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UNIVERSITY OF ILLINOIS

Volume III

Issued by Agronomy Department, University of Illinois During the Period September 5^ 1955^ to June l8, 1956

AGITI^

ACES LIBRARY UNIVERSITY OF ILLINOIS 1101 S. GOODWIN AVE. URBANA.IL 61801

Digitized by the Internet Archive

in 2011 with funding from

University of Illinois Urbana-Champaign

http://www.archive.org/details/agronomyfacts03univ

TABLE OF CONTENTS

Miscellaneous

Pollination and Fertilization M-13

The Function of CO in Crop Production K-l4

Radiation and Plant Breeding K-15

The Yellow Dwarf (Red Leaf) Disease of Oats M-I6

Corn

Corn Hybrids for Specialized Farm and Market Uses C-7

Tomorrow's Hybrid Corn C-8

Temperature and Other Interrelated Factors in Drought Damage

to the Corn Plant C-9

How to Estimate Hail Losses to Corn C-10

Forage Crops

Identifying Common Legume Seedlings F-IT

Selecting Alfalfa Varieties F-I8

How Hybrid Sorghums Were Developed and Are Being Produced F-I9

Sudangrass in Illinois F-20

Orchardgrass and Its Management F-21

Small Grains

Winter Barley in Illinois G-I3

Winter Wheat G-lU

"Blast" in Oats G-I5

Winter Rye in Illinois^ G-I6

Soybeans

Root and Stem Rot of Soybeans E-5

Estimating Hail Losses to Soybeans S-6

Soil Fertility and Testing

Chemistry of Organic Nitrogen in Soils SF-37

1955 Wheat Yields--Illinois Soil Experiment Fields SF-38

Earthworms SF-39

Band Application of Fertilizers in Illinois — Part 1 SF-40

Band Application of Fertilizers in Illinois — Part 2 SF-4l

Progress Report on a Green-Manuring Project SF-U2

Composts SF-i|-3

The Nature of Exchangeable Calcium and Magnesium and Their

Relation to Soil Acidity and Lime Requirement SF-^ij-

-2-

Soil Management and Conservation

Objectives of Crop Rotations — Introduction and Erosion Control . . .SM-12

Effect of Crop Rotations on Soil Physical Condition SM-I3

Crop Rotations and Insects 5M-1^

An Analysis of the Nitrogen Status of the Agronomy South

Farm Rotations SM-I5

Economic Ohjectives of Crop Rotations £M-l6

Continuous Corn SM-IT

Soil Properties

The Productivity of Some Important Southern Illinois Soils SP-9

Corn Root Distribution in Fertilized and Unfertilized Flanagan

Silt Loam SP-10

The Productivity of Dark, Till-Derived Soils in Northeastern

Illinois SP-11

Bottomland Soils of Illinois SP-12

Organic Soils in Illinois SP-I3

Fragipans in Illinois Soils SP-1^

Basis for Separating and Classifying Soils SP-I5

Weed Control

Controlling Wild Garlic and Wild Onion W-6

Reaction of Various Weeds and Brush to 2,4-1 and 2,k,'^-T V-J

J.-/P: sc Aug. 1955

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

MISCELLANEOUS

AGRONOMY FACTS

M-13

POLLINATION AND FERTILIZATION

The pollen that we see flying in fields of corn in July and August plays an im- portant pai-t in the production of the corn crop. These tiny grains are essen- tial for the formation of the kernel; ■without them the cob vciold he hare and useless. Pollination is essential not only in producing corn, hut in producing all other crops. Without this process, almost all of the seed plants would disappear, leaving only those that repro- duce by cuttings or other special mechan- isms.

Pollen is produced by the male flowers of the corn tassel. The female flowers are borne on the ear. Plants of this sort, in which the flowers are carried separately, are said to have imperfect flowers. Most plants have perfect flowers; that is, the male and female parts are carried within a single flower, as in wheat, oats and soybeans. Plants that have perfect flowers are often self -fertilized, while those that have imperfect flowers are usually cross- fertilized. In many species with per- fect flowers, stray pollen is usually excluded because pollination occurs be- fore the flower actually opens. This makes it virtually certain that self- pollination will take place.

At the time of sexual maturity, matiure pollen is released from anthers in large amounts. It has been estimated that a single corn tassel will produce as much as 25, 000, ceo pollen grains. This esti- mate is probably high, but even the most conservative estimate would be that each silk produces at least 9^000 pollen grains ,

Mature pollen is transferred from the anther to a receptive surface, called a stigma, by wind, gravity, or insects. Upon alighting, the pollen grain germi- nates, and the pollen tube grows down the style (silk in corn) until it reaches the ovary.

Fertilization in Typical Grass Species (Schematic)

,Silk (stigma)

Polar Nuclei

Germinated Pollen I

Pollen Tube

Sperm

In corn this process usually takes 2k- to 26 hours. Two sperm move down the pollen tube and enter the ovary. One of these sperm unites with the egg and the other unites with two polar nuclei. The egg and sperm union produces the embryo (the new plant), and the polar nuclei- sperm \inion produces the endosperm. This process is called fertilization. Cell division proceeds in these tissues \intil the mature seed is produced.

Endosperm in corn consists of the aluerone layer and the soft and horny starch of the kernel. In soybeans the endosperm is microscopic, and the food for the new embryo is stored in stinctiires called cotyledons. Cotyledons are a part of the embryo itself, and in young soybean seed- lings they look much like two thickened leaves ,

Envirorment plays an important part in the success of pollination. For ex- ample, high humidity quickly bursts pol- len of red clover. The higher seed set of this species in dry climates is doubt- less due to the lower humidity. High temperatures usually reduce the time that pollen will live. Species vary in the length of time pollen remains via- able. Barley pollen is particularly short-lived if removed from the flower. In contrast, wheat pollen can be col- lected and stored at room temperatures for as long as six hovirs and still ef- fect fertilization. Corn pollen remains viable for a shorter period, possibly no longer than two or three hours under ordinary field conditions. Viability is lost much more quickly when temperatures are high than when they are low.

Under Illinois conditions, pollen via- bility rarely limits corn production.

In 100° temperatures, pollen remains via- ble for only a short time. During early morning hours when temperatures are lower, enough pollen is usually shed to insure a satisfactory seed set. How- ever, extremely high planting rates or drouth often causes late silking and many ears may not be adequately pollinated.

The pollination habits of a crop species largely determine the methods that plant breeders may use in improving that crop. In corn, the male and female flowers are widely separated, and hybrids may be produced easily and inexpensively. Thus their large-scale use is practical. Oats, wheat, and soybeans, however, can- not be easily hybridized because the flowers are perfect and tiny. Hybrids of these crop plants will therefore prob- ably never be ccmmercially available.

D. E. Alexander 10-17-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

MISCELLANEOUS

AGRONOMY FACTS

M-14

THE FUNCTION OF CO2 IN CROP PRODUCTION

Carbon constitutes kO-k-^ percent of the dry weight of most crop plants. Wo other element contributes as many atoms to the formation of a plant. Carbon mol- ecules linked one to another form the basic skeleton of the carbohydrates^ fats^ proteins, and other substances that make up a plant. The oxidation or "burning" of the reduced carbon in fat and sugar provides the energy for plant growth. Obviously, an adequate supply of carbon is imperative for good crop production.

The basic supply of carbon for plants is in the form of a gas, carbon dioxide, or CO2. Carbon in this form is at its low- est energy level — completely oxidized or burned--and is very stable. The nor- mal CO2 concentration of the atmosphere is about three parts in 10,000 parts of air, or O.O3 percent. Except in the vi- cinity of the soil or photosynthesizing plants, this figure is relatively con- stant. The constancy is maintained by a vast reservoir of CO2 dissolved in the

oceans, both

as the gas and as carbon-

ates (the reaction product of CO2 and H2O). Air passing over the oceans gains or loses CO2 until the normal concentra- tion is re-established, and large m.asses of air continually move from oceans to land and off to the oceans again.

The plant absorbs nearly all of the CO2 it requires frcm the atm.osphere, the gas diffusing in through small pores in the leaves. Some CO2 is absorbed by the roots and is translocated to the leaves in the upward-moving sap, but the amount so supplied is believed to be of minor importance (about 5 percent at most).

Plant leaves are amazingly efficient in absorbing CO2. They can remove as much as 50 percent of the CO2 from a layer of air which is rapidly passed over photo- synthesizing corn leaves . If it were

not for this high absorption efficiency, plants would make very poor gro-vrth, since the concentration of CO2 in the air is so very small.

The CO2 that is absorbed by the leaf is transformed to sugars in the chloro- plasts, which are small, more or less rounded bodies to be found in the cells of all green tissue. The chlorophyll of the chloroplasts absorbs light (prin- cipally the red and blue wave lengths, leaving the familiar green color) and uses the light energy to split off hydro- gen from water. The hydrogen thus gained is used to "reduce" carbon diox- ide to a higher energy state — the state in which it occurs in sugars and starch. This reduction to a higher energy state is an extremely ccmplicated biochemical process, but it can be summarized as follows :

1. The CO2 absorbed by the chloroplasts is added by an enzyme to aphosphory- lated 5-carbon sugar. This forms an unstable 6-carbon compound, which immediately splits to give two phos- phorylated S-cs^^'bcn acids.

2. The hydrogen produced by the split- ting of water is added to the 3-carbon acids, which then condense to give a stable 6-carbon sugar, a phosphory- lated glucose. The phosphorylated glucose is a key compound that can be readily transformed to starch, cane sugar, fat, amino acids, etc. The figure on the back schematica3J.y depicts the photosynthetic process.

Greenhouse and laboratory experiments have shown that the concentration of CO2 in the atmosphere is far frcm optimal for photosynthesis. By increasing the CO2 concentration about 2.5 times, the photosynthetic rate of plants in bright sunlight can be doubled. There is some

question, however, about the effect of still higher concentrations of COg. While short-time photosynthesis con- tinues to increase, the higher concentra- tions of CO2 have a toxic effect that reduces grovth.

Many investigators have grown crop plants to maturityin C02-enriched air in green- houses, and with few exceptions they re- port yield increases of 20 to 200 percent. Exceptions apparently occur when the CO2 concentration is raised too high. There is no accurate evaluation of just what concentration of CO2 would produce maxi- mum photosynthesis without injuring the plant, hut it appears that a 50-100 per- cent increase in concentration would he nearly optimal, depending on the species concerned.

Field studies on the effect of CO2 en- richment have also been carried out, and for the most part these results also shew yield increases. Field studies are much more difficult to make than

greenhouse studies, "because the gas is not contained and winds will carry it away. However, CO2 is a heavy gas, and if released near the soil it will tend to "hang" in the vegetation in high concen- tration if there is not excessive turbu- lence due to winds. Even though marked yield increases of such crops as sugar beets have been obtained by CO2 enrich- ment of the air, such "fertilization" is not commercially practical because of the excessive cost of supplying the gas.

Actually it appears that sizable yield increases could be obtained if one could only maintain the normal concen- tration of CO2 around the crop during the daylight hours. As it is, the CO2 concentration in a field of rapidly growing corn during the daylight hours will average about 25 percent less than normal. Measurements made at Ames, Iowa, show that even at 5OO feet above the cornfield the concentration will be reduced 10 percent. Such depletions occur on windy as well as still days

light

-3-

and leave no doubt that the crop can ah- sorh CO2 more rapidly than it can be brought down from the upper atmosphere.

The upper atmosphere is not the only source of CO2 for the plant ^ however. The respiration of microorganisms and plant roots produces large amounts of CO 2 in the soil^ which diffuses up into the atmosphere about the leaves of the crop. A fertile^ warm, moist soil, well sup- plied with organic matter, will give off as much as 3OO pounds of CO2 per acre during the daylight hours. Inasmuch as a very rapidly growing acre of corn will absorb about 400 pounds of CO2 in the same period, it can be seen that the soil can do much to maintain favorable concen- trations of CO2 about the leaves. If it were not for this evolution of CO2 from the soil, the concentration of the gas in the cornfield during the day would un- doubtedly be reduced more than the 25 percent below normal previously quoted.

The point bears emphasizing, however, that, if the soil is to be effective in this respect, it must be fertile, moist.

and warm, with a high organic matter con- tent and a structure conducive to rapid gas exchange. In short, production of CO2 by the soil will be maximal in those soils that have long been recognized as producing excellent crops. But just what share of the yield is to be at- tributed to increased COo concentration about the leaves? Experimental evidence does not permit this question to be answered with exactitude, although an ex- periment conducted in Sweden with sugar beets 30 years ago suggests that it might be appreciable.

In this experiment, manure, instead of being worked into the soil, was allowed to ferment in troughs between the beet rows. This fermentation prevented the roots from obtaining the nutritive ele- ments, but the air around the leaves was enriched by the escaping C02. A 19 per- cent increase in yield over controls was obtained by this treatment. Such results suggest that an appreciable part of record corn yields may be due to increased CO2 coming from the heavily manured soils that seem to be an invariable part of such yields.

J. B. Hanson 1-16-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

M-15

RADIATION AND PLANT BREEDING

In 1927 and 1928 Dr. H. J. Muller, now of Indiana University, and the late Dr. L. J. Stadler, of the University of Missouri, reported that X-ray and ultra- violet radiation "brought about heritable changes (mutations) in living organisms. (Doctor Muller was awarded the Eobel prize in Medicine in 19^6 for this work. ) Since the rate of mutation was thousands of times greater in irradiated material than in untreated material and, further, since some of the mutants appeared to have qualities that plant breeders were looking for, it was immediately suggested that plant breeders use this new tech- nique.

At that time corn breeders were perfect- ing hybrid corn, and other breeders were convinced that the new tool was not well adapted to their programs. Most breeders and geneticists were impressed with the fact that the vast majority of the mutations were deleterious, i.e., the plant that possessed the new character yielded lower or was otherwise less de- sirable than already existing strains. Hence the use of irradiation in breeding was largely neglected.

If we examine critically the changes brought about in the hereditary material of an irradiated individual, we can make some interesting observations. Muller and Stadler found that these changes could be roughly placed into three classes:

1. Intra-genic changes, i.e., changes within the gene itself that are simi- larto those found in nature. These changes behaved in a Mendelian fash- ion. No differences in viability of pollen or egg were evident and normal segregation occurred in the F2. Un- fortunately, these changes are the least common ones that are induced by radiation.

2. Deletion, i.e., destruction of a small part of the chromosome itself. Critical studies by Stadler revealed that many of these changes were so small as to be undetactable when he looked at the chromosome under a microscope, but genetic studies showed that a number of genes had been destroyed.

3. Structural rearrangement of chromo- somes. Many of the mutations in- volved the translocation of part of one chromosome to another chromosome, or the inversion, or change in gene order, of a single chromosome. These changes produced varying degrees of sterility, either on the female or male side, or on both.

Swedish plant breeders, however, started irradiation breeding in barley and other cereal crops and were able to show that mutants could be produced that matured earlier and had stiffer and shorter straw, greater resistance to certain diseases and, in a few cases, higher yield. However, these useful mutants were very rare. Swedish workers esti- mate that only one in a thousand of these mutations may be of value in a breeding program.

An increase in radiation breeding oc- curred after World War II in the U.S., largely because of the financial support of the Atomic Energy Commission. Radia- tion breeding in corn, wheat, oats, soy- beans, rye, peanuts, cotton, and several other field crop species is currently under way in agricultural experiment stations throughout this country. It is still too early to anticipate the even- tual outcome of all this work, but the conclusions on the following page appear to the justified as of now.

2.

It is improbable that the mutants produced in a strain by irradiation will be used directly by farmers. It is more probable that the new quality will be incorporated into new varieties by conventional plant breeding methods and that these va- rieties will be released only if they possess advantages over exist- ing varieties.

The use of radiation does not appear to be a profitable venture for plant breeders unless a desired quality does not exist or cannot be found in the species under improvement.

3. No drastically new and completely superior varieties can be expected through irradiation treatment alone. Since the discovery of the mutational effect of ionizing radiation in I926, millions of individual seeds,, plants, and pollen grains have been treated with X-rays, neutrons, and ultra- violet rays. Some heritable changes have been wrought. All of them are more or less similar to the changes that occur at rarer intervals without man's intervention, and most of them are deleterious to the individual that inherits them.

D. E. Alexander 3-26-56

UNIVERSITY OF ILLINOIS ■ COLLEGE OF AGRICULTURE

MISCELLANEOUS

AGRONOMY FACTS

M-16

THE YELLOW DWARF (RED LEAF) DISEASE OF OATS

The red leaf (yellov dvarf ) disease of oats probably has been present in the U.S. for many years. Excellent descrip- tions of what appear to be the eame disease were published as far back as 1898. Since 19^5:) however^ the disease has become increasingly more prevalent. The reason for this increase is not known,, but it does not appear to be as- sociated with the continual change-over in oat varieties.

Red leaf is caused by a virus that can be transmitted by at least five species of aphids commonly infesting small grain and grasses. The virus cannot be trans- mitted mechanically, in the seed, or through the soil.

The virus has been sho-vm to be identical with the one causing yellow dwarf dis- ease of small gi-ain in California. The name "yellow dwarf" was selected by Cali- fornia workers on the basis of outstand- ing symptoms produced by the virus on barley and wheat.

The disease usually appears first on the edges of a field and in "spots" or cir- cular areas varying from a few feet to 30 or more feet in diameter. Sometimes these areas may overlap, and in years when aphids are very abimdant a field may be uniformly affected. Farmers fre- quently have failed to associate earlier aphid infestations with the disease, since the first symptoms usually appear in about ik days. Sometimes nearly all aphids have disappeared by the time the first symptoms can be seen.

The first symptom of the disease in oats is the appearance, usually near the leaf tip, of faint yellowish-green blotches that can best be seen by holding the leaf blade up to the light. V/hen first

formed, the blotches are somewhat vari- able in size and shape and are usually less than a few centimeters in size. The blotches enlarge rather rapidly, merge, and turn various shades of red, broim, and yellow- orange. Cool temperatures (70° F. and lower) favor the appearance of red pigments in the affected leaves, whereas temperatures of 75° F. and above suppress their appearance. At the same time, the yellowish-green blotches con- tinue to appear on successively lower portions of the leaf in advance of the changes in color. The affected portions of the leaf often die rapidly.

In addition, a rather characteristic in- ward curling of affected leaves frequently occurs. Symptoms generally appear on the oldest leaves first and then succes- sively involve the younger leaves. Oc- casionally the youngest leaves will show a longitudinal striping resulting from a yellow-green color in the interveinal areas and a darker green in the tissue over the veins. The root system is as severely stunted as the tops of the plants.

Blasting of the florets is the most seri- ous aspect of the disease. It may vary from only a few blasted florets to com- plete failure of the plant to head. A shriveling and lower test weight of ker- nels also may occur. The severity of the disease depends on the variety of oat infected, the age of the plants at the time they become infected^ and the strain of virus involved.

Winged aphids moving into small grain fields in the spring from various grasses are believed to be responsible for the initial spread. Each adult aphid is cap- able of producing daily from 10 to 20 young, which upon maturity (one to two

weeks) also begin to produce. These later aphids are usually vingless and move about by crawling from plant to plant. When food conditions become un- favorable, winged forms develop which fly to other fields of small grain and grasses.

In order to transmit the virus to healthy plants, the aphid first must acquire it by feeding on diseased plants. However, once the aphid has acquired the virus, it apparently is able to transmit it for the rest of its life.

Virus -free aphids --less than a hundred per plant --cause very little damage to small grain. The greenbug is an excep- tion, since it secretes a toxin. A sin- gle viruliferous apple -grain aphid is able to transmit the virus to a healthy oat plant in as short a time as four hours.

For an aphid-transmitted virus to cause serious loss in an annual crop raised from seed, the virus must spread rapidly. Rapid spreading can occur only if the crop is easily infected, the source of the virus is readily available, and the vector is very numerous and active. For- tunately, all of these conditions do not usually occur at the same time, and losses therefore vary greatly from year to year and from locality to locality.

No oat variety tested has been found to possess satisfactory resistance to red leaf disease. Therefore, an intensive effort is being made to locate sources of resistance in oats.

Early planting is the only practice that can be recommended at present. This rec- ommendation is based on the fact that large plants are better able to "toler- ate" the disease than smaller ones.

R. M. Takeshita 5-li^-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

C-7

CORN HYBRIDS FOR SPECIALIZED FAR/V^ AND MARKET USES

Corn is an extremely versatile crop. Consequently, breeders are able to se- lect types for particular uses. They may work with dent, sweet, pop, flint, floury, or waxy corn. These types, how- ever, may be modified greatly by breed- ing and selection.

Livestock feed. From 75 to 90 percent of the corn crop in the United States is fed to livestock. In contrast, most of the corn crop in many other areas of the world is used for human food. Most live- stock feeders in the United States pre- fer a dent grain that is yellow, soft, and high in quality and quantity of pro- tein. Feeders in many other covintries prefer a white flint corn.

Corn has certain limitations for feed- ing. It is low in quality and quantity of protein and is relatively low in vitamins. Seme feeders also ccmplain of poor palatability and reduced gains from certain hybrids. Many feeders grind the harder types.

Corn breeders need to develop special hybrids with high tonnage and better quality of silage and green feed. Multiple -eared, heavy- tillering strains may be useful for this purpose. Consid- eration must be given to yield and per- centage of dry matter, proportion of ears to stalks and leaves, and percent- age 1 of crude fiber and protein. These studies should be supported by digesti- bility experiments and by feeding trials.

Milling industry. Wet millers desire strains that are high in starch, oil, and protein. Since corn contains about 70 percent starch (dry basis), a varia- tion of one or two percent is important in large-scale operation. The industry claims that flinty types do not steep and process so well as softer types.

Most dry millers prefer a kernel that is semihard and vitreous and that does not

have too much soft starch on either the tip or the dent end. They want neither the shoe -peg type nor small, roiond kernels. The dent must not be too deep or the hull too rough. Kernels of this type make chaffy or chalky products which are fit only to put into feed. The cob color is of little consequence.

An adequate supply of white corn is another requirement of dry millers. Con- s\jmers claim a distinct preference for the flavor and taste of meal made from white corn. The finished-product demand is for either pure white or pure yellow.

Protein content and quality. Protein is an expensive but necessary constituent of food and feed. The University of Illinois gave the first evidence that protein and oil content in corn could be greatly increased or lowered by breed- ing. After 50 generations of selection, the average protein content was 19.5 percent for Illinois High Protein and 4.9 percent for Illinois Lev Protein. These open-pollinated strains yield only about 50 percent as much grain as adapted hybrids. Fortunately, the high pro- tein trait can be transferred to stand- ard inbred lines by breeding procedvires.

Quality of protein is fully as inrportant as quantity of protein. The corn kernel contains two main types of protein. That found in the endosperm is primarily zein. Zein is deficient in tryptophane and lysine, which are essential for ani- mal nutrition. The other type of pro- tein, fo\ind in both endosperm and germ, contains both tryptophane and lysine and is biologically balanced. The corn breeder would like to increase the per- centage of these amino acids in the en- dosperm protein. The alternative is to add them to the diet from other sources.

Oil for industry and high-energy feed. Corn oil, a valuable by-product of the starch industry, is high in energy value

for livestock feeding. Most of ■'the oil is in the germ of the kernel. Germ pro- tein contains tryptophane and lysine, is biologically balanced, and is prob- ably more valuable for livestock feeding than endosperm protein. High- oil hy- brids having a high proportion of germ to endosperm should therefore benefit both the starch industry and livestock feeders.

