche”
that took place in geologic times on what is now
the Plateau of Tarabaca in northern Chile stands
as stark testimony to the enormous level to which
natural nitrate accumulation can occur.

Hilgard (55) discovered during his studies on
salinity at the University of California during the
latter part of the 19th century that there were a
number of locations in California and Nevada
where nitrate accumulated in the caliche. He re-
ported that a sample of caliche from the Colorado
Desert of southern California contained 80 per-
cent sodium nitrate, and that a caliche deposit near
White Plains, Nev., contained 50 percent sodium
nitrate.

Headden (53) studied the naturally occurring
“nitre” spots of eastern Colorado during the early
years of this century. He even found nitrate in
ground water 80 feet below the surface. In 1910,
when he first reported this observation, virtually no
chemical nitrogen fertilizer was used in Colorado.
Headden concluded that nitrate was being formed
currently by the biological oxidation of nitrogen
fixed in those spots by nonsymbiotic micro-
organisms. Seliakov (101) came to a comparable
conclusion to explain nitrate accumulation in the
saline soils of Russia.

Nitrate formed in soils by natural processes in
humid climates would be leached out by rain,
whereas they would accumulate near the surface
under arid climates. It is important to recognize
these early studies showing that nitrate may be
formed naturally and may move in the direction
of soil moisture movement, including percolation
to ground water.

The previously mentioned cooperative research
(9) between the U.S. Department of Agriculture

62 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

and the South Carolina agricultural experiment
station involving the fate of plant nutrients added
to Lakeland sand in lysimeters is especially perti-
nent. Lysimeter No. 16 grew no crop and received
no nitrogenous fertilizer except the 25 pounds of
nitrogen per acre received in rainfall over a 5-year
period. Nitrogen recovered in the percolate totaled
153.9 pounds for the 5 years. One could only hy-
pothesize that nitrogen was being mineralized in
this fallow soil, and readily being leached out in
the absence of growing crops.

Lysimeters Nos. 19, 20, 21, and 22, each received
679.1 pounds of total nitrogen over the 5-year
period as fertilizer, manure, and rainfall] additions.
Millet was grown on each of these lysimeters.
Nitrogen in the leachate from these four lysimeters
averaged 18.1 pounds for the 5-year period. It
would be difficult to conclude from this experi-
ment that adding fertilizer to a cropped field con-
tributed to the nitrogen found in the percolate
moving downward to the ground water.

Lysimeter studies were carried out at Cornell
University using a Dunkirk silty clay loam and
growing timothy grass continuously for 8 years.
In one set of treatments, the annual nitrogen ad-
ditions in pounds per acre were 93, 124, 155, and
217; and the annual nitrogen losses in the leachates
were 0.2, 0.2, 0.3, and 1.9 pounds, respectively.
These nitrogen losses to deep percolation under
grass cover were amazingly small.

The Kentucky agricultural experiment station
carried out a lysimeter experiment for 11 years
using Maury silt loam that received no nitrogen
fertilizer. Various forage crops were grown. The
average annual nitrogen losses in the leachates, in
pounds per acre, from the various cropping treat-
ments were as follows: uncropped 74, Korean les-
pedeza 58, alfalfa 9, and bluegrass 5. Kind of
cover may have a tremendous effect on deep perco-
lation of nitrogen even though no chemical is
applied to the soil.

Cooperative research between the U.S. Depart-
ment of Agriculture and Purdue University (74)
has shown that appreciable nitrogen losses can oc-
cur in surface runoff if ammonium nitrate is broad-
cast over the surface of both fallow and sod before
a runoft-producing storm.

Since the advent of high analysis fertilizers in
the 1930’s, considerable research has gone into
designing fertilizer applicators on planting equip-

ment so that the more concentrated fertilizers will
not “burn” the germinating seed, the fertilizer ap-
plied will be protected from runoff losses, and the
minerals will be placed where they will be maxi-
mally utilized by the growing crop. The California
Agricultural Experiment Station studied the ni-
trogen and phosphorus contents in tile drainage
effluent from irrigated areas in the San Joaquin
Valley (63). The amount of phosphorus entering
the drains was insignificant. The nitrogen content
of the drainage effluent varied from 1.8 to 62.4
p-p-m. One area under study during 1962 consisted
of 150 acres in cotton and rice that had received ap-
plication of 23,500 pounds of nitrogen. Assay of
the drainage water indicated that 14,800 pounds of
nitrogen were lost in the drains. That is, 63 percent
of the nitrogen applied went down the drain. This
finding is important in that it shows that there
may be plenty of room for improvement in effi-
ciency in nitrogen use under irrigation.

Research in Hawaii (85) has provided evidence
that water in an aquifer under an irrigated sugar
plantation receiving up to 300 pounds of nitrogen
per acre over a 2-year period may have an appre-
clably elevated nitrate content.

The University of Missouri has made extensive
studies to explain the high nitrate content in cer-
tain crop plants and in numerous samples of
ground water. The research findings indicated that
leachates from feedlots were the main source of
nitrate (or nitrite) in most contaminated aquifers.
The studies revealed that fertilizer nitrogen has
been of little importance in water contamination,
but could become important in the future. These
studies are being continued.

It has been known for many years that certain
well waters in California contain 100 p.p.m. of
nitrate or more, and that many of them contain
more than 10 p.p.m. One well near Riverside, which
yields water containing about 100 p.p.m. of nitrate,
has been used as a source of irrigation water for
over 30 years without material change in nitrate
content (66). The University of California has
research underway to ascertain the sources of ni-
trate found in California wells.’ Special attention
is being given to the 10-square-mile basin occupied
by Grover City and Arroyo Grande. This basin

"Stout, P. R., and Burau, R. Extent and Significance
of Fertilizer Buildup in Soils. Presented at Amer. Assoc.
Adv. Sci. Symposium, Washington, D.C., Dec. 29, 1966

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 63

offers an unusual opportunity to study complete
soil profiles through which nitrate transfer can be
traced from soils to underlying water tables. The
highly permeable subsoils of this basin facilitate
nitrate transmissions from uncultivated soils
downward to the ground water table within two or
three seasons under natural rainfall. Nitrification
occurs very rapidly in soils that have received
sewage efiluent devoid of nitrate. Concentrations
of 90 to 130 p.p.m. of nitrate have been found in
water percolating to the underground reservoir
from well-aerated permeable soils. This important
research is beg continued.

The U.S. Department of Agriculture has in-
itiated cooperative research with the Colorado
agricultural experiment station toward gaining
information on the deep percolation of nitrate
under various land uses in the valley of the South
Platte River. Analyses have been made on 129
cores varying in depth from 10 to 65 feet, as lim-
ited by bedrock or water table depth. Quantity of
nitrate in transit to the water table is emphasized,
but other water contaminants are also measured.
Cores from beneath native rangeland and irri-
gated alfalfa contain insignificant amounts of
nitrate. Those from cultivated dryland fields con-
tain significant amounts of nitrate below the
root zone even though rainfall in the area averages
only 15 inches a year. Slightly larger amounts of
nitrate are found under irrigated fields of corn
and sugar beets. Preliminary evidence indicates
that about 20 to 30 pounds of nitrogen as nitrate
per acre are lost to the water table during the
average year.

Highly variable amounts of nitrate are being
found under cattle corrals. The amount appears to
depend on the corral management, corral age, and
the water content of the profile, which affects
denitrification. As much as 5,000 pounds of nitrate
nitrogen per acre has been found in a 20-foot
protite. Nitrite is detected in the cores from some
corrals. Nitrate was not found in cores where
reducing conditions predominate, indicating that
nitrate is destroyed in profiles under corrals lack-
ing oxygen because of high microbial activity.
Corrals with good manure management from the
esthetic, “public nuisance,” and animal health
standpoint appear to be the worst in relation to
subsuriace contamination with nitrate (108).

Samples from water tables beneath corrals

frequently contained nitrite, ammonia, organic
carbon, and phosphorous. Samples were redolent
with a very offensive odor.

[Inorganic Salts and Minerals

Problems in agriculture related to the accum-
ulation of salts in soils, surface waters, and ground
water are as old as the arts of irrigation that
apparently began some 7,000 years ago in the
valleys of the Tigris and Euphrates (18, 60).

When earth materials weather, small amounts
of soluble salts are released. Under humid climates,
such solubles are leached away ; under arid or semi-
arid climates these solubles tend to accumulate
at the surface as a result of evaporation. Water
transports solubles from one part of the landscape
to another. For example, a desert storm abets such
salt accumulation in a playa basin. Irrigation
water brings solubles from miles away and abets
their accumulation in the irrigated fields unless
they are leached away through a proper drainage
system.

Following the transfer of E. W. Hilgard from
the University of Michigan to the University of
California in 1875, a real beginning occurred in
the United States on research on salinity problems.
Hilgard’s work in California (1875-1906) on the
kinds of salts that prevail in salted soils and
waters, their distribution in the soil profile, and
the relative tolerance of different vegetative spe-
cies to salts still stands as a monumental contribu-
tion.

By the turn of the century, or soon thereafter,
most of the agricultural experiment stations in
the Western States had initiated research pertain-
ing to the salinity or “alkali” problem associated
with irrigation agriculture. The U.S. Department
of Agriculture started investigations im this area
with the establishment of the Office of Western
Irrigation Agriculture in 1905.

W. P. Kelley of the University of California
was one of numerous leaders in salinity research
during early decades of this century. Based on his
research, Kelley set forth in 1934 five primary
points that must be considered in the management
of salt-aifected soils:

1. The adequacy of the drainage condi-
tions.

64. MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

2. The chemical composition of the soluble
salts.

. The content of adsorbed sodium on the
soil.

4. The nature and content of calcium min-

erals in the soil.

The composition and adequacy of sup-

ply of available irrigation water.

The Bankhead-Jones Act of 1935 authorized the
establishment of certain regional research labo-
ratories. The directors of the agricultural experi-
nent stations of the 11 Western States decided on
the establishment of a salinity laboratory. This
came into being at Riverside, Calif., in 1938.

(sx)

Or

The U.S. Salinity Laboratory has carried on a
continuing cooperative research program with the
agricultural experiment stations of the 18 West-
ern States on salt-affected soils, salts in irrigation
and drainage waters, and the reactions of economic
plants to salty water and soils.

Research findings have been made available
through publication in scientific journals and sum-
marized in agricultural bulletins and information
bulletins for use by farmers. Information has gone
directly to engineers and agronomists employed
by action agencies such as the Soil Conservation
Service, U.S. Bureau of Reclamation, water and
drainage districts, and pollution control beards.
USDA Handbook 60 (726), which summarizes
much of the findings up to 1954, has been trans-
lated into four languages and is widely used inter-
nationally as a text and reference book.

irrigation Water Quality

Studies have been underway for a number of
vears, and are continuing more intensively, on
developing sound criteria for assessing irrigation
water quality. Experience has shown that a single-
valued criterion of water quality for irrigation
under average conditions requires a high degree
of subjective judgment in its use. Research data
must be accrued to enable quantitative assessment
of irrigation water quality with reference to soi]
properties, climate, irrigation management, and
salt tolerance of plants.

The research approach underway to meet this
objective is to determine “the potential leaching
fraction” for a given salt-affected soil, taking into
account soil infiltration rate, evapotranspiration
and drainage rates, and the critical water manage-

ment practices, irrigation frequency, and duration.
On calculation of the potential leaching fraction,
the maximum permissible salt content of an irri-
gation water could be calculated by reference to
the maximum permissible limits of salts in the
soil solution for specific crops.

From the maximum permissible salt content of
the soil solution for the specific crops to be grown,
one can determine the fraction of the totai amount
of irrigation water of a given quality that must
be allowed to drain.

The above statement ignores the effect cf com-
position of irrigation water; the tendency of high
sodium waters and, to some extent, of high bicar-
bonate waters to increase the exchangeable sodium
percentage in the soil is an additional complicat-
ing factor.

Another aspect of water quality that needs fur-
ther study is its relationship with hydraulic con-
ductivity. The initial use of high salt water for
reclamation of sodic soils, with the salt concen-
tration of the water decreasing gradually with
time, tends to maintain a higher conductivity and
hence enhances the passage of leaching water.
This can result in drastically reduced time re-
quirements for reclaiming sodic soils.

The research on water quality will not only pro-
vide more rational characterization of water qua-
lity, but will also permit more efficient use of
water having a quality which is partially impaired
by asalt burden.

Soil Chemistry

Much research has been underway over the
years, and is continuing, on cation exchange re-
actions in salt-affected soils. Knowledge of such
chemistry is essential for making sound recom-
mendations on the management of saline anit sodic
soils.

It is known that calcium ions are adsorbed on
clay particles with a much higher energy of reten-
tion than potassium ions are, and that potassium
ions are retained with a higher energy than sodium
ions. The physical properties of soil colloids are
in turn affected by the nature of adsorbed cations.
Calcium-saturated soil colloids flocculate readily,
whereas those colloids predominantly saturated
with sodium tend to be highly dispersed. Soil
with appreciable levels of adsorbed sodium tend
to be intractable and impervious to water. Soils
begin to take on the characteristic of ‘sodium

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 65

soils” when about 10 to 15 percent of the base ex-
change capacity becomes saturated with sodium.
Thus, the base exchange characteristics become
an exceedingly important attribute in predicting
the manner in which waters varying in salt con-
tent will move into, through, and out of soils. The
behavior of soils with respect to adsorbed cations
also varies with the nature of the mineral pro-
viding the adsorption surface, that is, whether it is
kaolinite, montmorillonite, or vermiculite.

“Slick spots” are a common problem in many
areas in the Western States. These are areas in
fields that were at one time salt-affected soils—
specifically sodic soils. The soils became highly
dispersed and relatively impervious to water.
Hence, these “slick spots” are usually manifested
as barren spots in a cropped field. Understanding
the principles of base exchange phenomena afore-
mentioned has been necessary in developing field
technology for reclaiming these salt-affected soils.

Various amounts and kinds of soil amendments
have been used over the years as aids in the recla-
mation of salty soils. Research results have shown
that if the soil is afflicted with an accumulation of
neutral salts and has a low level of adsorbed so-
dium on the soil colloids, then leaching with good
water is all that is necessary for reclamation. Soils
containing appreciable levels of adsorbed sodium,
but also containing calcium and minerals such as
gypsum or calcium carbonate can be reclaimed by
adding sulfur, sulfuric acid, or other acidifying
amendments before leaching. If a soil contains
considerable adsorbed sodium but little or no cal-
cium, then it is necessary to add gypsum to the soil
before leaching. Understanding the principles of
base exchange reactions in soils is fundamental to
developing soil tests and predictive equations in
support of field management decisions on the use
of amendments for reclaiming salt-affected soils.

It has long been held that weathering of soil
minerals is the main process in the production of
soil salts. Recent studies involving spectrographic
analysis have indicated that negligible amounts
of chloride and sulfate salts are released during
the weathering of primarily igneous materials.
Current evidence suggests that too little consider-
ation has been given to the role of accumulation
of fossil salt in soil as the origin of solubles.

Soil Water

The only way that salts can move into, through,
and out of soils is by the vehicle of water. Conse-
quently, studies on the physics of water retention
and movement in soil become fundamental to an
understanding of salt behavior. Soil colloids retain
water molecules tenaciously. Water molecules
closely attached to the surface of the clay may be
held with energy forces equivalent to thousands
of pounds per square inch. Research studies show
that when the water content of the soil drops to
the level called “permanent wilting percentage,”
the water is held on the surface of the clay with
a force equivalent to about 200 pounds per square
inch. When soil is holding about all the water
it can against the force of gravity—a water con-
tent referred to as “field capacity”—the particle
surfaces are retaining the water with a force equiv-
alent to about 5 pounds per square inch.

To understand water behavior in soils and its
role as a salt vehicle requires basic knowledge and
means of measuring the energy status of water in
soils. Attaining such information, as well as de-
signing apparatus that would make meaningful
measurements, has been a key objective of scien-
tists working on salt-affected soils for the past 30
years. The problem of measuring the energy of soil
moisture by an inserted instrument is illustrated
by the fact that the relative humidity of the soil
atmosphere in a soil at field capacity is about 100
percent, whereas the relative humidity in the soil
atmosphere at the permanent wilting percentage
is about 98 percent. Thus, an exceedingly narrow
range in relative humidity prevails over the range
of soil moisture content available for crop growth.
This situation is the basis for the tremendous
difficulties experienced in making psychrometric
measurements of the energy of soil water. Over the
last few years, rapid strides have been made in
perfecting such instrumentation for field work.

Another fundamental need in determining salt
content of soils was instrumentation that would
measure salt content in situ without the tedium
of taking the soil into the laboratory to make
appropriate extractions and measurements. Dur-
ing the past few years rapid progress has been
made in developing a salt sensor that should be
practical for field use.

66 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

Piani Tolerance

Irrigation agriculture must provide for im-
proved growth of crop plants or it has no justifica-
tion for existence. Thus, when soils or irrigation
water have an undue burden of soluble salts, it is
essential to know how much salt various crops
will tolerate at different stages of growth. Re-
search has shown that certain barley varieties are
quite tolerant to irrigation water containing 20,000
p.p.m. of dissolved salt. Sugar beets are very sen-
sitive to salt at the seedling stage but highly toler-
ant after the young plants have become well
established. Beans are very sensitive to salty soils.
Most horticultural fruits are sensitive to salty
sous, but there are exceptions.

A study undertaken to ascertain the effects of
various rootstocks in permitting grapes to be
grown on salty soils showed that the rootstock
tremendously affected the amount of chloride that
accumulated in grape leaves. It was also found that
if the chloride ion accumulated to appreciable
levels in a grape leaf, it could canse necrosis, or
death, of the leaf. When grapes were grown on a
rootstock known as “Salt Creek,” only one-
fifteenth as much chioride accumulated in the
leaves as when grown on “Cardinal” rootstock.
Consequently, grapevines growing in soils having
appreciable chloride salts would show serious in-
jury if grown op Cardinal roots, whereas the same
varieties would show virtually no injury when
grown on Salt Creek roots,

Research is underway in the selection of genetic
lines of Pima cotton that are more tolerant to
saline conditions of the Southwest. Pima S-8, re-
cently released for commercial production, appears
to be considerably more tolerant to saline condi-
tions than the current commercial variety.

Limited research has shown the feasibility of
developing forage grasses that are superior with
respect to establishment, persistence, and yield on
saline soils. Grass varieties differ markedly in salt
tolerance. Evidence indicates that there are good
possibilities in selecting within species for im-
proved salt tolerance.

Research on the nature of salt tolerance and
selection or development of varicties superior in
salt tolerance, will provide valuable information
and planting material in the future. As economic
pressures on water supplies force agriculture to use
more and more water of impaired quality with

respect to salt loading, salt tolerant crops will in-
crease in Importance.

Decreasing Salt in Drainage Water

Plants preferentially absorb water and leave the
dissclved salts in the soil. This preference by
plants for water over salt increases with increasing
salinity of the water. Since this discrimination in
plant absorption is a basic plant characteristic, it
would appear that little can be done to alter the
fact that drainage waters from irrigated areas
will be higher in salt concentration than the orig-
inal irrigation water, and approximately in in-
verse proportion to the change in water volume
during the passage of the water through the plant
root zone. Since virtually all of the salt in the
drainage water was endogenous to the irrigation
water, no substantial decrease in total salt burden
of the water is possible without adversely aifecting
the agriculture of the area. In fact, increasing the
salt tolerance of plants—thereby enabling them to
concentrate the water still further—will only
result in a still greater increase in the salinity of
the drainage water. However, the reduction in
volume of the drainage effluent may be decidedly
beneficial if alternative methods for disposal of
drainage efliuent other than by return to streams
or reusable water reservoirs are developed.

Not all evapotranspiration is beneficial or un-
avoidable. Excessive irrigation, by keeping the
soil surface moist for longer periods, promotes
surface evaporation. In only rare cases is the re-
sultant lowering of soil temperature of definite
benefit to the crop. Therefore, improved irrigation
efficiency will not only conserve water but wii! also
decrease the volume of drainage water and the
quantity of salt that must in some way be venioved
from the crop fields. Research on planting tech-
niques for furrow-irrigated crops has produced
irrigations for thorough leaching of salt out of the
plow layer. This, again, conserves water and
reduces nonbeneficial evaporation of water from
the soi]. The elimination of weeds in fields, and of
phreatophytes along canals and field borders. will
further conserve water and decrease the magnitude
of the saline water disposal problem.

The removal of drainage waters from irrigated
lands, which prevents rising water tables and a
buudup of salt in the soil, is essential for the main-
tenance of the project. The collected drainage

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 67

waters, although commonly returned to rivers,
may—with efficient irrigation management—hbe so
saline that alternative methods of disposal should
be considered. Since some crop plants are 10 times
as salt tolerant as others, the drainage water, al-
though too saline for general use, often has pro-
ductive potential for crops with especially high
salt tolerance. Bermudagrass pastures and seed
crops of some other grasses can be grown with
waters too saline for general agricultural use. The
further concentration of the original drainage
waters by using them on a second salt-tolerant crop
may be an important step in disposing of large
volumes of saline waste waters.

Salinity Reconnaissance

There is 2 pressing need for rapid and effective
methods of evaluating conditions in extensive land
areas. Such information is needed in planning irri-
gation districts, drainage districts, conservation
districts, and river basins. Remedial measures are
more expeditiously applied as knowledge of the
nature and extent of the problems increases. The
occurrence and intensity of soil salinity, the prev-
alence of moisture excesses or shortages, and dis-
ease infestations are kinds of problems where
extensive evaluation is helpful. The use of remote
sensing techniques appears to offer unusual
advantages.