After 50 generations of selection at the University of Illinois, the average oil content of Illinois High Oil vas 15.^ percent compared with 1.0 percent for Illinois Lov Oil. Unfortunately, these open-pollinated high-oil strains are low yielding. High oil, however, was trans- ferred to standard inbred lines at the Illinois ' station by crossing, followed by back-crossing, selection, and self- fertilization. Selection for high oil was accomplished by selecting ears bear- ing kernels with large germs.

Breeding programs have been inaugurated by several Com Belt agricultural exper- iment stations and private hybrid seed corn companies to develop hybrids with high -oil or high -protein content. Seme of these hybrids appear to be very prom- ising. For example. 111. 6063 produced lij-,0 percent more protein, 32.8 percent more oil, and was 8.5 percent superior in grain yield to U. S. I3, a standard hybrid. However, these Illinois experi- mental combinations are not yet in com- mercial use.

Zein for special fabrics. Protein con- tent of corn grain may be increased by breeding and by high applications of nitrogen fertilizers. Most of the in- crease of endosperm protein is zein, whith is not high in nutritive value be- cause it is poorly balanced among its constituent amino acids.

Zein is obtained from the gluten in the corn wet-milling process. The Northern Utilization Research Branch of the U. S. Department of Agriculture, Peoria, Illi- nois, studied dispersion of zein in strong alkali, "spinning" it into a fi-

ber- and stretching and curing to give the fiber added strength.

This fiber, which is available on the market under the trade name "Vicarai'! is used mostly in blends with wool for such garments as socks, swimming suits, and sweaters. Possible increased use of zein for special fabrics has created seme interest in breeding comfbr-higlier zein content,

Amylose for plastics, cellophane, and films, Amylose is a linear-type molecule which can be made into thin, transparent films resembling cellophane. Acceptable films require amylose of 80 percent purity. Ordinary com starch contains about 27 percent amylose. Samples, how- ever, have been found in which the starch was 62 percent amylose. Consequently, it appears that it may be possible eventually to obtain dent corn with a high enough amylose content for the prac- tical production of plastics, cellophane, and films.

Vitamin A (B-darotene), An association has been foijnd between the yellow pig- ment and vitamin A in corn. There is a direct quantitative relation between vltemln A and the number of genes for yellow pigment in the endosperm. In fact, the yellow endosperm genes act in an arithmetic, cimiulative manner, each gene adding 2,5 units of vitamin A per gram of grain. Feeding tests have dem- onstrated that yellow corn is better than white corn for hogs on drylot feed- ing.

Niacin (nicotinic acid). Fortunately, wide differences in niacin concentra- tions have been found among various strains of corn. Hybrids tend to rank between their parents, and the seed par- ent generally exercises more influence than the pollen parent. Dent kernels are lowest in niacin content, waxy ker- nels intermediate, and sugary " kernels highest. Adequate niacin in the diet eliminates certain malnutritional dis- turbances.

R. W, Jugenheimer 9-5-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

C-8

TOMORROW'S HYBRID CORN

It is becoming more and more difficult to develop hybrids that are definitely- superior in all characteristics to the better ones nov available in the Corn Belt. For this reason, the Corn Belt hybrids of I965 may not be radically different from those of today. However, it should be possible to greatly im- prove the hybrids that are adapted to other areas of the United States and many other sections of the world.

Hybrids for special purposes and uses should soon be available. Producers and industry \d.ll be able to choose between better dent, flint, sweet, pop, waxy or possibly floury types.

Livestock feeders in the United States prefer a yellow grain that is soft and high in quality and quantity of protein. Multiple -eared, heavy -tillering strains will be useful for silage and green feed.

Industry will eventually be able to ob- tain more suitable types of corn. Dry millers prefer white kernels with smooth dent. Wet millers and livestock feeders will welcome high- oil hybrids. Waxy corn is available for food and glue. High-zein corn can be used for special fabrics, and a high-amylose corn would hybrids are better husk cover, better be valuable and films.

Hybrids differ greatly in drouth re- sistance. The leaves of some strains remain green, while others are badly in- jured by heat. Some hybrids set seed satisfactorily under conditions of high temperature and low humidity, while others shed little pollen for only short periods.

Excellent standability has contributed greatly to the popvilarity of hybrids in the Corn Belt, This desirable trait needs more emphasis in. many other places. Lodging lowers quality and yield and makes harvesting more difficult. Varia- tions in standability between hybrids are caused by differences in stalk struc- ture, root system, ear height, soil fertility, plant population, and resist- ance to insects and diseases.

For hand harvesting, farmers want single- eared strains with the ear borne at a convenient height. It may be possible to harvest future hybrids with a mechanical picker more easily and satisfactorily than the present types can be harvested. Hybrids with shorter plants may also be better adapted for field shelling and ccm.bine harvesting.

Other traits that may be added to future

for plastics, cellophane, grain quality, higher shelling percent- age, and resistance to chemical weed

Yields of grain, silage, and fodder will gradually edge upward because hybrids will be better able to resist hazards. Effective disease inoculation and insect infestation techniques will result in hybrids that have greater resistance to diseases and insects. In general, flint corn germinates better and the seedings grew more vigorously than dent in the cooler climates.

sprays ,

By 1965 the use of male sterility and pollen restorers will probably eliminate much of the detasseling now required in producing hybrid seed. This development should lower production costs and result in a better product,

R, ¥, Jugenheimer 10-10-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

TEMPERATURE AND OTHER INTERRELATED FACTORS IN DROUGHT DAMAGE TO THE CORN PLANT

C-9

The question, "Is it high temperature or lack of moisture that is damaging the corn plant?" commonly asked in a hot, dry year is exceedingly hard to answer. The reason for this is that the two variahles are so intimately interrelated that it is impossihle to separate them under normal field conditions.

Some of the factors involved in "drought damage" of the corn plant under field conditions in addition to temperature are listed below and show the complexity of the problem.

1. Metabolic status of the plant

2. Soil moisture

3. Atmospheric moisture or relative humidity

h. Physiological moisture

5. Variety of the plant

6. State of development of the plant

7. Part of the plant

Since under field conditions all of these factors may be in operation at the same time, it is extremely hard to dis- cuss the problem in general. This arti- cle will therefore emphasize temperature and try to relate the other factors to it .

The temperature factor. The following method is commonly used to determine the temperature that is required to kill plant tissue and cells: A leaf, branch, or section of tissue is cut off and im- mersed in water maintained at a constant temperattire . The material is removed after an appropriate time interval, and staining techniques are used to deter- mine whether the cells have been killed. By varying the temperature and the time of Immersion, and determining the per- centage of cells killed, it is possible to determine the "thermal death point." This term which is used to express the results is based on three components: tim£, temperature, and percentage of cells killed.

The main advantage of this method is that it separates temperature effects from many of the environmental factors. As an illustration, it was found that 100 percent of the cells of range grass roots were killed when immersed in water at 162 F. In contrast where the roots were placed in water which was slowly warmed over a 150-minute period, the lethal temperature was 126 F. This method, or modifications of it, has been used by many investigators to establish a critical temperature range that varies from 113 to l40 F. for many different plant species. The literature shows that the corn plant falls within this temperature range.

In visualising hew high temperatures kill a plant cell, it should be kept in mind that all the vital metabolic pro- cesses are carried out by proteinaceous compounds called enzymes. Heat, or de- hydration by heat, can inactivate the en- zymes by coagulation in much the same mamier as egg protein is coagulated by frying or boiling.

Leaves in general, and corn leaves are no exception, tend to maintain them- selves at the same temperature as the air surrounding them. Using over a thou- sand separate measurementF, experimenters at the Kansas Experiment Station found the average temperature of tiirgid leaves to be 87.2 F. compared to an average of 87 F. for air temperature. Wilted corn leaves measured from 3 to 8 F. higher. This indicates that transpiration does not have a major role in regulating leaf temperature. The leaf then must maintain its temperature by a) reflecting a por- tion of the light and b) radiating heat. The latter is accomplished in mu'h the same way as the "leaf -like" finned por- tion of an air-cooled motor dissipates heat.

Temperature and metabolism. Plants have two major metabolic systems that are "geared together," a) photosynthesis which synthesizes the carbohydrates

vhich are \ised for "building blocks" and for energy and b) respiration which oxi- dizes (burns ) carbohydrates to provide energy for maintenance and growth^ and to supply "building blocks" of different types needed in plant growth . At a tem- perature of 68 F. the photosynthetic process exceeds the respiratory process by a considerable margin. This supplies an adequate amoiont of carbohydrates for the respiratory process and also pro- vides the "building blocks" needed for grovth. As temperatui-e is increased, a compensation point is reached where in- put of carbohydrates just balances the consumption by respiration, while at higher temperatures (96 F. ) the respir- atory utilization exceeds that provided by the photosynthetic process. Prolonged exposiu:e of the plant to high temper- atures would therefore markedly curtail plant growth.

It has been observed that a wilted leaf absorbs but one-third the amount of CO2 taken up by a turgid leaf. Naturally, this would reduce the photosynthetic pro- duction of carbohydrates by the same amount. This emphasizes the interrela- tion of moisture and temperature.

Although the information is meager, there seems to be seme relationship be- tween the levels of carbohydrates, pro- teins, and colloids in the plant cells and their resistance to dehydration. It has been pointed out that dehydration of the proteinaceous material of cells can result in their death. These levels of cellular constituents are controlled by the metabolism of the plant.

Temperature and moisture. Three major factors involved in maintaining an ade- quate physiological moisture level in the plant are: soil moisture, water- conducting system of the plant, and rate of transpiration of water loss from the plant. Soil moisture is the major reserve of water supply and must be adequate to meet the demands made by the plant for maintaining its physiological moisture level and transpirational losses. Since water is conducted frcm the soil by the xylem system of the plant, this "piping system" must develop rapidly enough and be large enough to supply the demands of all parts of the plant. It has long been

known that certain varieties of corn are more susceptible to top leaf blasting than others. Recently it has been shcwnl/ that the susceptible varieties were much slower in developing xylem vessels in the leaves than the non-blasting varieties. Consequently, in high transpirational periods (hot, dry windy weather) the leaves of the plant with inadequately developed "piping systems" were severely desiccated and subsequently died. This desiccation could occur even with ade- quate soil moisture since the failure is in the water trajisport system.

The rate of transpiration from leaves depends largely on temperature, relative humidity, and air movement (wind cur- rents). The relationship between tem- perat-ure and rela.tive humidity is siio-rfn by the fcllov^ing: air at 50 , 68 , and 100 F. must contain, respectively; 0.3^ 0.6, and 3»5 oimces of water per cubic yard to achieve 100 percent relative hu- midity at each temperature. Air at 50 F. and a relative humidity of 80 per- cent if heated to 68 F. would drop to 40 percent relative hvunidity and at 100 F, would be only 0.6 percent satu- rated. The loss of water from leaves is controlled by the gradient between the relative humidity of the stcmata of the leaves (assuming 100 percent R.H.) and that of the air. Rapid air movement tends to keep this gradient at amaximum.

Temperature and part of the plant. Some parts of the plant are more susceptible to heat and desiccation damage than other parts. For example, pollen and silk seem to be most sensitive. In field trials2/ representing some 7^000 pollinations, a good correlation was ob- tained between high temperatures and failure to set seed. At 75 F« 'the per- centage of ovules setting seed was 65, while at IO5-IIO F, only eight percent seed set was obtained. Desiccation of pollen and silks rather than lethal tem- perature effects was considered the pri- mary cause of the damage.

1/ Private communication from Dr. L. A.

Tatum, Kansas State College, Manhattan,

Kansas.

2/ lonnquist, J. A. and Jugenheimer, R.W.

Jour. Amer. Soc. Agron. 35:923. 19^3*

R. H. Hageman 2-6-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

C-10

HOW TO ESTIMATE HAIL LOSSES TO CORN

Hail insurance on growing crops in this country increased gradually from 87 million dollars in 193^ "bo over 1 3/^ "billion in 1953^ or 20 fold. Payments to farmers for losses ranged from a low of 1.5 percent of the insured value to a high of 3-1 percent, with an average of 2.3 percent over the 20-year period.

The amount of damage inflicted by hail is hard to estimate. The stage of the crop when the storm strikes and the se- verity of the injury are the two main factors that need to be considered in appraising losses. Without data from experiments, an estimate of the loss re- sulting from a hailstorm might be no better than a wild guess. Fortunately, field trials have been conducted by agricultural experiment stations in Illinois (6 years), Iowa (7 years), Nebraska (9 years). South Dakota (2 years), and West Virginia (l year), in addition to some extensive tests by in- surance companies. The results of these experiments agree closely and make it possible to assess the damaging effect of a hailstorm on a crop of corn rather accurately.

this stage, the plant will therefore produce no grain. Removing all exposed blades when the plants are younger does little harm because defoliation at that time takes off only a little leaf surface and the plant produces new leaves as the stem pushes upwards inside the whorl. The later the blades are removed, the greater the percentage of leaf surface destroyed. Thus, grain yield goes down as blade removal is delayed, and this continues until the tasseling stage. After tasseling, however, grain yield goes up as blade removal is delayed. This relation between grain yield and stage of plant development at the time blades were removed was borne out in t"ne experiments in all the states. So if a hailstorm occurs, carefully note the stage of development your crop is in when the hail strikes it.

Degree of injury is also important in es- timating damage from hail. Any injury to the corn plant will usually decrease grain yield, because Nature does not pro- vide the corn plant with enough leaf sur- face to permit part of it to be sacrificed without affecting the yield.

Sometimes farmers are not fully satis- fied with the appraisal of injury to their hail-damaged crops. They ask how the losses are estimated. This brief discussion is presented to explain the factors that need to be considered in arriving at an estim.ate.

Stage of crop development has an im- portant bearing on the losses from hail injury. Corn plants in the tassel and ear-shoot-emerging stage are most sub- ject to injury so far as grain pro- duction is concerned. No grain has been produced before the injury, and no new blades can be produced afterwards. If all the blades are removed by hail at

Experimental results show that grain yields are reduced in direct proportion to the amount of leaf area that is re- moved. There is a tendency, however, es- pecially when only small percentages of leaves are removed, for the yield reduc- tion to be somewhat less than the amoimt of leaf surface that is lost. This sug- gests that the efficiency of the uninjured leaf surface is stepped up after some of the leaves have been removed, possibly because the remaining leaves get more light.

As soon as possible after the storm sub- sides, get as careful an estimate as you can of the amount of blade surface re- moved from the plants by the hailstorm.

Blade shredding, midrib breaking, and stalk and ear bruising are other forms of injury caused by hail. Tests show that as long as any part of the blade rem.ains attached to the plant it is capable of contributing to grain yield. In lowa^ when all the blades were severely shredded, yield of grain was 37 percent of normal even when the shredding was done at the beginning of tasseling. Severe shredding earlier and later caused progressively less damage.

Midrib breaking did not do much harm. With every midrib broken at the most critical time, namely, tasseling time, yield was 80 percent of normal.

Stalk bruising decreased yields about 10 percent beyond that caused by blade

shredding. Ear bruising did little harm to yield, but when it occurred at the milk stage the market quality of the grain was reduced somewhat because of the damage to kernels .

Believe it or not, under some conditions hail injury may actually increase grain yields. This happened in Iowa during the dry year of 1930- Cutting out blades reduced transpiration, and the moisture thus conserved was more beneficial to the plant than the leaf removal was harmful.

Experimental data have taken much of the "guess" out of estimating losses to corn from hail injury. Yet it is still neces- sary to weigh the significance of the many factors that have a bearing on the outc ome .

George H. Dungan 5-28-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

IDENTIFYING COMMON LEGUME SEEDLINGS

F-17

It is often necessary to identify cer- tain legumes before they have flowered or after they have been closely grazed. Many times it is necessary to identify

Cot yle denary leaves - the seed leaves of the embryo -which act as storage organs in seeds of plants.

Leaflet - one of the divisions of a com- pound leaf; e.g., the red clover leaf has three leaflets.

Petiole - the stalk of a leaf.

Pubescent - having fine, soft hairs.

In the following key to identifying legume seedlings, the cotyledonary leaves are considered to be the first and second leaves. Most of the common legvmes exhibit epigean emergence; i.e., the cotyledons emerge aboveground. The pea and vetch, notable exceptions, exhibit hypogean emergence; i.e., the cotyledons remain imderground during germination and emergence.

leg\minous plants in the seedling stage. The follo-vrLng definitions and distin- guishing featiires should be helpful in identifying some ccmnon legume seedlings.

Serrate - having sharp teeth.

Trifoliolate - having three leaflets.

Unifoliolate - having one leaflet.

Variegation - the barring (water marks) on leaves, seen in nearly all American strains of red clover.

Vein (nerve, rib) - nerve or rib in leaves, bracts, scales, sepals, etc.

This key is greatly simplified. It should be remembered that many weed seed- lings have characteristics similar to those of legume seedlings. Further, there are many variations within the different species presented in the key; e.g., most European strains of red clover are not pubescent. However, for practi- cal field use, the key will help to identify some common legume species in the seedling stage.

Key to the Seedlings of Some Common Legume Species

-la. Third leaf imifoliolate (fourth leaf trif oliolate ) _ 2a, Petiolar branches of vmequal length

3a • Leaflets one -third serrate - alfalfa

yo. Leaflets completely serrate - sveet clover

-213. Petiolar "branches of equal length _3a. Vegetative parts pubescent

Ua. Variegation present - red clover

4b, No variegation present - crimson clover

3b. Vegetative parts not pubescent

ka. No variegation present - alsike clover

I hh. Variegation present

. 5a- • Giant form - Ladino clover

I 5^3, Snail form - common vhite clover

lb. Third leaf trif oliolate or both third and fourth leaves

unif oliolate _2a. Third leaf trif oliolate, veins not prominent - birdsfoot

trefoil _2b. Both third and fovirth leaves unif oliolate, veins

prominent - common, Korean, and sericean lespedeza

A, W, Burger 10-31-55

UNIVERSITY OF ILLINOIS ■ COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SELECTING ALFALFA VARIETIES

F-18

The main point to consider in selecting an alfalfa variety is the time you ex- pect the alfalfa to stand before plowing it down. If you plan to use the stand several years for hay^ plant seed of a winter-hardjj wilt-resistant variety like Ranger or Buffalo. If you plan to use it only one or two years for hay^ you can use a winter-hardy^ wilt-susceptible variety like Atlantic or Du Puits. In either case, use certified seed.

Bacterial wilt does not reduce alfalfa yield until about the third year. Be- cause certain wilt -susceptible vari- eties, such as Atlantic and Du Puits, are as productive as Ranger and Buffalo dur- ing the first year or two, there is no advantage in usinga wilt-resistant vari- ety in short rotations.

Several varieties of alfalfa have been developed in the United States. There is a good seed supply of most varieties. Following are descriptions of several varieties and status of seed supplies.

Ranger, which is resistant to bacterial wilt, was developed at the Nebraska Ex- periment Station by intercrossing se- lected strains of Cossack, Ladak, and Turkistan. Ranger is a good forage pro- ducer and is as winter-hardy as the hardy common alfalfas. The flower color is variegated. Ranger is recommended for the northern two-thirds of Illinois. Seed supply is adequate.

Buffalo, also resistant to bacterial wilt, was developed by the Kansas Experi- ment Station out of Kansas Common. It is a good forage producer and is only slightly less winter-hardy than Ranger. Flower color is purple. Buffalo is rec- ommended in the southern two-thirds of Illinois. Seed supply is adequate.

Atlantic, a high-yielding variety devel- oped by the New Jersey Experiment Sta- tion, is not resistant to bacterial

wilt. It was developed especially for the eastern states, where bacterial wilt is not serious. It is about as winter- hardy as Buffalo. Flower color is varie- gated. Atlantic is recommended throughout Illinois for short rotations. Seed sup- ply is adequate.

Du Puits is a variety developed in France that has yielded exceptionally well in tests in Illinois and several other states. Lu Puits is not wilt-resistant. It is about as winter-hardy as Buffalo. Du Puits is recommended for the southern two-thirds of Illinois in short rota- tions. Seed supply is limited.

Vernal is a variegated variety developed at the Wisconsin E^cperiment Station. It is very cold-resistant and highly resist- ant to bacterial wilt. It is not so susceptible to leaf and stem diseases as Ranger. This variety has not been tested in Illinois long enough to deter- mine its value in relation to the recom- mended varieties. It is not reccmmended in Illinois at the present time. Seed supply is limited.

Narragansett, a high-yielding variety developed by the Rhode Island Experiment Station, is not resistant to bacterial wilt. It was developed for use in the eastern United States north of the area where Atlantic is adapted. Flower color is variegated. Atlantic is preferred to Narragansett in Illinois at the present time. Seed supply is limited, but it should be adequate to meet the demand.

Nomad has a high proportion of creeping plants that will root at stem nodes. It is from an old field in Oregon found to have this type of plant. Nomad is sus- ceptible to bacterial wilt, and it has not been tested long enough to determine its adaptability. In most tests it has not appeared to be so vigorous as other varieties. Because of its creeping habit of growth, it may be useful in pastures.

It is not recommended in Illinois at the present time. A limited amount of seed is available ccmmercially.

Rhizcma is a broad-crowned type of al- falfa developed at the British Columbia Experiment Sta.tion. It does not root at the nodes and thus is not a true creeping alfalfa. Rhizoma is a variegated^ very winter -hardy variety that is not resist- ant to bacterial wilt. It beccmes dor- mant very early in the fall and begins growth very late in the spring. For this reason it is not recommended in Illinois.

Certified seed is available for all the varieties recommended for use in Illi- nois^ and it should be used in preference to uncertified seed.

Certified seed may be produced outside the region of adaptation, principally in

California. For seed to be certified under such conditions, the seed fields must be established from seed produced in the region of adaptation.

Seed fields can remain down only six years; therefore certified seed of winter-hardy varieties that is produced in California is only one generation re- moved from plants that grew in the re- gion of adaptation. Also, in fields growing certified seed, precautions must be taken to prevent the growth of volun- teer seedlings. Winter-hardiness studies have shown that, when these precautions are taken, there is only slight loss of winter-hardiness. It is only when these varieties are grown for two or more generations outside the region of adap- tation that there is serious loss of winter-hardiness .

J. A. Jackobs 12-26-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

F-19

HOW HYBRID SORGHUMS WERE DEVELOPED AND ARE BEING PRODUCED

Varieties of grain sorghums like Martin, Midland, Westland, RedlDine 60, and Com- "bine Kafir 60 and varieties of forage sorghums like Atlas, Leoti Red, and Kan- sas Orange are pure lines- -just as are varieties of soybeans or oats. Hybrids of sorghums are first-generation single or three-way crosses between certain of these pure lines.

It has been known for a long time that. Just as in corn, hybrid vigor will result from crossing certain varieties of sor- ghum. However, in the past, controlling pollination has been a major problem. Since the anthers, or the pollen- shedding organs, of the sorghums are located in the same floral envelope as the female parts, it is impossible to use the prin- ciple of detasseling to control pollina- tion, as is done with corn.

Work to devise methods for producing hy- brid sorghum seed in quantity has been under way at the Texas Agricultural Ex- periment Station, in cooperation with the United. States Department of Agricul-

ture, for more than 20 years

In 1929

J. C. Stephens of the Texas Station dis- covered an antherless character in Sudan- grass, and in 1935 he discovered a better male -sterile in Texas Blackhull

Kafir. In 19^13 Glen H Kuykendall dis- covered a still better male-sterile in a field of the Day Milo variety on his father's farm in Cookeville, Tennessee, and in I95O J. C. Stephens and H. F. Holland foixnd cytoplasmic male-sterility in progeny of crosses between Milo and Kafir. The cytoplasmic type of male- sterility is utilized in single crosses and has advantages over the tln-ee-way cross which is used with the Day l^'ge of male -sterility.