Limited research in this area has been underway
for several years by the U.S. Department of Agri-
culture in the Lower Rio Grande Valley of Texas.
The earlier studies using aerial infrared color film
sensitive to wavelengths in the range of 0.5 to 0.9
micron showed tonal contrasts that correlated well
with measured soil salinity. Recent results reveal
an excellent correlation between leaf temperature
of cotton plants and salinity in the 0- to 5-foot
profile.

The Department of Defense and the National
Aeronautics and Space Administration have de-
veloped information through their research and
development programs that makes possible the use
of optical and thermal techniques in aerial map-
ping of large areas and in detection of environ-
mental conditions important to agriculture.

Little is known, however, of the specific effects
of plant and soil environmental factors on the op-
tical characteristics of land cover and of their re-
lation to specific agricultural problems. This phase
is now receiving direct attention in the research

and development programs of the U.S. Depart-
ment of Agriculture and several land-grant uni-
versities. Fundamental studies seek to establisli
the mechanisms whereby these environmental
factors affect the optical properties of plant ma-
terials and of the soil. From this information,
photogrammetry techniques and identification and
interpretation procedures are being developed for
use in the solution of many land-management
problems involving salinity and the status of soil-
moisture conditions.

Organic Wastes

The Chinese developed procedures for full utili-
zation of agricultural wastes centuries ago (69).
The peasants diligently collected all wastes—hu-
man, animal, and plant—made “patties” out of
them, and allowed them to dry in the sun. The pat-
ties were then stacked until distributed to the fields
at the proper time. Although this old Chinese art
provided for full use of organic wastes, the pro-
cedure has never found favor in the United States.
The point to be emphasized is that organic
wastes can be used, but we rightly insist on using
technology that takes into account health hazards,
social acceptability, and economic feasibility.
Research that pertains to organic wastes may
have one or more of the following six objectives:
1. To better characterize organic wastes.
2. To improve evaluation of the effects of
organic wastes in the environment.
3. To minimize production of organic
wastes.

4, To minimize adverse effects in the man-
agement of organic wastes.

5. To develop waste management and dis-
posal procedures and facilities with
high economic feasibility.

6. To develop technology with higher eco-
nomic feasibility for utilization of these
wastes.

Animal Wastes

Research was underway in the State agricultural
experiment stations on the characterization, han-
dling, and utilization of animal manures before
the turn of the century. The Cornell (New York)
station reported on such research in 1891 (93), and
the Ohio station in 1907 (770). Much of the early
research was oriented towards the use of manure

68 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

as a fertilizer. An excellent summary of this infor-
mation is found in Ohio Agricultural Experiment
Bulletin 605 (96). The conclusion was reached that
the crop production potential of manure is largely
derived from its nitrogen, phosphorus, and potas-
sium contents. The nitrogen in the urine was evalu-
ated as being equally as available as that in min-
eral fertilizers, but the availability of nitrogen in
solids of barnyard manure was considered to be
only 25 to 50 percent of that in chemical fertilizers
depending on the kind and nature of storage.
Availability of phosphorus and potassium in
manure was evaluated as about the same as that in
mineral fertilizers.

In further review of available evidence, the U.S.
Department of Agriculture (32) finds that on soils
of good tilth, manure has value only for its plant
nutrient content; but on soils in poor tilth, manure
has a value above and beyond its nutrient content.

Marked improvements in the techniques for
making fertilizer from atmospheric nitrogen were
made in the period before World War IJ. During
the war, the Federal Government built numerous
plants for the manufacture of fixed nitrogen for
munitions. At the war’s end, these plants became
available for making farm fertilizers at a relative-
ly low price. The price has remained compara-
tively low ever since, whereas other farm costs
have advanced appreciably. This has led to the
situation in which nitrogen from chemical ferti-
lizers is cheaper than that from manure, even if
only handling charges of the latter are taken into
account. This simple economic fact deters use of
manure for land improvement and contributes to
the problem of disposing of wastes that accumu-
late from large operations.

The Illinois Agricultural Experiment Station
(129) has studied the economic value of manure
handling from hog lots. The report on this study
states:

Spreading solid manure on cropland rather than
dumping it in a disposal area is still a profitable
practice because there is little difference between
spreading and disposal costs.

However, liquid handling systems for manure
are of increasing interest for those raising hogs in
confinement systems. The Illinois report also
states:

The most profitable practice for the average
farmer who raises hogs in confinement is to dis-

pose of the liquid manures in a lagoon and use
commercial fertilizer on his fields.
A report (86) of a study at Purdue University
on the economics of handling manure is also of
interest. Three statements are pertinent:
In general, the scale and efficiency of the opera-
tion and prevention of dilution of the manure
determine if the manure can be spread in the

fields at the cost equal to or less than the value of
the nutrients used by the crops.

Aerobie and anaerobie treatment of manure in
special low-cost facilities designed for use on the
farm seem to be practical solutions.

No profitable method of industrial utilization of

livestock manure can be forseen.
The high moisture content. of manure is a major
factor in its bulk handling cost. A number of State
agricultural experiment stations—for example,
Michigan, Nebraska, and New York—have re-
search underway to develop an economical proce-
dure for dewatering manure.

Efficient systems of handling manure analogous
to sewage-handling systems are being developed at
a number of State stations—for example, Massa-
chusetts, Minnesota, Ohio, and South Dakota. The
Pennsylvania station has carried on outstanding
research for using sewage effluent on the land.
Technical Bulletin 675 (58) reports on use of sew-
age effluent for irrigation of cotton and pasture.
The New Jersey station has developed a plow-
furrow-cover technique that tends to conserve the
value of manure, while minimizing its adverse
effects in the environment.

The use of lagoons for disposal of manures is
under study by the U.S. Department of Agricul-
ture and a number of State experiment stations
(33, 34). Many are poorly designed, overloaded,
and misused. The South Dakota station has re-
ported adversely on lagoons. The U.S. Department
of Agriculture is also studying the possibilities of
growing grasses hydroponically in lagoon and
other effluents to remove the plant nutrients
(N, P, & K) and trace elements. This procedure
would keep these nutrients from reaching and
supporting aquatic plant growths in receiving
streams and also help provide additional livestock
feed.

Several experiment stations in the Midwest are
making improvements on the Pasveer system—a
system developed in Holland to handle sewage
from small cities by artificial stirring to improve

SS

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 69

oxidation in a ditch. Promising reports on adapt-
ing this system for animal wastes have ap-
peared, even though animal wastes are much more
concentrated than sewage efliuent.

The Georgia and Ohio stations are investigat-
ing the treatment of poultry manure-litter with
micro-organisms. The treatment permits birds to
be replaced on the same litter and provides an
odor-free and fly-free environment.

Dilution of Organic Wastes in Streams

The adverse effects of animal wastes, sewage,
and processing wastes moving into streams are
conditioned by the flow of the stream. Consider
the Connecticut River. Average annual flow of
this river at Hartford is 10.4 billion gallons per
day. During September and October 1930, the
river reached a low flow of 1.9 billion gallons per
day; and the maximum was 207 billion gallons
per day in March 1936. Let us assume that organic
wastes from sewage, industry, and agriculture
dumped into this river in the Springfield-Hartford
area is equivalent in biochemical oxygen demand
(BOD) to that from the raw sewage of a popu-
lation of 3 million people. That is, it is assumed
that the daily BOD load dumped into the river is
500,000 pounds.

Under average annual flow of the Connecticut,
the added wastes would induce a BOD in the
stream of 6 p.p.m. (Water with 5 p.p.m. BOD is
considered to be on the verge of pollution.) Under
‘ow flows such as occurred in late summer of 1930
and 1966, the specified waste load would induce a
BOD of 31 p.p.m. Under a spring flow of 65 bil-
lion gallons per day, this waste load would induce
a BOD of 1 p.pm. (Water at 1 p.p.m. BOD is
considered relatively pure.)

The flow of the Connecticut is relatively stable.
But consider the Bad River in southwestern South
Dakota. This stream drains a watershed of 3,107
square miles and has an average daily flow of 114
million gallons per day. The Bad is dry 3 or 4
months every year. Peak flow has been recorded at
1.9 billion gallons of water a day. There is high
variability in the amount of organic wastes that
a stream such as the Bad could assimilate.

Engineers concerned with assimilation of wastes
in streams are interested in minimizing degree and
duration of low flows. Research and development

programs on watershed management in the U.S.

Department of Agriculture and land-grant uni-

versities are directly related to nature of stream-
flow.

Foresters have been interested in the relation of
forested watersheds to streamflow for over 100
years. A commission appointed by the Wisconsin
State Legislature in 1867 pointed out the relation-
ship between forest cover and streamfiow. The
American Forestry Congress in 1886 adopted a
resolution relating to the management of public
lands “with a view to maintaining and preserving
a full supply of water in all rivers and streams.”
Research in the National forests pertaining to
water yield began in Colorado in 1910. It became
immediately evident that reductions in forest
cover brought about increased total streamflow
because of reduced transpiration and increased
interception of precipitation at the ground sur-
face. More recent research separating water yield
into seasonal parts indicates the highest percent-
age increase from reduced cover occurs during the
normally low-flow season. A moderate level of
research relating forest cover to water yield is in
progress in most of the major climatic and vegeta-
tion zones.

In the Rocky Mountains of Colorado, studies
have shown that removal of half the lodgepole
pine-spruce-fir forest by strip and block cutting
from a watershed in the snow zone produced about
a 25-percent increase in total annual streamflow.
Most of this increase came mainly during the
spring freshet, but streamflow was also found to
be higher during the summer and autumn follow-
ing treatment.

Cutting woody vegetation in the mountains of
southern California produced an annual water
yield of 1.3 acre-feet per acre of riparian areas, and
0.11 acre-feet per acre of upland deep soils. In both
cases, the streams, which had formerly dried up in
the summer and fall, flowed continuously after
treatment.

At the Coweeta Hydrologic Laboratory in North
Carolina, water yield increased 17 acre-inches per
acre during the first year after all trees and shrubs
had been cut. Maintenance of clear-cut conditions
sustained an increase of 11 acre-inches in water
yield from the experimental watershed for more
than 15 years.

Clear-cutting the mature hardwood cover on a
watershed at the Fernow Experimental Forest in
West Virginia decreased the annual number of

70 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

low-flow days (less than 50 gallons per acre per
day) from 79 to 24 during the 4 years following
cutting. More recent clear-cuttings increased water
yield 6 inches in the 1965 growing season—by far
the driest growing season of record. Attaining this
increase during a drought is remarkable.

One-third of the United States is forested. These
forests, with associated range and alpine areas,
vield about three-fourths of the Nation’s stream-
flow. More than any other lands, the management
of our forests is important to the quality and
quantity of water. Research results indicate that
if studies are continued and improved watershed
practices are applied to suitable areas, the amount
of high-quality usable water available to the Na-
tion can be increased by 14 million acre-feet annu-
ally. Such a bounty would exceed the average an-
nual flow of the Connecticut River, 11.5 million
acre-feet, and approach that of the Colorado
River, 15 million acre-feet. Cost of producing this
extra water from forest lands is expected to be
about $10 per acre-foot—3% cents per 1,000 gallons.

Replacing forest with grass may not increase
water yield. Research at the Coweeta Hydrologic
Qaboratory showed that establishing well-fertil-
ized erass in place of forest produced no increase
in streamflow. With loss in fertility and resulting
poorer grass production, streamflow increased
slightly.

At the Coshocton Hydrologic Field Station in
Ohio, establishing a farm woodlot on a 44-acre
watershed reduced water yield. By the 19th year
after the trees were planted, runoff was 5.32 inches
below what it would have been had it not been
forested. This finding is the inverse of the results
for clear-cutting forests.

Estimates (40) indicate that phreatophytes
(deep-rooted, water-loving plants growing in
flood plains) nonbeneficially use some 25 million
acre-feet of water annually from the subsurface
flow of the streams in the Western United States.

Cooperative research involving the U.S. Depart-
ment of Agriculture, the Bureau of Reclamation,
and the Arizona, New Mexico, and Wyoming agri-
cultural experiment stations is underway to de-
velop economical methods of eliminating phreato-
phytes. Salt cedar is one of the worst pests among
phreatophytes. Studies indicate that applications
of 2,4-D and 2,4,5-T will kill a high percentage
of the top growth, but regrowth from the roots

takes place (7/1). Research indicates that a more
effective chemical method of controlling these
plants is urgently needed.

Forestry research pertaining to the abatement
of wild forest fires is important in the modulation
and continuity of flow of streams arising in forests.
When the surface mulch of the forest floor is
burned, rate of infiltration of rainfall and absorp-
tive capacity of the soil is greatly impaired. Run-
off during the storm becomes excessive, and re-
serve moisture in the burned-over soil is propor-
tionally lessened.

A forest fire started near Yucaipa, Calif., on
July 4, 1950, and burned some 650 acres of chap-
paral-covered foothills. On July 6, while mopup
crews were still on the fire, an intensive thunder-
shower dumped three-fourths of an inch of rain
over the burned and surrounding area. The high
runoff from the burned area caused a flood that
blocked roads, yet little or no water flowed from
adjacent unburned areas.

On a burn, snow cover melts faster during spring
than it does under forest trees. This impairs modu-
lation of streamflow. Also, frost will penetrate
into the soil of a burn and thereby accentuate run-
off. For example, at the Hubbard Brook Experi-
mental Forest in New Hampshire, the soil seldom
freezes in the deep forest, whereas the soil on a
burn would freeze.

The importance of improved technology on
watershed protection for modulation of stream-
flow is indicated by the fact that preliminary plans
for a program for cleaning up the Potomac River
include costly structures to be installed primarily
to avert low flows.

Plant Residues on Farms and Ranches

Farm wastes coming under the category of plant
residues do have uses: bedding for poultry and
livestock; mulch; soil organic matter; a small
amount in ensilage; and some use in manufacture
of corrugated cartons, insulating boards, ete. By
far the greatest use isas a mulch.