Sorghum plants with male -sterility do not shed pollen, and the flowers are readily fertilized by pollen carried by the wind from nonnal plants . With this type of sterility, it is a simple proc- ess to produce and maintain both sterile and fertilized plants in crossing fields for producing hybrid seed at a reason- able cost. To make it clear how hybrid seed is and will be produced, it might be well to follow the method of produc- tion tlirough all the steps from mainte- nance of parental stocks to production in farmers' fields. The necessary steps for maintaining stock and producing hy- brid seed are shown in the following diagrams, originally prepared by J. C. Stephens .

Diagrams Showing the Method of Maintaining Seed of a Cytoplasmic Male-Sx.erile Seed Parent and of Producing Hybrid Sorghum Seed

I. The maintenance and increase of a male-sterile line is illustrated. Male -sterile strain A and normal strain A are identical except that the male -sterile strain does not have anthers that shed pol- len. The chromosome complement of both strains is the same, since the male-sterile strain is main- tained by backcrossing to the normal A strain.

I MAINTENANCE AND INCREASE OF MALE-STERILE STRAIN

MALE-STERILE A COUNTERPART

NORMAL STRAIN A

MALE-STERILE

PRODUCING

/^

WIND-BLOWN

/r\ ^ ^

POLLEN

X

ISOLATED FIELD

II. Hybrid sorghum seed will be pro- duced in a second crossing block in which the seed parent rows will be male-sterile strain A ard the pollen parent will be normal strain B. Lines chosen as male parents must restore normal fertility in the succeed- ing crop, give a good hybrid of combine height, and be good pol- len producers. The hybrid seed from the male-sterile female rows is harvested and used for commercial production.

I[ SEED-GROWER CROSSING BLOCK

MALE-STERILE STRAIN A

\

NORMAL STRAIN B MALE-FERTILE RESTORING

WIND-BLOWN

POLLEN

X

ISOLATED FIELD TO PRODUCE

III. The seed produced in the second crossing block will be planted by sorghum growers for commer- cial production. This is the single-cross A x B sorghum. All plants are completely male and female fertile. With these hy- brids it is necessary to pur- chase new seed each year, just as is true of hybrid corn.

m SINGLE CROSS (A X B) HYBRID SORGHUM

NORMAL CROP ON FARM

At present work in the main sorghum states is devoted to crossing many lines and testing to find the most suitable hy- brid combinations. It will prob- ably be several years before seed stocks can be increased, the various hybrids can be tested for adaptability, and seed of "proved" hybrids is made available for commercial production to any ex- tent.

It should be emphasized that not all sor- ghum hybrids can be expected to be supe- rior, but yield increases of 30 to 50 percent above those of present commercial varieties have been reported in states where these hybrids have been evaluated. Testing is needed and is being carried out in Illinois to determine the per- formance of hybrid sorghums at various locations in the state.

C. N. Hittle i+-23-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SUDANGRASS IN ILLINOIS

Sudangrass is ideal for use as a summer supplemental pasture in Illinois. It may also be harvested for hay or silage. This forage grass, which is a sorghum and an annual, is very leafy, tillers profusely, and has great capacity for regrowth after cutting or grazing. It becomes somewhat dormant under condi- tions of severe drought, but resumes growth when rains come during mid- or late summer.

Sudangrass for Pasture

Sudangrass should not be pastured until the crop is l8 to 2h inches tall. At this stage the plants will contain roughly from 10 to 13 percent protein, and both common and sweet types will be readily eaten. The possibility of poi- soning from hydrocyanic (prussic) acid is increased if Sudan is pastured at shorter heights. The grazing management should consist of rotational grazing with heavy stocking so that the growth may be grazed down rather quickly. The crop should then be allowed to grow until there is time for l8 to 2^+ inches of regrowth before it is grazed again. The place of Sudan in a balanced pasture program is for late summer grazing in conjunction with cool-season perennial pasture crops for spring and fall usage.

When Sudangrass is to be used for pas- ture, it may be planted with soybeans. This combination furnishes considerably more roughage than either crop alone and is ready for use in midsummer when other pasturage is short. Soybeans also pro- vide added protein to the forage and, since they are not injured by chinch bugs, they aid in reducing the chinch bug damage on the Sudangrass.

Other Uses

Although Sudangrass is difficult to cure, it may be harvested for hay. The best quality hay is obtained if cut and prop- erly cured when the very first heads begin to appear. Yields of up to three tons of good-quality hay may be expected

from the finer-stemmed varieties. The coarseness of some of the new varieties makes them unsuitable for hay.

Sudan may also be ensiled and, when properly stored, makes good-quality si- lage. The yield for silage would be the best when the crop is heading to soft dough in stage. For use as hay or si- lage, it should be harvested before leaf drying occurs.

Frussic Acid Poisoning

Sudangrass contains a glucoside called dhurrin, which releases hydrocyanic acid when hydrolyzed in the ruminants. This may cause HOW (or prussic acid) poison- ing. Quantities of prussic acid large enough to cause sickness are usually fatal, and a poisoned animal may die in a matter of minutes . However, a remedy that has sometimes proved effective is the intravenous injection of sodium thiosulfate. Symptoms of poisoning are depression, paralysis, stupor, and dif- ficult breathing.

Shortly after animals are first turned in to a Sudan field, they should be ob- served closely for symptoms of prussic acid poisoning. Sudangrass whose growth has been slowed by drought or partially killed by frost may be dangerous to graze, since the cattle will graze the young, tender shoots that are much high- er in dhurrin. Grain and silage sorghioms are usually much higher in the glucoside than is Sudangrass, and if they are al- lowed to cross with Sudan the resulting hybrids will usually be higher in poten- tial HON producers than Sudan.

The danger of prussic acid poisoning can be largely eliminated by:

1. Using only certified seed or seed that is known to be pure Sudan.

2. Letting the crop grow at least l8 inches before grazing.

3- Not feeding excessively hungry cattle.

h. Not grazing frosted or drought- stunted crops.

Diseases

Probably the most severe disease of Sudangrass in Illinois is leaf blight, caused by the fungus Helminthosporium turcictim. Leaf blight lesions appear first as water-soaked areas. Drying out occurs as the lesions spread to elon- gated, irregular areas. Entire leaf blades may be and frequently are killed. Bacterial leaf diseases may also cause considerable damage. Best control of the leaf diseases may be obtained by the use of resistant varieties. Such vari- eties as Piper, Greenleaf , and _ Lahoma showed a relatively high degree of dis- ease resistance in Illinois in 195^ and 1955.

Insects

The chinch bug is more harmful to Sudan than any other insect; and in years when chinch bug infestations are severe, stands of Sudan may be practically elim- inated. None of the varieties are com- pletely resistant to this pest, but the sweet types possess more resistance than do the common varieties.

Varieties

There are two main classes of Sudan- grass: those which have sweet and juicy stalks and those which are non-sweet or relatively dry-stalked. The mid-rib of the leaf of sweet types is cloudy ap- pearing, and the pith in the stalk is almost completely juicy. The palata- bility of the sweet types is high, even at later stages of growth, and they are generally eaten more readily when pas- tured than the non-sweet types. The dry-stalked varieties cure more readily when cut for hay and are usually higher in yield than the sweet types.

Sweet Sudangrass was developed in Texas from a cross of Sudangrass and Leoti sorghum. Its performance in Illinois has been good, and excellent quality certified seed has been available from Oklahoma, Texas and California. _The damage caused by leaf diseases on Sweet

varies considerably, depending upon the location and the year. Sweet is a juicy- stalked variety, quite early in maturity, and has reddish-brown colored seed.

Piper was developed by the Wisconsin Experiment Station and released in 1950' It is generally more vigorous in the northern states than other varieties, is mostly dry-stalked, has a lower level of hydrocyanic acid potential and increased resistance to leaf blight and anthrac- nose. The strain is not homozygous, be- ing somewhat variable in seed and foli- age color. In variety trials conducted in Illinois during the past two years. Piper has consistently outyielded all other varieties and has been damaged only slightly by leaf diseases.

Common, a dry-stalked type, was devel- oped from many of the early introduc- tions. In Illinois Common yields well, but because of its susceptibility to leaf diseases and extreme early maturity, it is not recommended when seed of other varieties can be obtained.

Greenleaf is a new juicy-stalked variety of Sudangrass released by the Kansas Experiment Station in 1953- It has a low HCW potential, and the seed is loni- formly mahogany-colored. Preliminary results in Illinois show that it is exceptional in resistance to leaf dis- eases and degree of leafiness, but is somewhat lower yielding than many other varieties . Further testing of Greenleaf is necessary before its adaptability in Illinois can be determined.

Lahoma is a sweet Sudan and in tests in Oklahoma, where it was developed, it has shown uniformity, good leafiness, palata- bility, and greater resistance to leaf diseases and later maturity than other sweet Sudans. It is rather tolerant to chinch bug attack. At Urbana and Browns- town, Illinois, the yields of Lahoma have been relatively low, but at Carbondale it has performed very well. Lahoma also needs further evaluation in this state before its performance can be deter- mined.

Carl W. Hittle 5-7-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

F-21

ORCHARDGRASS AND ITS MANAGEMENT

Orchardgrass is a long-lived perennial and a distinctly bunch-type grass with folded leaf hlades and compressed sheaths. Because it does not produce stolons or linderground rhizomes^ it forms an open sod. This characteristic makes it a good companion crop for pasture and hay when seeded with such legumes as al- falfa^ Ladino clover, red clover, and lespedeza.

Orchardgrass owes its common name to its shade tolerance and its consequent use in orchards and other shaded areas. In many other English-speaking countries, it is commonly known as cocksfoot, a name that aptly describes its distinctive stiffs finger-like panicles upon which spikelets are "borne in dense clusters or glomule s .

Characteristics. Although less i-7inter hardy than some of the other pasture - type grasses, orchardgrass starts to grow early in the spring and grows very rapidly. It matures for hay or seed about two weeks earlier than smooth bromegrass and about three weeks earlier than tim- othy. It recovers rapidly after mowing or grazing and produces large quantities of leafy pasturage or aftermath. It may produce less first-crop hay or silage than some of the other pasture -type grasses, but because it continues to grow during the summer, its total production of hay is equal to or higher than that of many other grasses. Because it will grow during the drier, warmer part of the summer and recovers rapidly follow- ing defoliation, its seasonal yield is also more uniformly distributed.

Regions of adaptation. Orchardgrass is grown most extensively and is most im- portant in the southern half of the so- called timothy-bluegrass belt, extending from southern New York to southern Vir- ginia and westward through Kentucky, Ten- nessee, southern Ohio, southern Indiana, southern Illinois, Missouri, and eastern Kansas. However, it can be grown to advantage in the northern part of Indiana and Illinois as well.

Orchardgrass is better adapted to and more productive in the southern range of the timothy growing belt than smooth bromegrass or timothy because it will tolerate more heat and drought. It will survive and grow better on thinner and less fertile soils than timothy and especially smooth bromegrass. However, orchardgrass is not well adapted to tight, poorly drained soils, especially if they tend to be cold. It responds well to high levels of soil treatment, particu- larly nitrogen supplied either from a chemical source or by a legume seeded in a grass -legume mixture.

Uses of orchardgrass. Orchardgrass is used primarily for pasture, but it can be used for hay and silage as well. It is recommended for use in permanent pasture mixtures along with annual lespedeza, white and Ladino clover, and other grasses. It is frequently substituted for timothy in mixtures with red clover or alfalfa for hay; however, it may ma- ture somewhat earlier than the legume^ and the legume may have to be harvested sooner than normally to prevent the orchardgrass from becoming too mature.

Because of its vigor and productiveness, orchardgrass lends itself well to use in pasture renovation where short-term pas- tures are fitted into a forage program. Seedling stands are easily established,and excellent yields of forage can be ob- tained the first crop year.

Management . Although generally con- sidered to be tolerant to grazing, orchard- grass does not persist \inder continuous close grazing. To best utilize the

forage^ it is therefore necessary to fol- low a program of rotational grazing.

To maintain a high-quality orchardgrass pasture;, remove the early spring gro\vrth by grazing or clipping before it reaches the full head stage. Then rotationally graze the regroirth so that an area vill be grazed for about one week and allowed to rest from three to four weeks. To control weeds and permit uniform re- groirth; clip the grazed area to a height of about four inches with a field mower following removal of cattle. Undergraz- ing or delaying grazing not only reduces palatability and feeding value ^ but may also weaken the legume stand in a mixture as a result of excessive competition from the grass.

Orchardgrass makes excellent hayandpro- duces high yields if cut in the earlier stages of maturity, preferably at the early head stage. After this stage it m.atures rapidly and becomes woody and unpalatable. This early maturity is of- ten a disadvantage at the first cutting when orchardgrass is seeded in a mixture with alfalfa.

Orchardgrass makes excellent silage. If it matures before it can be grazed^, it can therefore be ensiled. The silage can be used to supplement late summer pasture or as winter roughage. Often the entire first crop is removed for silage. Orchardgrass should be ensiled at about the early head stage to insure high yields of good-quality silage.

Seedling establishment. The best time to seed orchardgrass is usually in the early spring , although late summer or fall seedings are successful if made early enough to allow the seedlings to become established before mnter. Or- chardgrass seedlings are less winter hardy than many of the common pasture grasses, and fall seedings are more sub- ject to winterkilling, particularly in the northern part of the state. Spring seedings should be made early enough to permit the seedlings to become estab- lished before weeds become a problem.

In general, good stands of orchardgrass can be obtained in mixtures seeded at four to eight pounds per acre. In pure grass stands, the rate should be in- creased to 10 or 12 pounds or more, de- pending on the germination percentage of the seed. Either broadcast or band seeding m.ethods can be used, but band seeding requires less seed. For best results, soil fertility should be kept as high as possible. Orchardgrass is not seriously troubled with insect pests, but such diseases as anthracnose, leaf stripe, leaf rust, and scald do reduce the quality of the forage and may reduce the vigor of the stand.

Varieties of orchardgrass. Recently Potomac , a new variety, has been released for certified seed increase. It has some resistance to leaf rust and shows some superiority over the common strains in seedling vigor and leafiness.

Earl C.

Spurrier 6-U-56

JNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

G-13

WINTER BARLEY IN ILLINCIS

Winter barley is not a new crop in Illi- nois, but there is a demand at present for a small grain crop to be planted on areas taken out of wheat production by- acreage allotments. Winter barley might well substitute for wheat on these areas in the southern half of Illinois.

Winter barley has several advantages over spring -planted barley. \Tiien ' it survives the -vrinter it yields more and its quality is better than the yield and quality of the spring types. Winter types normally mature earlier and thus escape the higher temperatures and some diseases that are serious hazards to the spring crop.

Winter barley makes excellent fall pas- ture and is a good companion crop for legumes and grasses. The grain makes ex- cellent livestock feed and is considered nearly equal to corn in feeding value when fed to poultry and certain types of livestock.

U. S. Route 3*5, or a line from Hannibal, Missouri, through Decatur, Illinois, is usually considered about the northern limit for winter barley. But the right variety, planted early under favorable conditions, has a good chance to sur- vive somewhat farther north. \-Jhile it is scme\^hat hazardous to grow imiter barley north of U. S. Route 36, if it winterkills you can still plant a spring crop •VTith little extra seedbed prepara- tion. Your only loss would be the cost of seed plus planting charges.

Cultural practices. Winter barley is not so winter hardy as winter wheat or winter rye, but it is hardier than win- ter oats. Early seeding is recommended to give the crop a chance to become es- tablished before cold weather prevents further growth.

Seed in time to insure a good root growth and at least four inches of top growth before the crop becomes winter dormant. The right date is about 10 days to two weeks ahead of normal wheat seeding, that is, from September 15 to October 15, depending on how far south you are. Seed with a grain drill at the rate of eight pecks an acre on a well- prepared seedbed.

Barley responds well to fertilizers, and fertile soils mean good root growth and more winter hardiness. A high nitrogen content in soils may cause barley to lodge. The straw of all barleys will break rather quickly once they are ma- txore. For this reason it is important not to delay harvesting.

Varieties. Besides yield, winter hardi- ness and straw strength are the most im- portant characteristics to consider in choosing a variety of barley. At pres- ent the fo.iJLowing varieties are being recommended: Kearney, Reno, and Ken- tucky #1 for the area between U. S. Route 36 and U. S. Route 50 (which is frcm St. Louis east to Vincennes, Indiana) and these three plus Kenbar and Mo, B-UOO for the axea south of U, S, Route 50*

Kearney is one of the most winter hardy varieties, is medium early, and has a medium stiff straw. Reno has a slightly stiffer straw than Kearney but is not so winter hardy. Kentucky #1^ is vlliter- hardy, has a rather weak straw, and is later than either Kearney or Reno.

Kenbar is the earliest and the shortest of the varieties recommended. It is not quite so hardy as Reno but it has a much better straw. It is more resistant to smut, mildew, and scald than Reno, Kearney, or Kentucl^y /)-l.

Mo. B-UOO is a high-yielding variety early as Kenbar nor does it have so good that is resistant to loose smut, mildew, a straw, and splot blotch. Because it grows rap- idly and vigorously in the fall it makes The 1955 yields of the recommended vari- excellent fall pastxire. It is not so eties are shown in the following table:

		Per acre	yield
Variety	Urbana	Brownstown	Dahl gren	Carbondale	Average
	bu.	bu.	bu.	bu.	bu.
Kearney	55.7	39.9	24,3	25.2	36.3
Reno	68.6	52,0	26.0	32.9	it4.9
Kentucky #1	5^.0	39.8	19.6	30.7	36.0
Kenbar	2k, Q*	60,9	26,9	18,8^^	32.8
Mo, B-1+00	62.4	• • • •	, , , ,	31.1	U6,7

*Poor fall stands due to low germination reduced yields at these locations.

R, 0. Weibel 9-12-55

AGRONOMY FACTS

G-14

WINTER WHEAT

Winter wheat ranks third as a cash grain crop in Illinois. The agricult-ure of southern Illinois is strongly supported hy this crop. The climate and soils of this area are veil suited to the produc- tion of high-quality soft red winter wheat. On the other hand, hard red win- ter wheats produced in Illinois, espe- cially in the southern half of the state, are usually too low in protein to produce a satisfactory bread flour. And because of the characteristic of the protein, the flour is not suitable for cakes or pastry.

Reccmmended Varieties

Soft

Saline

Knox

Seneca

Hard

Pawnee

We star Pone a

Acceptable Varieties

Soft

Royal

Vigo

Butler

Hard

Triumph

Growing both soft and hard wheats in the same area has caused a considerable amount of concern. Because local eleva- tor personnel cannot always distinguish between them, they are often mixed in handling or in shipment. Thus they are graded mixed wheat when they reach the inspection points. Mixed wheat is below the straight grades on the market. To protect himself, the local buyer, if in doubt, must class the wheat mixed.

This problem will continue as long as there is a price differential in favor of hard wheat and as long as we have no quick way to determine protein at the local buying points. We can help con- siderably by recommending that growers know the variety they are growing. All persons selling seed should stress the name of the variety and sell only those that are reccmmended.

Variety Descriptions. All of the varie- ties listed below have produced good yields in Illinois. All have acceptable grain quality for their class.

Mew Varieties Being Increased

Soft

Dual Vermillion

Of the recommended soft varieties. Saline is the tallest and also the latest. Knox has the shortest straw and is the earliest, Seneca is intermediate. Pawnee and Ponca, hard wheats, are very similar in maturity and straw strength. Both are a few inches shorter, a little ear- lier, and have slightly stiffer straw than We star.

The grain of Ponca will not bleach out in the field so readily as Pawnee, and hence its milling quality is better. Westar is more resistant to mosaic than Pawnee or Ponca, but all three may be- come heavily infested when conditions are favorable.

Other characteristics of the reccmmended varieties are given in the tables on the back.

Table 1. --Characteristics of Varieties of VJheat Reccmmended for Illinois

		Area of	Lodg-	Winter	"■"Rela-
	CI.	state vhere Test	ing	hardi-	tive	Head	Grain
Variety	Ko,	adapted* weight	res.	ness	height	type	texture

Saline Knox	1267^^ 12798	All C &	S	Med. Med.	Excel. Excel.	Excel. I-med.	Tall Short	Bearded Smooth	Soft Soft
Seneca Royal	12529 12558	S C &	S	Low High	Excel. Med.	Fair Excel.	Med, Tall	Smooth Bearded	Soft Soft
Vigo Butler	12220 12527	c & s	S	Med. Med.	Med. Excel.	I-med. I-med.	Tall Tall	Smooth Bearded	Soft Soft
Dual Vermillion	13083 I27I+8	c & All	S	Lew Med.	Excel. Excel.	Excel. Excel.	Med. Med.	Smooth Smooth	Soft Soft
Pavnee Ponca	11669 12128	N & W &	c c	Med. Med.	Med. Med.	Excel. I-med,	Short Short	Bearded Bearded	Hard Hard
We star Triumph	12110 12132	N &	c c	Med. Med.	Med. Med.	Excel. I-med,	Med, Short	Bearded Bearded	Hard Hard
* W = North;	C = Central; S =	South.

1

Tahle 2. --Reaction of Wheat Varieties to Diseases Common in Illinois

		Leaf	Stem	Loose	Covered		Sep-		Hessian
Variety	Mosaic	rust	rust	smut	smut	Mildew	toria	Scab	fly
Saline	R	I	I	S	S	S	S	S	s
Knox	R	R	S	S	S	S	S	S	s
Seneca	R	S	S	I	S	S	s	S	s
Royal	R	S	I	S	S	S	s	S	s
Vigo	R	I	S	I	S	S	s	S	s
Butler	R	S	s	I	I	&'	s	S	s
Dual	R	R	S	S	S	I	s	S	R
Vermillion	R	R	s	s	S	S	s	S	s
Pawnee	S	I	R	R	R	S	s	s	S
Ponca	S	I	R	R	R	s	s	S	R
Westar	I	I	S	I	S	S	s	s	s
Tri\iQiph	S	S	S	I	S	s	s	s	s

R = Resistant; S = Susceptible; I = Intermediate,

R. 0. Weibel 9-19-55

AijRONOMY rMciS

"BLAST" IN OATS

G-15

"Blast" is a term that is applied to a type of sterility in oats. It is evi- denced by white, empty glumes in the lower branches at the base of the pani- cle about the time the oats are in full head. The condition is also called blight, blindness, and white ear.

Blast is not a disease; it results from inability of some of the spikelets to develop completely. Anything that in- terferes with the physiological processes during development of the plant, partic- ularly the panicle, may cause blast. Late seeding, lack of moisture, nutrient deficiencies, insect attacks, and dis- ease, either singly or in combination, will increase the condition. Tillers are affected more than main stems.

The base of the panicle is where blast is most prevalent. The sequence of de- velopment in the oat panicle makes it easy to imderstand why. An oat panicle is composed of many branches, each of which ends in a many-flowered spikelet in which usually only two flowers pro- duce seed. The main axis of the panicle terminates in a spikelet. Beneath the tip spikelet, and placed alternately on the main stem of the panicle, are five to six groups of spikelet -bearing branches. The number of spikelet -bearing branches increases from the tip of the panicle downi-ra-rd.

The first structure ■ that develops from the main axis of the panicle is a branch primordium (a branch of the first order), which is the beginning of the group of branches at each node of the panicle.

From the first -order branches, branches of the second order are formed; from the second order, the third order; and so on. At the nodes, especially the basal group, branches of the fifth and sixth orders may be found.

The oat panicle starts to develop from the tip spikelet and proceeds to the base. At any node, development begins with the first -order branch, followed in sequence by the second, third, etc. Con- sequently the panicle is oldest at the tip and yo\ingest at the base, and at any node the first -order branches are oldest and the fifth- or sixth-order branches are youngest.