Spreading plant residues over the ground has
been referred to in English as “mulching” since
1802. Horticulturists have long been interested in
this use of plant residues. In the early years of this
century, the preferred culture of apple orchards in
New England was that of using a deep mulch un-
der each tree. Use of stubble mulching for erosion
control and economy of operation was attempted

~~~

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 71

at a number of locations on the Great Plains soon
after the turn of the century (77).

The first intensive research in this practice was
started under cooperation between the U.S. De-
partment of Agriculture and the Nebraska agri-
cultural experiment station in 1937. Cooperative
research on this use of plant residues was under-
way in Idaho, Iowa, North Dakota, South Caro-
lina, Texas, and Washington by the early forties.

The research proved conclusively that adequate
residue cover is an effective use for this waste in
controiling wind and water erosion (739).

Use of plant residues as a mulch affected the
chemical, microbiological and physical character
of the soil surface.

Leaving crop residues on the surface may in-
crease or depress yields. Proper residue manage-
ment requires maintaining an adequate supply of
soil nitrogen, controlling weeds, and adapting suit-
abie cropping sequences.

Research has developed machinery capable of
effectively managing residues on the soil surface
and oi planting field grains and soybeans directly
into deep mulch without prior tillage.

Research on chemical weed control has greatly
abetted research on the feasibility of stubble mulch
farming.

Plant residues do sometimes aid in the carryover
of crop diseases and harmful insects. Research has
not yet solved these problems inherent in the use
of mulches.

Trash in Forests

As nointed out in “Organic Wastes” in appen-
dix Ii, some 25 million tons of logging debris are
left in the woods annually. This is a serious fire
hazard. Research is underway to develop ways of
disposing of this trash alternative to controlled
burning, but the probability of discovering an eco-
nomically feasible method is not bright. Burning
costs only $1 per ton; chipping costs $12 a ton.

Processing Wastes

In “Organic Wastes” in appendix IT, data were
presented indicating that the annual effluent of
organic wastes from the pulp, paper, and wood
fiber industry was equivalent in BOD to that of
the raw sewage from a population of 216 million
people. It is obvious that research towards devel-
oping processes that would lessen such waste pro-

duction would be an important contribution to
abatement of stream pollution.

Over the past 25 years, many of the processing
steps in the manufacture of pulp paper and wall-
board have been studied towards better recovery
of byproducts and consequent decrease in stream
pollution. In recent years, pulping factories have
begun to use wood chips from sawmills and veneer
mills. This use of a byproduct is now involved in
25 percent of all pulp produced in the United
States. In kraft pulping, chemicals are now recov-
ered and oxygen-depleting substances are removed
by sedimentation to minimize stream pollution.
Wastes from the older sulfite plants are still a
problem.

In newly built sulfite mills, use of the mag-
nesium-base pulping process developed by forest
products research eliminates much of the polluting
effluent (723). A new polysulfide modification of
the kraft process results in greater pulp yields, less
waste, and reduced air and water pollution.

Cheese whey fermentation processes that lessen
amount of polluting eflluent have been developed,
and are in industrial use. The first process that can
successfully dry the acid cottage cheese whey has
been developed recently (57). This process lessens
waste effluent and is being rapidly utilized.

A technique for recovering sugar from pear
processing wastes has been developed, enabling the
recovered syrup to be used for canning.

A process for recovery of feed and fertilizer
values from chicken feathers was developed and
is in general use (28).

Processes for decreasing the amount of wastes
from wool scouring have been found (4/, 42).

The cost of farm and ranch produce and, par-
ticularly, timber products is such that every effort
must be made to improve technology that increases
product yields and reduces wastes. Since these
wastes have potential economic value for produe-
tion of boards, paper, animal feeds, and chemicals,
the research problems are not so much ones of
waste disposal or elimination for esthetic reasons,
as they are of finding and developing products of
high economic value. Thus, a large part of the
product development research in the U.S. Depart-
ment of Agriculture and the State agricultural
experiment stations ultimately contributes to pol-
lution abatement.

We MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

Infectious Agents and Allergens

A real milestone in civilized progress occurred
in 1864. Louis Pasteur announced as a result of
his beautiful experiments on fermentation that
very minute organisms were the active agents in
the process. Organisms—yeasts—involved in the
development of good wine were found to be quite
different from those that cause wine to go bad.

In 1865, Pasteur isolated bacilli of two distinct
diseases that were killing the siIkworms and ruin-
ing the silk industry in southern France.

Pasteur became the first distinguished research
investigator on the diseases of farm animals. He
isolated the causative organisms and developed
vaccines for chicken cholera, animal anthrax, and
hydrophobia.

Thomas J. Burrill of the University of Illinois
became fascinated with Pasteur’s findings while
traveling in Europe in the early 1870's. He was the
first to show that a plant disease—fire blight of
pears and apples—is transmitted by bacteria
(21). Even before the discoveries of Pasteur and
Burrill, DeBary in Germany had shown that
microscopic fungi caused rust and smut diseases
of plants.

Animal Disease Agents Contaminating the En-
vironment

Before 1848, animal diseases were a minor prob-
lem in the United States. By 1883, the year before
the establishment of an organized animal disease
eradication program, there were 146,388,329 do-
mestic animals on farms, valued at $2,338,241,519.
Hog cholera killed $25 to $30 million worth of
hogs annually. Sheep raising was precarious in
many sections because of scab and parasitic dis-
eases. Tuberculosis and brucellosis were spreading.
Anthrax and blackleg were on the increase in
most States. Texas fever was feared by cattle
raisers. The causes of most of these destructive
diseases were unknown, or in dispute, and live-
stock owners were largely defenseless. Nothing was
known of the extent to which a contaminated en-
vironment abetted transmission.

Contagious pleuropneumonia was such a prob-
lem that our export cattle and sheep were denied
admission into Great Britain. Our pork was pro-
hibited in most of the markets of Europe.

The Bureau of Animal Industry of the U.S.

Department of Agriculture was established in
1884. The wording of the act indicated that the
first duty of the Bureau was to take charge of the
eradication of pleuropneumonia—disseminated by
contaminated air—in cooperation with authori-
ties in the States where the disease existed. The
disease was eradicated in 5 years at a cost of
$1,509,100.72 (122, p. 2) in Federal moneys.

D. E. Salmon, the first Chief of the Bureau of
Animal Industry, U.S. Department of Agricul-
ture, isolated Salmonella bacteria in 1885. There
are over 1,000 strains of these bacteria that cause
salmonellosis in man and animal. This infectious
agent, transmitted by water and food, is still very
much with us.

To find the cause of tick fever was the next task
of the Bureau of Animal Industry. While study-
ing the cause and control of a cattle fever at the
turn of the century, Department scientists dis-
covered that ticks were carriers of the disease. To
the average citizen this might seem to be a bit
of routine information, but it was much more than
that. It was the first positive proof that arthropods
could carry a disease from one animal to another.

Brucellosis organisms may contaminate the en-
vironment. The disease is widespread and costly;
it mainly affects cattle, swine, and goats. The pre-
dominant clinical signs of the disease in pregnant
females are abortions, birth of weak calves, re-
tained placentas, and vaginal discharge, often
followed by a temporary or permanent infertility.
Exposure to infection takes place by ingestion of
contaminated feed and water. Treatment of brucel-
losis in cattle has not been successful. It can be
prevented only by sanitation, good herd manage-
ment, or vaccination, or any combination of them
that may be necessary (75).

Cattle, poultry, swine, and other animals may
be affected by tuberculosis. Theobald Smith dis-
covered that the human tubercle bacteria are not
the same as bovine tubercle bacteria. Tubercle
bacilli usually enter the body via contaminated
food or water. Sometimes they are breathed di-
rectly into the lungs. Control of the disease in
cattle includes environmental sanitation and the
prevention of contamination of healthy animals.
A Federal-State program started in 1917, in which
cattle were tested with tuberculin, infected ani-
mals were killed, and an indemnity paid for
slaughtered animals, has successfully reduced

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 73

bovine tuberculosis from 4,900 per 100,000 to 70
per 100,000 (62).

Anthrax is a disease of all warm-blooded ani-
mals, including man. It is characterized by acute
septicemia. The cause is a spore-bearing rod,
Bacillus anthracis. 'The spores are very resistant
and have been known to survive for many decades
in the soil, in water, or on hides, and then grow
and produce disease when introduced into a suit-
able medium. The first vaccine for anthrax, made
by Pasteur in 1879, was widely used in many parts
of the world for many years. Improved products
are available today.

Tetanus is caused by Clostridium tetani and they
or their spores may be in old farming areas, espe-
cially ones which were heavily manured (90). The
disease is common in people and horses. Active
immunization against tetanus was introduced in
1931 (92).

Blackleg causes greatest losses in catitle-raising
and cattle-feeding areas in the Central West and
Far West. Occasionally, sheep and goats contract
the disease. The spores of Clostridium chauvoei
survive in soil for many years (49). An effective
immunizing product against this disease was de-
veloped by researchers in Kansas (99).

The larvae of the parasite known as Dictyocau-
lus viviparus, which cause verminous pneumonia
in cattle, may survive several months in the soil
(95).

Swine influenza is an acute, highly contagious,
infectious disease caused by the concerted activity
of a bacterium, Hemophilus influenzae var. suis,
and a filterable virus. Swine influenza would die
out except for an ingenious mechanism for sur-
vival. Eggs laid by female lungworms in the lung
of swine sick with influenza contain the virus. The
eggs are coughed up, swallowed, and passed in the
feces. Earthworms ingest the lungworm eggs and
the eggs hatch in the earthworm. The lungworms
develop through several stages and finally imbed
themselves in the hearts and gizzards of the earth-
worm. A single earthworm may harbor 2,000 lune-
worm larvae which are freed on digestion of the
earthworm. Swine root out and eat the earth-
worms with relish, thus setting the stage for the
influenza to infect the animal (202, 103). Sanita-
tion of the environment is the only means of
control.

Listeriosis, an infectious disease, is caused by a
bacterial organism that affects sheep, cattle, swine,
chickens, and other animals. In large domestic ani-
mals, the disease is characterized by central nerv-
ous involvements—encephalitis and paralysis. The
exact mode of transmission of listeriosis under
field conditions is not well known. It may spread
by contact and by contaminated feed and water.

Swine erysipelas is present in the United States
wherever hogs are raised. The organism, L'rysipe-
lothrix rhusiopathiae, may live in the soil as a
saprophyte and can multiply under favorable con-
ditions of moisture in a soil rich in humus. Anti-
biotics alone and antiobiotics with a specific im-
mune serum are useful in treating swine erysipe-
las. Biologics are available te the veterinarian
(104).

Pullorum disease is an infection afilicting the
ege-producing organs of the hen or turkey. It is
transmitted from the hens to the chick through
the egg. Pullorum disease may be spread among
chickens and turkeys through breathing or con-
suming contaminated dust, down, or other mate-
rial in the incubator, shipping box, brooder, or pen.
It is also transmitted through consumption of con-
taminated litter, feed, or water. It is controlled by
detecting and eliminating adult carriers, because
the disease is largely eggborne (135).

Paratyphoid is spread from bird to bird by con-
sumption of litter, feed, or water contaminated
with infected droppings (734).

People can get ornithosis (psittacosis) through
contact with sick birds (57, ch. 10). Infectious si-
nusitis in turkeys may be spread from one genera-
tion to the next through infected eggs and by
direct contact or indirectly by contaminated air
and dust (715). The disease is controlled by detect-
ing and killing infected adults.

Infectious bronchitis of chickens is spread by
direct or indirect contact with infected birds. The
air in the poultry house becomes contaminated
with the virus attached to dust and this may
spread the disease far. It can enter all except spe-
cially constructed poultry houses (65).

Coccidiosis is caused by microscopic protozoan
parasites, which have been known to survive in the
soil and elsewhere for many months (732). Numer-
ous species of coccidia are known and distinct spe-
cies account for the economic disease in cattle,
sheep, and poultry. In general, there are effective
methods of treating the disease (7).

74 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

3lackhead of turkeys and chickens is caused by
a microscopic, single-celled animal, Wistomonas
meleagredis, that attacks the ceca, or blind gut,
and the liver. Occasionally the bird ingests the
naked organism but usually a second parasite, the
cecal worm, Heterakis gailinae, is involved. The
protozoan spends part of its life cycle in the eggs
and larva of the cecal worm. The cecal worm egg
is sturdy and may survive in the soil for a year or
longer. Recently, U.S. Department of Agriculture
scientists learned that eggs of cecal worms are often
eaten by two or three earthworm species (//2).
This leads to a concentration of cecal worms and
blackhead parasites in the earthworms, which are
readily eaten by poultry.

Turkeys also may get hexamitiasis by consum-
ing food, water, or soil contaminated with drop-
pings of infected birds. Research has provided no
satisfactory treatment.

-A number of worms are parasitic to cattle, swine,
and poultry. Many of these can live for long
periods in the soil (122). For example, the eggs
of large intestinal roundworms of swine can live
up to 7 years in soil. Threadworms of sheep may
develop into adult free-living males and females
that can give rise to a large number of infective
larvae in the pasture. Sanitation is the preferred
method of control.

Salmon poisoning is a rickettsial disease of dogs
and other canines, such as foxes, that eat uncooked
salmon or trout parasitized by the intestinal fluke
Nanophyetus salmincola. This fluke carries the
rickettsial micro-organism. The disease is usually
fatal. The disease-carrying fluke requires two in-
termediate hosts to complete its life cycle—a fresh-
water snail and a fish. In streams, each fluke egg
hatches into a miracidium, a free-swimming form
that enters the snail, Oxytrema plicifer. There the
fluke passes through two more stages, emerging
from the snail as larva that penetrates the body
of salmon or other fish of the same family. In the
fish, fluke larvae encyst in the muscles and internal
organs. Research has disclosed that the fluke and
infective rickettsial micro-organisms survived in
migrating salmon for as long as 4 years after fish
were experimentally infected (773).

Tremendous research progress has been made in
the development of insecticides and miticides that
control arthropods transmitting animal diseases

in the environment. (See appendix ITI, “Agricul-
tural Chemicals,” p. 76.)

Plant Disease Agents Contaminating the Envi-
ronment

Most plant diseases contaminate the environ-
ment in one way or another. This whole area of
research is too vast for detailed consideration in
this report, but a few examples of how air, water,
and soil are contaminated by plant disease agents
are in order.

Black shank of tobacco appeared near Quincy,
Fia., about 1915, but was not identified until some
years later. The fungus disease, Phytophthora
parasitica var. nicotianae, can spread rapidly into
new areas and is a serious threat wherever it occurs.
It almost always appears first in a low place in

he field. About midsummer a few plants wilt. In

the early stage one or more of the large lateral
roots are blackened and killed. Then the entire
root system and the base of the stalk decay and the
plant dies.

Black shank is spread by moving contaminated
water, soil, or plants. The disease spores can con-
taminate ponds or streams into which infested
fields drain. In some areas, once a field became in-
fected it remained so, although a rotation of 5 or 6
years might reduce the infection to a trace. In
another locality the disease has never persisted.
The story of developing plants resistant to black
shank begins with the work of W. B. Tisdale at the
Florida agricultural experiment station when he
intercrossed and selected many varieties in order to
develop a resistant commercial shade tobacco (24).

A combination of planting resistant varieties of
tobacco and rotating crops is the best control in
many areas where tobacco is grown (46).

Stem rust of wheat is an example of a plant dis-
ease that may be spread, with disastrous results,
by contaminated air. For example, in 1953, 60 per-
cent of the wheat crop in Minnesota and some
neighboring States was lost. The loss that year for
the whole country was about a quarter of the wheat
crop.

The fungus, Puccinia graminis tritici, causes
stem rust of wheat, barley, and many wild grasses
and is itself a plant. As any other plant, the fungus
germinates, grows, and fructifies. It multiplies by
countless billions, mutates, and hybridizes contin-
uously to form types that may attack varieties of
grain previously resistant or immune to the rust

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 75

disease. Thus, countless kinds were made in the
past and more are continually being made (106).
Control of the disease has been possible through
a continuous program of breeding work to develop
resistant varieties of wheat, oats, and barley.

Red stele disease of strawberry is an example of
a plant disease fungus that can live for many years
in soil even if strawberries are not present. The
fungus spreads through the soil by microscopic
swimming cells known as zoospores. Flood and
drainage water can carry the spores long distances
and thus infect other areas. The disease can be
spread by moving soil on machinery or planting
stock, and such. Several strains of Phytophthora
fragariae, the fungus causing red stele, exist. The
disease is controlled by breeding resistant varieties
of strawberry plants (67).

The Texas agricultural experiment station was
established in 1888, and work started the first week
in March, with “not much being done, however,
until the last week in the month.” After deliberate
consideration it was thought best to take up, first,
a study of a practicable and economical method of
cattle feeding, and second, “a study of the disease
of the cotton plant known as ‘Cotton Blight’ or
‘Root Rot’” (48). Bulletin No. 4 of the station
dated December 1888, is “Root Rot of Cotton, or
‘Cotton Blight’” (97). The general character-
istics, the infectious nature, and the treatment of
the disease were discussed. The statement was
made “It will be somewhat difficult to treat this
disease.” Experience over the past 80 years in the
Blacklands area of Texas has proved that this
comment was an understatement.

Now we know that more than 2,000 species of
wild and cultivated plants are attacked by the soil
inhabiting fungus Phymatotrichum omnivorum,
which causes cotton root rot. The disease has been
one of the more difficult to control. The search for
cotton varieties resistant to the disease has vielded
negative results. The greatest promise of practical
control of root rot appears to lie in the use of
organic manure, particularly in the form of
legumes. The use of organic manures, plus rota-
tion, early fall plowing, and early maturing
varieties, should provide satisfactory control of
root rot (74).

Cabbage yellows is a disease caused by a fungus,
Fusarium oxysporum f. conglutinans. The fungus
can exist indefinitely in soil. It may be dissemi-

nated in soil moved by wind, water, animals, and
man. It is most destructive throughout the Corn
Belt and as far north as central Wisconsin.
Yellows was so destructive in 1910 that research
was undertaken at the Wisconsin agricultural ex-
periment station on the disease. All attempts at
practical control were unsuccessful but, by selec-
tion, a resistant variety, Wisconsin Hollander, was
obtained and released in 1916. Through selection
and hybridization, yellows resistant varieties to
suit most seasons and market requirements have
been obtained. The work of breeding new varieties
to meet changing requirements continues (130).

White stringy root rot of conifers is a disease
caused by the fungus Fomes annosus Fr. and is
present throughout softwood forests nationwide.
It had been observed rotting white pine roots in
the early part of the century but was of small con-
cern. The disease has been a source of considerable
loss in continental Europe where planting has
been an important method of reforestation for
generations. Scientists of the U.S. Department of
Agriculture reported in 1944, as a result of study-
ing white pine plantings at Biltmore, N.C., that
75 percent of previously thinned plots had root
and butt rots. The rots were caused mostly by
FP. annosus.

The disease frequently becomes established
when a healthy conifer stand is thinned. Airborne
spores of the fungus inoculate freshly cut stumps.
The spores germinate and the fungus grows into
the stump roots. Roots of healthy trees in contact
with infected stump roots become infected. Also,
sporophores are produced on the stump, thus a
foci for dissemination of airborne spores is estab-
lished. Once tree roots are infected, the fungus
may survive below ground for 50 years or more
(72).

Based on British experience, creosote has been
recommended for control of 7’. annosus. However,
cooperative research of the U.S. Department of
Agriculture with the Missouri agricultural experi-
ment station suggests other materials such as urea,
sodium tetraborate decahydrate, and borax are
superior to creosote for control (73). The stumps
must be treated after each thinning.

Allergens

Any weed-control practice performed before
flowering will prevent pollen formation. There is
no research underway that is designed specifically

76 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

for the control of plant species, such as ragweed
and bermudagrass, that produce allergenic pollen.
Much has been learned about problem species,
however, through observations incidental to other
research projects.

Information is available for the control of rag-
weed, for example, but that knowledge has not
been put to use in a widescale control operation.
Since the seed is disseminated by wind and can
remain viable in soil for long periods of time,
areawide treatments would be necessary for ade-
quate control.

The prevention of pollen production by trouble-
some weed species would alleviate much suffering
and save many thousands of dollars in medical
expenses.

Agricultural Chemicals

Insecticides

Paul Miiller of Basel, Switzerland, was
awarded the 1948 Nobel Prize in Physiology and
Medicine in recognition of his outstanding work
in development of DDT as an insecticide. Miiller’s
product first showed its dramatic power when used
to control an infestation of Colorado potato beetles
in Switzerland in 1939. During the war years,
researchers in the U.S. Department of Agriculture
determined the value of DDT for controlling a
number of disease vectors, and the insecticide was
used extensively by the Armed Forces to control
arthropodborne diseases. Miliions of illnesses were
prevented ; thousands of lives were saved (71). No
adverse effects on humans were recorded.

Following the war DDT and a number of
similar insecticides were developed for agricul-
tural pests. Extensive use of DDT to control insect
pests of field crops and forests sometimes has re-
sulted in the direct kill of small numbers of fish
and storage of DDT in the tissues of survivors;
sprays used to kill bark beetles that transmit
Dutch elm disease fungus have led to contamina-
tion of earthworms in the soil with DDT and
robins feeding on the worms were sometimes
killed; eagles and other predatory birds were
found with DDT in their tissues. Wildlife con-
servationists became concerned, not only over
possible adverse effects of DDT but also over other
broad spectrum pesticides, including endrin,
aldrin, dieldrin, heptachlor and toxaphene.

Rachel Carson’s book, “Silent Spring,” shocked
the general public. People began to wonder if Miil-
ler’s discovery had not created many more ominous
problems than it solved. Objective evaluation (64,
133) has made a strong case that development of
DDT was indeed a tremendous contribution to
man’s welfare.

Fetention in the Environment.—The U.S. De-
partment of Agriculture began laboratory studies
on the persistence of DDT in soils in 1948 (38).
Soil samples were collected from 85 different lo-
cations infested with the Japanese beetle and
treated with 25 pounds of DDT per 3 acre-inches.
The average results for all soils, based on bioassay,
were as follows:

Persistence after years indicated: Percent DDT
remaining

hy SE ee Ee ee 97

Drees See a apart ee aes Ch sun ee ee 90.

0} Ca Dee ne eee ene ee 79

Fpl tee eer ee reeh see Ue of EA 64

ee lg eC te te le 56

Se Sl SSH EEE LSE eae sO acl A eeey 44

Persistence tended to be greater in sandy than in
fine-textured soils, and to be inversely related to
organic matter content of soil. In soil containing
29 percent organic matter, the persistence after 3
years was 24 percent, whereas in soil containing 0.7
percent, the persistence was 94 percent.

The high degree of persistence of DDT in soil
found in this laboratory study has been confirmed
many times.

Comparable studies (39) showed that chlordane
was somewhat persistent in soil but not nearly so
persistent as DDT. A number of problems related
to the persistence of chlorinated hydrocarbon in-
secticides were discussed in the 1952 Yearbook of
Agriculture (17).

Research toward characterizing the resistance to
degradation of such insecticides as the chlorinated
hydrocarbons still is under intensive study at the
Wisconsin and other State agricultural experiment
stations. The Wisconsin (72, 73) work has shown
that the 10 most important factors that influence
the persistence of insecticides in soils are the chemi-
cal specificity of the insecticide itself, the soil type,
soil moisture, soil temperature, wind or air move-
ment, cover crops, soil cultivation, mode of appli-
cation of the insecticide to the soil, the insecticidal
formulation, and soil micro-organisms. Studies
show that the most important factor among these