It takes some time for a panicle to de- velop. At Urbana a panicle of Clinton requires 15 to 18 days, or from about May 10 to 25 or 28, to develop fully. Heading occurs about 15 days later.

Adverse changes during panicle develop- ment, especially the first half, will affect the youngest parts more than the oldest. The youngest parts are more susceptible because they are farthest from producing seed. We can thus expect to find more blast in the basal groups of branches because that is where the largest number of high-order branches are found.

Varieties differ' in amount of blast even though their environment and maturity are similar. This fact would indicate that plant breeders can produce varie- ties that have a low percentage of blast and hence higher yields.

0. T. Bonnett 9-26-55

AGRONOMY

G-16

WINTER RYE IN ILLINOIS

The acreage of -winter rye has climbed steadily since 1951/ according to the Illinois Crop Reporting Service, The crop harvested in 1955 vas the largest since 1919 . Perhaps we should take a closer look at this age-old crop that is making a ccmetack in Illinois. Why the increased interest in rye?

1, Wheat and corn acreage allotments have resulted in extra land.

2, More rye is being used for pasture and forage.

3, Rye is being inter seeded as a winter cover and as a green maniire crop in corn and soybean fields both before and after harvest.

Characteristics . Winter rye is the har- diest of the cereals — "the roughest, toughest of them all." It will grow on poorer soil, in drier soil, and in colder weather than our other grain crops. It will produce in soil that is sandy or low in fertility where other cereals will do little or nothing. On good soils rye is capable of making high yields, although not so high as wheat.

Two-year comparisons of average acre yields from several rye varieties with average yields frcm wheat varieties grown in the same field showed the following res\ilts: Urbana, central Illinois - wheat k8 bu. and rye 39 bu. DeKalb, northern Illinois - wheat 3^ bu. and rye 30 bu.

Although a little spring rye is grown in the western United States, the Illinois rye crop is all of the winter type and therefore is fall seeded. Rye differs from the other common small grains in being almost completely cross ferti- lized. That is, the flowers on one plant are fertilized not by their own pollen, but by pollen from other rye plants.

Culture . Rye ^d-ll respond to good cul- tural practices and to fertilizers, but the return for fertilization is generally greater on wheat and other grains. A seeding rate of 5 "to 6 pecks per acre is thought best for Illinois. The crop can be sown frcm August to Kovember, Al- though a good seed bed is desirable, rye has the ability to germinate and grow under poor seeding conditions.

Uses. Rye may be used as a cash grain, as a grain feed, as pasture, or as a green manure crop.

As a cash grain the crop generally goes into the following trade channels: dis- tilling, dry milling, feed, export, and seed. The distilling industry uses rye for whiskey and alcohol. The dry millers make rye flour, which is generally blended with wheat flour to make the kind of rye bread Americans prefer. The feed indus- try also blends rye with other grains.

Although rye may be used as a feed crop on the farm, it is less valuable than corn, wheat, or barley. Alone, it is somewhat unpalatable and is considered heavy and sticky. For best results, it should be mixed with other grains.

Rye makes excellent fall and spring pas- ture. It is superior to other small grains in Illinois because it will grow later in the fall and start growth ear- lier and more rapidly in the spring.

The protein content of young rye plants may run 30 percent or higher in the spring on fertile soils.

Use of rye as a green manure is rela- tively new in the Corn Belt. At present the agriciiltural experiment stations are doing a great deal of research on the various aspects of this potentially im- portant cultural practice. In addition

to supplying organic matter^ rye serves as a winter cover or guard against ero- sion and it may also be pastured. If corn is to follow rye, the land should be plowed in late April or early May, and nitrogen should be added.

The success of rye as a green manure will depend to a great extent en soil mois- ture. In late, wet springs, the crop will mature before it can be plowed, and in dry springs it will remove large amotints of water from the soil profile before corn is planted.

Results from Winter Rye Variety Trials at Urbana and DeKalb, Illinois,

195^ and 1955

Adams

Balbo

Caribou

Emerald

Imperial

Pierre

Tetra Petkus

	Yield	Test weight	Height	Plant erect- ness	Head-
	Urbana DeKalb	ing
Variety	195^ 1955 Av. 195'J- 1955 Av.	date

bu, bu, bu, in. 7 ^3.8 i^2.8 37.9 ^^.9 ^1.^

bu. bu, bu, 22,0 3^.5 28.3 29. i^ 30.6 30.0

37.3 38.1^ 37.9

29,1 i+1,9 35.5

3>h,S Uo.8 37.7

37.0 36.9 37.0

I • • • • • • •

33.2 3G.k 34.8 3i^.3 36.6 35.5 30,7 32.8 31.8

lbs.	in.	perct.
51.7	57	^5	May 9
51.5	55	57	" 3
51.2	50 •	• •	" 13
51.0	56	hi	" 9
51.0	57	55	" 10
51.8	5^	51	" 8

• • • •

13.i+

• • • t

50.1

53

75

16

Balbo is believed to be the first choice for pasture because it will grow earlier in the spring. In extreme northern Illi- nois, however, it may siiffer from winter-

killing and Pierre or Emerald might be better. Tetra Petkus has larger kernels and wider leaves, but it has not out- yielded Balbo in either grain or forage.

J. W.

Pendleton 10-3-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

m

S-5

ROOT AND STEM ROT OF SOYBEANS

Root rots occur on soybeans in Illinois from time to time^, depending largely on weather conditions. They are likely to he noticeable in wet seasons^ especially in low spots in fields where drainage is poor. One of these root rots is caused hy Rhizoctonia, a fungus that is present in most soils where crop plants are grown. The fungus usually attacks young plants when the soil is abnormally wet^ causing a reddish-brown decay of the outer layer of the main root and basal stem. Much of the secondary root system is destroyed^ and the plants wilt and die. Dead plants occtu: typically in areas four to 10 feet in diameter, usually distributed irregularly over a field. In most seasons Rhizoctonia root rot is of little economic importance.

During the 1955 season, xa. root and stem rot new to Illinois was discovered in five or six fields in northern and central Illinois. This disease affects plants of all ages. Seedlings that have just emerged may shrivel and die, leaving gaps ranging from a few inches to several feet in the rows. Older plants wilt and ic"y 'U-P, or they may be severely stunted and perhaps wilt only slightly at midday. When such plants are dug or pulled, they show a badly decayed root system. The disease is, however, not confined to the roots; often the brown decay is noted on the stem several inches above the soil line.

Although this root and stem rot is espe- cially damaging in poorly drained areas of the field, it sometimes occurs on

higher ground. The disease is not wide- spread or serious in Illinois at present, but it should be watched closely because of its potential threat to soybean pro- duction.

This same root rot has "been present in northwestern Ohio since 1951« It has be- come prevalent and destructive in the clay soils of the old lakebed region. The disease is caused by a fungus, iden- tified by Ohio Experiment Station pathol- ogists as a Phytophthora. Sometimes it is impossible to differentiate the Phytophthora root rot from the one caused by Rhizoctonia. However, the Rhi- zoctonia root rot lesion usually has a reddish brown color, while that of the Phytophthora root rot is brown. Also, the Phytophthora root rot seems to per- sist throughout most of the growing sea- son, while the Rhizoctonia root rot usually disappears before mid-July.

Work at the Ohio Station indicates that the varieties Illini, Monroe, and Black- hawk are resistant to Phytophthora, while Hawkeye, Lincoln, and Harosoy are susceptible. Seed treatment has no value in preventing seedling blight. It is recommended that rotation mth other crops be practiced on land where the root rot has appeared.

Investigations on Phytophthora root and stem rot are under way at the Illinois Experiment Station, and more information on this disease will be made available as controls are developed or resistant varieties are released.

U. S.

D. W. Chamberlain

Plant Pathologist

Dept. of Agriculture

5-21-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

S-6

ESTIMATED HAIL LOSSES TO SOYBEANS

Because soybeans grow throughout the cropping season, they are subject to in- jury by hailstorms. Fully two-thirds of the hailstorms that occur in the Corn Belt come between May and September, when soybeans are in the field.

Insurance to protect the farmer against loss of his crop by hail is becoming more common each year. Insurance companies have conducted and are conducting experi- ments designed to get information on how to evaluate losses to soybeans from hail injury. Experiment stations, too, have studied the problem, and the insurance companies have supported some of this work. Illinois has been conducting such tests for six years, Iowa for six years, and North Carolina for one year.

Results at the Iowa Station showed that when all leaves were removed at the blos- soming stage the yield of beans was l8 percent of norm.al, and when the stems were broken in addition to 100 percent leaf removal the yield was l6 percent of normal (see Stage 7 in diagram). Leaf removal earlier and later than this critical period caused progressively less reduction in yield.

Recoverability is highest when plants are about three weeks old and after three or four trifoliate leaves have un- rolled. Although leaf removal at this stage causes some reduction in yield, the drop-off in production is less than before or after this stage. In the dia- gram this stage is shown as 2.

Effect of stage of development on recov- ery from injury. The soybean plant pos- sesses great ability to recover from injury, particularly at certain stages of development. Knowing the stage at which the damage occurred is therefore just as important in estimating losses as knowing the extent of the injury.

Unless the plants are broken off at the ground or are otherwise destroyed by beating of the hail, they will yield some grain. That is to say, there is no stage when injury will completely elimi- nate all yield.

The stage of lowest recoverability is just at the end of blossoming. At this time the pods on the lower branches are nearly full length and beans are devel- oping in them. Tlie pods on these branches are far enough along to yield some grain, but pods in the top part of the plant are just starting to form. No new blos- soms or leaves form afterward, and removal of the leaves robs the plants of the photosynthetic area when it is needed most.

Extent of injury. In general, yield is reduced in direct proportion to the per- centage of leaf surface rem.oved. Bruis- ing of the stem also affects yield. Tests at Iowa showed that breaking of stems lowered yield below that caused by leaf removal. This decrease amounted to only 15 percent at the first-bloom (2) stage, but increased to over 50 percent at the critical (7) stage.

A severe storm that kills plants out- right will reduce the stand and conse- quently the yield, but the reduction v;ill vary with stage of growth. If it occurs during the early (l to 3) stages, as many as 50 percent of the plants can be destroyed without any great reduction in yield. But at Stage 6 or later, a re- duction in stand will mean a marked de- crease in yield. By the end of the blooming period, the plants have lost their capacity to spread out and take up the extra space.

Other effects

Loss of leaw

the critical (7) stage delays matui' the plants, but such injury aft^.

stage seems to hasten maturity. Actu- ally, however, maturity only appears to be speeded up. The crop comes only from the most advanced pods because the leaf area is not sufficient to provide reserves for the later formed pods.

large leaf losses reduce seed size and also decrease the oil content of the seed if the loss occurs while the grain is filling.

Estimating losses. It is hard to deter- mine the percentage of leaves removed by a hailstorm. It is possible to tell the stage of plant development by carefully observing the plants immediately after a storm. But figuring out how many leaves remain in relation to the number before the storm is like probing in the dark.

Because of this difficulty, Dr. James C. Weill, who did his Ph. D. thesis on the effects of artificial hail on soybeans at the University of Illinois, suggested the possibility of determining the de- gree of injury by counting the terminal buds that had been knocked off. In two- year tests (1950-51) Weill blew cracked ice through a three-inch rubber tube onto

soybean plants at various stages of de- velopment. In this way he inflicted in- juries similar to those caused by natural hail, removing different percentages of leaves and at the same time damaging stems and removing terminal buds .

Weill counted the leaves before treat- ment and then counted those left on the plants after treatment. He also coimted the plants from which the topmost or terminal bud had been removed. In both years in which he made these tests he found a very high correlation between the percentage of leaves lost and the percentage of terminal buds lost.

Because in these tests the correlation between loss of leaves and loss of ter- minal buds was so close and because the percentage of terminal buds that are lost can be easily and accurately deter- mined after a hailstorm, Weill suggests that the severity of injury be estimated by counting the number of plants in a himdred from which the terminal buds have been rem^oved.

G. H. Dungan 6-18-56

100

+3
a
Q)	CO
C)	-P
U	C
(U	^^
PnrH
	yu
C
-H	Ti
	(i)
Ti	u
M	:3
fl)	"-n
•H	r,
>^	•H
	a
i^	D
•H
01	<+-l
!h	C)
0

20

lOC;^ leaf remova-l ^. + stem breakrage

3 ^ 567

Stages in plant development

10

Diagram of grain yield reduction as a result of f-: . _ . hail damage at 10 stages of soybean plant development.

"erities of

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

AND -^^Z TESTING -^^
■■■' S

SF-37

CHEMISTRY OF ORGANIC NITROGEN IN SOILS

Nitrogen is different frcm the other nu- trient elements in the soil because it occurs almost entirely in organic ccm- "bination. Only a very small fraction of the nitrogen- -usually frcm 1 to 3 per- cent --is in the inorganic forms at any one time.

During the year nitrogen is released slowly from the organic matter to the mineral forms ^ which are the available forms of nitrogen in soils (see SF-4). The amount that is released depends on the kind and amount of nitrogen in the organic matter^ on climatic conditions;, and on the physical condition of the soil.

Several methods are used to estimate the quantity of nitrogen converted to the available forms during the growing sea- son, but all of these methods have cer- tain limitations (see SF-I7). If we knew more about the nature of organic nitrogen in soils, we could overcome seme of the uncertainties involved in estimating nitrogen availability and in making fertilizer recommendations.

Unfortunately, we know very little about the nature of soil organic nitrogen or about how soils differ in their contents of organic nitrogen compounds. Do fer- tile soils contain nitrogen compounds that are not found in infertile soils? Are some nitrogen compounds in humus easily mineralized while others resist attack by soil microbes? Are well- fertilized and manured soils different from infertile soils in their contents of certain kinds of organic nitrogen com- pounds?

To answer these questions the Department of Agronomy has a research project under way that is concerned with the chemistry of humus nitrogen. As indicated above, the purpose of this study is to find out what forms of organic nitrogen the soils

contain and to determine how cropping and management practices affect these forms.

Recently a study was made of the protein nature of soil humus. The building units of the proteins--the amino acids-- were isolated frcm several soils and their amounts were determined. Briefly, the results showed that soils differed in the quantity and quality of their pro- teins. In seme soils as much as half of the nitrogen was in the form of pro- teins; in others less than a third of the nitrogen was proteinaceous. Also, the amino acid composition of the pro- tein material in one soil was quite different frcm that in another. This difference suggests that the ability of humus to supply nitrogen to the plant may depend considerably upon the nature of its proteins.

The famous Morrow Plots at the Univer- sity of Illinois were used to determine the effects of some long-time rotations on the distribution of amino acids in soils. The results of this study were very interesting. It was foimd that the proteins in the soils from the untreated plots (such as the i^ntreated continuous- corn plot) were low in the kinds of ami- no acids that would be expected to be ready sources of nitrogen--for example, mono -amino acids like glycine, alanine, valine, and leucine, and the amino acid amides, asparagine and glutamine. The proteins in the soil frcm the corn-oats- clover rotation plot that had been manured, limed, and supplied with phos- phate were high in these amino acids.

These results show that when soils are heavily cropped they lose heavily in cer- tain kinds of amino acids. Hence, not only does an intensive system of farming deplete the soil of proteins, but the protein material that remains is of low quality.

Needless to say, more research needs to be dene before the full practical signif- icance of these findings can be deter- mined. But the results obtained thus far have served to emphasize the desir- ability of using management practices that will furnish a continuous supply of actively decomposing organic matter to the soil. The soil organisms use plant residues and manures as sources of food. During growth and reproduction they syn-

thesize body proteins. It is these pro- teins that later become good sources of mineralizable nitrogen.

Research work on the chemistry of organ- ic nitrogen in soils is continuing. In the future we can look forward to unrav- eling seme of the mysteries surrounding the availability of hiimus nitrogen in soils.

F. J, Stevenson

10/31/55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AND TESTING

AGRONOMY FACTS

SF-38

1955 WHEAT YIELDS - ILLINOIS SOIL EXPERIMENT FIELDS

Cropping 123^56789

Location system 0 M ML MLF 0 R RL RIP RIPK

Dark-colored soils

bu. bu. bu. bu. bu. bu. bu. bu. bu.

Mercer C-C-O-W kk h2. 39 ^0 U6

Macoupin C-B-W-H 26 "^h 39 38 31 32 37 ^0 ij-5

Hancock C-B-W-H 28 36 !+3 i+3 29 2h 28 32 39

Adams C-B-O-W I8 29 30 33 37

Lee C-O-H-W lj-2 1+8 5I 50 4l hG hh 52 1+9

Logan C-C-O-H 1+1 1+7 1+1 1+3 39

Will C-B-C-0-W-H 20 26 29 3!+ I7 I5 20 3I+ 36

Henry C-O-W-H 31 36 hh 51 1+9

St. Clair C-B-W-H 11 25 33 36 I3 12 28 35 37

Putnam C-C-O-W 17 37 38 1+3

Woodford C-C-O-W 37 39 37 39 ^2

Ogle C-O-W-H j_L.ij.iZ. ♦• 18213137 37

25 36 39 5o 28 32 35 1+0 5l

Field

Ale do

Carlinville Carthage Clayton Dixon Hartsburg Joliet Kevanee Lebanon McWabb Minonk Mt. Morris Average

Lip;ht- colored soils

Brownstown	Fayette	C-B-W-H	• •	• •	• •	• •	• •	1	33	^5	51
Enfield	White	C-O-W-H	1+	11	26	30	1+	1+	15	20	33
Eving	Franklin	C-B-W-H	0	1+	23	31	2	1+	17	20	27
Oblong	Crawford	C-B-W-H	13	27	36	1+1	0	9	26	1+0	ho
Raleigh	Saline	C-O-H-W	6	13	27	26	15	12	17	25	32
Toledo	Cumberland	C-B-W-H	9	22	52	56	10	11	21+	36	39
Average			6	15	33	37	7	7	22	31	37

Cropping System Symbols:

Soil Treatment Symbols:

C = Corn, B = Soybeans, W = Wheat, 0 = Oats, H = Hay (legumes and mixed grasses).

0 = Untreated land, M = Manure returned equal to crops removed,R = Crop residues, L = Limestone, P = Rock phos- phate, K = Muriate potash.

(Continued en back)

Average whea.t yields in Illinois for 1955 were the highest on record, 31»5 "bushels. Nevertheless yields varied widely from location to location and with different soil productivity and management pi-actices. Yields from the Illinois experiment fields (see tahle) illustrate those variations, as they rep- resent a cross section of the produc- tive capacity of Illinois soils.

On untreated dark-colored soils yields ranged from I3 to kh bushels an acre. On fully treated land the range was 32 to 52 bushels. The response to treat- ment varied from none to 26 bushels. Similar variations occurred on the light - colored soils of the state.

This kind of information should alert agricultural workers and farmers to the danger of making prodictions regarding the response that can be expected from a given fertilizer or management prac- tice in any one year. The data also show the advantages of keeping a soil adequately supplied with plant food and ready for any favoi'able growing condi- tions that come along, such as those of 1955.

The yields given in the table were ob- tained after bulk application of such fertilizing materials as manure, crop residues, limestone, rock phosphate, and muriate of potash (on individual plots) and under the cropping system described. In these experiments no attempt is m.ade to fertilize the individual crop. Mate- rials have been applied in quantities adequate to determine the needs of the various soils and to supply all crops in the system under a wide range of seasonal conditions.

On many of the fields additional tests have been made with complete mixed ferti- lizer, various phosphate carriers, nitro- gen, and potash. In seme cases yields have been increased by annual direct ap- plications, and in other cases they have not.

A detailed explanation of the treatments, cropping systems, and soil types is given in Illinois Bulletin 516, "Effect of Soil Treatment on Soil Productivity. " This publication is supplemented by a mimeograph pamphlet that brings data on each field up to date for each year. These publications are available from the Agronomy Department, University of Illinois, Urbana.

A. L. Lang ll-li|-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SF-39

EARTHWORMS

In 1777 Gilbert White published a paper in which he said: "Worms seem to be the great promoters of vegetation^ which would proceed but lamely without them, by boring, perforating, and loosening the soil, and rendering it pervious to rains and the fibers of plants, by draw- ing straws and stalks of leaves and twigs into it; and, most of all, by throwing up such infinite numbers of lumps of earth called worm-casts, which, being their excrement, is a fine manure for grain and grass. . .the earth with- out worms would become cold, hard bound, and void of fermentation, and conse- quently sterile."

Since 1777 much information concerning the relation between the earthworm population and soil conditions has been collected. In spite of this knowledge concerning the activities of earthworms and the conditions under which they flour- ish, it still is not clear whether they affect the productivity of soils materi- ally.

Certain facts are, however, recognized and a few of them are worth enumerating:

1. Earthworms occur in fairly large num- bers in many farm soils. Observa- tions in the United States and in other countries indicate that under favorable conditions the number may exceed a million an acre, with a to- tal live weight of more than l/h ton.

2. The worms are most abundant in soils that are high in organic matter. Consequently they may be found most extensively in forest, pasture, and heavily manured soils.

3. Cultivated soils are less favorable for earthworm survival than are areas that are covered with sod

crops. This difference is explained in part by their sensitivity to sud- den changes in the soil temperature when the late-fall freezes occur. They apparently need the insulating protection that vegetation cover gives the soil.

k. Earthworms appear to need a contin- uous supply of calcium, which they excrete from their digestive tract. Their numbers therefore decrease as the pH of the soil goes down. Dif- ferent species also differ in their tolerance to soil acidity.

5. In virgin soils and in pastures the worms drag into their burrows leaves and other dead surface litter. Mi- croorganisms then attack the litter and convert it into the so-called humus fraction of xhe soil.

6. It is believed that earthworm activ- ity improves soil aeration. The channels the earthworms make help to improve air and water movement. These channels may also serve as passageways for plant roots. Since the worms that burrow deeply in the soil may carry lime and plant nutri- ent elements into their channels in the subsoil, the occurrence of roots in subsoils, which ordinarily would be unfavorable for them, may be due to earthworm activity.

Correspondence wwith farmers indicates concern in seme areas about the effect of use of anhydrous ammonia on the earth- worm population. Although no experi- mental data are available on this subject, the lack of proof of the value of earth- worms in soil productivity suggests that arguments for and against the use of anhydrous ammonia should be based on fac- tors other than its effect on the earth- worm population.

0. H. Sears 11-21-55

UNIVERSITY OF ILLINOIS ■ COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SF-40

BAND APPLICATION OF FERTILIZERS IN ILLINOIS - PART I

Banded fertilizer may "be defined as any fertilizer that is banded or drilled with seed. Banding or drilling ferti- lizer has been a standard practice in the East and South for many years. In- terestingly enough, fertilizer so applied is generally called starter fertilizer in the Midwest. An eastern or southern farmer merely says that he is fertilizing his crop.

other good management practices are fol- lowed.

On the other hand, there are alternative management and fertilization practices through which high yields can be secured without the use of banded fertilizers. The farmer's choice of the alternatives is not solely an agronomic problem--it is a joint agronomic -economic problem.

Banded fertilizers may serve a number of useful functions. It is perhaps lonfor- tunate, therefore, that the term starter fertilizer was coined. Under certain conditions, banded fertilizers promote rapid, early plant growth and vigor. The seedlings, therefore, are better able to overcome such early hazards as grape colaspis, a root-feeding insect, and adverse weather. Also, by promoting early, liniform, vigorous growth in row crops, banding makes it possible to do a more thorough job of weed control. These functions help to get the better stands that are essential for top yields.