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 77

is the chemical nature of the pesticide itself. The
chlorinated hydrocarbons have a very low solubil-
ity in water and tend to be adsorbed on clay par-
ticles and organic matter. Accordingly, these sub-
stances are very resistant to downward leaching.
The Wisconsin studies showed that a silt loam soil
retained 84 to 96 percent of these insecticides In
the surface 3 inches even after 17 months.

Cooperative studies between the U.S. Depart-
ment of Agriculture and the Georgia agricultural
experiment station showed that the nature of the
soil could have a marked effect on the amount of
chlorinated hydrocarbon insecticide removed
under extended leaching with water. When 40-
gram samples of six different soils were eluted
with 1.600 milliliters of water, the results were as
follows:

(az) In general, lindane was the one
most readily leached; 54 to 88 percent
of this chemical was removed from the
six soils.

(6) No trace of endrin was found in
the leachate from three of the soils, but
51 to 95 percent of that added to the
other three soils was leached.

(ce) Dieldrin showed wide variability
in behavior among the six soils. Only 1
percent of the dieldrin was leached
from Magnolia sandy loam, whereas 65
percent was removed from Lakeland
sand. Results from the other four soils
were scattered in between these ex-
tremes.

(d) Aldrin was very resistant to leach-
ing. Only a trace was removed from five
of the soils, and 16 percent from the
Lakeland sand.

(e) Heptachlor also was very resistant
to leaching: none was found in the
leachate from four of the soils, and only
15 percent from the other two.

When one considers this divergent heterogene-
ity among six sandy soils found within a 50-mile
radius of Tifton, Ga., one can surmise what the
results would have been had a wide range of soils
from all over the United States been studied.

In experimental plots in Texas where DDT,
benzene hexachloride (BHC), toxaphene, and
dieldrin were applied to soil and plowed to a depth
of 6 inches, about 20 percent of the amount applied

was found present after 4 years, except for BHC
(1.5 percent of the amount applied was recovered).
When granular dieldrin was applied at the rate of
10 pounds per acre (5 p.p.m. to plow depth) to
three kinds of soils, the residues recovered after 1
year were 14.2 p.p.m. dieldrin in the sandy soil,
4.7 p.p.m. in the medium-textured soils, and 2.3
p-p-m. in fine-textured soils.

Experience has shown that whenever root crops—
potatoes, carrots, sugar beets—are planted in soil
containing aldrin or dieldrin, one can expect to
find residues of aldrin or dieldrin in these root
crops. Research information on the persistence of
insecticides in soils may be vital to a determination
whether major crops, such as alfalfa, sugar beets,
peanuts, and soybeans, can be planted without
hazard of contamination.

Samples of well water and surface water from
the grounds of two U.S. Department of Agricul-
ture laboratories were analyzed by gas chromotog-
raphy. Chlorinated hydrocarbon insecticide had
been used in experimental spraying of livestock
for the contro] of insect pests for 17 years at one
laboratory and 2 years at the other. No insecticide
was found in any of the water samples.

Analyses for DDT and its metabolites in sam-
ples of water from creeks and rivers in areas of
Idaho that had been sprayed to control spruce
budworm showed less than a 0.0002 p.p.m. of DDT
in 66 percent of the samples. Less than 2 percent of
the samples exceeded 0.0013 p.p.m. of DDT.

Cooperative research in Oregon and Washing-
ton indicated that spraying forests for control of
the Douglas fir tussock moth with DDT at three-
fourths of a pound per acre resulted in a general
increase of DDT and its isomers in the food chain
of fish and animals. The highest residue, 1.2 p.p.m.,
was found in trout and the lowest, 0.02 p.p.m., in
herbivores.

The U.S. Department of Agriculture has car-
ried on a monitoring program to ascertain whether
insecticides are accumulating in soils and related
waters as a result of agricultural use. The findings
are typified by results from a study near Green-
ville, Miss.§

*Iverson, L. K. MONITORING OF PESTICIDE CONTENT IN
WATER IN SELECTED AREAS. Presented at Amer. Assoc. Ady.
Sci. Meetings, Washington, D.C., Dee, 27, 1966,

78 MISCELLANEOUS PUBLICATION NO.

This involves 1 square mile in which there is a
slough. This slough retains water draining from
800 acres of surrounding cultivated land. The
rotation followed on this cropland involves soy-
beans, corn, and cotton. Insecticides are used on
these crops whenever necessary for pest control.
Although other chemicals were found in trace
amounts, endrin residues have shown an interest-
ing sequence of analytical peaks which have some
significance.

The treatment history of this study area shows
that an average of 7.5 applications of endrin at
0.3 pound per acre had been applied to cotton
fields since 1956. During 1965, when the follow-
ing data were obtained, the 37-acre cotton field in
the 300 acres being studied received weekly appli-
cations of endrin from July 14 to September 3.
Endrin residues in the soil of the watershed area
under study averaged 0.30 p.p.m. in the spring of
1965 and 0.32 p.p.m. in the fall following the
treatment period.

One part per million equals approximately one
pound per acre in the surface 3 inches of soil. In
the 9 years endrin has been used on this acreage,
a total of approximately 22.5 pounds per acre
had been applied and residues remaining in the
soil amounted to approximately 0.3 pound per 3
acre-inches, or approximately the amount applied
in a single application.

Development of Improved Insecticides —The
public concern regarding certain insecticides that
may impair the quality of our environment is be-
ing met through research on the development of
improved insecticides with a higher degree of de-
gradability, and with minimum toxic effects to
humans, farm animais, fish, wildlife, and benefi-
cial insects. Most every State agricultural experi-
ment station, as well as the U.S. Department of
Agriculture, has research underway on use of less
persistent organic phosphorus and the carbamate
insecticides in place of the chlorinated hydrocar-
bon insecticides.

Following availability of the chlorinated hydro-
carbon insecticides in the forties, research and use
experience soon began to show that these insect
killers were highly persistent in soils and in water.
Of even greater concern, it was found that in-
secticides such as DDT, dieldrin, and heptachlor
would accumulate in animal tissues. Meat and
milk showed high residues when the livestock con-
sumed feeds containing substantial residues of
these materials. When animals were sprayed with
chlorinated hydrocarbons to control flies, ticks,
lice, and other livestock pests, the insecticides were
absorbed through the hide, and residues appeared

1065, U.S. DEPARTMENT OF AGRICULTURE

in meat and milk. Once present in animals the
residues persisted in the tissues for some time,
slowly decreasing for weeks or months. They were
not readily degraded in animal tissues. Wildlife
biologists found that the residues would magnify
in animal tissues through food chain organisms
and even result in death of animals at the top of
the food chain.

Research showed that organophosphorus com-
pounds and carbamates degrade more rapidly in
soils and water and on plants. Even more impor-
tant, these types of insecticides were found to de-
grade rapidly in animal systems, thus the prob-
lem of residues in meat and milk was largely
avoided, and the problem of biological magnifica-
tion in wildlife was prevented. Unfortunately, the
organic phosphorus compounds as a class are gen-
erally more toxic than the chlorinated hydrocar-
bons to man and animals that have had acute ex-
posure. Both classes include materials that are
highly toxic to beneficial insects.

Zectran and stabilized pyrethrins appear, from
current research, as possible substitutes for DDT
in the control of forest defoliators such as the
spruce budworm.

Research on aerial spraying of forest insecti-
cides indicates that the addition of fluorescent
particles to the spray provides an excellent means
to track deposits.

Many changes and adjustments in recommenda-
tions and registrations have been made as the re-
sult of research on the biodegradable properties
of insecticides in soils, water, plant tissues, and
especially in livestock. As a result of these find-
ings, the use of DDT and certain other persistent
insecticides on dairy animals and on crops grown
for dairy foods was discontinued by the late for-
ties. Their use on beef animals and on forage for
beef animals was greatly restricted.

To protect forage crops as well as livestock from
insect attack, such insecticides as methoxychlor,
malathion, and carbaryl, have almost completely
replaced the persistent tissue-accumulating chlori-
nated hydrocarbon insecticides. This has greatly
alleviated the problem of residues in meat, milk,
and poultry products.

Scientists in industry, as well as in public-
supported research institutions, recognize that bio-

degradable insecticides must eventually replace

the nondegradable types in situations \ here wild

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 79

and domestic animals can become exposed to the
insecticides used.

Basic research on degradability, fate, and me-
tabolism of the newer insecticides is accelerating
the solution of the residue problems brought about
through the use of persistent insecticides. In spite
of the progress made, there is still extensive use of
the persistent insecticides in agriculture for con-
trolling insects on nonfood crops, soil insects, and
medically important insects.

Alternate Methods of Pest Control—Although
use of conventional chemical insecticides for insect
control has received much research attention in the
past, most of the current research on insects in the
U.S. Department of Agriculture and the State
agricultural experiment stations is oriented to the
development of ways to control insects by various
biological or physical means, or by developing
highly selective chemicais such as insect attract-
ants to which only the target insect will respond.
Thus, it is hoped to eventually achieve control of
most of the important insect problems without
creating the adverse effect on other organisms that
is so characteristic of broad spectrum chemical
insecticides.

The chief biological methods for the contro] of
insect pests are by the use of other insects (para-
sites and predators) or microbial pathogens.
Foreign exploration for insect parasites and pred-
ators in the native home of pests accidentally in-
troduced into the United States constitutes one of
the important lines of research that has been em-
phasized for more than 70 years.

The first successful introduction of a foreign
predator to control an insect involved the intro-
duction of the vedalia beetle in 1889 to control the
cottony cushion scale on citrus.

The gypsy moth was accidentally introduced
into Massachusetts in 1869. Without natural ene-
mies, it became a ravaging pest of forest, orna-
mental, and fruit trees. In 1905, the State of Mas-
sachusetts and the Federal Government began to
introduce natural enemies of the gypsy moth. The
control of this insect by predators was not at first
highly successful. Alternative hosts for the preda-
tors were not present in this country. However,
continued research on gypsy moth parasites has
developed a situation in which the gypsy moth is
now a relatively manageable pest in most States
even though major control programs are occasion-
ally needed.

The success of early efforts to control insect
pests by introducing beneficial insects has led to
the introduction of a wide range of parasites and
predators. The results of this research approach
have ranged from highly successful to complete
failure.

Imported parasites and predators for control of
balsam woody aphid and larch casebearer have ex-
erted control in some areas. Control of these two
pests is especially encouraging.

The continuing worldwide search for beneficial
insects has produced parasites of such recently in-
troduced pests as the cereal leaf beetle and the im-
ported fire ant.

In the past, most research on biological control
agents was allocated to the collection and release
of biological agents with the expectation that such
agents would survive and multiply on their own,
and thereby play a vital role in control of the tar-
get pest. In recent years, more effort has been allo-
cated to the mass production and sustained release
of biological! agents for direct control of the pest.

Insecis are subject to infection by a wide range
of disease organisms, including bacteria, viruses,
fungi, and protozoa. Most of the research on bio-
logical control of pests has involved microbial
agents. Several hundred kinds of insect pathogens
have been found to cause diseases in insects. Re-
search with laboratory animals and human yvolun-
teers has indicated that certain insect viruses are
not harmful to warmblooded animals, and gener-
ally do not even adversely affect closely related
insects.

Research on the nutritional requirements of in-
sect pests has contributed to a capability to arti-
ficially produce pests en masse. This, in turn, en-
ables production of parasites, predators, and
pathogens in enormous numbers as needed. For
example, cooperative research between the U.S.
Department of Agriculture and Canadian insect
pathologists has enabled the production of a virus
disease of the European pine sawfly. The control
of the Douglas fir tussock moth with polyhedrosis
virus has been brought to the pilot-plant stage.

Insect attractants have been recognized since the
thirties, when considerable work was done on at-
tractants for bark beetles. Only in recent vears has
a widespread interest developed in exploring this
profitable area of research. Insect attractants pro-
duced by plants (food or ovipositional lures), by
insects themselves (sex lures), or synthetically by

80 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

organic chemicals offer a remarkably simple
means of detecting insects and possibly of control-
ling them, when used in conjunction with insecti-
cides or chemical sterilants.

An attractant for the gypsy moth was synthe-
sized several years ago. This substance has been
found to be valuable in making surveys of gypsy
moth populations and significantly reducing the
cost of the surveys.

Eradication of the Mediterranean fruit fly by
the use of a protein hydrolysate bait containing
malathion is one of the most significant recent de-
velopments. Early programs to eliminate medflies
cost millions of dollars; eradication in 1966, at
Brownsville, Tex., cost $200,000 and took only 44
days from the time the outbreak was discovered.
The last eradication effort was aided materially by
the use of another attractant, a synthetic chemical
called “medlure.” The synthetic attractant pro-
vided an effective means of detecting medflies so
that the bait spray could be applied before the pest
had spread over wide areas.

A bait containing peanut oil and a toxicant,
mirex, 1s now used to control imported fire ant.
This bait-insecticide combination permits the con-
trol of this insect by the use of only a few grains of
insecticide per acre. This bait, which is harmless
to fish and wildlife, replaced heptachlor, a per-
sistent residue-forming insecticide that created
hazards to wildlife.

Methyl eugenol, a powerful synthetic attractant
for males of the oriental fruit fly, can be used in
conjunction with an insecticide to eradicate this
insect.

Insect repellents have been used successfully for
protecting man from attack by disease-carrying
and pest insects. Considerable research on repel-
lents for livestock has been conducted with some
success. No effective repellents for agricultural in-
sects have been found.

Varieties or strains of plants that are resistant
to the attacks of specific insects may be selected or
developed. This approach to insect control has
been recognized for many years. In 1860, the grape
industry in France was threatened by a root-feed-
ing aphid from America. The problem was solved
by grafting European grapes on resistant root-
stock from the United States. The first research on
this approach to insect control in the United States
was initiated at the Kansas agricultural experi-

ment station about 1920. In 1928, a sorghum
variety resistant to chinch bugs was released to
growers.

Cooperative State-Hederal research involving
plant breeders and entomologists has developed
varieties of wheat that are highly resistant to the
Hessian fly, one of the major pests of wheat in the
United States.

Excellent progress has been made in the devel-
opment of resistance in field corn to the European
cornborer.

Alfalfa varieties have recently been developed
that are highly resistant or almost immune to
damage by the spotted alfalfa aphid. This intro-
duced pest threatened the alfalfa crops in the
Western States about 10 years ago.

Tree resistance to insect pests has been studied
by forest entomologists since about 1945. Most in-
terest has been focused on developing strains re-
sistant to tree-killing bark beetles. Pine oleoresin
constituents associated with resistance to the
western pine beetle have been identified. This is an
important step toward selecting resistant strains.
A hybrid pine has been found that is resistant to
the pine reproduction weevil.

Crop varieties resistant to specific insects are not
readily attained. Ten or more years of research is
usually required to develop a satisfactory strain.
Farmers generally need solutions to insect prob-
lems as quickly as possible. Research resources are
generally inadequate to carry on both immediate
and long-range solutions to problems.

Self-destruction of insects by methods involving
sterility and other genetic principles offers a new
approach to the control of insects since it was first
investigated about 1950. The screw-worm fly, one
of the most destructive insect pests of livestock, is
now controlled by the release of radioactively
sterilized males. This success has increased efforts
in exploring the feasibility of inducing sterility to
control other major pests. Included are tropical
fruit flies, codling moth, boll weevil, pink boll-
worm, tobacco hernworm, gypsy moth, locust
borer, and the European pine shoot moth. Sterili-
zation offers promise as the primary means for
controlling certain insects, but its greatest value
will be in integrating it with other procedures for
controlling insects.

Research has shown that insect sterilization can
be accomplished in three ways—by the use of

=

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 81

atomic radiation, by use of chemicals that sterilize
insects, or by achieving genetic sterility by cross-
ing genetically incompatible lines.

Bioenvironmental methods of controlling in-
sects continue to offer promising lines of research.
The approach has a long history since such meth-
ods were among the few ways of controlling in-
sects before the development of most modern in-
secticides.

Cultural control methods tiat are desirable
agronomic practices are often readily adopted.
When such measures are based on a modification
of necessary farm operations, they are cheap
methods of control. Fall plowing results in high
mortality of overwintering forms of the corn ear-
worm and the European corn borer, and thereby
reduces the number of adults that emerge the fol-
lowing spring.

Infestation of the grapeberry moth has been
greatly reduced by burying the overwintering
cocoons under a layer of soil so that the moths are
unable to emerge and make their way to the sur-
face in the spring.

A mechanical method of controlling cotton boll
weevils is being developed. It involves picking up
and destroying cotton squares that have been
punctured by weevils, killing the larva, and break-

-ing the life cycle.

Burning trash in sugarcane fields has destroyed
as many as three-fourths of the overwintering sug-
arcane borers.

Destruction of tobacco stalks after harvest re-
duces the number of late-stage tobacco worms, to-
bacco budworms, and corn earworms.

Production of mosquitoes, horseflies, deerflies,
and other pests that breed in aquatic and semi-
aquatic habitats can be minimized and in some
cases prevented by proper alterations of the en-
vironment and by appropriate water management
procedures.

Logging western pine on a selective basis—
“sanitation salvage’—prevents the tree-killing
western pine beetle from getting a foothold in the
stand. This approach was the basis for studies in
California showing that the trees most susceptible
to attack could be identified by visible
characteristics.

The insecticide era brought about curtailment in
the study and practical use of many cultural prac-
tices for insect control. Yet, with insects becoming

resistant to many insecticides and the emergence
of many problems resulting from insecticide resi-
dues, there is a resurgence of interest in research
towards improving cultural contro]. In some cases,
cultural and bioenvironmental methods may elim-
inate the need for using insecticides or may re-
duce the number of applications required. This
would contribute to the avoidance or amelioration
of contamination in the environment.

Electromechanical devices for capturing and de-
stroying insects are receiving more and more re-
search attention. The attractiveness of various
wavelengths of radiation for stimulating responses
in insects has been known for many years. Until
recently, practical usefulness of the approach has
been quite limited. Extensive early work on light
traps for such insects as the European cornborer,
tobacco hornworm, and codling moth failed to pro-
vide practical results. In 1952, cooperative re-
search between the U.S. Department of Agricul-
ture and the Texas agricultural experiment station
revealed that the pink bollworm moth was readily
attracted by radiation in the near ultraviolet
region (black light).

The Indiana agricultural experiment station
found that insect traps equipped with blaciz-light
lamps were effective in reducing losses due to
cucumber beetles.

Recent results of a 3-year experiment showed
that using three black-light traps per acre in a
large-scale experiment, integrated with other con-
trol procedures, reduced tobacco hornworm popu-
lations and greatly curtailed the need for
insecticides.

The more favorable results experienced recently
with electromechanical devices arise from a new
concept in experimental design. Traps are used in
sufficiently large areas to provide treatment of the
total population, or a large serment of the popula-
tion, to limit the influence of immigrating insects.
The favorable results have renewed research inter-
est in practical black-light techniques. This has
stimulated research on other forms of electromag-
netic radiation as a means of trapping insects for
destruction.

Herbicides

About the earliest research on selective herbi-
cides in the United States took place at the North
Dakota agricultural experiment station during the
first years of this century (75). Inorganic chemi-

82 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

cals such as common salt, iron sulfate, copper sul-
fate, and sodium arsenite were evaluated and
found to have promise for selective weed control
under selected conditions.

Following this initial work, interest in use of
selective herbicides to control weeds did not thrive
in the United States until the forties. During the
period 193442, scientists at the Boyce Thompson
Institute reported the results of their research on
the responses of plants to synthetic growth regu-
lators. In 1942, they were the first to report (138)
that 2,4-dichlorophenoxyacetic acid had properties
of a growth regulator when applied to plants in
very dilute concentrations. Two years later, a
report from research in the U.S. Department of
Agriculture (76) indicated that an application of
2,4-D killed dandelion, plantain, and other weeds
in a bluegrass lawn.

From this point, research on a wide array of
organic chemicals for use as possible herbicides
boomed. Commercial use of 2,4-D and related
chemicals expanded rapidly during the sixties.

Persistence in the Environment.—In the sum-
mer of 1959 a tolerance of zero was established
for the herbicide amino irlazole. Research had
shown that this compound might be capable of pro-
ducing cancer in test rats when it was fed at high
levels. Under the Delaney amendment to the Fed-
eral Food, Drug, and Cosmetic Act a tolerance of
zero was mandatory.

The registration and recommendations for the
use of amino triazole for weed control in cranber-
ries specified that the chemical be applied only
after the berries had been harvested. Some grow-
ers did not follow these recommendations.

On November 9, 1959, the seizure of lots of cran-
berries containing illegal residues of amino tria-
zole was announced. Large blocks of cranberries
were seized, and the market for cranberries was
demoralized within 24 hours.

Cranberry growers vigorously denounced the
manner in which the seizure action was taken. Re-
gardless of the pros and cons of the situation, the
public was alerted to the problem of the use of
pesticides in the production of foods.

U.S. Department of Agriculture and the State
Agricultural experiment stations are continually
carrying on studies on how different herbicides
might contaminate soil, water, and crops. This re-
- search begins well before the first experimental

label is granted and usually continues as long as
the herbicide is used.

Scientists are concerned with several problems
involved in the persistence of herbicides in differ-
ent kinds of soil: Nature and capacity of the ad-
sorption complex, photodecomposition, chemical
reactivity, microbial degradation, vapor transfer,
and leachability.

Adsorption of a herbicide by a soil (30) is de-
termined by the specific surface of the soil, organic
matter content, the nature of the ciay mineral,
moisture status, temperature, nature and degree of
base saturation, and structure and polarity of the
herbicide molecule. Specific surface of soils may
vary from 300 square centimeters per gram for a
sandy soil to over 30,000 square centimeters per
gram for clay. Adsorption of organic molecules
such as herbicides is also determined by the nature
of the adsorbing surface. For example, montmo-
rillonite clay, kaolin clay, and colloidal organic
matter differ in their adsorbing specificity. There
is wide diversity in the extent to which the adsorp-
tion mechanism of a soil affects persistence and de-
activation of the many different herbicides.

Amino triazole forms relatively stable com-
plexes with metal ions in soils (109). Formation
of the complex detoxifies the herbicide.

Hydrolysis and oxidation of herbicides in differ-
ent soils under varying conditions have received a
modest level of research attention (50). The wide
diversity of conditions involved in this research
has not opened up a path to sweeping generaliza-
tions (44, 78).

Probably one of the most important factors re-
sponsible for the detoxification of herbicides in
soils is the soil micro-organisms. Their importance
in the detoxification process is readily apparent
when one compares the persistence of a herbicide in
sterile and nonsterile soils (728). With few excep-
tions, herbicides in the latter are detoxified far
more rapidly than in the former. Soil bacteria,
fungi, and actinomycetes have been implicated as
the most important agents in the degradation proc-
ess. Soil micro-organisms either possess constituent
enzymes or can be induced to form enzymes to
catalyze the breakdown of many diverse organic
herbicides. Many of these micro-organisms have
been isolated and identified, and in a few cases, the
enzyme responsible for carrying out the initial de-
toxification reactions have been isolated and char-

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 83

acterized. It is largely because of the activity of
these soil micro-organisms and other dissipation
mechanisms that most herbicide residues in the
soil are not showing a progressive buildup.

Phytotoxic residues of herbicides may persist
longer in soils when the herbicides are applied in
combination than when each is used individually.

The degree to which a herbicide is soluble in
water or is adsorbed on soil particles determines
leachability of the herbicide by rain or irrigation
water (127). Obviously, the amount of water mov-
ing through the surface soil is an important deter-
minant in the amount of herbicide leached away.

Klingman (70) has summarized research infor-
mation on persistence of herbicides in soils, For
some uses, 2,4-D is not completely satisfactory be-
cause it lasts only 1 to 4 weeks. On the other hand,
simazine applied as a soil sterilant may persist for
2 to 4 years or more. The evidence does indicate
that the adverse effects of persistence of herbi-
cides are those upon succeeding crops.

Cooperative research by the U.S. Department of
Agriculture and the Arizona, California, and Mis-
sissippi Agricultural Experiment Stations was
carried out over several years on the presistence
of herbicides in cotton fields. Use of repeated an-
nual application of dichlobenil, trifluralin, di-
phenamid, DCPA, monuron, diuron, and linuron
on weeds in cotton caused no buildup of the chemi-
cals to levels harmful to cotton. By contrast, treat-
ment of the cotton fields with diuron, trifluralin,
linuron, prometryne, or dimethyl 2,3,5,6-tetra-
chloroterephthalate (DCPA) resulted in residue
accumulations that were toxic to succeeding crops
of barley, milo, oats, soybeans, and sugar beets.
This research confirmed the need for existing re-
strictions on the use of several herbicides.

Potentially the most serious problems associated
with the use of herbicides are their (1) downward
movement in the soil to depths of 4 to 15 feet
where degradation mechanisms are relatively inef-
fective, and (2) movement from large watersheds
into drainage systems and our major water
resources.

Inactivation and dissipation rates of herbicides
in soils vary widely. Cereals planted in the fall
after crops have received summer applications of
1 to 4 pounds per acre of such herbicides as atra-

zine, simazine, and diphenamid have been injured .

by phytotoxic residues. Injury to soybeans, sugar

beets, oats and forage grasses and legumes has
been encountered in some instances 10 to 12 months
after application of atrazine to corn. Tobacco, cot-
ton, peanuts, and soybeans have been injured by
fenac residues 1 to 2 years after application at
rates used for selective weed control in corn.

Certain of the benzoic, phenylacetic, and pico-
linic acid herbicides persist in soils for several
years. These same chemicals, especially 2,3,6-TBA
and fenac may often move downward in soils
through volatilization and percolating water. In
the arid areas of the Great Plains, phytotoxic resi-
dues of the benzoic and phenylacetic acids have
been detected at depths of 4 to 12 feet in certain
soils. Single applications of these herbicides are
used to control deep-rooted perennial weeds such
as field bindweed (Convolvulus arvensis L.) at
rates of 4 to 40 pounds per acre. However, when
these herbicides move 4 to 12 feet downward in the
soil, they are not readily degraded and thus pose a
potential problem, if these uses should become
extensive.

Although low levels of phytotoxic residues of
the substituted urea and s-triazine herbicides and
some of the phenylacetic and benzoic acids have
persisted from one season to the next, data from
many sources indicate that accumulation of exces-
sive residues has not occurred and is extremely un-
likely. Inherent phytotoxicity of herbicides pro-
vides a natural indicator for residues and serves
as a defense against their accumulation when used
for selective weed contro] in crops.

There is little evidence of adverse effects of her-
bicidal residues on fruit trees and shrubs. Research
in New Jersey underway over 5 years has revealed
no undesirable residual effects from annual appli-
cations of a number of different herbicides on
apple, peach, blueberry, and cranberry plantings.

Movement in the Environment—The winds
carry mists and dusts. And the wind does not dis-
criminate because of chemical specificity. Mists or
aerosols or dusts containing pesticides are carried
at the same rate as those that are uncontaminated.

Water moving downstream is an effective ve-
hicle. The amount and physical character of sus-
pended material transported depends on velocity
of flow. Gravel and even sand settle out as flow re-
tards. Colloidal material of clay and organic mat-
ter may even stay suspended in still waters. Col-
loidal materials can readily be carriers of

84 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

pesticides. Concentration of herbicide in true solu-
tion in a stream does not vary in relation to rate
of flow. A herbicide with low degradability in wa-
ter actually becomes a good tracer.

Consider the following study. Cooperative re-
search between the U.S. Department of Agricul-
ture and the Washington agricultural experiment
station revealed that six applications of acrolein
could be quite effective for control of aquatic weeds
which clog irrigation canals. An average concen-
tration of only 0.1 p.p.m. (weight basis) in the
water during exposure periods averaging 48.4
hours at intervals of 3 to 4 weeks in 1965 controlled
pondweeds for 10 to 20 miles from the point of
application in a canal with an average flow of
2,023 cubic feet per second (4,000 acre-feet per
day). Control was still adequate from 20 to 50
miles downstream. Pondweeds in many branch
laterals were adequately suppressed, particularly
those within 20 miles of the point of application.
The concentration and total quantity of acrolein
required for pondweed control were much less than
in previously used methods of application. Acro-
lein will kill most species of fish at concentrations
required to kill aquatic weeds in irrigation canals.
Fish production should not be attempted in canals
that are to be treated with acrolein.

Temperature of the water very much affects loss
of acrolein during transport. In July, with water
at 70° F., 32 percent of the acroleine was lost dur-
ing the first mile of canal flow when the chemical
was introduced at 0.1 p.p.m., whereas 42 percent
was lost when introduced at 0.6 p.p.m. (weight
basis). In cooler water in September—about 61°
F’.—the losses of acrolein in the first mile of flow
were only 20 percent when the chemical was intro-
duced at either of the above concentrations.

Some of the more seriously adverse effects from
use of herbicides have occurred as a result of un-
toward air transport. To counteract the inadver-
tent introduction of these chemicals into the
atmosphere during application, research is under-
way to (a) develop invert emulsions to reduce
spray drift, (6) develop granular and _ pelleted
formulations to minimize volatilization and drift
during aerial applications, (¢) incorporate the
herbicide directly into the soil, (d) combine with
invert materials to retard volatilization and photo-
decomposition.

Development of Improved Herbicides —There
is a continuing need for herbicides that are more

efficient in destroying the target weeds, carry an
appropriate degree of degradability, have a mini-
mum toxic effect on crop plants, and have no ad-
verse effects on humans, farm animals, wildlife,
or fish.

Research has shown that chloroxuron is much
more toxic in acetone than in water, and that
surfactants enhance the activity of many herbi-
cides. In both cases, the enhanced activity means
that effective weed control can be obtained with
less herbicide.

Degradability in soil is much more rapid for
2,4-D, a chlorosubstituted phenoxyacetic acid, than
for fenac, a chlorosubstituted phenylacetic acid.
The faster degradability of 2,4-D has been used
to advantage in the control of witchweed.

Development of Alternate Methods of Weed
Control—Edwin Markham in his sad little poem
“The Man With the Hoe” sought to portray a
human soul engaged in the very essence of drudg-
ery. Those of this latter day who have “chopped”
cotton or sugar beets know well Markham’s mean-
ing.

Mechanization of this art has largely removed

the drudgery and evolved effective and economi-

cally feasible practices. Mechanization is not new.
Jethro Tull invented the horse hoe before 1822.
George Esterly patented a straddle-row cultivator
pulled by horses in 1856, and a tractor-mounted
cultivator became available in 1918.

An important landmark in mechanical weed
contro! was the report of Cates and Cox in
1912 (23) that the principal virtue of cultivation
was to kill weeds. They found that there was no
merit in plodding down the rows and cutting off
roots if there were no weeds to kill. Later work has
shown that if the soil crusts over following a rain
and impairs soil aeration, breaking the crust has
beneficial effects beyond weedkilling.

Research underway in the U.S. Department of
Agriculture and a number of State agricultural
experiment stations indicates that nonchemical
weed control still has a place. This method of weed
control is still predominant in the production of
most crops. Use of shallow tillage tools such as the
rotary hoe early in the season has been found to be
satisfactory for weed control in soybeans, peanuts,
and many other crops.

Flame cultivation has been developed as an eco-
nomical and practical means of controlling mid-
season and late-season annual broad-leaved weeds

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 85

and grasses in the cotton row. It requires the ap-
plication of a carefully controlled flame to the drill
row of cotton plants at a rate that does not injure
the crop while killing the more delicate weeds.

Chemicals can be used to artificially stimulate
seed germination. Such stimulation has the poten-
tial of providing an even-aged weed population
that is less difficult to control. Recently, two un-
known germination stimulants of witchweed were
isolated from cotton roots. An unidentified alkali-
labile corn root exudate was also found that would
stimulate germination of witchweed. Witchweed
is an exceedingly serious pest along the middle
Atlantic seaboard.

The biological control of plants was firmly es-
tablished in the thirties following the introduction
of a moth, Cactoblastis cactorum, from Argentina
into Australia for the control of pear cactus in that
country. The snail, Marisa cornuarietis and two
fish genera have since shown promise for the con-
trol of submersed water weeds.

The control of Klamath weed (Hypericum per-
foratum) in northern California, Oregon, and
Washington by beetles of the genus Chrysolina is
a good example of biological control of weeds. By
1944, over 2 million acres of California rangeland
were infested with this weed. Release of the beetles
in California began in 1945. As soon as beetles be-
came abundant, collecting programs were orga-
nized at county levels so that ranches could assist
in distributing the insects. In 4 years it became evi-
dent that good control was being obtained. In 7
years. the weed was under control. In 1956,
Klamath weed was removed from the list of nox-
ious weeds in California.

Fungicides

Persistence in the Environment—The adverse
effects of fungicides upon our environment are not
widespread. Where harmful effects have been
noted or suspected, the heavy metal component of
the fungicide was usually involved. Many fungi-
cides contain copper, zinc, mercury, iron, or man-
ganese. The literature pertaining to the persistente
of these metals in soils and their adverse effects
on plants has recently been reviewed.°

Apple orchards in England with a long copper-
spray record were found to contain in the surface

9 LAGERWERFF, J. V. HEAVY-METAL CONTAMINATION OF SOIL.

Presented before the Amer. Assoc. Ady. Sci. Meetings, Washing-
ton. D.C.. Dee. 29, 1986.

mat more than 1,500 p.p.m. of copper. The surface
soil in old vineyards in France was found to con-
tain up to 845 p.p.m. of copper. In sandy soils used
for citrus in Florida, copper concentrations in the
surface layer were found to exceed 50 p.p.m. This
level was sufficiently high to be toxic to citrus
seedlings. Clover and alfalfa plants are particu-
larly sensitive to copper in the soil.

Research has developed copper fungicides that
hold the copper in a chelated, less available, form.
Zinc and manganese can accumulate to toxic levels
in soils, but the evidence indicates that application
of fungicides containing these metals is usually not
at fault.

Mercury found in soils usually comes from
fungicides. Mercury vapor can be toxic to plants
and the effects are usually noted in greenhouses
where ventilation is low.

Research has shown that the unfavorable effects
of heavy metals on plants can generally be allevi-
ated by (1) increasing the soil pH above 6, such as
by liming, (2) adding organic matter to the soil,
(3) applying an iron chelate either foliarly or to
the soil, and (4) applying phosphatic fertilizers
if the pH is managed properly.

Alternates to the Use of Fungicides —Seeking
ways and means to alleviate the ravages of plant
diseases is as old as the arts of agriculture.
Through crop rotation, cultural practices, sanita-
tion, and elimination of alternate hosts, many a
plant disease is controlled or partially kept in
check, thereby reducing or eliminating the need
for fungicides. Breeding varieties that are resistant
to diseases has been the most effective approach
towards controlling disease without resorting to
the use of chemical fungicides.

Brown rot can be exceedingly destructive in a
crop of peaches. The sources of infection are spores
formed by “mummies”—infected peaches that
dried on the tree before dropping—that come into
direct contact with the soil. Peaches rotting on the
ground rarely form mummies. Thus, studies have
shown that field sanitation during pruning or har-
vesting should be that of preventing many mum-
mies on trees from dropping to the soil and be-
coming sources of infection.

Bacterial blights of beams can spread very
rapidly over a field when the vines are wet from
dew or a shower. Cultivating and harvesting damp

86 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

vines can spread the infection in a few plants to
a whole field. Thus, proper cultural and harvesting
practices become important in disease control.

Clubroot can be a serious disease of cabbage.
However, studies have shown that it can largely
be kept in abeyance by maintaining the soil reac-
tion close to neutral or slightly alkaline by liming.

Potato scab requires the opposite treatment for
control from that indicated for cabbage clubroot.
Potato scab is kept in abeyance if the pH of the
soil is maintained below 5.2.

The need to use chemical fungicides is sometimes
avoided by eliminating the alternate host of a
plant disease. The fungus causing the cedar rust of
apples must alternate its life cycle between para-
sitism on pome fruits such as apples, crabapples,
quinces, hawthorn, serviceberry, and the overwin-
tering hosts of several species of juniper. This
cedar rust in apple orchards can be largely con-
trolled by eliminating appropriate species of cedar
within a mile or so of the orchard.

Stem rusts of wheat and other cereals have
caused tremendous damage in grain production in
the United States. An important alternate host is
the stem rusts for the common barberry. An exten-
sive program of eliminating wild barberries in the
wheat-growing areas of the United States has done
much to eliminate sources of infection for stem
rusts.

White pine blister rust became a serious menace
to white pines in the United States during the first
quarter of this century. The disease organism must
have alternate hosts such as provided by goose-
berries and currants. An extensive program of
eliminating the susceptible species of alternate
hosts has done much to hold in abeyance the threat
of white pine blister rust.

White pine blister rust is also attacked by an-
other approach to biological control. It has been
found that the hyperparasite Zuberculina maxima
inactivates many of the cankers formed from in-
fection over white pine blister rust but not enough
to provide effective control of the disease. Research
has also shown that certain fungi compete well
with oak wilt fungus in the bark of killed trees or
with the disease agent Fomes annosus in old pine
stumps and roots. Research is underway towards
finding how to stimulate the protective organisms.

Plant breeding and selection has long been an
effective approach towards developing strains of
economic plants that would avoid the ravages of

plant diseases without the use of chemical sprays
and dusts. Mildew-resistant cantaloups have been
developed. Wilt-resistant varieties of watermelons
have been produced. Sugar beets resistant to leaf-
spot have been developed. These are just a few
examples of plant diseases that would normally be
controlled by the fungicides if the plant did not
carry disease resistance. There are a tremendous
number of examples of plant breeding for disease
resistance wherein use of fungicides was not feas-
ible and thus resistance of the crop plant was
virtually the only hope; for example, use of fungi-
cides in forests is of questionable economic feasi-
bility. Great progress has been made in research
towards eliminating the need for such chemicals
in the forest by developing hybrids of forest trees
that are immune or highly resistant to white pine
blister rust, fusiform rust, brown spot, littleleaf,
mimosa wilt, and chestnut blight.

In fact, one could summarize by saying that the
contributions of agricultural and forestry research
towards controlling ravaging diseases without use
of chemicals has been one of the great contributions
of all research endeavor.

Socioeconomic Evaluation

The solution of waste disposal problems lies in
part outside the influence of the market system.
The price system works effectively for many of the
quantitative aspects; however, it is difficult to at-
tach monetary significance to esthetic values which
are diminished by offensive odors or unsightly sur-
roundings. Despite these difficulties, it is essential
to consider esthetics when attempting to answer
questions such as: What level of waste treatment
do we want? How much can we afford to spend?
How much are we willing to pay for specific levels
of quality improvement ?

The analyses of alternative systems of alleviat-
ing waste problems are seriously hampered by the
general lack of information. A number of studies
are underway at State agricultural experiment sta-
tions and within the U.S. Department of Agricul-
ture. These studies will enhance the decision-
making process and contribute to the optimal eco-
nomic and social solutions to waste problems. These
studies are related to pesticides, water quality,
plant nutrients, and organic wastes.

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 87

Pesticides

A wide variety of chemicals, varying in degree
of toxicity, are available for use in controlling
agricultural pests. Little information is available
regarding the economic impact of the use of the
various chemicals and associated practices in the
production of specific crop and livestock commodi-
ties in the different agricultural regions of the
United States. Reports are being compiled to deter-
mine the increased crop productivity due to pesti-
cides and to evaluate alternate methods of pest
control. Information in these reports will facilitate
evaluations of the contributions of pesticides to
agricultural production.

Economists in the U.S. Department of Agricul-
ture are tabulating and analyzing data from the
Pesticide and General Farm Survey for 1966. In
the evaluation of problems concerning the chemi-
cal pollution of our natural environment, compari-
son of the 1966 data with the 1964 data will indi-
cate trends in the intensity of pesticide use by
geographic areas, types of farms, and specific crops
and livestock.

As in the 1964 survey, the 1966 questionnaire in-
cludes information on the use of pesticides in agri-
culture, and related information on farm organiza-
tion and operations. About 10,000 farmers
were interviewed. In contrast to the previous sur-
vey, these farmers represent all the economic
strata. The farmers with low sales were excluded
in the 1964 survey.

Statistical data from the 1964 nationwide pesti-
cide survey show the quantities of selected pesti-
cide ingredients applied to crops and livestock by
region, by type of farm, by economic class of farm,
and by type of pesticide.

The basic economic questions inherent in the
pesticide issue concern the effect that restrictions
on the use of toxic chemicals in the control of agri-
cultural pests will have upon production costs,
farm incomes, and the supply and quality of food
and fiber produced. Information obtained in the
1966 nationwide survey can be useful in evaluating
approaches for reducing contamination from
chemicals.

Water Quality —The U.S. Department of Agri-
culture and the land-grant universities have
initiated economic research related in some degree
to land and water quality problems. The studies
include evaluation of erosion control, water qual-

ity, and the impact of high-salinity irrigation
waters on land values.

Recent research objectives are concerned mainly
with waste disposal and management. They in-
clude studies on the accumulation, movement, and
adverse impacts of pesticide residues on soil and
water resources and ways to reduce these effects;
economic analysis of pesticide residues and agri-
cultural waste problems in a watershed of river
basin planning complex; a study, cooperative with
the Oregon State University, of legal-institutional
approaches for pulpmill waste disposal where con-
trol needs involve mill and recreation interests;
and a study of the Federal Water Pollution Con-
trol Act to determine the implications of the act
for agricultural and other rural resources.

Plant Nutrients—There is a continuing re-
search program in the economics of fertilizer use.
These studies provide current information on the
amount and type of commercial fertilizers used in
agriculture and returns from their use. They show
that, over the period 1960-64, farmers received an
average return of $2.50 for every dollar spent on
fertilizer. Projections of fertilizer use to meet 1980
production needs do not consider any harmful
effects associated with the use of commercial fertil-
izers. Economic questions related to the impact of
restrictions on fertilizer use could be evaluated in
terms of production costs, farm incomes, and the
supply and quality of food and fiber produced.
These economic studies have a primary interest in
farm production, and only secondarily in nutrients
that may impair the quaiity of surface and ground
waters.

Organic Wastes——Cooperative research cn the
economies of size and livestock operations and
materials handling is underway at the University
of Illinois, University of Minnesota, and Colorado
State University. Current studies consider the
economics of waste disposal only as a part of the
overall feeding operations.

New and different methods of materials han-
dling and livestock confinement are an important
part of modern major feeding operations. Concen-
trated milking and feeding operations permit econ-
omies as the size of the operation increases. But, as
such operations become larger, conventional
methods of waste disposal become less adequate.
Modern livestock waste disposal systems are pri-
marily limited to large hog and livestock feeding

88 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

operations. They are also an important part of a
few specialized dairy and poultry operations in
areas near large metropolitan centers. Pertinent
economic aspects of alternative means of waste
disposal and regulation of disposal methods in-
clude effects of disposal methods on production
costs, farm incomes, and the supply and quality
of food produced.

Many firms processing agricultural commodi-
ties have serious problems in disposing of their
byproducts or wastes. Most of the past research has
been directed at developing new products, or uses
for existing products, or finding a low-cost method
of disposing of the wastes. Industries with the
most acute waste problems include dairy, meat,
poultry, cereal milling, and wool scouring proces-
sors. Waste materials from these industries include
offal, blood, bones, feathers, grease, starch, and
water. Research conducted since the late 1950’s to
help put these wastes in a more marketable form
has been highly successful.

In response to the President’s message concern-
ing the Water Quality Act of 1965 pertaining to
our “rivers flowing red with blood from slaughter
houses,” new methods for handling packinghouse
wastes are being investigated. Two methods which
currently look favorable are (1) treating these
wastes with polyelectrolytes, and (2) converting
them into a protein supplement by a phosphoric
acid digestion method.

Research Accomplishments—Numerous market-
ing research reports have been published during
the last 10 years in an effort to find new markets or
develop new products for the wastes from in-
dustries processing agricultural products. Resuits
indicated that (1) spent sugarcane can be used for
making paper; (2) hide trimmings and fleshings
can be converted to a high-protein feed; (3) irri-
gation is a low-cost disposal method for poultry
and dairy sewage; (4) drying of blood in poultry
and meatpacking plants increases returns; (5)
development of hydrolized feather meal increases
returns to poultry processors; (6) citrus pulp is
an economical feed; (7) recovery of wool grease
is economical in some instances; and (8) alterna-
tive methods and their costs are available to the

cereal starch industry for controlling stream
pollution.

Detailed studies of waste treatment methods for
canners of tomatoes, corn, apples, peaches, cherries,
beans, and mixed products were completed in 1958.
Results indicate fruit and vegetable canners can
adequately contro! their effluent by screening, bio-
logical treatment, lagooning, or spray irrigation.

In 1964, farmers spent, on the average, about
$300 for pesticides (77). This did not include pesti-
cides used for treating seeds, stored crops, or stor-
age buildings, or in farm households, farmyards
and gardens. Expenditures ranged from a high of
$882 per farm in the Pacific States to $119 in the
Northern Plains. Ninety-four percent of the
farmers surveyed used some pesticides. The pro-
portion of farms using pesticides did not vary
appreciably from region to region or among differ-
ent types of farms. Farmers with the highest sales,
that is $40,000 or more annually, accounted for
43 percent of the money spent on pesticides.
Eighty-five percent of the pesticides were used on
crops, and 11 percent were used on poultry and
livestock.

Many firms processing agricultural commodities
have put the recommendations of marketing re-
search into action. The best examples are the re-
covery of blood, offal, feathers, and grease from
livestock and poultry industries. Other examples
are the installation of irrigation systems for using
waste water from the poultry and dairy industries.
Currently, 14 tanners and hide dealers have in-
stalled processes for converting hide trimmings to
high-protein feed.

Although past and current research does assist
in making decisions in regard to waste disposal,
the efforts are inadequate to provide optimal solu-
tions to waste disposal problems. There is an ur-
gent need for national and regional surveys of
rural waste problems. Likewise, studies should be
initiated to identify economic and social implica-