On moderately phosphorus- and potassium- deficient soils, banded fertilizers may promote deeper and more extensive root- ing. In wheat, this reduces winter heav- ing and assures better winter survival. Banding may also lead to more complete fertility exploitation by all crops. Critics of banded or starter fertilizers often cite this argument to discredit band or row applications, saying that banded fertilizers make it possible to more thoroughly mine or deplete soils. This may be true where small amounts of low-analysis fertilizer are applied, but it is not true where adequate amounts of high-analysis fertilizer are applied for each crop. In fact, it is possible not only to maintain the mineral fertility of productive soils, but also to main- tain very satisfactory yields on infer- tile soils by applying adequate amounts of high analysis fertilizer provided

In Illinois the fields are frequently large and the rows long. Application of banded fertilizers, particularly in ade- quate amounts, requires frequent filling of hoppers, adds to the labor and re- duces the acreages planted per day as much as 25 percent. Many farmers are sold on the value of banded fertilizers, others question their need, and occasion- ally seme even say that yields have been reduced. Virtually all complain of the added labor and weight-lifting.

In most cases starter effects induced by banding fertilizer are primarily a re- flection of seedling response to highly available soluble phosphorus. So let us examine the chemical aspects of applying soluble phosphates to soils. This will help to clarify the reasoning that gave rise to the practice of banding or drill- ing phosphatic fertilizers or mixed fer- tilizers containing available phosphorus.

When soluble phosphorus is applied to strongly acidic soils or soils that con- tain excess lime, phosphorus fixation takes place. Soil chemists at first be- lieved that phosphorus fixed by strongly acidic soils was permanently converted into unavailable forms. The original thinking behind placement of phosphorus - containing fertilizers, therefore, was to minimize soil-fertilizer contact. Concentrating the fertilizer close to the seed made it possible for the plants to take up most of the phosphorus they needed before fixation occurred. The

-2-

economic loss of phosphorus through fix- ation was believed to be reduced.

A "better understanding of the chemistry of soil phosphorus has developed in re- cent years. Soil chemists have found that the phosphorus fixed by acidic soils is not permanently lost. The fixed phos- phorus is now merely considered "diffi- cultly available" to plants. It has been learned that the use of sufficient lime makes it possible for plants to use the phosphorus that acidity had made physio- logically unavailable. Strongly acidic soils already containing large amounts of difficultly available phosphorus will not respond to phosphorus for several years when first limed to neutrality. This does not mean that lime can be sub- stituted permanently for phosphorus on such soils. It means that lime makes it possible to reclaim much of the phos- phorus previously unavailable to the plant .

The fixation of phosphorus to difficultly available forms in calcareous (shelly) soils is a more serious matter. It is sometimes claimed that rock phosphate is produced. Chemically this is an untenable hypothesis. On calcareous soils the fixation to difficultly available forms is caused by excess lime. There is no practical way to remove the lime. For- tunately the reversion to difficultly available forms is slow, usually taking a full growing season. Annual applica- tions of phosphate-containing fertilizers are preferable on calcareous soils.

lizer is applied just ahead of seeding. Top-dressing of permanent meadows in the spring is preferable. Banding or drill- ing is best, however, and leads to the most efficient use of soluble phosphates, particularly where small applications are made.

A second problem in the use of mixed fer- tilizers containing phosphorus is posed by the immobile nature of soil phospho- rus. For all practical purposes plant roots must forage for phosphorus. The degree to which seedlings are stimulated into faster growth depends, therefore, on the extent of the soil phosphorus de- ficiency. An estimate of the early growth stimulation of various crops is illustrated in Figure 1. It is evident that on very phosphorus-deficient soils the starter effects can be quite large. Early plant stimulation may or may not be reflected in final yields. On moder- ately acid soils testing medium to high in available phosphorus, the growth stim- ulation effects, except for wheat and clovers, are apt to be small or even ab- sent.

Potassium is likewise an immobile nutri- ent for which plant roots must forage. The stimulating effects of potash in mixed fertilizers will vary with the level of soil potassium availability, much as is the case for phosphorus. On most soils, however, early growth stimu- lation is essentially a phosphorus ef- fect because the phosphorus requirements of seedlings are usually very high.

To avoid excessive fixation, the ferti- lizer may be banded or drilled with the seed. Broadcasting is also satisfactory if excessive mixing (disking) is avoided and if the phosphate-containiDg ferti-

The production of radioactive phosphorus by the Atomic Energy Commission at Oak Ridge, Tennessee, has made it possible, through the use of tagged radioactive phosphorus, to trace the proportion of

Table 1. --Percent of Phosphorus in Corn Secured From Banded Fertilizer During the Growing Season

Available phosphorus	Percent	of	phosphorus	m	plant from fertilizer
in soil	30 days		60 days		90 days	110 days
Low High	58 26		36 21		28 17	23 15

-3-

the phosphorus absorhed hy plants from fertilizers throughout the growing sea- son. Results of such an experiment con- ducted with corn in North Carolina are given in Table 1.

These data indicate that during the first 30 days of growth corn absorbed slightly more than twice as much phospho- rus from band applications on soils that were low or deficient in available phos- phorus as from the same applications on soils that were high in available phos- phorus. In other words, the phosphorus in banded fertilizers can be expected to be more effective in promoting rapid, early growth with increasing soil phos- phorus deficiencies.

The data also show that, regardless of the level of available soil phosphorus, less and less phosphorus is derived from the fertilizer as growth progresses and the root system develops. After 110 days, on soils that were high and low in available phosphorus, only 23 and 15 per- cent, respectively, of the phosphorus needs of the crop came from the applied fertilizer. The remainder of the phos- phorus that was absorbed--some 77 sjid 85 percent--came from the soil. This ex- plains why, on moderately fertile soils, early growth stimulation of corn by banded fertilizers often is not reflected in the final yield. This being the case, benefits other than yield increases must be assigned to banded fertilizers for some soils.

Fig. 1. — Estimated Relative Early Growth Stimulation Induced by Soluble Phosphorus Applied in Bands to Soils of Different Soil Phosphorus Test Values

a o

•H

-p H I

•H -P CO

o u o

a

(U 0) CD

i) > •H

1^ H (U

Ti

V

-p

-P to

\^^^^M wheat and Clovers Corn

Soybeans and Oats

i

b^

t^

^

i:^

El

Low Slight Medium High Illinois Soil Phosphorus Test Values

E. H. Tyner 12-5-55

UNIVERSITY OF ILLINOIS ■ COLLEGE OF AGRICULTURE

^oiL PERTitmr

AND ,^

TESTING , -

AGRONOMY FACTS

SF-41

BAND APPLICATION OF FERTILIZERS IN ILLINOIS - PART 2

The preceding Fact Sheet was devoted pri- marily to some of the fundamental aspects of hand fertilization. This sheet will deal with the more practical aspects of the problem- -amounts^ fertilizer ratios in relation to soil test values^ etc.

Except on calcareous (shelly) soils ^ banding fertilizers with each row crop is not urgent on soils testing at least M- in available phosphorus or above 170 pounds in available potassiiim. On such soils the primary benefits from banded fertilizers, if any, are likely to be secured only with wheat and legumes (see Fig. 1, Fact Sheet SF-ij-O).

Under these conditions applying mainte- nance amounts of phosphorus and potassium once in the rotation will maintain enough mineral fertility for high crop yields, assuming adequate nitrogen fertility. Moreover, these amounts can be applied with bulk distribution equipment during slack periods. One exception might be where grape colaspis must be controlled, but it can also be controlled with pes- ticide sprays. Farmers who have serious grass weed problems or who are shooting for extraordinary yields may still prefer to apply seme banded fertilizer in order to insure better stands.

Banded fertilizers applied to each crop, however, have a definite place where de- pleted farms are operated by tenants with uncertain tenure, or where capital is not sufficient for build-up applications or where it is needed more in other phases of the farm business than for rapid build-\ip of basic soil fertility.

In general, on very deficient soils one cannot apply enough fertilizer to get maximum yields by hill-dropping or band- ing in the row. Even so, it is possible to get good yield increases with mixed fertilizers alone, provided the analysis supplies reasonable amounts of the most needed nutrients and provided nitrogen

fertility is adequate. Table 1 lists first-year phosphorus and potassivmi re- quirements for moderately high yields at various soil test values.

Table 1. --Phosphorus and Potassium Re- quired the First Year at Vari- ous Soil Test Values

	Phosphorus	Potassium
Test value	(P2O5)	(K2O)
	lb. /A	lb. /A
L-	60
L	5^
L+	kQ
S-	k2
S	36
s+	30
Uo	• •	120
80	• •	70
120	• •	1|0
170-200	• •	30

The above requirements are stated in terms of phosphorus (P2O5) and potassium (K2O) needed per acre. How can we use such information in determining the prop- er fertilizer analysis to buy: Let us assume that the soil test indicates phosphorus availability as L- and potas- sium availability as 120 pounds. On the basis of this information, we would need to apply 60 poimds of P2O5 and ^0 poionds of K2O per acre. The P205:K20 ratio needed in a mixed fertilizer would therefore be 1.5 to 1.0. It would be difficult to find a mixed commercial fertilizer with this ratio. Therefore, we will choose a fertilizer with a 2 to 1 phosphorus-potassiijm ratio, such as 0-20- 10. If we were to apply 3OO pounds of this analysis per acre, it would supply the 60 poimds of P2O5, but only 30 pounds rather than to pounds of K2O. Even so, we could still obtain satisfactory yields.

Can this amount of fertilizer be hill- dropped or banded for row crops? Large amounts of fertilizer close to the seed can delay or even prevent germination. The reason is that the "salt action" in- hibits moisture uptake by the seed or the

roots just emerging frcm the seed. In general practice, it is only the nitrogen and potassium in mixed fertilizers that are "hot" and that interfere with germi- nation.

A good rule-of -thumb is not to hill-drop or band more than 30 pounds of "hot" solubles (nitrogen (n) plus potassium. (K20))per acre. It is apparent that the safe amount will vary with the analysis, e.g., 3-12-12 (200 pounds), 10-10-10 (150 pounds), 3-9-27 (100 pounds). The 30-pound rule is for dry to average sea- sons. In wet seasons higher rates may not be injurious. According to this rule, the 3C0-pound application of 0-20- 10 could be made provided the fertilizer attachment would deliver this amount. If not, 100 pounds could be banded and the rest broadcast and either plowed Tinder or disked in.

This explanation shows why it is diffi- cult to prescribe certain fertilizer ra- tios for use on crops grown on soils that may vary considerably in basic fer- tility. Moreover, a certain analysis may be satisfactory to apply for a few years, but carry-over effects may cause the ratio and the amount to change. Pe- riodic soil testing will help to deter- mine the most practical and profitable ratios and rates.

How necessary is nitrogen in mixed banded fertilizers? This is a question on which agronomists do not agree. Experimental evidence indicates that nitrogen in- creases the uptake of phosphorus. It may therefore be argued that nitrogen in banded fertilizers serves a very useful purpose. This may be true on soils that are highly deficient in available phos- phorus, but it is not so important on soils that are moderately supplied with available phosphorus. More will be said on this point later.

In general, where experience indicates a substantial response to nitrogen, large amounts of nitrogen must be applied. It is usually best to apply a nitrogen ma- terial, e.g., 20-0-0, 33-0-0, 82-0-0. This does not mean that 12-12-12, etc., are not satisfactory sotirces of nitrogen.

Such analyses, if used in amounts ade- quate to supply the required nitrogen, often supply more phosphorus and potas- sium than can be used efficiently. But the excess phosphorus and potassium are not lost through leaching and can be used later.

Applying nitrogen in large amounts in mixed fertilizers can, therefore, lead to inefficient use of phosphorus or po- tassium if the soil already tests moder- ately high in these elements. Where high nitrogen mixed fertilizers are used, the carry-over effects of excess phosphorus and potassium should be carefully ana- lyzed before subsequent fertilizer appli- cations are made.

In general, conditions preceding planting and level of available soil phosphorus should determine the advisability of ap- plying amounts of nitrogen in mixed fer- tilizers, such as 3-12-12, Normally the decay of soil organic matter will take care of the small nitrogen requirements of seedlings. If the weather is abnor- mally cool with frequent rains before corn is planted, it might be advisable to use a mixed fertilizer containing seme nitrogen, particularly on phosphorus defi- cient soils. On the other hand, if tem- peratures are normal and moisture is average, it is questionable whether ni- trogen will be needed in starter ferti- lizers even to increase phosphorus uptake. Nitrogen in mixed fertilizers may, however, be beneficial in most sea- sons on weedy fields where a considerable amount of trash, particularly straw, has been plowed under.

Is nitrogen necessary for establishing stands of winter wheat. If wheat follows soybeans and is seeded just after the fly-free date, the value of applying ni- trogen in mixed fertilizer to stimulate fall growth is questionable. On the other hand, if seeding is delayed because of wet weather, seme nitrogen- -perhaps not more than 3 to 5 pounds per acre --might be desirable. Applying nitrogen in the fall on clay-pan soils to avoid the need for spring applications is a different matter. See Fact Sheet SF-28.

E. H. Tyner 12-12-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SF-42

PROGRESS REPORT ON A GREEN-MANURING PROJECT

In 1953 3.n experiment was started to de- termine the value of northern and south- ern alfalfa varieties, red clover, ladino clover, sweet clover and lespedeza as green-manure crops. A comparison of the green-manure crops with chemical nitro- gen was also included.

The Series 1102 plots on the Agronomy South Farm, where the various green-manure crops were seeded in oats in 1953^ had the following crop history:

19^8 Corn followed hy an application of 1^ tons of manure an acre.

1949 Corn

1950 Soybeans harvested for seed

1951 Oats in which clover was seeded but failed

1952 l-Jheat (straw left on land)

1953 Before oats were seeded, three tons of 200-mesh limestone, 5OO pounds of 0-20-0, and 110 pounds of O-O-5O were applied

The Series W-6C0 plots had been in a rotation of corn, corn, oats, and clover for 50 years. The clover failed in 1953 and oats were seeded again in 195^ as a companion crop for the green-manure crops .

In each series the green-manure crops were plowed under about a yea^ after seeding. To some plots where a green manure had not been seeded (NHi^)2S0i^. was applied in 195^ ^nd plowed under at once. KHPIO3 was used in the same way on certain plots in 1955. Corn was planted by hand at the rate of four kernels per hill. A nearly perfect stand was sec\ired in each year.

The yields of No. 2 corn on these plots for the years 195^ snd 1955 are given below.

CORK YIELDS FOLLOWING GREEN-MANURE CROPS AND WITH NITROGEN FERTILIZERS

	Acre	yields
Green-man\ire crops	195^	1955
	bu.	bu.
Alfalfa
African	119	102
Chilean	120	111
Indian	123	103
New Mexico	120	108
Northern Common	^\?^	109
Ranger	119	110
Clover
Ladino	119	103
Medium red	124	103
Lespedeza (Korean)	122	103
Sweet clover
White blossom	117	109
Yellow blossom	116	109
AVERAGE	120	103
None	119	103
None plus nitrogen
60 poiinds/acre	m	97
None plus nitrogen
120 pounds/acre	—	99

In each year a randomized block design ■vriLth four replications was used. Conse- quently it was possible to make a sta- tistical analysis of the data.

Although seme differences in corn yields were associated with the previous green- manure crops and with nitrogen fertilizer these differences were not statistically significant. On the basis of this

Information, it cante concluded only that neither nitrogen fertilizer nor legumi- nous green-manure crops had a measiirahle effect on yields of corn in these plots in 195^ and 1955* This information should not be interpreted to mean that in other years or on other soils in the same years the use of leguminous green-manure crops or nitrogen fertilizers would not or did not affect corn yields favorably.

The question then arises why increased corn yields did not occur. While it is not possible to say with authority why these results were obtained, some possi- ble ejcplanations can be presented: Obvi- ously these soils were furnishing a larger amount of available nitrogen than is usually the case. Again the question why arises naturally.

In the years 1953, 195^ and 1955;, there were no periods of excessive rainfall. In fact, a moisture deficiency occurred for several extended periods in each of these years. As a result, it seems rea- sonable to postulate that the soils, even

without green m.anure, fiirnished suffi- cient available nitrogen for maximum yields under the seasonal conditions that prevailed. This large amoiuit of available nitrogen was the result of:

1. Moisture and temperature favorable for nitrate formation.

2. IJot enough soil moisture to cause leaching losses of nitrate nitrogen or denitrification.

In other areas on the Agronomy Farm there was evidence that the availability of soil forms of nitrogen was high in 195^ and 1955* Consequently the response to added nitrogen was less than many people expected.

These data should not be construed to mean that leguminous green-manixre crops and chemical nitrogen are not important in the nitrogen economy of the land. Rather, they indicate that seasonal con- ditions must be considered in evaluating the worth of any soil-improving practice in a particular year.

J, A. Jackobs

0. H, Sears 1-9-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SF-43

COMPOSTS

Composts have iDeen used in agricultiire for centuries. Roman farmers prepared composts from the strav and chaff of grain crops and from the leaves of for- est trees. Although the farmers of an- cient times did not understand all of the principles involved, they were famil- iar vith the kinds of ingredients needed for successful composting.

One kind of composting, knovn as sheet composting, has been used in Illinois for more than half a century. It con- sists of plowing under such materials as straw, manure, and green manure crops grown for soil improvement purposes.

Composts have "been used extensively in the United States for mulching shrubbery where it is not desirable to incorporate the organic residues in the soil. They have also been used to some extent in vegetable crops and flower gardens to conserve moisture and to prevent the soil structure from being destroyed by beating rains.

be used, but grease and meat scraps will develop offensive odors and attract rats and flies.

During composting a considerable part of the materials decay and part of them go into the air as gases. The remainder is similar to well -rotted stable manure. A good manure from composts must go through this decomposition process.

Bacteria and molds are largely responsi- ble for decomposition. Although they de- rive energy from the refuse which they decompose, they also need other sub- stances for growth. One of the most es- sential is nitrogen. Because most of the substances which go into a compost heap are low in this element, it is nec- essary to furnish additional nitrogen if a rapid rate of decay is to be obtained.

In the process of decomposition, acids are produced. Some nitrogen fertilizers also form acids. Consequently, it is ad- vantageous to add limestone.

One advantage of decomposing organic ma,t- ter is lost when composts are prepared in a compost heap. One reason for in- corporating organic m.atter in the soil is to improve soil structure or tilth. As the organic materials decompose, the microbes produce substances that in- crease the aggregation or crumb struc- ture of the soil. Although soil tilth is not improved solely by microbial activity, it is recognized generally that microbes have an important function in keeping soils in good physical condi- tion.

Many materials can be used in the com- post heap, including leaves from trees and shrubs, weeds, la^-m clippings, and garden residues. Even table scraps can

A satisfactory compost may by using the following:

be prepared

Organic residues (dry weight) 100 pounds

Ammonium sulfate 5 pounds

Limestone 5 pounds

Five hundred pounds of green plant resi- dues will contain about 100 pounds of dry material. A bushel of leaves weighs about 5 to 8 pounds, depending upon con- dition and packing.

To build a compost heap, place about 1/5 to 1/6 of the leaves, grass clippings, or garden residues in a layer 10 to 12 inches thick. Moisten this layer and spread I/5 to 1/6 of the mineral mixture over it. Alternate the layers of residues

and minerals until the stack is complete. Make the top of the stack concave to catch and hold rain. If the material is kept moist, rotting will proceed rapidly. One ton of dry material will produce about 2 1/2 tons of moist artificial ma- nure.

If the heap is made in early or even late summer, the compost will "be avail- able for early spring use. However, if the materials are not composted until late fall, when the temperatures are low, decay will be slow, and a sufficient de- gree c£ decomposition may not be obtained by early spring.

Although it is not necessary to add phos- phates to decompose the residues, 2 pounds of superphosphate added to the

mineral mixture will increase the value of the manure, particularly if it is to be used on soils that are low in avail- able phosphorus.

Even though artificial manure in the stack does not have a noticeable odor during decomposition, when spread it has an odor resembling that of natural ma- nures.

Prepared mineral niixtures are available in some localities. More recently a num- ber of commercial products which are said to contain the microbes needed for decomposition have been sold. Investi- gations in California and Florida indi- cate that there is little need to apply microbial concoctions. The same results may be secured by adding small amovmts of fertile soil to the coiirpost.

0. H. Sears i<-2-56

.^IIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

AND TESTING	m
> ■

SF-44

THE NATURE OF EXCHANGEABLE CALCIUM AND MAGNESIUM AND THEIR RELATION TO SOIL ACIDITY AND LIME REQUIREMENT

In moist soils calcium and magnesium are present mainly in exchangeable form. This form is attached by valence bonds to the surfaces of the soil clay and or- ganic matter particles. Exchangeable potassium also occurs on these siirfaces, although usually only in small amounts in relation to calcium and magnesium.

The exchangeable form is usually the principal available form of each of these soil nutrients --the form the plant de- pends on for grovth. ^^

However^ calcium and magnesium play an- other role in soil fertility. They control the acidity or pH of the soil. If the clay and organic matter particles are covered mostly with calcium and mag- nesium;, the soil will be nearly neutral or "sweet." But whenever a cation like the calcium or magnesium ion is lost by leaching or removed by plant roots, hy- drogen, the "acid" ion takes its place and the soil becomes more acid. Liming is merely the process of replacing the exchangeable calcium and magnesium lost by leaching in order to bring the soil back to a pH favorable for plant growth.

In the claypan soils of southern Illi- nois, the native soil is usually highly acid. The calcium and sometimes the mag- nesiiim are so low that liming is needed for two purposes: First, liming adds calcium and magnesi'um and thus overcomes deficiencies to the extent that these nutrients are supplied in available form. Second, proper liming corrects the acid- ity sufficiently to make the soil reac- tion (pH) favorable for plant growth.

In one sense the two fimctions of liming are completely independent of each other. In fact, except in southern Illinois , most of the soils in the state already contain so much exchangeable calcium and

magnesi'um that they provide plenty of nutrient for plant growth, yet they are often so low in these elements in rela- tion to the acid ion that the soil can be harmfully acid to some crops. Except in these claypan soils, therefore, the chief purpose of liming is usually to change the soil reaction.

One effect of changing the pH upward is that it makes it possible for plants to feed more efficiently on the available phosphorus in the soil. Another is that many legumes nodulate only at the higher pH levels. (A low pH means a more acid reaction. ) Organic matter appears to decompose more readily at the higher pH levels.

Except in soils that are very low in clay and organic matter, a favorable pH level is practically a sure sign that calcium will not be deficient. In such soils a high pH could theoretically be due mostly to potassium and magnesium. But such situations have never been found in Illinois.

The pH of a soil is not determined by how much or how little exchangeable cal- cium and magnesium it contains, but rather by the proportion of these basic ions to the acid hydrogen ions. The to- tal amount of exchangeable cations Ca++, iy[g++^ and H+ held on the clay surfaces is called the base exchange capacity and is measured in terms of milligram- equivalents per 100 grams of soil (m.e. per 100 grams).

One m.e. per 100 grams is about the amount of calcium and magnesium contained in 1,000 pounds of high-grade lime- stone. If a soil contains on its clay and organic matter surfaces 8 m.e. of bases and 2 m.e. of acid ion, or a total of 10 m.e., it will be in the sweet

range because it is 80 percent saturated with exchangeable bases and only 20 per- cent saturated with the acid ion. If it contains l6 m.e. of bases and ^4- m. e. of acid^ it will have a total of 20 m.e., but the percent of saturation and also the pH will be the same as before. So the degree of acidity or pH depends not on the actual amount of acid that is present; but rather on the proportion of acid to base.

Lime requirement is another matter. Sup- pose the first soil has 5 m.e. of bases and 5 m.e. of acid, for a total of 10 m.e. It is then 50 percent saturated with bases and is in the unfavorable range of acidity. A more favorable range is 80 to 90 percent saturation with bases. This means that from 3 "to ^ m.e. of hydrogen must be neutralized. This is equal to 3^000 to ^,000 pounds of pure limestone. Hence the tentative lime re- quirement is 3^000 to ^,000 pounds.

Wow suppose a 20 m.e. soil is also only 50 percent saturated and it is desirable to increase the saturation to around 80 to 90 percent. Fifty percent of 20 m.e. is 10 m.e. of the bases present. Eighty to 90 percent saturation is 16 to I8 m.e. of bases needed. If 10 m.e. are present and I6 to I8 are needed, then 6 to 8 m.e. or 6,000 to 8,000 pounds of limestone is the tentative lime require- ment.

Silt loam and clay soils have higher base requirements for the same pH value than do the lighter soils. Sands gener- ally have the lowest.

Theoretically, in order to estimate a practical lime requirement, one should first know the magnitude of the base- exchange capacity and the sum of the mil- liequivalents of the bases present. This would require a quantitative estimate of the exchangeable calcium, magnesium, and hydrogen (acid ion).

But that is not all one would have to know. Knowing that, theoretically, it would take 6,000 pounds of pure lime- stone to sufficiently neutralize the soil is only one item. Next one must consider the neutralizing value of the limestone. If it is only 90 percent C.C.E. (calcium carbonate equivalent ), the orig- inal 6,000-pound calculation must be increased to compensate for the 10 per- cent impurities. This increases the requirement to 6^666 pounds.

However, this is still not the answer.

The fineness of the limestone must be rated according to its rate of neutrali- zation, i.e., how much acid it can neu- tralize within a relatively short time. For years, until a government agency took over limestone inspection, such ratings were made on all Illinois limestones and an effectiveness score was given to the stone. If the effectiveness score is low, more limestone is needed. Wow suppose the limestone has a score of 85 percent effectiveness over the first three years. This was about the average score for Il- linois quarries at the time effectiveness inspection was discontinued. Applying this correction to the above 6,666 pounds gives 7,840 pounds as the corrected requirement.

But again this is not the whole story. Many, if not most, soils have acid sub- soils. But the acidity of the subsur- face varies; in the claypan soils it is higher than in the dark-colored silt loams. With deeper plowing this acid soil gets mixed with the top soil, in- creasing the acidity. Also the transfer of bases downward increases when sub- soils are more acid. These things would all affect the need for limestone over a period of years.

And, last, there is the matter of quick- ness of leaching. A sandy soil with a sufficiently low exchange capacity can become acid through the loss of only one

-3-

milliequivalent of calcium. And more water moving through such a soil hastens leaching. But heavy soils change in pH much more slowly because their capacity is higher and less water goes out the tile. The limestone reconmiendation must include recognition of this point.

So estimating a practical lime require- ment is not merely a matter of knowing the amounts of exchangeable bases and acid present^ although this is the soundest starting point for estimating the theoret- ical requirement. Other considerations are the effectiveness of the limestone (fineness)^ purity of the limestone, acidity of the subsurface, and rate of leaching of the exchangeable bases. When all of these things are considered, the final recommendation may appear to have little relation to the theoretical re- quirement .

For example, some sands in Illinois have a base -exchange capacity of 3 milli- equivalents per 100 grams. This means that they can hold calcium and magnesium equivalent to not much over 2., 500 pounds of a fine 100 percent C.C.E. stone. Yet when they are acid, 3 "to 4 tons of ordi- nary limestone are commonly added after considering screen score, C.C.E. , and especially the high rate of leaching on sandy soils. On the other hand, a soil like Muscatine silt loam with a base- exchange capacity of 20 m.e. per 100 grams will, at the same pH, have a much higher theoretical requirement, but the practical requirement may be little higher than the practical requirement for the sand when all the other factors are considered.

It is therefore not "fool proof" to base the lime requirement on measurement of the exchangeable bases and the exchange- able hydrogen (acid) alone.

The lime requirement recommendations based on pH or thiocyanate readings have resulted from practical experience over a period of 30 or more years. VJhile a thorough study of Illinois soil types

and of their base-exchange capacities and pH — degree of saturation relationships was made a couple of decades ago, it has not yet appeared practical to apply this knowledge to refining the lime require- ment recommendations made in our county laboratories.

The Missouri "Lime Meter" method repre- sents one approach to this problem, but when corrected for these other factors it correlates too closely with our recom- mendations based on pH or thiocyanate to make it practical to use.

The pH and thiocyanate methods, while they do not involve a determination of the bases and acid, do give a measure of degree of saturation with bases and can be Interpreted in terms of lime require - m.ent when the base -exchange capacities of the soil types are known.

In general, the high-capacity soils occur in the northern two-thirds of Illinois, and their capacities and pH vs. degree of saturation relationships have been thoroughly studied and found sufficiently similar to make it practical to use pH or thiocyanate as a measure of the lime requirement.

On the other hand, the soils of southern Illinois, while lower in base-exchange capacity^ have much more acid subsoils, which would tend to increase the rate at which a limed soil becomes acid and thus require more than the theoretical amount of lime.

Measuring the theoretical amount is there- fore not the whole answer. The higher cost of the required tests leads to a tendency to run only one or two samples, whereas in the Illinois plan 11 samples in a UO-acre field are analyzed. Given a choice, the 11 samples run by the pH or thiocyanate test are generally preferable and may be more accurate than a single composite of a whole field run by a the- oretically better method. In fact, some results reported to us of interpretations

-1^-

based on theoretically better determina- tions indicate that the interpretations must have oeen made "by persons mth so little knovledge of soil chenistry that the recommendations -were unsoimd and vorthless.

Years ago this station put out a very siniple titration-indicator method that involved using several samples of the same soil and shaking each one •'.■ri.th a

salt containing a different amount of a base. This procedixre measured the theo- retical lime requirement directly^ re- gardless of variations in base-exchange capacity, and is easier to run than methods involving the total of each ion involved.

Roger H. Bray 6-11-56

UNIVERSITY OF ILLINOIS ■ COLLEGE OF AGRICULTURE

AGRONOMY FACTS

MANAGEM CONSERVATIO.

SM-12

OBJECTIVES OF CROP ROTATIONS - INTRODUCTION AND EROSION CONTROL

This is the first in a series of five Agroncmy Fact sheets devoted to the "Ob- jectives of Crop Rotations." This one is concerned with control of soil ero- sion. The second one ■will discuss the effects of crop rotations on soil physi- cal properties^ such as absorption of rainfall;, internal drainage^ and compac- tion. Nvunber 3 will explain how crop rotations may help to control insect pests and crop diseases. Number h -vrill take up the problem of plant nutrients with particular emphasis on nitrogen. The fifth and last of this series will discuss the economic factors to be con- sidered in deciding what crop rotation to follow.

Crop Rotations and Erosion Control

The effectiveness of a crop rotation in controlling soil erosion depends upon the type of growth^ the amount of growth and the time of growth of the crops in- cluded in the rotation and the propor- tion of the time that the crops with different characteristics are on the land.

Type of Growth

Grasses and legumes are erosion resist- ing crops. If a good stand of such crops occupies the land^ erosion losses are negligible even on relatively steep slopes. At the other extreme is bare soil which is subject to serious erosion even on gentle slopes. Inter-tilled crops, like corn and soybeans, furnish some protection against erosion and are therefore better for the soil than no crop. Small grains are intermediate be- tween grasses and legumes and inter- tilled crops in holding down erosion.

Amount of Growth

In the case of any crop the amount of top growth determines to a considerable extent its effectiveness in controlling erosion. The more completely the soil is covered by a crop the less it is

exposed to the beating action of rain- drops which break up the soil crumbs or graniiles. The character and extent of the root system of a crop are also impor- tant. For example, in August a crop of soybeans ma,y cover the ground as com- pletely as a crop of alfalfa and still the soil may be subject to much greater erosion losses . This is due to the fact that the bean ground is in a looser con- dition than the alfalfa ground. The bean roots are also less extensive and are usually localized in rows.

Abundant root growth of crops improves the physical condition of soils so that water is more readily absorbed and the soil is less damaged by the beating action of raindrops. A soil full of roots also resists the cutting action of water concentrated into small streams.

Time of Growth

The amount of erosion that m.ay be attri- buted to a particular crop depends largely on the time of its groirth. In Illinois much of the corn is planted in May, when the amount and intensity of rainfall is relatively high. Since the soil is loose from tillage and the soil gets no protection from, the crop^ erosion losses are usually high. In June the corn is in the active growing stage, the soil is cultivated and the amount and the intensity of rainfall are relatively high. In this month also erosion losses are high. From kO to 60 percent of the annual soil losses from corn land on the Agronomy South Farm occurred in June.

Expected Soil Losses

From available data it is possible ^- -r- timate the soil loss by erosio:. -, u will occur on different slopes, from different kinds of soils under a particu- lar rotation. If the sril loss is greater than the estir. ermissable loss, then more sc;^ .;-- be included in the rotation. .' in Illinois

-2-

farmers are interested in growing corn and soybeans. To figure out a crop rota- tion that will satisfactorily contx'ol erosion just enough sod crops are included to keep the soil loss dovn to a per- missahle amount. Permissable loss is the amount in tons per acre which it is estimated can "be lost annually from a particular soil and still maintain the land in continued productivity. (The table appearing at the end of this re- port shows how this works . )

Supporting Practices

By using supporting practices a rotation may he followed that would permit too

high soil loss without the supporting practices. It works like thisl A farmier selects the crops he wants to grow and the amount of a particular crop^ like corn, he wants to include in the ro- tation. This is checked for the condi- tion of his land, the percent .of slope, the length of slope, the kind of soil and its condition, particularly with reference to past erosion damage. If the erosion losses are higher than per- mis sable under the conditions, the use of supporting practices, such as contour- ing, strip cropping, and terracing may reduce the soil loss enough so the de- sired rotation can be followed.

Expected Soil Losses from Selected Rotations on Four Soil Types on a 200-foot Contoured Slope in Illinois

a

:/

Rota.tion— '

CCCG*

CCCGM

CCGM

CGM

CGMM

CGMMI#I Permis sable Loss

Flanagan 2i Slope	Siv-ygert 5i	Clinton epjo	Grant sbur 5fo
Tons /A	Tons/A 6.2	Tons/A 14.6	Tons/A
1.9	7.8
1.2	4.2	9.8	5.3
1.0	3.4 2.0	7.8 4.5	4.2
.6	2.4
.k	1.2	2.8	1.5
.2	0.8	1.8	1.0

4.5

1.5

3.0

2.5

(Losses below heavy line are small enough to permit use of

rotation indicated. )

a/ Calculations are based on expected losses on soils with 8 or more inches of siirface soil remaining. Average management is assumed in preparing the table. With poor management the losses should be multiplied by 1.3. For high-level management of crops and soil multiply by 0.7. b/ C - corn; G - small grain; M - meadow. *G - small grain with catch crop to plow down.

C. A. Van Doren & R. S. Stauffer

1-30-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

MANAGEMENT & CONSERVATION

EFFECT OF CROP ROTATIONS ON SOIL PHYSICAL CONDITION

SM-13

The physical condition of soils is de- termined largely by their texture^ state of compaction, and degree of aggregation. Cultural practices have little effect on soil texture, hut such management vari- ables as organic matter management, sur- face cover, and tillage will change soil compaction and aggregation and thus help to determine physical condition.

Organic matter management . The degree of aggregation is closely related to the amount of readily decomposable organic matter in the soil. For this reason, cropping systems that add large amounts of readily decomposable organic matter to soils are the systems that promote good aggregation and thus improve physi- cal condition. The effectiveness of residues in increasing organic matter in the soil, and thus improving soil aggre- gation, depends on the amount of resi- dues, their ability to decompose, and the thoroughness with which they are mixed with the soil.

If other conditions are constant, crop rotations that add the greatest amount of readily decomposable crop residues to the soil will be most effective in cre- ating good physical condition.

Surface cover. The amount of protection provided by the crops grown in the

rotation also affects soil physical con- dition. Cropping systems that provide a protective vegetative cover, either living or dead, for the soil during the greatest part of the year help to lessen the impact of raindrops. Heavy rains destroy aggregation in the surface soil and often cause serious crusting. Air and water cannot then move freely into the soil, and seedlings may not be able to emerge.

Tillage . Tilling tends to cause soil physical condition to deteriorate, par- ticularly when the soil is wet. Crop rotations differ greatly in the amount of tillage they require. Intertilled crops have a greater structure -depleting effect than others.

Sod crops provide readily decomposable organic matter and vegetative cover and require fewer tillage operations than intertilled crops. It is thus easy to understand how the sod crops help to im- prove soil structure. Possibly some of the new techniques now being used to produce intertilled crops may eventually reduce their structure -depleting effect enough to make it necessary to reevaluate their usefulness in crop rotations for improving soil physical structure .

M. B. Russell 2-13-56

JNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

MANAGEMENT & CONSERVATION

SM-14

CROP ROTATIONS AND INSECTS

Cultural practices are essential in com- bating attacks of many species of in- sects. Crop rotations are a cultural practice that reduces the number of in- sects farmers have to combat and thus cuts down the amount of insecticide they have to use. Insecticides are only a supplementary means of controlling in- sects. If populations were not reduced by rotations and other cultural prac- tices^ as well as by the weather, the insecticide bill on each farm would be astounding.

Northern corn rootworm is a good example of how insects can be controlled by cor- rect crop rotation. This pest, which has a life cycle of one year, presents a serious problem where corn is grown in the same field for more than two years in succession. The rootworm overwinters in the egg stage, and the small larvae hatch in the spring and stay in the soil waiting to feed on the corn roots. The damage they do may cause the corn to lodge seriously.

Correct rotations will adequately con- trol this pest. Growing other crops in the rotation for two years after corn reduces the niitnber of larvae and emerg- ing adults, providing adequate control without use of an insecticide. A two- year break is necessary, however, be- cause rootworms will survive for one year on some crops besides corn. ^-Jheat jointworms can also be partly controlled by rotating crops.

White grubs are another pest that can be controlled by rotations, but not so eas- ily as the northern corn rootworm. Be- cause grubs have a three -year life cycle, rotation plans must be made two years before the damage is expected. In the first year of the cycle, June beetles, the adults of white grubs, lay their eggs in the spring. The grubs hatch, feed, and overwinter. The next summer, during the second year of the cycle, they feed heavily, severely damaging the crop roots. During the third year, they feed during May, pupate, and remain in the soil as adults the following winter, emerging in the spring to lay eggs.

To avoid damage from grubs during the year of heavy feeding, it is necessary to have had some crop on the land that was not suitable to the adults for lay- ing eggs during the previous season (the first year of the cycle). Such crops are clover, alfalfa, and corn. At one time soybeans were included in the list of resistant crops, but there is now one species of grub that will lay eggs in this crop.

A carefully planned rotation will also reduce some species of wireworms and cutworms. If length of life cycle and other facts about the insect are known, then a crop rotation can be planned that should reduce its attacks on the crop.

H, B. Petty 2-20-56

(Over )

SM-14

CROP ROTATIONS AND DISEASE

It is obvious that continuous cropping perpetuates and increases the pathogenic organisms in the soil. Good examples of this process in Illinois are the in- crease in the amount of take-all and of bunt through soil infestation in fields where wheat has followed wheat for two successive years. Under such situations rotating crops would constitute a good method of control. Crop rotation may^ however, be recommended as a means of controlling disease without considering whether the pathogen or pathogens would be effectively reduced.

The first question to consider in rec- ommending crop rotation as a means of controlling a specific disease is to de- termine whether the pathogen that is re- sponsible for the disease is a true soil inhabitant or whether it is a soil in- vader of short duration. Some organisms are capable of living in the soil for 10 to 20 years without coming into contact with their natural host. Some examples are species of Fusaria and damping-off and root-rotting fungi like Pythium. Crop rotation could obviously be of lit- tle value in controlling diseases caused by this group because it would take too long to eliminate them.

may be at least partly eliminated by ro- tating crops. Most of these fungi, how- ever, are parasites of vegetable crops. Some of the more common ones are the or- ganisms causing bean anthracnose, black- leg of cabbage, and bacterial blight of common beans.

Some work done in Illinois to determine the persistence of the soil-borne wheat mosaic virus showed that growing nonsus- ceptible crops for at least four years reduced the amount of virus but did not eliminate it. Therefore crop rotation cannot be recommended as an adequate con- trol for this disease, in which the virus is known to persist in the soil for a long time.

In most cases rotation is of little value as the sole means of controlling soil- borne diseases in agronomic crops. On the other hand, crop rotation together with other types of control could be very effective. Often the two combined will keep the disease-producing organisms from building up or hold them to a mini- mum so that they will cause little loss in yield. If they accomplished no other purpose, this result alone would make crop rotation worth while.

On the other hand, those fungi that can live for no more than two to four years in the soil without their natural host

Wayne M. Bever Department of Plant Pathology

2-20-56

( Over )

UNIVERSITY OF ILLINOIS ■ COLLEGE OF AGRICULTURE

AGRONOMY FACTS

MANAGEMENT & CONSERVATION

SM-15 AN ANALYSIS OF THE NITROGEN STATUS OF THE AGRONOMY SOUTH FARM ROTATIONS

Numerous experiments ha"ve shoi-m that sat- isfactory^ although not necessarily maxi- mum, grain yields can be maintained by using rotations where the legume -grain crop ratio is 1 to 3 or 1 to ^4-. The marked improvement in soil physical con- dition (tilth) caused by the legume mead- ow and the noticeable deterioration in physical condition after several years of tillage have tended, however, to ob- scure the primary fiinction of legumes in rotations, namely, to restore and main- tain nitrogen. It is only when nitrogen is applied to grain crops several years removed from the legume that it becomes evident that the decline in crop yields which necessitates a return to legumes is primarily a reflection of lower ni- trogen fertility rather than of tilth deterioration.

The transitory nature of nitrogen fer- tility in rotations where legumes are the primary source of nitrogen is illustrated in Figure 1. The corn, corn, oat, wheat rotation was planned to determine the effects of catch-legxanes sown in small grains en subsequent grain yields . There were check plots where legumes were not seeded and plots where legumes were seeded. Thus it is possible to evaluate the yield effects of seeding the catch legumes.

Figure 1 shows that the catch legume in- creased yields of all grains. The yield effect of the legume, however, expressed as percent of increase in yield, was al- ways greatest the first year. A rather sharp break in the residual yield effect of the legume is evident in the second year. The yield effect of the legume continues to decline thereafter, but at a lesser rate.

The data in Figure 1 for the yield ef- fects of commercial nitrogen indicate that commercial nitrogen is equally as

50

0)

o

c

0)

30"

so- lo

-^

For nitrogen

^

For catih legume

Corn

Corn

Oats

Wheat

Fig, 1, Percent of Increase In grain yields for planting a catch legume and using nitrogen only where yields of plots receiving no nitro- gen or legume seedlngs are the standard for comparison. For nitrogen graph line only: first corn, 100 lb. N; second corn, no N; oats, 20 lb, N; wheat, 20 lb. N. (Data from Illinois Agronomy South Farm)

satisfactory as legume nitrogen in so far as first-year corn yields are concerned.

The residual effects of commercial nitro- gen applied to first-year corn on second- year corn yields were insignificant. In this respect legume nitrogen was superior to commercial nitrogen. It is quite ap- parent, however, that the leg-ume system did not supply enough available nitrogen for maximum small grain yields, because oat and wheat yields were higher when nitrogen was applied.

The preceding discussion presented evidence of the transitory nature of nitrogen fertility. Figure 2 gives a generalized concept of the nitrogen fer- tility pattern one might expect in rota- tions where the ratio of non-legume to legume crops is 3 to 1. The pattern is carried through nine years, or two full rotation periods, to show the saw-toothed cyclic nature of nitrogen fertility in- duced into rotations by periodic legume growth.

-2-

4J		\			\		/
■H H -p		\				\l			/
0) c		\				\		/
bO O U			■\^				X	/
B

Years 1234567 89

Non-legume crops Non-leguKe crops

Legume meadow Legume meadow

Fig, 2, A generalized nitrogen fertility pat- tern for rotations where the grain to legume ratio Is 3 to 1.

Two areas in the nitrogen fertility pat- tern are of interest : the peak and the floor. In terms of minimum rotational nitrogen availability^ the floor can be expected to vary with the organic matter content of soils ^ the activity of decay of this organic matter, and the residual legume nitrogen. If the legume is not sown or if it fails, there can be no peak. The floor of minimal nitrogen availability would then appearto broaden and gradually sink, since nitrogen avail- ability at this point depends primarily on the decay rate of an ever-decreasing soil organic matter supply.

If the stand is pure, the height to which nitrogen availability or fertility rises following a legume would appear to be determined primarily by the amount of nitrogen the legume contributes. Lower peaks, and frequently double peaks, with the higher of the two peaks in the second year, are possible where mixed legume - grass sods or legumes mixed with a con- siderable amount of straw are turned under.

Figure 3 shows examples of multiple ni- trogen availability peaks of this nature. Thus the generalized nitrogen fertility pattern illustrated in Figure 2 can vary with different rotations. Moreover, the peak nitrogen fertility associated with

a specific rotation may not represent the optimum nitrogen fertility needed for maximxim grain yields.

3_.0 _ Critical leaf nitrogen

„ "content {2.3fa N) 2.8

2.6

2.4 2.2 2.0 1.8 1.6

n

2345

Rotation No.

6 7 8 9 10 [See Table 1)

Fig, 3. Nitrogen adequacy peak measure by leaf analysis for various rotations, Illinois Agron- omy South Farm.

Leaf analysis studies with corn have in- dicated that a leaf nitrogen content of 2.9 percent gives maximimi corn yields. This is the critical leaf nitrogen per- centage for corn. By means of leaf analy- sis it has been possible, in terms of leaf nitrogen contents, to define the ni- trogen fertility peaks associated with various rotations at the Agronomy South Farm, Ten rotations and associated corn leaf nitrogen contents are listed in Table 1. The results are presented graphically in Figure 3«

Table 1. Rotations and associated corn leaf nitrogen contents at the University of Illinois Agronomy South Farm*

Rotation number Rotation

1 Corn, soybeans

2 Corn, oats

3 Corn, oats**

4 Corn, oats, wheat**

5 Corn, corn, wheat**

6 Corn, oats, wheat, timothy

7 Corn, oats, wheat, alfalfa

8 Corn, corn, oats**, wheat**

9 Corn, corn, soybeans, wheat** 10 Corn, soybeans, oats, wheat**

Percent leaf nitrogen

2.42

2.17

2.67

2.67

1.80 & 1.70

2.14

2.85

1.82 &

2.07

1.94 & 2.07 2.05

*A11 plots Included In rotation experiment have been limed and phosphated. Soil test Indicates adequate potash, **Catch legumes seeded.

-3-

Rotation 7? which is a corn, oat, wheat, alfalfa sequence, was the only rotation in which soil nitrogen fertility, as in- dicated by leaf analysis, approached that considered optjjnum for first-year corn. Rotations 2, h. 5^ 6, 8, 9, and 10, judged by the same standard, gave soil nitrogen fertility peaks that were substantially suboptimum for maximum corn yields.

The leaf nitrogen content observed for rotation 1, a corn-soybean sequence, is of considerable interest. Most workers do not consider that harvested soybean residues contribute m.uch nitrogen to the soil. Yet, except in rotations 3 and J, the leaf nitrogen content of corn fol- lowing soybeans exceeds that for other rotations.