tions of selected problems. Alternatives for allevia-
tion of waste problems should be evaluated to pro-
vide essential information for arriving at rational
compromises between production efficiency and en-
vironmental quality.

APPENDIX IV

Problems in Waste Management Needing Attention in Agriculture and Forestry

As America’s technological giant continues to
grow, it becomes ever more ravenous for better
information. In doing so, this giant also casts a
powerful spotlight over broad areas of ignorance—
untilled fields that should be producing food for
the giant.

The development of digital computers opened
up a capacity to effectively digest vast quantities
of complex data towards attaining an optimal
solution to sophisticated problems. As an example,
these computers are the sine qua non in advanced
planning for river basin development. They en-
able the programer to take into account all perti-
nent inputs, both stochastic and determinative; all
prevailing constraints; and all desirable attain-
ments on development. This provides for a realistic
appraisal of alternatives in social and economic
objectives. The capacity of the computer to handle
such programs has often focused onto the serious
dearth of accurately accrued data, both physical
and economic.

Experience has amply shown that an advance-
ment in one area of science or technology may have
wide ramifications in many other areas. In the
process, the demands for pertinent technical and
economic information snowball.

When Fritz Hiber of Germany synthesized am-
monia from atmospheric nitrogen in 1910, one can
rest assured that he gave no thought that his dis-
covery would cause massive problems on animal
waste disposal in the United States. Following
World War II, synthetic nitrogenous materials for
fertilizers were produced so abundantly and so in-
expensively that it became cheaper for the farmer
to supply plant nutrients to his fields from the bag
than from barnyards and feedlots. Endless prob-
lems arose as to just what to do with huge accumu-
lations of a socially unattractive product.

World War I gave a major impetus to the work
of organic chemists in new products. By the end
of World War II, a whole array of organic com-
pounds began to appear that worked miracles on
controlling pests of people, crops, livestock, and
forests. Unfortunately, some of these chemicals had
other repercussions in the environment. A myriad

of new problems arose concerning their use and
abuse.

When Henry Ford developed the assembly line
in 1912 and initiated mass production of a low-
cost car, he opened the door to literally putting
the United States on wheels. Unfortunately, a gas-
eous exhaust system was also associated with the
wheels. The effects of air pollution emanating from
millions of automobile exhausts upon human
health and comfort, and plant and animal life,
have become of prime concern in our efforts to im-
prove environmental quality.

Because of a successful test at Los Alamos, N.
Mex., on July 16, 1945, our atmosphere will prob-
ably never again be free of radioactivity.

Past experience reveals that technological prog-
ress usually spawns whole families of unforeseen
problems. Research must not only seek answers for
the problems of today, but also anticipate the key
questions that will loom up in the future.

The need for sound information relative to pro-
duction, management, use, and control of wastes is
so vast that no one responsible for direction of re-
search in this area will ever emulate the U.S. Com-
missioner of Patents in the early 19th century who
resigned from his post on concluding that every-
thing that could possibly be invented, had been in-
vented. As a consequence, the director of research
pertaining to wastes must carefully evaluate all
the possibilities and place his resources on the most
promising ones.

Radioactive Substances

The need for additional information on how to
cope with radioactive contamination of the en-
vironment depends on things to come; things
largely unknown but rife in speculation. If the
problems were confined to the effects of natural
radioactivity found in the effluvium from uranium
mines, the need would not be serious. If we are to
be prepared to counteract accidental releases of
radionuclides from research laboratories or nu-
clear power plants, then we must be confident of
available decontamination procedures. If radio-

89

90 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

active fallout should increase substantially by (a)
accidental release from underground tests; (0)
breaking of the ban on atmospheric testing now in
effect by the U.S.S.R., the United States, and the
United Kingdom; or (¢) intensification of atmos-
pheric testing of nuclear explosions by nations re-
specting no bans; then, our problems will be much
more serious.

If nuclear warheads should become the last re-
sort in deciding international disputes, then we are
going to need a great deal more information
on decontamination and other defensive pro-
cedures than we have. One suspects that the
United States is better supphed with these war-
heads than with countervailing information to
cope with those that might come to us.

We need far better information on the duration
and effects of retained fallout particles on plants in
order to improve validity of prediction of radia-
tion doses to plants and animals. Information is
especially needed on heavy fallout conditions. We
need to more fully evaluate the forces tending to
dislodge fallout particles from plants. These
forces include wind, rain, shaking, and brushing.
Characteristics of leaves that affect ease of dis-
lodgment need far better evaluation. Distribution
of retained particles on plant surface needs to be
measured.

The foregoing information is needed to develop
more expedient and practical procedures for de-
contaminating forage in the field. This capability
is urgent. Research will probably find certain crops
are far more easily decontaminated under field
conditions than others. A sprinkler irrigation sys-
tem could have new uses, but it would be necessary
to know optimal time of sprinkling during fallout.

Radically new techniques are needed to reduce
the thickness of surface soil that must be removed
to decontaminate soils. For example, it should be
possible to develop mechanical methods for re-
moving thin plastic coatings that have been al-
lowed to harden on contaminated soil surfaces.

Much research information is needed on the
physiological specificity of different varieties of
crop plants to (a) exclude most entities in radio-
active fallout from absorption by the roots; (0)
exclude these entities from entry into the vascular
system even if absorbed by the fine roots; and (c)
exclude these entities from foliar absorption. A
crop plant that would not absorb radioactive ma-

terials under heavy fallout would indeed be the
nonpareil in a nuclear emergency.,

Chemical Air Pollutants

Improved Technology for Evaluation of Damages
From Airborne Toxicants

Evidence of significant damage by airborne toxi-
cants to farm crops, ornamentals, and forest trees
continues to grow each year. There is no question
that vegetation is very sensitive to air pollutants.
Adverse effects occur around every industrial and
populated area. For example, in Metropolitan
Washington, D.C., an ozone-sensitive variety of
tobacco only makes half as much growth in pre-
vailing air as when grown in the same environment
but with carbon-filtered air. Even a resistant vari-
ety of tobacco accumulated one-third less dry
weight in the prevailing air.

Losses due to various airborne toxicants are
difficult to estimate and reliable data are very lim-
ited. Estimates published in 1956 (83), 1961 (8Z,
p. 444), and 1965 (5, pp. VII-280) show that
photochemical air pollution causes millions of dol-
lars of damage annually to crops in California and
that the amount of damage has been increasing
rapidly. In 1959, there was an estimated 12 to 20
percent loss to cigar-wrapper tobacco growers in
the Connecticut Valley (54, 97). In 1965 and 1966,
ozone-induced weather fleck caused significant
damage to Florida shade-grown tobacco (27, 29).
The damage was more general over the area in
1966 and resulted in greater economic loss. It was
estimated that fleck damage in 1966 averaged at
least one Jeaf per plant for every acre planted.

In view of the gross evidence of mounting losses
from these airborne toxicants, there is an urgent
need to improve the validity of the techniques
available for assessing damages, particularly
chronic damages. Valuable information can be ob-
tained by comparing plant growth in ambient
versus carbon-filtered air, If adverse effects in the
ambient air are noted, it is essential to ascertain
the entities that are responsible. Further informa-
tion is needed to enable identification of the spe-
cific effects of each toxicant on the many different
plant species of concern.

Physical facilities must be available that enable
controlled exposures of plants for long periods to
low levels of toxicants. Methods of identifying

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 91

and measuring specific air pollutants must be im-
proved. Physical and biological data must be so
accrued as to be amenable to sound economic
analysis.

The potential exists for improving the design
of physical facilities towards improving assess-
ment of losses to agriculture, including the relative
significance of each specific pollutant. Parallel
field studies will be needed to check the validity of
laboratory findings for field conditions.

Effects of Airborne Toxicants on Plants, Including
Interactive Effects

That air-polluting chemicals damage leaves and
blooms of salable plants is an established fact. But
little is known of the actual physiological mech-
anisms by which these harmful effects take place.
A better knowledge of how these toxicants alter
the biochemistry of leaves is a prerequisite for the
development of counteractive measures.

The potential for improving procedures to
ameliorate air pollution damage has not been ade-
quately developed. Ozone fleck in tobacco has been
partially diminished by ozone-resistant varieties.
However, plant resistance is relative. The floor
for injury of a resistant variety may be exceeded if
pollutant concentration increases. Cultural prac-
tices and use of chemical protectants promise some
control of air toxicant damage.

The best way to alleviate air pollution damage
to agriculture and forestry would be the use of
technology to eliminate industrial and automotive
sources. The prospects for this happening are dim.
Therefore, the highest promise for alleviating the
damage now being inflicted on crops, ornamentals,
and trees is to foster adequate research for resist-
ant varieties as strains, and for effective chemical
protectants from the adverse physiological changes
that air toxicants induce.

Development of Tolerant Species, Varieties, and
Breeds of Plants

There is an urgent need for information on tol-
erance of species, varieties, and breeds of plants, if
profitable production of sensitive species, such as
pines, citrus, tobacco, and leafy vegetables, is to be
maintained in certain areas of the country. The
situation is already acute in southern California.
It is becoming increasingly serious in the densely
populated stretch from Boston, Mass., to Rich-
mond, Va. Information on tolerance of orna-

mentals is especially needed by city planners and
landscape architects.

The apparently unlimited potential for develop-
ing plants more tolerant to air toxicants should be
exploited more fully. Systematic studies to develop
tolerant vegetation have just tegun. Evidence
shows that white pine trees can be selected that are
resistant to ozone and other toxicants.

The effort needed to develop tolerant plants is
large because of the tremendous number of plant
species involved, and the need to genetically com-
bine yielding ability, quality characteristics, and
resistance to diseases with tolerance to airborne
toxicants.

Adequate physical facilities will need to be pro-
vided for maintaining a controlled level of toxi-
cant in progeny evaluation studies.

Evaluation of Air Cleansing of Toxicants by
Foliage

Plant species vary considerably in their reaction
to toxic substances in air. For example, a few parts
per billion of fluoride in the air are extremely toxic
to gladiolus, corn, sweetpotatoes, prunes, and apri-
cots; but other species such as alfalfa are tolerant
and may accumulate levels about 500 p.p.m. with-
out injury. Other toxicants such as sulfur dioxide
cause injury to pines, alfalfa, cotton, and grains
at relatively low concentrations; but citrus, privet,
and apple are very resistant.

When sulfur dioxide enters leaves, it is con-
verted to sulfite. Then sulfite is slowly oxidized
to sulfate, which reduces the sulfite toxicity by a
factor of about 30. Consequently, if sulfur di-
oxide is not added to the system too rapidly, a large
amount may be added without resultant toxicity.
More information is needed on the extent to which
sulfur dioxide may be a source of sulfur nutrition
of crops on sulfur-deficient soils.

It is known that plants exposed for several days
to about 1 p.p.m. of nitrogen oxide become greener,
although somewhat stunted in growth. This sug-
gests that some plants may be able to use nitrogen
from this toxicant.

Conifers appear to be more efficient in air cleans-
ing than maples because they have greater leaf
surfaces and are not deciduous.

Much more information is needed about the rela-
tive rate at which plants remove toxicants from
air during different seasons. It is important to

92 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

know if plants are as effective at night as during
the day in this removal. Would certain chemical
sprays aid removal of air toxicants by plants with-
out resulting injury to the plants? Developing
such information would be especially important
for growers near urban areas and for metropolitan
planners.

Research on the air-cleansing capacity of foliage
is just beginning and needs to be expedited.

Development of Protective Chemical Treatments

Antioxidants and antiozonants protect plants
from ozone injury. Lime dusts reduce fluoride
injury.

On cigar-wrapper tobacco, zineb is used com-
mercially for the control of a pathogenic disease,
but it also reduces the amount of ozone fleck. More
effective chemicals than zineb are available, but
the problem of residues remains to be solved.

Little information is available about the use of
chemical protectants against other airborne toxi-
cants. But current information indicates that the
development of chemical protectants is a promis-
ing area of research.

Rapidly growing plants are generally the most
sensitive to air pollutants. Seedlings sometimes
appear to be more sensitive than older plants.
Plants supplied with adequate soil moisture are
much more sensitive than those subjected to soil
moisture stress.

The interrelated effects of nitrogen metabolism,
carbohydrate metabolism, and organic acid me-
tabolism in plants on their resistance to toxicity
appear to be very complex. Certainly these effects
are now poorly understood. Research information
is needed on these indicators of plant nutrition to
develop guides for better mineral fertilization
practices under conditions of chemical air
pollution.

Development of Information and Procedures To
Lessen the Hazard and Intensity of Forest
Fires

Forest fires contaminate the air by producing
tremendous quantities of smoke and hydrocarbons.

For example, every commercial airport in the

State of West Virginia was closed for nearly a

week in 1964 because of smoke from forest fires.

Research into forest fire control is constantly
producing improved procedures that reduce the
total acreage burned and, consequently, the smoke

and hydrocarbons produced. Such research has had
high benefits in relation to its costs. It is certainly
in the national interest to take every step possible
to reduce the hazard of forest fires and their tre-
mendous effluent of smoke and hydrocarbons.

Develop Improved Procedures To Diminish Forest
Fires Caused by Electrical Storms

Lightning causes more than 7,500 forest fires
during the average year. Such fires are excep-
tionally expensive to control because, unlike man-
caused fires, they often occur in inaccessible coun-
try. In the Rocky Mountain States, lightning
sparks more than 70 percent of all forest fires.
Smoke from these fires has severely curtailed air
operations as far east as New York and Boston.

Cloud-seeding techniques offer a strong potential
for reducing or eliminating lightning-caused fires.
In recent field trials, heavy overseeding with silver
iodide gave a one-third reduction in cloud-to-
ground lightning. The urgency in preventing
forest fires, not only to avoid contributions to air
pollution, but also to protect watersheds and con-
serve timber stands, indicates that appropriate re-
search move forward as rapidly as possible.

Airborne Dusts

Airborne dusts can be irritating, exasperating,
and frustrating. They arise from cement plants
and lime kilns, cotton gins, and alfalfa mills,
natural sand dune areas, unprotected fields and
rangelands, highway construction, and suburban
and industrial development. Dust clouds emanat-
ing from soil blowing on the Great Plains com-
prise big, dramatic, and usually disastrous events.

Soil Blowing

Masses of soil particles transported by the
winds have been known to cause physiological
damage to humans and livestock, depletion of the
soil resource, abrasion damage to growing crops,
increased home and office cleaning, reduced visi-
bility resulting in increased automobile accidents,
and many other costly effects. Recent findings
have revealed the presence of hydrocarbons from
chemical pesticides absorbed on air-transported
soil particles.

Reduction of airborne soil particles depends
upon control of soil blowing. Although past re-
search has provided information toward under-
standing the processes, for the development of

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 93

control practices and means for predicting the
extent and probability of duststorms, the potential
for improvement in understanding, control, and
prediction remains high.

New research must include further study of
the wind erosion processes and the definition of
principles to form a scientific basis for design of
more effective control practices such that the pro-
ductivity of farmlands will be preserved and pol-
lution of the atmosphere reduced or prevented.
The studies must consider various concepts for
describing and delineating the influence of atmos-
pheric wind and turbulence on soil detachment and
transport; the effect of wind and related atmos-
pheric factors on soil drying and creation of soil
surface conditions susceptible to high rates of
detachment; the modification of tillage practices
and machines to provide effective and lasting crop
residues and soil cloddiness conditions to resist
soil detachment; the theory of barriers, their
effect on the microclimate, and optimum design
and orientation based on analysis of wind factors
and probabilities; the use of chemicals and petro-
leum-derived soil stabilants as a part of control
systems; the tolerance of crop plarts to abrasion
for windblown soil particles; the development and
selection of better strains and varieties of grasses
and crops to tie down soils susceptible to blow-
ing; improved prediction equations for flow con-
ditions; and interrelations of soil erosion rates,
dust deposition, soil properties, soil treatments,
environmental pollution, and soil renewal.

Windbreaks

Land in the Great Plains is almost constantly
exposed to the damaging action of winds. Winter
gales remove the snow from open fields on the bare
soil; plants become sparse and are sometimes win-
ter-killed. During dry springs and summers, soil
blowing and erosion damage from high winds is
greatly increased. Strips of trees (windbreaks and
shelterbelts) across open areas are a powerful
means of amelioration, influencing not only the
immediate site but also remoter areas. Crop pro-
duction is increased by the conservation of soil
and soil moisture, and livestock are afforded pro-
tection in shelterbelts. Living conditions are im-
proved not only through beautification of the
homesteads, but by reduced fuel costs.

Cover is effective in reducing soil movement by
wind. Where grasses thin out or disappear due to

drought, cultivation, or overgrazing, vast dust-
storms may result. Brush invades when grass dis-
appears. Grasses stabilize sand dunes, ditchbanks,
and roadbanks.

To fulfill the many needs for protective belts
of trees and other vegetation, expanded research
must focus on the development or selection of
suitable species. A wide array of species of trees
and shrubs will need to be evaluated to meet the
diverse needs of varying climatic conditions.
Other needed research information includes that
on optimum depth and spacing of plantings; cul-
tural practices to maintain vigor, density, and
longevity of plantings; disease and insect control ;
and the effect of the vegetation on wind movement.

Feedlots

Large feedlots are now under criticism for the
dust nuisance they create. These dusts are not only
a nuisance to the housewife but of serious concern
to those with dust allergies. It is also suspected
that dust in these feedlots reduces efficiency of
weight gain. Sprinkling is one technique that has
been used with some success. However, further
study of the problem is needed to develop alter-
nate methods and more economical sprinkling
techniques.

Where dusts arise from feed grinding, mixing,
and handling, techniques for pneumatic convey-
ing and use of cyclones—mechanical devices to
remove dusts from air—offer a means for control-
ling dust. Cyclones, when properly used, can ap-
proach efficiencies very near 100 percent removal.
When not properly used, however, their efliciency
is very low. Cyclones are presently designed pri-
marily on a trial-and-error basis so that they
usually only apply to the special set of circum-
stances for which they were developed. Research
is needed to develop the methodology for the
rational design of cyclones so that they can be
utilized for control of dusts.

The relationship of weather conditions to dust
problems is recognized but needs much further
study.

Cotton Gin Dusts

Under average conditions, about 1,000 pounds
of trash accrue with each bale of cotton ginned.
Some of this is disseminated into the atmosphere
as very fine dust. In addition to its plainly irritat-
ing effects, it is adverse to the respiratory health
of people miles to the leeward of the gin. Burning

94 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

of the trash at the gin appears to be impractical—
the smoke produced is also a nuisance. Returning
the trash to the field is inadvisable unless it is
decontaminated of insect and disease pests.

People living in the neighborhood of gins are
convinced that it is urgent to improve engineering
technology to effectively filter the air from gin-
ning operations, and to develop an inexpensive
technique to decontaminate gin trash enabling its
return to the fields as noninfesting organic matter.

Analogous problems prevail around alfalfa
mills.

Sediment

There is no basis at the present time for a really
adequate estimate of the impacts of sediment upon
the national economy. The Army Corps of Engi-
neers has estimated that flood damage in down-
stream areas amounted to $538 million annually
under 1957 conditions and that potential damage
under conditions in 1980 would be about $739 mil-
lion (720). The Soil Conservation Service has esti-
mated the average upstream flood damage in the
contiguous United States as being slightly in ex-
cess of $1 billion annually (43). Any separation of
flood damages between water and sediment com-
ponents can be only arbitrary at best, but it would
seem safe to guess that sediment damages asso-
ciated with floods, considering both upstream and
downstream areas, average at least about $500
million a year.

Soil erosion is a natural geologic process which
has been accelerated manyfold in most parts of the
country by man’s use of the land. Reduction of the
rate of accelerated erosion is the only positive and
permanent cure for the sediment problem. How-
ever, the development and widespread application
of Jand management practices to control all ero-
sion is a dream of the future and specific measures
for transporting, storing, or otherwise handling
sediment will be required in many situations. But
before development of more acceptable Jand use
practices can be effectively pursued, increased
knowledge of the erosion processes and definition
of the basic principles governing the movement
and loss of soil must be attained.

This research will involve study of detachment
and movement of soil particles by raindrop splash
and flowing water, surface sealing and related
phenomena that result in decreased infiltration,

water intake and movement through soil during
freezing and thawing periods, the role of plant
cover and crop residues in reducing erosion, and
concepts relating erosion to topographic, climatic,
and soil factors. Control practices need to be de-
veloped and integrated into systems that will re-
duce runoff a maximum amount and provide for
the safe removal of any excess drainage water. The
control practices for farms must be compatible
with modern farming methods, and for residential
and commercial development sites, with efficient
construction practices. Attention needs to be given
to the development of improved prediction
equations.

The potential of land use and management prac-
tices for ameliorating sediment problems of water-
sheds and river basins is one aspect of the prob-
lem needing much further study. New concepts
and procedures for identifying critical sediment
source areas and predicting sediment delivery
from such areas as affected by climatic factors,
soils, geology, topography and land forms, stream
channel characteristics, erosion-control practices,
and watershed protection measures are required.
Increased knowledge of the physics of sediment
genesis and movement in watershed systems is re-
quired for isolation and selective treatment of
critical sediment source areas.

Criteria for the engineering design of sediment
traps and debris basins are inadequate. A better
understanding of the mechanics of sediment trans-
port in tortuous channels of alluvium, and the
resistance of cohesive materials in channels to hy-
draulic forces is necessary for design and mainte-
nance of stable stream channel systems.

Additional formation on rates and processes
of sediment deposition in reservoirs and water de-
tention structures, on floodplain Jands, and in
estuaries and harbors will also be required for
effectively coping with sediment problems.

Little or no information is available on the role
of sediment as the transporting agent for residues
of pesticides and other chemicals in streamflow.
The affinity of sediments, particularly clays and
organic fractions, for pesticides must be defined
and, if significant, measures for keeping such
wastes from streams must be developed. More eco-
nomical and effective techniques to stabilize
streambanks are required. New technology to sta-
bilize eroding soil in developing urban areas, on

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 95

roads and highways, and on other construction
sites is a new requirement of great urgency.

Increasing demands for greater quantities of
water of improved quality may soon require that
positive steps be taken to stabilize and control crit-
ical sediment source areas in urban, agricultural,
and forested environments. In urban areas, erosion
from construction and development sites is a po-
tent contributor to the sediment content of streams.
Studies have shown that erosion in the Washing-
ton, D.C. metropolitan area is a primary source of
sediment polluting the Potomac River estuary and
will have to be controlled before this portion of
the Potomac River can be restored to its natural
beauty and used for its full potential.

Economically feasible erosion-control techniques
are needed for use in suburban development and
preparation of industrial construction sites. Better
means of channeling and trapping uncontrollable
sediment delivery from these sites must be de-
veloped.

Soil erosion by water, the dominant problem on
179 million acres of cropland, is feasible to treat
with measures that reduce soil losses (25). Highly
mechanized farming on large tracts, monoculture,
and intensive culture, all focus on the need for new
technology that will provide for more economic-
ally feasible systems of erosion control under these
systems.

More than 40 million acres of forest and related
rangelands are eroding because of disturbances or
destruction of cover. They produce an estimated
100 million tons of sediment each year. Approxi-
mately 90 percent of this sediment is produced by
roads, logging skid trails, and burned areas. Not
only are these lands reduced in productivity, but
they are sources of sediment-laden floods and mud-
rock flows, which destroy crops, homes, roads, and
other improvements, and impair water quality for
irrigation, industrial, and domestic use.

Research towards diminution of forest fires,
gully development, and overgrazing of rangelands
would contribute very much to reduction in sedi-
ment delivery.

Strip mining for coal and minerals has become
more economic with the advent of large, powerful
machinery. Tremendous spoil banks and barren
areas are formed. These piles of raw earth ma-
terials are usually highly erodible. Revegetation

of these barren areas is frequently very difficult
because of high acidity and low content of mineral
nutrients,

Revegetation is difficult on gullies, spoil banks,
roadbanks, strip mine areas, overgrazed range-
lands, forest burns, and other badly disturbed, un-
stable, or deteriorated sites where growing condi-
tions are severe. Adapted species, varieties, or
strains must be found or developed to revegetate
and stabilize these critical sediment source areas.
This will require extensive research on selection,
evaluation, and culture of promising plant ma-
terials. Revegetation may involve a succession of
species, with the first cover probably involving
plants that can become established quickly under
conditions of low fertility and drought.

Engineering modification of barren surfaces
and addition of specific soil amendments will need
research attention for effective revegetation of
many of these deteriorated sites.

Plant Nutrients

Concern is growing over the eutrophication of
lakes and rivers. The enrichment of these waters
with plant nutrients, particularly nitrogen and
phosphorus, enables the growth of algae and
other water plants that are the base of the eutroph-
ic process. These nutrients may come from many
different sources: Domestic sewage, including the
phosphate in detergents; processing wastes; gar-
bage and refuse dumps; animal wastes; land run-
off; and land drainage.

More and more evidence is appearing on the
prevalence of nitrate in ground waters. Possible
sources include fertilization of farmland, feedlots
and barnyards, septic tanks and other domestic
sewage, processing effluent, and natural sources
such as niter spots in semiarid regions.

When phosphorus or nitrate is found in water,
the relative importance of possible sources of ori-
gin is largely conjecture. This provides fertile
ground for arguments. To the extent possible, con-
jectures should be replaced by sound information.

Very little modern information is available on
the phosphorus content of runoff from land vary-
ing in geochemical characteristics, treatment with
chemical amendment and fertilizers, cultural prac-
tices, and hydrologic conditions. The data avail-
able indicate that total quantities of phosphorus

96 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

in water derived from either surface or subsurface
land runoff are at levels that are completely in-
significant in terms of agricultural production, but
may be approaching significance for growth of
algae which respond to as little as 0.05 p.p.m. of
phosphorus in the growth medium.

Far more study is needed on the method of de-
termining phosphorus content of water in terms
of biological significance. Trying to interpret the
significance of values for total phosphorus con-
tent of river water is analogous to grinding up a
whole cow and then testing a bit of the resulting
hamburger to see if the animal had ketosis.

The development of suitable analytical proce-
dures may help us to distinguish at least four dif-
ferent states of phosphorus in water samples: (a)
That which is in true solution as orthophosphate ;
(6) that which is in solution in a nonpolar form
as an organic polyelectrolyte; (¢) that which is
adsorbed on the surface of suspensoids; and (d)
that which is a component part of the mineral
of the suspensoid. Information is_ especially
needed as to the degree of liability of phosphorus
in entities (6) and (c) in terms of growth of water
plants.

It is urgent that we rapidly alleviate the grave
dearth of qualitative and quantitative information
on the phosphorus in runoff and drainage water
from agricultural and forested lands as affected by
soil type, fertilizer practices, cultural practices,
vegetative cover, and climatic conditions.

The lability of phosphorus in bottom sediments
in streams is little understood in terms of its avail-
ability for growth of algae even if it is available
to bottom-rooted plants. We need to know how tur-
bulence in stirring up bottom sediments, presence
of organic matter, prevalence of aerobic vs. anaer-
obie conditions, and the activity of metallic ions
such as iron and aluminum, affect release of phos-
phorus adsorbed on sediment particles.

In terms of eutrophication of surface waters,
we also need information on nitrogen and potas-
sium moving from the land into streams, even
though need for information pertaining to these
two elements does not appear to be as pressing as
that for phosphorus.

Whereas phosphorus appears to be the nutrient
that limits the growth of free-floating plants,
such as algae, different circumstances may control
the growth of bottom-rooting plants which have

direct access to the phosphorus reserves in the bot-
tom muds. Evidence shows that when nitrogen
supplies are adequate, the growth will be con-
trolled by the supply of potassium in the water.
The extent to which this is supphed from ferti-
lizers is not known.

Nitrate is found in ground water and there is
concern on the readiness with which this anion may
be reduced to nitrite and cause methemoglobinemia
in babies or nitrite poisoning in ruminants. There
is evidence that nitrate in ground water does not
come from fertilizers apphed to fields; and there is
evidence to the contrary, Supplementary informa-
tion to fully explain this apparent contradiction
must be attained.

Nitrate is formed naturally in soils. In arid or
semiarid regions, it accumulates near the surface
as caliche or as “brown alkali”—niter spots—in
the surface soils. No one has adequately explained
whence this nitrate came. Under the right hydro-
logic conditions, 1t may be leached into ground
water. If it is formed in humid regions, it is so
leached.

Ividence is at hand that nitrate does enter the
ground water system in Jeachate from cattle pens
and feedlots. In a restricted locality such down-
ward movement of nitrate may be appreciable, but
little is known of the total contribution of this
source to overall content of nitrate in an aquifer.

Domestic sewage is certainly a source of nitrate
in ground water. This may be the main source of
such nitrate in rural communities. Certainly there
is need to replace unwarranted supposition with
irrefutable evidence.

As nitrate and associated entities move down-
ward from the surface soil to the water table, there
is much need for information on the prevalence of
conditions for the formation of nitrite at various
horizons as well as in the ground water.

Inorganic Salts and Minerals

Tnorganic salts and minerals in the effluent from
certain metallurgical and chemical industries, and
the acidic drainage from many operating and
abandoned mines, can seriously impair the quality
of water. All fish may be killed. Use of an afflicted
stream for recreation areas in forests or in other
parts of upstream watersheds may be seriously im-
paired. Such water is generally unusable for irri-

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 97

gation and livestock. Agricultural and forestry
leaders planning and developing upstream water-
sheds for optimal social benefits need far better in-
formation on possible measures for coping with
these seriously harmful mineral additions to
streams.

A number of metallic salts and related materials
have been added to soils over the years as (@) in-
secticides or fungicides, (b) micronutrient supple-
ments, or (c) inadvertently as impurities in
fertilizer. Lead arsenate was the main insecticide
used to control codling moth in fruit trees for
many years. This metal salt accumulated to rela-
tively high levels in soils of apple orchards of the
Northwest. On orchard removal, succeeding crops
have been injured. Calcium arsenate used to con-
trol cotton insects accumulated to toxic levels in
some cotton soils. Copper compounds, for example,
bordeaux mixture, have long been prime fungi-
cides. Copper may be found in some vineyard soils
at relatively high levels. Copper or zinc salts need
to be added as supplemental minor elements in
some soils. Evidence from a few areas suggests
that the practice may be overdone. Some ores used
for fertilizer production may carry undue quan-
tities of boron, arsenic, zine, or fluorine. These im-
purities are usually not harmful.

Serious losses from soil contamination by min-
eral salts have not occurred. Enough warning
lights are on the horizon, however, to signal the
need for more adequate information on the action
of these contaminants in soils and the availability
of counteractive measures.

The heavy salting of highways to facilitate
traffic movement following snowstorms has caused
serious damage to right-of-way vegetation and has
increased siit damage to streams when erosion fol-
lowed killing of the vegetation. This type of dam-
age has been felt by adjacent property owners—
both rural and urban. It has been particularly
serious in part of New England. In humid areas,
rainfall eventually remedies the damage.

Research is needed to assess the problem and
adjust findings of saline soil and water research for
irrigated lands to solution of the highway salinity
problems.

Mineral salts have long been serious contami-
nants in the soils and associated waters of irrigated
areas in arid regions. With competition for water
increasing in the water-short sections of this coun-

try, one can expect that the needs of irrigation
agriculture will net rank high. If waters of vary-
ing quality are available, agriculture will un-
doubtedly have to get along with that which is less
than the best. All indications the world over point
to greater need for information on the evaluation
and management of salt-affected soils and waters.

Water available for irrigation use varies widely
in quality. Previous use or treatment (softening)
of the water can affect its quality for irrigation.
More elastic criteria are needed to characterize
water quality for this use as modified by climate,
soil characteristics, management practices, drain-
age, quantity of water available, and kind of crops
grown.

Advances in atomic power plants for generation
of electricity and in processes for desalting sea
water have prompted feasibility studies of plants
to produce both low-cost power and water. Cost
estimates for the water imply a level currently ac-
ceptable to irrigation users. Advancing technology
should in time provide water well within the eco-
nomic reach of many irrigation users. As this
water is essentially free from any dissolved chem-
icals, its use on saline and sodic soil may present
problems of water intake and Jeaching of salts al-
ready in the soil. Research must be conducted on
the use of such water for irrigation in areas now
successfully irrigated with water containing rela-
tively high amounts of salts, such as the Imperial
Valley where each acre-foot of Colorado River
water imports 1.2 tons of dissolved salts. The first
use of the pure water may be as a dilutant of cur-
rent supplies or particularly for the high-salt-
content flows leaving irrigated fields as tile drain
effluents.

Salts in, or previously in, soils affect their physi-
cal and chemical characteristics. The interrelation-
ships are complex. An increasing body of knowl-
edge is needed on the chemistry, mineralogy, and
microbiology of the hundreds of different kinds
of soils affected by salinity. Better means of assay-
ing these salty-soil problems are needed as related
to their irrigation by waters varying widely in
chemical characteristics.

Salts move in soils only with water as the ve-
hicle. Information on the physical state of water
in these soils is fundamental to understanding the
principles of salinization and desalinization, With
recent breakthroughs on techniques for measuring

98 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

the energy state of water in soils, research on water
retention and movement can be and must be
expedited.

Genetic lines of many crops vary greatly in their
response to saline and sodic soils. Indications of
this variability have been found in cotton, cereal
grains, grasses, and fruits. Plant breeding research
to develop lines with superior salt and alkalinity
tolerance should be expedited.

Far more definitive information is needed on the
biochemical and physiological mechanisms in
plants that determine their tolerance to various
salt-affected soils. Unfortunately, little informa-
tion is available on the effect of climatic condi-
tions in modifying inherent salt tolerance of crops.
Such information is essential to crop and soil
management in soils subject to salinization. In-
creased knowledge of salt rejection by biological
membranes could be extremely helpful in desalt-
ing sea water. It is also essential to plant breeders
working to develop varieties and strains with
higher salt tolerance.

Fence lines sometimes show wide differences in
salinity damage. Even with identical water supply,
identical soil, and identical crops, diverse manage-
ment practices by different operators on either side
of the fence may be the difference between success
and failure. Accordingly, much better practical in-
formation is needed to unerringly predict the
combination of management practices for maxi-
mum production efficiency under a given set of
conditions pertaining to salty soils or waters.

Hard experience in the Western States has re-
vealed that successful irrigation requires effective
drainage. Accumulating salts must be continually
leached out. This is the only practical means
known today for maintenance of irrigated agricul-
ture In many areas and for reclamation of areas
already salted out. Excess leaching wastes water
and plant nutrients. For most efficient use of water
and maintenance of a favorable salt balance in the
fields, better mathematical expressions are urgently
needed for the calculation of leaching require-
ments, drainage requirements, and the proper salt
balance.

Fields and irrigated areas already seriously im-
paired by salinity must be treated with the most
economic reclamation procedures available. It is
essential that more research attention be given to
minimizing the cost of amelioration procedures on

salinized lands for redeveloping productive soil-
water-plant systems.

The return flow from an irrigated area is almost
invariably saltier than the incoming water. The
salt that comes in must go out, but part of the
water carrying the salt in is lost in evapotranspira-
tion from the field. Hence, Nature’s principles dic-
tate that there be a corresponding concentration of
salt in the outflow water. If the drainage return
flow enters a stream, the downstream users accuse
the irrigation project for contaminating the
water. One of the most pressing needs for infor-
mation in irrigation agriculture is the development
and evaluation of other procedures for disposal or
reclamation of return flow—procedures that seek
to maximize beneficial use of total water available,
while minimizing contamination for downstream
users.

Experience has already shown that one of the
prime contributions the United States can make in
the Food for Peace Program is sound technical in-
formation on the management of salt-affected soils
in the irrigated areas of the world.

Organic Wastes

It is most fortunate for 20th century man that
there were conditions in prehistoric times under
which a vast production of organic wastes from
prolific vegetation was not completely oxidized,
but accumulated under water as muck and peat
to become a wealth of coal and oil eons later.

It is most fortunate for 20th century man that
there are conditions now by which a vast produc-
tion of organic wastes is rather rapidly oxidized
by bacterial activity, conflagration, or other means
back to CO, and H.O. Our problems with organic
wastes arise because oxidation does not take place
as rapidly or as acceptably as we would like.

New, more extensive, or more useful information
is needed on the production, handling, and dis-
posal of organic wastes, including animal wastes,
reclaimed sewage effluent, crop residues, forest
slash, and processing effluent.

Animal Wastes

Production of farm animals has become big
business. There are highly mechanized dairies car-
rying 400 head; feedlot operations handling 10,000
cattle; and automated poultry enterprises caring
for 100,000 fowl. An operation involving 400 milk

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 99

cows produces about 14 tons of solid wastes and
4.5 tons of liquid wastes daily. An outfit with
10.000 cattle on the feedlot produces 260 tons of
solid wastes and 100 tons of liquids daily. A
poultry enterprise with 100,000 birds produces 5
tons of wastes daily.

Economic studies indicate that fertility value
of these wastes to the jand is not equivalent to cost
of hauling and spreading. If allowed to accumu-
late, these wastes emit offensive odors, afford
breeding areas for flies and other vermin, and
provide concentrated sources of pollution for
surface and ground water.

There are many possibilities for improved man-
agement, handling, disposal, and reclamation tech-
niques in meeting animal waste problems. These
problems are rather new on their present scale,
and consequently, have received relatively little
research attention.

There is a pressing need to develop basic design
criteria that are amenable to some adjustment to
meet the widely varying constraints associated
with different enterprises in different parts of
the country. Elements of the problem include
characteristics of manures, removal of manure
from livestock and poultry quarters, storage,
transport, feasibility of use on land and disposal
by burning, use of lagoons or similar facilities,
or burying. Disposal problems include handling
carcasses, milk-room wastes, and silage effluents.

Most of the present methods for handling live-
stock and poultry wastes are no longer economi-
cally justifiable nor esthetically acceptable. New
methods and systems are essential. Engineering
competence will be needed to evolve a com-
pletely new family of agricultural equipment and
processes.

The possibility of using livestock and poultry
wastes as a culture medium for the propagation
of organisms antagonistic to known plant pests
und diseases should be evaluated. If the use of
manure as a culture medium for the production of
organisms antagonistic to plant pests and diseases
were practical, this would justify the higher costs
of spreading manure on the fields. The value of
manure in soil sanitation has not been fully ap-
preciated. The possibilities of combining agricul-
tural and industrial wastes as an effective soil
amendment to reclaim marginal or badly eroded
Jand needs much more consideration. For example,

industrial wastes such as fly ash and cinders, would
improve the structure of some soils by providing
better aeration of the root zone. Organic wastes
provide some fertility and may appreciably im-
prove the structure of intractable soils.

Procedures for disposal of carcasses by incinerat-
ing need to be improved to alleviate their nuisance
in producing odors, smoke, and fly ash. Incinera-
tion is often necessary to control dissemination of
diseases.

Much information is needed on the effect of
materials used for litter and bedding on bulk water
absorption and other properties of manure.

Plant molds exist that are known to be toxic
to poultry and, presumably, livestock. Specifically,
there is a mold that infects peanuts and is toxic
to poultry. Peanut hulls are one of the best ma-
terials that can be used for poultry litter, but the
presence of this mold renders it useless. The hulls
become a liability instead of an asset.

Chemical analyses of manure from beef cattle on
different diets in feedlots would provide useful
information towards developing potential uses and
methods of disposal. More information is needed
on the effects of feeding and management of dairy
cattle on the chemical nature of the solid wastes.

Emanations from large livestock feedlots must
be evaluated in terms of esthetics as well as health.

Much effort should be allocated to identify the
odor-producing organisms prevalent in manures
and to develop techniques to destroy such
organisms.

The massive amounts of manure that accumu-
late under certain operations permit houseflies to
reproduce prolifically. These flies create serious
health problems in addition to irritating man and
animals.

Treatments of manure that would keep flies
and other vermin from using it as a breeding
ground are especially needed.

Even when it is feasible to spread manure on
cropland, it may be done only during certain peri-
ods of the year. More acceptable procedures for
storage and distribution without emission of of-
fending odors and possibility of contamination of
runoff waters are needed.

Encroaching suburbs in many rural areas are
forcing farmers to change and improve procedures
for handling animal wastes, but the cost-price
squeeze that continually hovers over farmers de-

100 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

mands that any changes in handling procedures
be made at the lowest cost possible.

Use of Reclaimed Sewage and Industrial Effluent

Effluent from industry and domestic sewage is
now a costly waste disposal problem. Possibilities
exist in many regions of the United States for
utilizing these waste waters for agricultural pur-
poses. Criteria need to be established for agricul-
tural use of such waters in irrigation. In addition
to the nature and content of organic constituents,
water use for various crops on different soils will
be affected by such water quality aspects as total
dissolved solids, suspended solids, acidity, and
content of metallic elements. Smmce demands for
irrigation water are seasonable, storage or other
uses of such waters may need to be developed.

Evidence indicates that the best way to reclaim
sewage or industrial effluent is to permit it to per-
colate downward through soil. Overirrigation
should be explored as a means of purifying water
and recharging aquifers.

Crop Residues

A major use of crop residues is as a part of
stubble-mulch farming to protect fallow lands
against the erosive forces of wind and water. Un-
der some conditions such mulches appear to de-
press crop yields. Also, the mulch may harbor
diseases and insects and form sources of reinfec-
tion. Additional information is needed so that the
soil-protecting aspects of mulch may be realized
without undue losses from the adverse effects.

The process of microbial decomposition of crop
residue is accompanied by great changes in the
microbial populations in the soil. There is ample
evidence that plant pathogens are sometimes sup-
pressed or eliminated during this surge of micro-
bial activity (79). If the basis for this biological
control (79) of disease organisms was known so
that the residue could be treated or amended to
augment this response, it would be one of the most
important breakthroughs in soil microbiology.
Much research effort is being placed on this prob-
lem throughout the world, but so far with little
success. Since it is known, however, that the dis-
ease-controlling effect can be modified by simply
changing the C/N ratio of the residues, there is
definite hope that accumulating knowledge will
lead to useful biological control practices.

It is also known that certain decomposing crop
residues have a toxic effect on subsequent crops,
particularly in the seedling stage. Detailed knowl-
edge on the chemistry and biological effects of
residue decomposition may reveal many unsus-
pected harmful or beneficial effects on crop growth.
Eventually, it may be possible to manage the de-
composition of crop residue, not only to reduce
harmful effects, but even to stimulate crop re-
sponse.

Another possible side effect of improved man-
agement of crop residues is the detoxification of
pesticide residues in soil. Many pesticide materials
are adsorbed or complexed by the organic matter
in soil and the enhancement of microbial activity
should be advantageous in favoring decomposition
of those pesticides that are susceptible to microbial
degradation.

The straw from grass seed harvesting is pres-
ently burned ii the field along with remaining
stubble. The emitted smoke and hydrocarbons
often create a serious air pollution problem in the
immediate locality. Other ways of handling this
residue need to be found—ways that will also pro-
vide disease and insect control.

In some grain production areas, and in many
areas In some years, straw production is too great
for efficient use of equipment under stubble-mulch
farming. Progress in breeding varieties of cereals
with short straw without sacrificing yields needs
to be expedited.

In rangeland renewal operations, the prevail-
ing brush is frequently bulldozed, chained, or
otherwise mechanically removed. Evidence indi-
cates that the brush residue may be distributed
over areas newly seeded to grass, thereby reducing
moisture losses and aiding emerging grass seed-
lings. This possibility needs to be vigorously ex-
ploited as a means of utilizing brush residue in
meeting the urgent demands for grassland restora-
tion.

Forest Slash

The millions of tons of forest slash produced
each year provide a serious fire hazard, a serious
air pollution problem when burned, and a source
of insect and disease infestation when not burned.
Thus, there is an urgent need to develop new tech-
nology for slash disposal. Mechanical means in-
volving chipping, crushing, or mastication are far

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 101

too expensive at the present time. Expediting slash
disintegration by chemical treatment has not given
positive results. Likewise, fungal inoculation to
hasten decay appears to offer little hope. There
can be marked improvement in burning techniques
that reduce atmospheric pollution. This approach
appears very promising and research to this end
should be expedited.

Processing Wastes

lt can be conservatively estimated that over a
billion pounds of milk goes into sewers annually
from fluid milk processing plants; over 20 billion
pounds of whey and buttermilk containing over
1 billion peunds of solids result from cheese and
butter production. Over 500 million pounds of bio-
chemical oxygen demand are produced in cannery