The microbial demands for nitrogen set up by corn residues probably have no ef- fect on yields of nodulated soybeans. Thus soil nitrogen perhaps contributes toward the decay of most of the corn residues diiring the season in which soy- beans occupy the land. ' Corn following soybeans would then appear to grow in a soil environment that is virtually free of microbial competition for nitrogen. Thus the greater part of the available nitrogen is released from soil organic matter. This nitrogen plus that re- leased from partly decayed corn and de- caying soybean residues probably makes the soil nitrogen fertility status higher than one might expect. It should be ob- vious, however, that this practice can not assure above-average corn yields in- definitely because under this highly nitrogen-deficient rotation the soil or- ganic matter will eventually be drastic- ally reduced, leading to progressively lower corn yields.

The effect of the kind of residues that precede corn on net soil nitrogen avail- ability can be evaluated by comparing rotations 1 and 2. Where soybeans pre- cede corn, microbial nitrogen demands

are probably at a minimum for the rea- sons previously given. Where corn follows oats (rotation 2), microbial com- petition for available nitrogen appar- ently persists during most of the growing season. This is reflected in lower leaf nitrogen contents and lower corn yields for the corn-oat sequence. Planting a catch legume in the oats (rotation 3 ) appears to greatly increase the net ni- trogen availability, and this increase is reflected in a higher leaf nitrogen content.

Multiple nitrogen fertility peaks, with maximiim nitrogen fertility in the second year, are not uncommon for some rota- tions. This is true for rotations 8 and 9. It would appear that the nitrogen contributed by the catch legume that preceded corn was not sufficient to over- come all of the microbial nitrogen de- mands occasioned by the decay of the wheat straw. Thus first-year corn is produced in a less favorable soil nitro- gen availability environment.

The initial decay processes that reduce first -year nitrogen availability, how- ever, appear to be more or less complete prior to August of the second year. The subsequent release of available nitrogen previously withheld during decay then gives a higher second-year nitrogen fer- tility pattern, as the data for corn leaf composition show.

The nitrogen fertility pattern illus- trated in Figure 2 might be considered to represent a normal nitrogen fertility pattern. The data in Figure 3^ however, indicate that rotations can alter the normal pattern, i.e., multiple nitrogen peaks. Moreover, it is apparent that the nitrogen fertility peaks achieved by some rotations do not constitute ni- trogen adequacy in so far as maxim'um yields are concerned. Supplementary nitrogen fertilization throughout such rotations is needed to obtain maximum grain yields.

Edward H, Tyner 2-27-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

MANAGEMENT & CONSERVATION

AGRONOMY FACTS

SM-16

ECONOMIC OBJECTIVES OF CROP ROTATIONS

Four previous Agronomy Fact sheets have discussed the various agronomic objec- tives of crop rotations: controlling erosion;, maintaining desirahle soil physical properties^ controlling insects and diseases, and supplying plant nutri- ents to crops. Attaining any one of these four objectives to the fullest ex- tent is likely to mean sacrificing the complete fulfillment of one or more of the others. They must therefore he bal- anced when a rotation is selected and put into effect in the farm business.

An economic analysis of this problem should consider the "best" use of labor and capital, as well as the "best" use of the land. In short, the economic ob- jective of crop rotations should be to select the rotation that will give the maximum profit for the total farm busi- ness over a period of years.

Economic Principle Involved. One crop can be substituted for another to vary- ing degrees in rotations. For example, going from a C-C-0 (clover catch crop) rotation to a C-C-O-M rotation means that meadow is being substituted for part of the corn and oats. In terms of total production of each crop (per acre yield times number of acres), the result of substituting one crop for another in a rotation is not always the same. For example, the number of bushels of corn sacrificed for each ton of legume hay gained is likely to be less in shifting from, say, a C-C-O-M to a C-C-0-M-M ro- tation than in shifting from a C-O-M-M to a C-0-M-M-M. This difference is due to the different effects of crop se- quences on yields as the proportion of land in each crop changes.

The economic principle involved in se- lecting a rotation is that, in order to maximize profits, one crop (for example, meadow) is substituted for another (for

example, corn) until the returns sacri- ficed by decreasing corn production are exactly balanced by the gain in returns from increasing meadow.

Rotation experiments frequently show a "complementary" effect on corn when leg- \imes are added to the rotation in small amoionts. That is, total corn production (per acre yield times number of acres ) increases, up to a point, as legumes oc- cupy a larger percent of the rotation. If legumes and corn are complementary, adding legumes to the rotation will be profitable even if the roughage that is produced is not sold or used by live- stock. In m.any commercial fertilizer programs, however, this complementary re- lationship disappears, and corn and leg- umes compete throughout a wider range of rotations. This means that the farmer has a larger ntmiber of choices, and thus his decisions regarding cropping systems become more difficult,

Basic Data Needed for Choosing Rotation. The economic principle can be applied by using expected yields from each alter- native rotation. The expected yields summarize, in a sense, the combined ef- fect of the relationships described in the four previous Agronomy Fact sheets on rotation objectives. Since the prob- lem of selecting a rotation cannot be divorced from that of applying fertilizer to individual crops within the rotation, alternative fertilizer programs and their expected effects on yield must be considered in combination with each ro- tation.

Except where a cash-grain system is to be followed, the livestock system must also be considered. Roughage -consimiing livestock may be desirable to use labor during slack seasons. Livestock may in turn require a higher percent of leg- umes in the rotation than would be dic- tated by a simple cost-returns analysis of the cropping system by itself.

For example, a cost-returns analysis of the cropping system made independently of the livestock system might show a catch-crop rotation to "be more profit- atile than a stand-over rotation. If, however, the farm is small and the farmer wishes to increase his vol'ume of busi- ness by using roughage-consuming live- stock, the stand-over rotation will be more appropriate.

The place of manure and its effect on yields also needs to be taken into ac- count. And the effect of substituting supporting practices for meadow to sat- isfy soil conservation objectives must be estimated.

Comparing Relative Profits of Rotations. Using the basic data outlined above, the farmer can make a "budget" of estimated costs and returns for each alternative rotation, including other parts of the farm business that are related to the rotation. This comparison of costs and returns can be simplified by considering only those costs that differ among the alternative plans. For example, "such fixed costs as taxes, interest on land, overhead on machinery, etc . , can be omitted because they stay the same re- gardless of rotation. Operator and fam- ily labor can also sometimes be omitted. Since all costs are not included, the resulting figures should not be confused with "profits . " This budget is simply a tool to help compare the effects of dif- ferent rotations; it is not a measure of profitability of the farm business.

Legume Nitrogen vs. Commercial Nitrogen. An added advantage in selecting a rota- tion as part of the total farm business is that there is less need for "internal" accounting. We need not, for example, attempt to calculate a cost for produc- ing nitrogen from legumes. So long as the yield estimates for each rotation adequately reflect the effect of the crop sequence, and varying levels of ni- trogen are considered in combination with the rotations, the value of the leg- ume will show up in subsequent yield

increases and, in a livestock system, in increased livestock production. In- terest should focus on the comparative returns from the alternative total farm plans and not on the value of " goods- in - process. "

Computing Met Returns for a Period of Years. Adoption of a rotation implies that the farm operator expects to re- ceive income and to inctir expenses over a period of years. Alternative cropping systems may give him a choice in the way his income and expenses are spread over this period. For example, some cropping systems may require heavy initial ex- penses for fertilizer, while others may require smaller initial expense but cover a longer time. The time at which the crop sequence will affect yields also differs among rotations. The farmer must consider these differences in developing a budget that is designed to help him pick a rotation.

Budgets of returns and expenses over a period of years can be compared more ac- curately by using a discounting proce- dure. This will give the net returns over a period of time from each plan in terms of its present value. For in- stance, using an annual discount rate of 5 percent, we find that an income of $100 three years from now is worth only $86 today. The same procedure must be applied to costs. Discounting is espe- cially important in comparing alterna- tive plans that have widely different timing of expenses of income.

Comparative Risks. Some farmers prefer a lower, more stable income to one that is higher but varies more from year to year. Since weather and price fluctua- tions do not affect all crops in the same way, rotations differ in variability of returns as well as in average level of returns. In the final selection of a rotation, these differences in risks need to be balanced against the compara- tive returns from the alternative rota- tions.

Earl R. Swans on 3-5-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

MANAGEMENT & CONSERVATION

CONTINUOUS CORN

SM-17

How often should corn be grown on (pro- ductive) corn-belt soil? This much- discussed question has been studied experimentally for 80 years on the Morrow plots on the campus of the University of Illinois. Many other tests have been made on experiment fields and on farmers' fields throughout the state.

At the Momence soil experiment field in Kankakee county;, corn was grown continu- ously for 1^ years, beginning in 1902. Average yields were 6.5 bushels an acre on untreated land; 4ij-.3 bushels with limestone, phosphate, and potash (LPK); and 50«6 bushels with limestone, phos- phate, potash, and nitrogen (lIPKW).

Fertilizers were applied at the following acre rates each year: phosphorus as bone meal, 200 pounds; potassium as mu- riate of potash, 150 poimds; and nitro- gen as dried blood (l2foNO), 8OO pounds. The soil was peaty loam.

On the Davenport plots at Urbana, a con- tinuous corn experiment was operated for 13 years, beginning in I9OI. Fertilizers were used in the same amounts as described above in the tests at Momence. Average yields were as follows: LPK, 50.1; and LPKN, 6l.h. During these same years (1901, 1913) J a, rotation of corn, oats, clover, and wheat catch crop was also used on the Davenport plots. Average yields were 57«9 bushels with no soil treatment and 78.7 bushels with LPK. No nitrogen fertilizer was used on the rota- tion plots. The soil on this area was Flanagan silt loam.

A continuous corn culture study was started on the Dixon soil experiment field in 1932. To maintain a high test level, soil treatments have included lime, superphosphate, and potash. Since 19^2, 600 pounds of ammonium sulphate an acre have been plowed under each year, and 130 pounds of 3-12-12 have been used

as a starter. Rye has been seeded in the fall as a cover crop since 1951-

Twelve-year average corn yields 0-9^^-55) for these plots and for corn under rotation at Dixon and at the Morrow plots are reported in Table 1. Growing costs are indicated in terms of bushels of corn (calculated at $1.25 a bushel). These costs were subtracted from yield to give "take-home" corn per acre .

During recent years hybrid corn, cheaper nitrogen fertilizers, and corn price sup- ports have caused renewed interest in continuous corn. At the Lebanon experi- ment field on Jarvis-LeClaire silt loam and at the Newton experiment field on Cisne silt loam, tests with continuous corn were established in 1951 on land that had been in rotation with soil treatment for many years. Treatments with continuous corn include the use of non-legume cover crops and nitrogen at the rate of 1^0 pounds each year. Yields were low as a result of severe drought in 195^ and moderate drought in 1955 • Table 2 gives average corn yields for the four years 1952-1955 with continuous corn and with corn in a corn, beans, wheat, hay rotation.

At the Urbana Mumford (M-9) plots an area of land has been in continuous corn culture since 1935* Average yield on the untreated areas of these plots from 19^0 to 1952 was 6h bushels an acre. Table 3 lists treatments and yields for the past three years (1953-1955 )• This soil is a Drummer clay loam that has been adequately limed and phosphated.

A. L. Lang

L. B. Miller

C. H. Farnham

P. E. Johnson

D. L. Mulvaney

3-26-56

Table 1. Continuous Corn Versus Rotation Corn at Dixon and at Morro-w Plots

12-yr. Averages^ 19ij-i4-1955

					Costs in	bushels		Ratio-/ of
					of corn per acre	"Take-
	Soil		Acre	Soil	Total / costs-	home"	yield to
Rotation	treatment		yield	treatment	corn	"Take -home"
	Dixon Soil	Experiment Field - Tama	Silt Loam
				bu.	bu.	bu.	bu.
Continuous corn	LPKN	3-12-	12	75.9	18.0	58.2	17.7	4.29
Continuous corn	L			^9.2	1.0	38.6	10.6	4.64
C-O-Cl-W	LPK			95.1	5.0	i^7.0	48.1	1.98
C-O-Cl-W	0			58.5	-	38.5	20.0	2.92
C-0-W( legume)	LPK			80.2	6.0	k6.6	33.6	2.39
C-O-W	LPK			^6.0	k.o	i^l.3	4.7	9.79
		Morrow	Plots - Flanagan Silt	Loam
Continuous cox-n	0			22.0	M	39.0	-17.0	X
Continuous corn	MIP			64.0	5.0	41^.0	20.0	3.20
C-O-Cl	0			68.0		39.4	28.6	2.38
C-O-Cl	I/ELP			108.0	5.0	48.2	59.8	1.81

1/ Includes fertilizer costs, harvesting, and marketing @ 125z!/bu. plus all other costs, based on Detailed Cost Report for Central Illinois. (A. E. Mimeo 2969)

2/ This ratio indicates how many bushels of corn must be harvested for each bushel of net or profit. It also shows hov many bushels must go to market or be added to surplus for the producer to maice the same net profit.

Table 2. Continuous Corn vs. Rotation Corn at Newton and Lebanon, 1952-1955

	Soil		Average corn yields
Cropping	treatment	Neirton	Lebanon
			bu.	bu.
Corn continuous	LPK		35.7	61.0
Corn continuous and cover crop	LPK		30.1	54.3
Corn continuous	LPKN		35.1	63.0
Corn continuous and cover crop	LPKN		37.9	64.3
Corn, beans, wheat, hay	LPK		45.9	83.4
Table 3* Continuous Corn With and	Without Rye,
Mumford Plots,	M-9, Urbana
Year K Rye K	K Rye nV	10	-lo-ioV Nl/	lo-io-ioi/ '17
bu. bu.	bu.		bu.	bu.
1953 57 66 1954 58 65	69 69		79 72	74 68
1955 59 71	87 75		88	90
Average 58 67	79	77

1/ Treatment 5OO lb. /A 10-10-10, N - 100 lb. N alone or 50 lb. with 10-10-10.

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SP-9

THE PRODUCTIVITY OF SOME IMPORTANT SOUTHERN ILLINOIS SOILS

In the last few years a considerable amo-unt of interest has centered on in- creasing the yield possibilities of seme of the southern Illinois soils. This interest has arisen as a result of the relatively higher prices received for central and northern Illinois soils and some rather favorable responses to soil management on experimental fields in the southern area.

Productivity is the ability of a soil to produce crops or other plants under vari- ous management practices and weather con- ditions. Productivity may be measured in per acre yields of certain crops or in terms of an index of combined yields of grain crops_, forage^ or timber (see AG-141+3 ) .

The soils included in this report occur generally south of a line from Calhoion county, Illinois, on the vest to Clark county on the east. On the soil associ- ation map (see AG-l4^3) they occur in Areas M, N, 0, and P. These soils have generally developed in less than five feet of loess lying on a weathered gla- cial till of Illinoian age (SP-l). In most cases they are leached of free car- bonates, and their degree of base satu- ration is low (SM-7).

Soils in Areas M, N, and P were gener- ally developed under a native prairie grass vegetation and are somewhat better supplied with organic matter and with the desirable base nutrients (Ca, Mg, K) than are the soils of Area 0. The soils

Table 1. --Average Per Acre Yields of Hybrid Corn, Soybeans, and VJheat Obtained by Farmers on Southern Illinois Soils Under Medium and Moderately High Management Levels*

		Hybrid	corn,	Soyb	2ans,		.Jheat,
Soil	Soil type	management**	manag	iiaent**	management**
assn.	or		Mod.		Mod.		Mod.
area	associated types	Med.	high	Med.	hiph	Med.	high
		bu.	bu.	bu.	bu.	bu.	bu.
M	Herrick silt loam and
	Virden silty clay loam	61	68	#	#	#	M- tr
M	Herrick silt loam	5h	59	25	28	30	32
N	Ccwden silt loam and
	Oconee silt loam	1+8	62	JL	.J.	25	27
N	Cowden silt loam	hi	56	#	7r	2k	26
P	Cisne silt loam	^5	53	22	30	21	21+
0	Bluford silt loam and
	Ava silt loam	1+6	57	ir	#	19	20

*About 95 percent of data represent the I9I+O-5O decade. **The standard error of estimate of these figures, when considered as 10-year average yields, is calculated to be about + 5 percent.

//Insufficient data reported.

-2-

of Area 0 were generally developed under forest vegetation and are usually quite acid (pH 5»0) iJ^ their untreated state.

The yields presented in Table 1 are hased on data reported by farmers who have been cooperating with the Agronomy Department in a state-wide project aimed at evaluating the productivity of some major Illinois soils. The calculated yields^ based on farm-reported data^ are tiiven for two levels of management. For convenience, these management levels are referred to as medium and moderately high and are expressed in terms of pounds of nitrogen, phosphate, and potash used and the interval of time between legumes and the crop under study.

For hybrid corn and soybeans, yields were calculated by assuming 6.5 inches of total rainfall and an average maximum temperature of 90 for the months of July and August. These figures are aver- ages for the period I925-5O reported by the weather stations in the area.

A medium level of management for esti- mating hybrid corn yields consisted of 50 pounds of N per acre in the current and the previous year, contributed from both legume and nonlegume sources; 20 pounds each of equivalent PpOc and K„0 per acre, applied or estimated as resid- ual from previous applications (30 pounds for Bluford-Ava soils); and a legume or legume -grass mijcture two years before the corn crop.

Comparable figures for a moderately high level of management were 100 pounds of W per acre, ^l-O pounds of PpO^ (60 pounds for Bluford-Ava soils), 60 pounds of K 0 {kO pounds for Herrick soils), and the equivalent of an alfalfa — red clover mix-

ture immediately preceding the corn crop.

For soybeans and wheat the comparable figures for medium and moderately high management are approximately one -half of those given for corn.

Table 2 lists yields from similar crops gro-ji/n on University of Illinois soil ex- periment fields having the same soils as those included in Table 1 or closely associated soils. Huey silt loam listed in Table 2 includes many of the so- called slick spots in southern Illinois (AG-li|i4-3 and SM-8).

The check-plot yields show the productiv- ity of these soils in an untreated condi- tion, and particularly the influence of so-called slick spot soils. The combina- tion of slick spots and low organic mat- ter content in the soil surface may be partly responsible for the low soybean yields at the Sparta field. Good germi- nation and early growth are frequently poor because of "crusting" after rain.

The yields on the plots having full treatment show how these soils respond to adequate fertilization and appropri- ate rotations. These yields are higher than those reported for a moderately high management level in Table 1. Farmers whose long-time yields are similar to those given in Table 1 may wisely examine their crop production practices not only with regard to soil management, but also weed and disease control, choice of hy- brids or varieties, planting rates, and harvesting procedures. The adoption of appropriate improved management prac- tices should bring their soil up to such a level that they could, within a reason- able time, expect to obtain yields similar to those shown in Table 2.

-3-

Table 2. --Average Per Acre Yields of Hybrid Corri;, Soybeans, and Wheat Obtained on University Soil Experiment Fields, 19i|0-195^-^

Soil	Soil type	Hy.	corn.	Soyb	eans,	Wheat,
assn.	or	treatment	treatment	treatment	Experiment
area	associated types	None	Full**	None	Full**	None	Full-J«^	fields***
		bu.	bu.	bu.	bu.	bu.	bu.	Clayton
M	Dominantly Herrick							Carlinville
	silt loam	h9	90	23	32	1?	32	Lebanon
P	Cisne silt loam	23	73	11	21	5	27	Oblong
P	Cisne silt loam and
	Hoyleton silt loam	18	62	8	21	2	25	Ewing
P	Cisne silt loam and
	Huey silt loam	9	58	9	21	1	22	Nevton
0	Wynoose silt loam
	and Huey silt loam	6	52	2	12	3	26	Sparta

*See 111. Bui. 516, Effect of Soil Treatment on Soil Productivity, for history of fields and yields prior to 19^2. **Full treatment represents an average of yields obtained on plots treated with manure, limestone, and phosphate (MIP) and with residues, limestone, phosphate, and potash (RIPK). ***See SF-21 for rotations used. A rotation of corn-soybeans-wheat-hay is used on most of the fields.

R. H. Rust 11-28-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SP-10

CORN ROOT DISTRIBUTION IN FERTILIZED AND UNFERTILIZED FLANAGAN SILT LOAM

Comparison of corn root development in fertilized and unfertilized Flanagan silt loam at Urbanaj Illinois^ during the moderately dry season of 195^ shoved greater root penetration and root growth and also higher corn yield on the ferti- lized than on the unfertilized plot.

Over a long period^ the fertilized plot had received residue (stover^ straw, leg- umes), lime, and rock phosphate, whereas the unfertilized plot had received only crop residues.

Soil tests indicated that, except for ni- trogen, the greatest difference in fer- tility was in the sizrface soil, where the available phosphorus was high on the fertilized plot and low on the unferti- lized plot. There was very little dif- ference in available phosphorus below the surface soil, and practically no dif- ference in acidity or in available po- tassium throughout the soil profiles from the two plots.

Although Flanagan is a dark-colored, per- meable, naturally fertile soil, crop yields invariably decrease with con- tinued farming unless a good soil manage- ment program is followed.

Corn yield was 79 bushels an acre on the fertilized plot and 66 bushels on the unfertilized plot. Total root weight on the unfertilized (r) plot was 1,398 pounds an acre, and the roots penetrated to about hQ inches (see illustration on

back). To this depth this soil is capa- ble of storing about 10.5 acre-inches of available water.

On the fertilized (RIP) plot, total root weight was 1, &^6 poiinds an acre, and the roots penetrated to about 60 inches. VJith this larger rooting volume, the soil had a greater available soil mois- ture storage capacity (l2.8 acre-inches) and a greater supply of nutrients for the crop to draw upon.

Calculated acre weights of corn roots by soil horizons are given in the table on page 2. Soil horizons are marked on the left of the photographs on page 3'

Roots were sampled with a soil-core sam- pling machine that took four-inch diam- eter cores to a depth of 72 inches. Core samples were taken in five concen- tric rings each four inches wide aroiind corn hills. In this way were obtained up to corn hill, or halfway since the corn was inches. Each of the five vertical sec- tions of roots in the photographs is from one four-inch diameter core 72 inches long at distances from the corn hill specified at the top of the root panels .

For comparison of corn root development in fertilized and unfertilized Cisne silt loam during the moderately dry sea- son of 1952, see Agronomy Facts SM-5.

J, B, Fehrenbacher 12-19-55

root samples

20 inches from the

to the next hill,

checked i^-0 by kO

-2-

		Calculated	Calculated	Percent
Soil		root weights	root weights	of total
horizon	Depth	per acre	per acre-inch	roots
	in.	lb.	lb.	perct.
		R Plot
^1	0-li+	kkk	32	31.8
^	11^-18	11.5	36	10.1+
\	18-23	168	3i^	12.0
\	23-39	1^58	29	32.7
^	39-i^3	85	21	6.1
^1	^3-5^^	77	7	5.5
\	5U-72	21	1	1.5
Total		1,398	--	100.0
		RIP Plot
h	0-16	769	1^8	1+1.7
s	16-20	li^3	36	7.7
\	20-2I4-	142	36	7.7
\	2^4-^0	435	27	23.6
^3	ko-k6	165	27	8.9
^1	h6-^l	138	13	7.5
^1	57-72	3h	k	2.9
Total		l,eh6	--	100.0

CORN ROOTS IN FLANAGAN SILT LOAM-R PLOT

CORN ROOTS IN FLANAGAN SILT LOAM-RLP PLOT

INCHES FROM HILL 0 4 9 12 16 20

SURFACE Ai

SliBSURFACE_ Aj^ Bi

SUBSOIL Ba JV' |te4

2>:

SUBSTRATA b:> .