wastes (dry weight). Neither the farmer nor the
processor has a direct interest in water pollution
from farm products. Costs for additional treat-
ment of these wastes must be borne by the con-
sumer or the general public through taxation.

In the forest products field, processing losses
annually include nearly 400 million cubic feet of
logging residues and 230 million cubic feet of
coarse wood residues at manufacturing plants.
Progress in use of manufacturing wastes has been
phenomena! ; wood waste burners have almost dis-
appeared and 25 percent of all pulp is made of
chips from sawmill and veneer mill residues. Yet,
the pulp industry indicates that its wood require-
ments in 1967 will expand by 10 million cords over
those of 1966. The need for better utilization of
the resource continues to grow.

Because of the potential economic value of agri-
cultural and forest product wastes for chemicals,
pulp, and other manufactured products, the first
priority of research should be in new product de-
velopment using available residues.

The potential for improving processes so that less
waste results, or less deleterious wastes, is very
good. Many steps in processing were developed
some years ago when not much attention was paid
to stream contamination by effluents. These need to
be restudied and changed. Water reuse or counter-
current use should lower both cost and water con-
sumption. Completely new systems are possible;
“dry floor” evaporated milk operations illustrate
the possibilities.

Progress in pulp and paper manufacturing
processes to reduce water pollution has been good,
and at newer plants control can be effected. No
economical way is as yet available to further re-
duce the pollution problem at older plants which
are not equipped to adopt new and improved
processes.

The first step in increasing the efficiency of utili-
zation of waste from processing agricultural and
forest products is an evaluation of the waste’s
physical and chemical properties and a study of
potential outlets or uses for these materials. Efflu-
ents from some food-processing plants are being
used as a source of much-needed irrigation water
in some areas. The sugar industry effectively uses
filter press mud as a soil amendment and bagasse
as a source of cellulose for making paper or for the
preparation of furfural. Certain organic wastes
from the food- and timber-processing industries
are also used as soil amendments. Lignin, making
up one-fourth to one-third of all wood, is a by-
product of some pulping processes and may have
great potential as a source of chemical products.
The livestock-processing industry has made great
strides in efficiently utilizing many of its wastes as
byproducts. Increasing needs for protein in the fu-
ture make research on fermentation of carbohy-
drates more promising.

Where wastes cannot be used directly because of
the presence of a detrimental characteristic or
component, some minor amelioration processes
might be developed to make the waste product
more compatible with a potential use. This might
include filtration of an effluent to remove harmful
solids, dilution of a saline effluent to make it more
suitable for irrigation, etc. Some wastes may be
converted to satisfactory soil amendments, but in
some instances, byproducts of greater economic
value may be obtained through the development of
new and improved technology. It is important
that, where possible, some of the wastes of today
be developed into profitable products of the future.

Infectious Agents and Allergens

The latter part of the 19th century has been
aptly called the period of “the Great Sanitary
Awakening” (35). The research of two outstand-
ing medical authorities provided the foundation
for this awakening. John Snow demonstrated to

102 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

the world in 1849 that epidemics of cholera de-
rived from fecal pollution of drinking water.
From 1857 onward, William Budd investigated
the nature and mode of spreading typhoid fever.
Over the past century, civilized people have de-
veloped a well-founded awe for the grave conse-
quences that may arise from water and soil con-
taminated with infectious organisms.

The potato famine of 1846 in Ireland demon-
strated with widespread human suffering that a
famine caused by an airborne plant disease can be
just as ravaging as an outbreak of typhoid fever.
Animal Disease Agents

As our population expands, all phases of our
livestock industry—including production, trans-
portation, slaughter, and processinge—may be ex-
pected to increase in magnitude, with these opera-
tions becoming more concentrated geographically.
Consequently, greater opportunity will exist for
environmental contamination by disease-produc-
ing agents of animal sources. In other words, as
time passes our pollution problems due to animal
wastes will become more serious.

Research is underway but must, in the future, be
pursued more diligently on parasitic and infec-
tious diseases of cattle, swine, sheep, and poultry.
Many of these disease agents are capable of infect-
ing man as well as livestock; others, in the ght
of our present knowledge, cause losses only in our
livestock populations. All, in one way or another,
affect the well-being of man.

The following are a few specific examples of
animal diseases that are presently receiving re-
search attention : brucellosis, leptospirosis, enceph-
alitis, tuberculosis, salmonellosis, and ornitho-
sis. This research will have as one of its prime
benefits the reduction of sources of environmental
contamination by infectious organisms.

Research underway on parasitic diseases will
reduce environmental contamination in two dis-
tinct ways: First, by reducing environmental con-
tamination by parasite-infested animal wastes
through development of methods to reduce para-
sitism in our livestock population: and second, by
reducing the opportunity for environmental con-
tamination by pesticides through development of
methods of reducing or eliminating parasitism
based on biological control, immunization, im-
proved management, or the more efficient use of
better chemicals. Much remains to be done in the
field of parasitological research, and adequate fa-

cilities and an increase in overall effort are
urgently needed.

Research is being pursued to define the toxico-
logical and pathological effects of insecticides,
herbicides, fungicides, and other agricultural
chemicals on livestock and poultry.

Other current efforts include investigations on
the role of endoparasites in the transmission of
infectious diseases of livestock.

Important primary considerations in disease
research are the adequate control and containment
of the disease-producing agents with which the in-
vestigator is working. This includes protecting the
researcher, protecting the integrity of the experi-
ment, and protecting the surrounding environ-
ment from inadvertent contamination.

Although constant effort is being made to meet
these requirements, increased research and facili-
ties are needed to further assure the proper han-
dling of infectious or obnoxious aerosols and
animal and laboratory wastes associated with
research installations.

Research has already accomplished much to re-
duce the hazards from environmental contamina-
tion by disease-producing organisms, and the
great plagues of the past are now, in most areas
of the world, only a matter of history. Even today,
however, this is not invariably true; and in our
modern society, constant vigilance against such
diseases as bubonic plague and smallpox are recog-
nized as an ever-present necessity. If the pressures
and concentration of modern society are not to re-
sult in the appearance of new epidemics or even a
revival of old ones, we must increase our research
efforts to consistently reduce pollution of our en-
vironment by disease agents.

Plant Disease Agenis

Plant disease organisms continue to contaminate
the air, soil, and water of agricultural areas in
spite of extensive research to reduce and eliminate
them. Such contamination leads to the perpetua-
tion and spread of the organisms, with resultant
reductions in yield and quality of crops. For ex-
ample, the airborne rust diseases of wheat are
estimated to cause an average reduction of over 6
percent annually in the potential production of
that crop. Ear and stalk rots of corn cause over 5
percent average reduction of the potential corn
crop each year. These rots survive on the debris of
the previous corn crop. The potential cotton crop

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 103

is reduced by 12 percent by cotton diseases each
year. When such major crops as wheat, corn, and
cotton are reduced by plant diseases to the extent
noted above, the magnitude of the problem comes
into focus, and the benefits to be derived from
curtailing these losses become significant.

A great deal has been accomplished and is be-
ing accomplished to reduce the waste associated
with plant-disease-causing fungi, bacteria, nema-
todes, and viruses. The reduction has been achieved
by applying the results of continuing research
programs by the U.S. Department of Agriculture,
the State agricultural experiment stations, and
private industry.

Chemical controls have been effective for many
diseases, especially on high-value crops or when
small amounts of the chemical will control the dis-
ease on low-value crops. However, this type of con-
trol has added to costs of production and in some
cases has had undesirable side effects in the form
of undesirable residues.

Many diseases are controlled through the use of
resistant varieties, and breeding for resistance to
diseases is potentially the most effective and effi-
cient method for controlling many crop maladies.
However, the evolution of new disease organisms
that can attack such varieties remains a constant
threat, and control by resistance has not been found
or used successfully for numerous destructive
diseases.

Neither chemical control nor plant resistance is
available for certain diseases, notably those attack-
ing the roots of plants. These are some of our most
sinister pathogens because the infected organs are
out of sight beneath the soil, and the losses may be
attributed to drought, infertility, or anything but
disease organisms. The effects of these organisms
can be lessened to some extent by various cultural
control measures such as crop rotation and sanita-
tion, but these provide only small measures of
relief.

Thus, it is obvious that disease controls presently
available are not sufficient to prevent all of the
waste caused by plant disease agents.

All methods of control discussed should be ren-
dered more effective through diligent research
efforts. Chemicals that will not contaminate the
environment, but will provide better and more
economical control of diseases and nematodes
should be developed. Additional effort could pro-

vide pesticides with greater specificity, improved
modes of action, and less persistence in soil and
water. Methods of application must be improved,
especially for nematocides and fungicides applied
to the soil. Viricides need to be developed to con-
trol virus diseases.

To date, the breeding of crop plants for resist-
ance to diseases and nematodes has been largely
empirical. Additional research is needed on tlie
nature of such resistance, emphasizing the genetic
and biochemical systems of both the host and tlie
pathogen so that resistant crop plants may be
bred on a more scientific basis. Extensive explora-
tion for additional resistant strains should be
made, particularly in the areas of the world where
our crops originated.

Research on the control of plant pathogens that
contaminate the soil needs particular attention,
since few are subject to control by either chemi-
cals or breeding. The use of crop rotation, soil and
water management, and other cultural practices
can be made more effective by basic research to
understand how the organisms survive in the soil
and compete with other soil flora and fauna, and
where they may be vulnerable to control by man-
agement practices.

Greater attention must be paid to integrated
control measures for specific diseases. This type of
control brings several methods to bear simulta-
neously on the problem. In the past we have tended
to concentrate on only one type of control. For
example, control of the rusts of grain crops has
depended almost exclusively on breeding for resist-
ance. This has had disastrous results from time
to time when the resistance, frequently consisting
of a single gene in the crop plant, has broken down.
We need to have available many types of rust re-
sistance, including safe, cheap chemicals and other
methods that can be applied for rust contro] when
necessary.

Although the potato blight epidemic in Ireland
occurred more than 100 years ago, we still know
very little about plant disease epidemics. We need
extensive research programs where plant patholo-
gists cooperate with climatologists, meteorologists,
and ecologists to work out the basic principles of
plant disease development and spread.

Finally, in these days of vastly increased air-
plane travel and with the supersonic air transport
age almost upon us, we must be able to cope with

104 MISCELLANEOUS PUBLICATION NO. 1065, U.S.

plant diseases that may be introduced from other
parts of the world. To prepare for such accidental
introduction, we need to study plant pests poten-
tially destructive to U.S. crops. This will require
an isolated research facility where plant diseases
and their vectors from all parts of the world can
be investigated.

Allergens

Bees gathering pollen from flowers do not take
all of it. About 1.7 million tons of this delicate dust
enters our atmosphere. Allergenic pollens cause
mild to severe distress to untold thousands of peo-
ple. In addition, the cost of prevention and allevia-
tion of allergies caused by pollen is tremendous.
The prevention and therapeutics of allergen-
induced disease are still more art than science.

It was indicated in appendix ITI that no research
is underway designed specifically for the control
of plant species that produce allergenic pollen. Of
even more importance is that there is no complete
catalog of allergenic pollen. Consequently, the dis-
tress caused by pollen cannot even be assessed
properly.

Many of the weeds producing troublesome pol-
len occur naturally in uncultivated wastelands.
The only cultural method of control would be re-
peated mowing or cultivation that would keep the
ground bare. Neither method is desirable. Chemi-
cal control offers a very real possibility, however.
Information on the chemical control of other weed
species could be extended to weeds that produce
allergenic pollen. Control practices that would sig-
nificantly reduce pollen incidence in the atmos-
phere would have to be widespread because pollen
is blown for long distances by wind. An additional
approach would be to study the prevention of pol-
len formation.

Improved technology, widely applied, has the
potential for significantly reducing the incidence
of troublesome airborne pollen, thus alleviating
the distress of afflicted persons.

Agricultural Chemicals

Senate Document 85 (7/17) provided an amend-
ment to P.L. 88-573, the act making appropria-
tions to the U.S. Department of Agriculture for
fiscal year 1965. Senate Document 85 stated:

The requested changes for the U.S. Department
of Agriculture would provide an additional $29

DEPARTMENT OF AGRICULTURE

million to accelerate work on pesticide residues,
making a total 1965 request of $69 million for
pesticide research, education, and regulation in
the Department.
This action by the Congress was eloquent, testi-
mony to the interest of the people in problems
posed by pesticide residues as possible contami-
nants of the environment.

Insecticides

The discussions in appendices I, II, and III
point out the many complex problems associated
with the use of pesticides. Even though progress
is being made through research to ameliorate some
of these problems, the problem of pesticide resi-
dues, both the hazard and the legal issues, con-
tinues to be one of major interest.

Toxicologists who have investigated the effects
of pesticides on laboratory animals, and even on
man, see no evidence that our food supply is not
safe. Even though there is no proof that low-level
residues in foods constitute a hazard to man, the
mere presence of such residues, regardless of in-
finitesimal amounts, incurs apprehension in some
people. In spite of the great benefit derived from
pesticides, and the essential role they play in the
production of the Nation’s food supply, some peo-
ple hesitate to accept any risks to man that might
be involved in their use.

Wildlife conservationists object to the risks of
widespread dissemination of pesticides in our en-
vironment.

The U.S. Department of Agriculture and the
State agricultural experiment stations strive to ob-
tain information needed to assess the risks of pesti-
cides in the environment. Hazards are corrected
within the limitations of available information.

Taking the long view, it is more realistic to place
major effort on ways to deal with specific insect
problems that completely avoid hazards to man
and other forms of life. Any system of insect con-
trol that has adverse effects on a wide range of
organisms will be regarded as objectionable, either
because of economic losses from the adverse effects
on nontarget organisms, or because of the esthetic
value that the public places on such organisms
even though they may not be of economic im-
portance. If pesticides were to create hazards to
the survival of a species of wildlife, this would be
looked upon as a calamity by many. Excessive loss

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 105

of honey bees is important from the standpoint of
economics as well as the viewpoint of the apiarist.

Broad-spectrum insecticides, such as DDT, mal-
athion, or carbaryl, will each control many kinds
of destructive insects. Research to develop controls
that are insect specific will be expensive, and
their use will increase the cost of control proce-
dures as well as reduce potential environmental
contamination.

In view of the progress that has already been
made, prospects look good fer developing com-
pletely selective methods of controlling practically
all of the major insect pests. The techniques in-
clude biological agents, specific insect attractants,
insect-resistant crop varieties, self-destruction
mechanisms such as sterile males, and chemical
insecticides that act on selective physiological
systems peculiar to the target insect.

The existing coordinated research program
needs to be continued to develop better informa-
tion on insect population trends, insecticides with
higher biodegradability and lower persistence,
better knowledge of the chemical behavior of in-
secticides in soil and water systems, better predic-
tive techniques for forestalling insect invasions,
better methods of insecticide application to mini-
mize drift and to reduce rates, and physical at-
tractants to aid in nonchemical control.
Fungicides

During the 1950’s, estimates of losses in produc-
tion potential owing to diseases of pasture and
range plants varied from 3 to 9 percent. Compar-
able figures for fruit and nut crops, and for vege-
tables, are 2 to 38 percent and 2 to 23 percent,
respectively. Many of these diseases are controlled
by fungicides or bactericides. In some instances
residues of the chemical are present on the crop.
Although pollution from fungicides does not
appear to be significant, trace amounts of tetra-
chloro nitrobenzene (TCNB) and dithiocarbamate
fungicides have been detected in total diet studies
conducted by the Food and Drug Administration.
One of the best nonchemical means of disease con-
trol is breeding for resistance, as is evidenced by
the large number of disease-resistant crop plants
under production. The result of additional re-
search in this area would be certain to result not
only in reduced danger of pesticide pollution, but
in substantial savings to the producer and ulti-
mately to the consuming public.

Nematocides

Nematocides are widely used for control of
nematode pests of crops, particularly crops of a
high per acre value. The leading nematocides do
produce residues that may be a potential hazard
on more and more agricultural land. It is therefore
essential to develop other methods of nematode
control.

As with insects, breeding for resistance to nema-
todes can go far toward eliminating present and
potential residues from use of nematocides. Here
again it is the most economical form of nematode
control. Nematode-resistant varieties of important
field and truck crops have been developed, incluc-
ing stem nematode-resistant alfalfa, and nema-
tode-resistant soybeans and sugar beets. Addi-
tional research is needed on breeding and develop-
ment of methods of breeding for nematode
resistance in all crops and in ornamentals. Addi-
tional research to assess the impact of nematodes,
particularly on certain crops, also is needed to
properly assess the magnitude of the problem.

Herbicides

Use of herbicides has increased rapidly over the
past two decades because of their effective counter-
action to the waste in resources and effort caused
by weeds and brush. Weeds cause waste in pro-
ductivity and efficiency of land use, losses in
product quality, and reduced efficiency of water
management. Weeds and brush can impair the
health and efficiency of people and of livestock.
They harbor insects and disease organisms that
attack crops. Weeds and brush in water sources,
and on ditch banks, highway, railroad, and utility
rights-of-way, in fence rows, and on other areas
serve as reservoirs for invasion of fields through
movement of seeds and vegetative parts by wind,
water, soils, and man and animals.

Weeds waste water, fertilizer, light, space,
equipment, and labor. The waste and losses caused
by weeds in crops ranged from 2 to 20 percent of
the crop value for the period 1951-60. Farmers
spend about $214 billion annually to control weeds.
Yet, during the period 1951-60, the estimated an-
nual loss owing to reduced crop yields and quality
caused by weeds ranged from 3 to 25 percent, de-
pending on the crop.

The economic and social significance of efforts
to reduce the losses and waste caused by weeds can

106 MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE

be illustrated by the enormous scope of weed-
control operations in this country each year. Cul-
tural, mechanical, ecological, and other bio-
environmental methods of weed control are used
on about 365 million acres of intertilled and drill-
seeded crops each year. In addition, nonchemical
methods of weed control are used on most of the
more than 1 billion acres of forage and grazing
land.

Farmers supplement nonchemical methods of
control with chemical methods. In 1966, herbicides
were used on about 120 million acres of land. Each
year herbicides are being applied to about 35 per-
cent of the national cultivated crop acreage.

Herbicides have been used under soil and
climatic conditions not previously explored, which
resulted in most of the problems associated with
the use of herbicides.

Far better information is urgently needed on
the fate of herbicides in soils, plants, water, and
air, including the cultural practices and climatic
conditions that incur a modifying influence. The
residual toxicity of herbicides on succeeding crops
is In many instances unpredictable.

Effort to develop superior herbicides with better
specificity and fewer adverse residual or side
effects must go on apace. There is an urgent need
for better herbicides to control water weeds with-
out adverse effects on fish life, domestic use, or
recreation potential of the water.

Many of the serious problems from use of
herbicides stem from drift to nontarget areas.
Concentrated effort is needed on engineering,
chemical, and biological principles to develop
better techniques to minimize drift. The physical
nature of herbicide materials may be improved
to abate drift.

Better information is needed to guide disposal
of herbicide containers and unused herbicides.

There is a real need to develop more feasible
weed control techniques that involve nonconven-
tional chemicals. For example, a chemical that
was specific in inhibiting pollen production only
on ragweed or only on cheatgrass would be a
tremendous boon. Selective, specific, nonpersistent,
low-toxicity chemicals that stimulate or inhibit
weed seed germination would have a revolu-
tionary effect on the development of safe, effective
methods of weed control.

Economic Intelligence and Research

There is an immediate need for periodic na-
tional, regional, and State surveys of waste
problems. These economic surveys should include
general and special surveys. The general surveys
should be designated to yield comprehensive infor-
mation on the kind, location, and seriousness of
a broad range of waste problems. Special surveys
should be designed to provide information on
specific pollutants as radionuclides, chemical air
pollutants, airborne materials, sediments, plant
nutrients, inorganic salts and minerals, organic
wastes, infectious agents and allergens, exotic
organic chemicals, and thermal pollutants. These
special surveys should be designed to provide in-
formation on economic effects, abatement costs,
existing institutional control arrangements, etc.

Economic surveys would highlight critical
problems requiring studies of greater depth. Case
studies are needed to determine the socioeconomic
relationships in selected problem areas, These
studies would serve to trace the economic implica-
tions for selected problems, to specify feasible
alternatives for solution, and to provide informa-
tion for the determination of rational com-
promises between production efficiencies and
quality of the environment.

There is a continuing need for research to
facilitate changes in our institutional structures.
There are serious problems of economic adjust-
ments to meet changing standards in the entire
area of environmental quality. Local ordinances
and court actions have caused abrupt cessation of
agricultural operations in some areas. The estab-
lishment of water and air control standards may
influence the method of waste disposal. Sub-
stantial financial burdens could be imposed on
agriculture.

Thus, there is an imperative need to generate
information on the economic implications of de-
cisions made, the alternative means of regulation,
and the alternative adjustment possibilities for
affected firms and industries. The research must
be based on expanded knowledge of the control
programs in existence and those that are emerging
under Federal, State, and local regulatory au-
thorities and financial arrangements, This infor-
mation should be supplemented by information on
the organization of firms and the structure of
relevant industries and markets. It is probable
that some types of regulation may influence pat-

WASTES IN RELATION TO AGRICULTURE AND FORESTRY 107

terns of interregional competition and the size of
efficient firms within particular industries.

There is also an obvious need to improve ana-
lytical techniques to assess external economies and
diseconomies, secondary economic effects, and the
nonmonetary benefits and costs of waste disposal
systems and pollution control programs. Pro-
cedures are needed for benefit-cost analysis in sup-

port of programs with multiple objectives and
multilevel decisionmaking framework.

Analytical capabilities need to be improved for
tracing the economic implications of waste dis-
posal regulations in a systematic manner. One
possibility is the development and testing of
simulation models for use in analyzing a variety
of waste problems.

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(9)

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