SURFACE A I

SUBSURFACE

SUBSOIL

B3

SUBSTRATA

INCHES FROM HILL 0 4 B 12 16 20

if

I FT

2 FT

3 FT

4 FT

5 FT

6 FT

Corn roots in Flanagan silt loam from a fertilized (RLP) plot on the left and an unfertilized (r) plot on the right. In both photographs each of the five vertical sections of the root panels is from one soil core k inches in diameter and 72 inches long. Distance of each vertical section from the corn hill is indicated at the top of the root panel.

jNIVERSin >-yr ILLINOIS ■ COLLEGE OF AGRICULTURE

AGRONOMY FACTS

I

SP-11

THE PRODUCTIVITY OF DARK, TILL-DERIVED SOILS IN NORTHEASTERN ILLINOIS

Soils in the northeastern one -fifth of Illinois are derived primarily from cal- careous glacial till of Wisconsin age. Although most of these soils are dark colored and appear similar to the casual observer^ they differ widely in produc- tivity (Table l).

These differences in productivity of the various soils are related to the texture of the subsoil and underlying glacial till (SP-7). The underlying parent ma- terial of Clarence -Rove soils contains so much clay that moisture movement (data in Soil Sci. Soc. Am. Proc.^ Vol. l^i: p. 51-55^ 1950^ and Agricultural Engi- neering^ Vol. 30: p. 38if-386;, 19k9) and

root penetration (unpublished data of J. B. Fehrenbacher ) are restricted and crop yields are rather low^ even under a moderately high level of management. In contrast^ such soils as Saybrook^ Lis- bon^ and Drummer^ which are derived from permeable loam till^ produce consider- ably higher crop yields under comparable management. Such management problems as drainage and erosion are also much more difficult on Clarence-Rowe soils than on Saybrook, Lisbon, and Drummer. The phys- ical properties, productivity, and man- agement problems of Swygert-Bryce and Elliott -Ashkum soils are intermediate between those of the preceding two soil associations.

Table 1. --Average per acre yields* of corn, soybeans, and oats obtained by farmers on certain northeastern Illinois soils under medium and moderately high levels of management

Soil	Texture of underlying		Corn	Soybe Me-	2 ans Mod.	Oat	s
associ-	Me-	Mod.	Me-	Mod.
ation	glacial		dium	high	dium	high	dium	high
area**	till	Soil series**	mgt.	mgt.	mgt.	mgt.	mgt. bu.	mgt.
			bu.	bu.	bu.	bu.	bu.
C	Loam	Saybrook, Lisbon,
		and Drummer	70	79	28	33	56	65
E	Silty clay
	loam	Elliott and Ashkum	62	66	27	30	50	53
G	Silty clay	Swygert and Bryce	56	6k	25	26	kk	51
G	Clay	Clarence and Rowe	53	61	21	27	36	k9

*About 95 percent of the yield data represent the decade from 19^0 to 1950. The standard error of estimate of these figures, when considered as 10-year average yields, is calculated to be approximately + 5 percent. **Described in Illinois Agricultural Experiment Station publication AG-1^^3^ en- titled "Illinois Soil Type Descriptions."

The crop yields in Table 1, which are based upon detailed records kept by farmers, are given for two levels of management. These two management levels, designated 'inedium" and "moderately high," are defined in terms of pounds of nitrogen.

phosphate, and potash used and the in- terval of time between legumes and the crop under study.

For corn and soybeans, yields were cal- culated by assiffiiing 6.1 inches of total

rainfall and an average maximum tempera- ture of 86 F, for the months of July and August. These figures are averages for the period 1925-50 reported "by the weather stations in the area.

A medium level of management for estimat- ing corn yields consisted of 50 pounds of N per acre in the current and previ- ous year^ contributed from both legume and nonlegiime sources; 20 pounds each of equivalent P2O5 and K2O per acrO;, applied or estimated as residual from previous applications; and a legume or legume - grass mixture two years before the corn crop.

Comparable figures for a moderately high level of management were 100 pounds of K per acre_, kO pounds each of equivalent P2O5 and KgO per acre^ and the equiva- lent of a legume mixture^ such as alfalfa- red clover^ immediately preceding the corn crop.

For soybeans and oats the corresponding requirements for medium and moderately high management were approximately 70 percent (ranging from ^+0 to 100 percent) of those given for corn.

Crop yields on the Joliet experiment field, which is located on Elliott silt loam and Ashkum silty clay loam, are given in Table 2. These data indicate that both limestone and phosphate are needed on these soils if near -maximum crop yields are desired. Comparison of yields obtained with RIPK treatment on the Joliet experiment field (Table 2) with the yields in Table 1 for Elliott and Ashkum soils indicates that farm yields under the moderately high level of management are approximately 80 to 90 percent of the yields with RLPK treat- ment. These results indicate that with improved management practices farmers may obtain higher crop yields on Elliott - Ashkum and probably other till-derived soils in northeastern Illinois.

Table 2. --Average per acre yields of corn, soybeans, and oats obtained with various soil treatments* on Elliott silt loam and Ashkum silty clay loam at the Joliet Experiment Field, 19^^-1955

Yields with various treatments*

Crop

**

RL

RIP

RLPK

First- year corn (after alfalfa — red clover) Second- year corn (after soybeans) Soybeans Oats

bu.

ko

32 23 51

bu. 53

hi

25

52

bu. 77

60

29 62

bu.

8lf

72 32 58

^Symbols for the various soil treatments are: 0 = no treatment; R = crop residues; L — limestone; P = rock phosphate; K = muriate of potash. Refer to Illinois Agri- cultural Experiment Station Bulletin 5I6 for information on soil treatment and cropping prior to 19^2. **The cropping system followed is corn, soybeans, corn, oats (legume catch crop), wheat, alfalfa — red clover.

R. T. Odell 1-2-1956

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

SP-12

BOTTOMLAND SOILS OF ILLINOIS

Because interest in the management of bottomland soils has heen increasing, the following brief discussion and the key on the opposite page are given to help identify such soils and group them J according to their management needs and adaptation.

' All of the soils in the very poorly drained column in the key need drainage. Bonnie_, Jacob, Fordyce, Karnak, Darwin, Turtle Creek, Muskrat, and Wabash are so slowly permeable to water that drainage by tile is usually not practical. In such soils open ditches are recommended and are usually used. Jacob is so diffi- cult to drain that it is best used for timber or pasture. Some of the others, like Karnak, Darwin, Muskrat, and VJabash, sometimes occur in sloughs where very poor outlets make drainage impractical. Such areas are best used for production of water-loving species of trees or for wildlife.

Most large areas of any of the very poorly to poorly drained soils except Romeo need some dredging to get proper outlets for either tile or open-ditch drainage systems. Some of the soils having sandy substrata, like Wewart, Riley, Gorham, and Ambraw, may present difficult problems of ditch-bank main- tenance if ditches must be cut through them into the sandy, underlying mate- rials.

The soils in the moderately well to well drained column do not need drainage. Some of the soils in the imperfectly drained column, like Belknap, Dupo, VJake- land, Coffeen, Tice, and Gorham, need drainage for best crop growth. Of this group, Bellaiap is least responsive to tile drainage, and in it open ditches are usually recommended. The others usu- ally have low enough water tables and are permeable enough to keep drainage from becoming much of a problem.

Surface soil texture and also organic matter content, of which color is a fairly good indicator, determine work- ability to a large extent. So far as possible in the key, surface texture is arranged within pH groups, with the coarser textures at the top and the finer textures at the bottom. On the fine-textured soils (silty clay lo.am or finer), plowing in the fall and working only when moisture conditions are favor- able will help to prevent compaction and cloddiness.

Assuming adequate drainage, the light - colored soils have the highest nitrogen needs, and the dark-colored soils the lowest nitrogen needs for satisfactory crop growth. The strongly to moderately acid (pH<5.8) light-colored soils have the highest limestone, phosphate, and potash needs. Superphosphate and mixed fertilizers should be used for specific crops on those soils that are alkaline (pH>7.5)» Limestone should not be used on the soils that have high pH values.

Most of the soils having pH values with- in the range of 5«8 to 7*5 are mediiun to high in available phosphorus and available potassium. However, the soils in this group having pH values near ^.Q will need some limestone, phosphorus, and potassium to produce high yields of most crops, particularly legimies.

Two of these bottomland soils, Burnside and Romeo, are not well suited for gen- eral crops because they have only shal- low soil profiles over bedrock. Pasture, or in some cases timber, is the best use for these two soils. Perks, because of its very sandy texture, is usually drouthy and not well suited for simmer crops like corn and soybeans.

Lack of space makes it possible to show only the major characteristics that are useful in identifying and classifying the bottomland soils in the key.

, A			KEY TO BOTTOMIAND SOILS OF ILLINOIS	/	(
Colorft/ sur- face soil	of pro- file	Inches of sur- face	Texture	Soil seriesii/ grouped according to natural drainage;^/ of profile
Surface soil	Below surface	Very poor to Door	Imperfect	ModerateOj well to well
Light	<5.8	12-36	silt loam	sandstone		Burns ide	Btirnside
>8e/	silt loam	silt loam		BeUcnap	Sharon
<8	silt loam	silt loam	Bonnie
silty clay loam	silty clay loam	Piopolis
silty clay to clay	silty clay to clay	Jacob
5.8 to 7.5	12-36	fine sandy loam	sand			Landes 1
15-ij-o	silt loam	silty clay loam to silty clay	Dupo	Dupo	Arenzville
>8	silt loam	silt loam		Wake land	Haymond	1
<8	silt loam	silt loam	Birds
silty clay to clay	For dye e
silty clay loam	silty clay loam	Petroli^
silty clay to clay	silty clay to clay	KarnakL/
>7.5	>8	sand	sand			Perks
silt loam	silty loam to siltv clay loam		Jules	Jules
Moder- ately dark	5.8 to 7.5	30-ito	silt loam	sand		Newart
clay loam to silty clay loam	sand		Newart
8-30	silty clay loam	sand		Riley
>8	silt loam	silt loam	Coffeeni/	Coffeeni/	Kempers/
silty clay loam	silty clay loam	Beaucoup	Tice	Allison
gravelly clay loam.	gravelly clay loam	Beaucoup	, /
clay loam to silty clay loam	clay loam to silty clay loam	Ambraw^/	GorhamS/
silty clay to clay	silty clay to clay	Darwin Turtle Creek		1
Dark	5.8 to 7.5	12-30	silt loam	silty clay loam		Radford
>8	loam	sandy clay	Muskrat
sandy loam to clay loam	Otter		Huntsville
silt loam	silt loam			Huntsville
gravelly clay loam	gravel			Huntsville
silty clay loam	silty clay loam	Sawmill
clay loam	silty clay loam	Sawmill
silxy clay to clay	silty clay to clay	VJabash
>7.5	>8	loam to silt loam	loam to silt loam	Millington	DuPage	DuPage
2-10	silt loam	limestone	Romeo	Romeo	i
a/ Light colors have values of k or more on Munsel soil color charts (dark gray to hrovn or; lighter). Moderately dark color values are usually 3 (very dark gray to dark hrown). Dark color values are usually 2 ("black to very dark "brcvn). h/ pH refers to reaction: pH < 5.8 is strongly to moderately acid; pH 5.8 to 7.5 is slightly acid to neutral; pH >7.5 is plkaline (usually calcareous), c/ Soil series name plus surface soil texture equals soil type name, d/ For an explanation of natural soil drainage classes, see Agronomy Facts SP-3. e/ The symbol > 8 means more than 8. The symbol <C 8 means less that 8. f/ The pH of Karnak may be as low as 5«0« g/ Tentative series (not yet correlated), h/ Ambrav and Gorham are sandy below Uo inches. J. B. Fehrenbacher 1-23-5^

UNIVERSITY OF ILLINOIS

AGRONOMY FACTS

.-.ULTURE

ORGANIC SOILS IN ILLINOIS

SP-13

Organic soils are soils that contain more than ahout 25 to 30 percent of or- ganic matter. They occur in moist to wet locations where organic materia.1-- primarily plant remains --accimiulated faster than hirnius decomposed or decayed.

to the botanical composition of the plant remains and to the nature of accumula- tion. These in turn are responsible for differences in texture ^ color ^ shrinkage, etc.; and determine the uses to which the peat m.aterials may be put.

Organic soils are of two kinds : peat soils are those in which the plant re- mains are sufficiently well preserved to permit the plant forms to be identified. Muck soils are those in which the plant remains are so thoroughly decayed that the plant parts cannot be recognized.

In most areas peat probably formed be- fore muck. Some muck may possibly have formed without first going through the long period of thick peat accumulation. The development of muck in this way, how- ever, would have required short but reg- ular wet periods for organic matter to acciomulate, alternating with drier peri- ods for it to decompose. This alternat- ing wet and dry cycle would have had to continue throughout the entire period of muck development.

About one-foiirth to one -third of the total area of organic soils in Illinois is peat, and the remainder is muck. Little or no true woody peat exists, al- though shrubs and trees contributed part of the plant rem.ains in som^e areas, such as the area at Manito in Mason county. Also, there is very little true Sphagnum moss peat in this state. This is the strongly acid type of peat so well kno'i-m in Canada and northern United States. Only two small areas, located in Lake coiinty, are known in Illinois.

Peat materials in Illinois are chiefly of two kinds: fibrous (reed-sedge vari- ety) and sedimentary or colloidal. Dif- ferences between these two peats are due

Fibrous peat is the most commonly kno'^-m peat in Illinois. It is formed in shal- low water from marsh plants like sedges, reeds, certain grasses, and rushes. These are upright -growing plants that live where the watertable remains permanently at or near the surface. A few of the more common mosses, particularly some s ■ :lytrichum and Hypnum, also hc_kCL. ^o i^iiii the fibrous peat, but not to the same extent as the m.arsh plants.

Fibrous peat in Illinois is . . ji or felted, stringy mass that resembles firmly compressed, half-rc"^""- -traw. It is usually bro^^m in color _-_ . .ut neu- tral in rea.ction it .3 large amounts of snaj._L .^nells oi- c-ne_l fragments. The shells and shell frag- ments scm.etimes give a grayish cast to the : --"' ' mass and also provide an ex- cess 1 /:iount of calcium, carbonate. Freshly exposed fibrous peat usually gives off hydrogen sulfide gas, which has a very distinctive odor.

Fibrous peat is low in ash, usuaJ.j.y con- taining: less than about 8 to 10 percent. It i in organic matter, averaging f • art between 60 and 70 per-

-atively high in nitrogen, : ween 2 and k percent. It

has about as much total phosphorus as the surface .l;:vr:v of an average brovm silt loam pra ' il, such as Saybrook or Elliott. It contains less total po- tassium and somewhat less total magnesivim than the surface of Saybrook or Elliott. It is- lered high in cellulose, hemi-

cell^^^.^^,. and lignin.

Sedimentary peat is foi-med in small lakes where the water is at least a foot or two deep. It is composed primarily of the remains of aquatic plants^ such as water lilies, pondweeds, and stone - worts, and free-floating plants, such as algae, duckweeds, and diatoms. The re- mains of such plants tend to disinte- grate rather thoroughly- -except diatoms, which are already very small --and upon settling to the lake bottom form a finely divided, incoherent, structureless ooze.

The sedimentary type of peat is mostly gray in color and calcareous--i.e. , high in lime--and will effervesce with dilute hydrochloric acid. Compared with fi- brous peat, it is high in ash, averaging between kO and 50 percent. It contains less organic matter than fibrous peat (about 30 percent) and considerably less nitrogen (between 1 and 2 percent ) . It is also relatively low in cellulose, hemi- cellulose, and lignin.

Sedimentary peat is soft and smooth when wet, shrinks greatly upon drying, and dries to a fine, powdery dust. This dust is easily stirred up by tillage and by wind, and the diatoms, which have si- licified cell walls, cause itching when the soil contacts the skin.

In Illinois most sedimentary peats are covered by a layer of fibrous peat. After drainage and cultivation, however, this layer of fibrous peat decays rapidly and soon becomes muck. Most mucks are black and usually contain some added mineral matter. Although muck soils are harder to form than the mineral soils, they are more stable than the peats and usually need less specialized fertilizer treatment and management.

More than 90 percent of the organic soils in Illinois are in the northeast- ern one -fifth of the state or in the re- gion lying north, northeast, and east of

McLean county. The few remaining im- portant areas are in V/hiteside, Henry, Bureau, and Mason counties, although other small spots occur in various other parts of the state.

Individual areas of organic soils vary in size from small spots of less than one acre up to more than 1,000 acres. The combined area of such soils in Illi- nois totals about 25O square miles. Al- though this area is small compared with the total area of the state (about l/2 percent), the organic soils are extremely important on the individual farms where they occur. They often differ radi- cally from the mineral soils with which they are associated in drainage and fer- tilizer requirements, workability, and adaptation to crops.

Three series of organic soils --Houghton, Lena, and Edwards - -have been established in Illinois to date. Houghton peat (No. 97 ) is fibrous peat that is about neu- tral in reaction, and Houghton muck (No. 103) is muck that is approximately neu- tral in reaction and that decomposed pri- marily from fibrous peat. Lena peat (No. 32^) is primarily calcareous fi- brous peat or fibrous peat that is highly charged with snail shell fragments, and Lena muck (No. 210 ) is calcareous muck formed from both calcareous or shelly fibrous peat and calcareous sedimentary peat. Edwards muck (No. 312) is neutral to calcareous muck between 12 and 36 inches thick on marl. It is decomposed from either fibrous or sedimentary peat. No areas of sedimentary peat that are -cov- ered by fibrous peat have been mapped. A few areas of peat and muck consisting of shallow to mineral material of sand, silt, and clay textures are known, but to date they have not been described and designated as separate soil series.

H. L. Wascher 3-12-56

UNIVERSirt

AGRONOMY FACTS

SP-14

FRAGIPANS IN ILLINOIS SOILS

The term fragipan was formed by combin- ing paxt of the Latin word fragilis (fragi ), meaning brittle, with the word pan which, in reference to soils, means a horizon or layer that is strongly com- pacted and dense, indurated, or very high in clay.

Fragipans differ from claypans in usually being relatively low in clay, but having a high silt and/ or sand content. Fragi- pans that are high in silt have often been called "siltpans." These veiy slowly permeable, dense horizons that are ex- tremely hard when dry usually occur in soils in the lower part of the subsoil.

In Illinois fragipans are most common in seme of the upland soils in the southern

part of the state. In this area upland soils that developed from moderately thick and thin loess usually nave "pan" horizons. On the flats, claypans are found; and on the moderately rolling, but not steep, better drained areas, soils with fragipans are common. The Grantsburg, Hosmer, and Ava soils of southern Illinois all have fragipan hori- zons of varying degrees of development in the lower part of their subsoils. In the tlilck loess areas bordering the Mis- sissippi and Wabash river valleys, weathering or soil development has not progressed far enough for fragipans to have formed. However, there is little doubt but that soil development in these thick loess areas is in the direction of fragipan formation.

A| -Dark grayish -brown silt loam, crumb structure.

A2 -Brownish -yellow s: I t loom, ploty structure.

Yellowish-brown silty clay loam, granulor to

' fine subongulor blocky structure.

Bj -Yellowish-brown silty day loom, subongulor blocky structure.

_ Yellowish- brown silty clay loam, subongulor blocky 5roy '-°i'"' "nodyigj heovily cooted with gray silt.

B _ Yellowish-brown silty cloy loom mottled with groy, priimotlc Structure breoking to blocky oggregotes.

Yellowish-brown silt ipom mottled with groy , extremely Frogipon — lorge prismatic polygonal aggregates or mony sided

blocks surrounded by very gray streaks of cloy and silt.

The usual morphology of southern Illi- nois soils with fragipan horizons is shown in the diagram on the opposite page. The major type of structure in each horizon is shown in the diagram and is also indicated along with color and texture in the description at the right.

The upper part of the profile above the gray layer has uniform colors of a well drained soil} hut because of the mottled colors in and below the gray layer, the entire profile is considered to be only moderately well drained. Fragipan hori- zons are mixed yellowish brown and gray. \Then dry they are very hard and brittle, but upon thorough wetting they slake down to a noncohesive or only slightly plastic mass. They seem, therefore, to be reversibly cemented by some agent. \lhether the cementing agent is chemical or whether it is small amounts of cohe- sive clay between closely packed silt particles is still a question.

such as Grantsburg and Hosmer, water moves readily through the upper part of the profile above the gray layer. Be- cause of the very slow permeability of the fragipan, the water often moves lat- erally in the gray layer above the pan. During late winter and early spring the upper part of the profile often is satu- rated with water, whereas the fragipan may be only moist. The moisture stor- age capacity of the fragipans of south- ern Illinois, in the range available to plants, is reasonably good, but the in- ability of roots to penetrate the pan means that plants are usually deprived of most of this water.

In Illinois soils fragipans occur at -vari- ous depths, depending on soil type, slope, and amovmt of erosion. In most uneroded areas the top of the pan is be- low 2^ or 3 feet. The lower boundary is often indefinite, but the pan is commonly 2 to 3 feet thick.

Fragipan horizons are not entirely lack- ing in structure, although the structural aggregates are usually very large, as shown in the diagram on the opposite page. The large aggregates are separated by gray or almost white streaks that are composed largely of clay. The sides of the large aggregates next to the gray streaks are often covered with a black substance. The vertical dimensions of these large aggregates, bounded by the gray streaks, are usually greater than the horizontal widths so that in excava- tions with big machinery, such as is used in road construction or strip min- ing, the aggregates break out as large prisms.

Fragipans are very slowly permeable to water and restrict root penetrations largely to the gray streaks. In soils

At present there is no proved and prac- tical means of correcting the adverse conditions in fragipans. Deep tillage or mechanical breaking up of the pan re- quires tremendous power, and the benefi- cial effects of such treatment, if any, are unknown. Chemical treatment has not been tried to any great extent to date. Fragipans usually have low pH values, ranging from k.'^ to about 5»5» Base saturation and available phosphorus are low, but available potassium is generally moderate to high. The poor chemical prop- erties appear to be easier to correct than the adverse physical properties.

Controlling erosion on soils with fragi- pan horizons is doubly important. Ero- sion not only removes valuable topsoil, but also reduces the depth to the fragi- pan and thus reduces the rooting depth of plants.

J. B. Fehrenbacher lf-9-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICl '"

AGRONOMY FACTS

LAllii.

SP-15

BASIS FOR SEPARATING AND CLASSIFYING SOILS

Soils are characterized and classified primarily for two reasons: (a) to under- stand hov they differ and why they differ and (h) to develop^ as a result of laho- ratory, greenhouse and field research^ systems of management suitable for dif- ferent kinds of soils.

The identification and separation of soil types are hased upon the important characteristics of the profile (see SP-2)^ especially the following:

1. Color of the various soil horizons

2. Wumher, thickness^ and arrangement of the horizons

3. Texture of the horizons k. Structure of the horizons

5. Chemical characteristics of the ho- rizons^ such as total cation exchange capacity, kind and amount of ex- changeable ions, percentage of base saturation, pH^etc.

6. Mineralogical composition of the ho- rizons, with special emphasis on the clay mineral fraction.

Color is one of the most easily observed soil characteristics. In Illinois, as elsewhere, color tends to indicate two entirely different properties: (a) or- ganic carbon accumulation and (b) degree of oxidation and diffusion of iron and manganese compounds.

Organic carbon is black and its accumula- tion is responsible for the very dark gray to dark brown to black soil colors, particularly of the upper or surface ho- rizons. The acc^umulation of organic carbon (organic matter) tends to be greater under grass vegetation than under forest, other things being equal (see SP-1 and 2), and greater under

anaerobic (wet) conditions than londer aerobic (dry). Thus the greatest accumu- lation of organic carbon and resulting blackness of the surface or "A" horizon occurs under grass vegetation in wet places. Oxides of manganese are also dark brown to black, particularly in the hydrated state, but in Illinois they are never present in sufficient quantity to produce more than a few dark concretions or dark splotches on some of the soil aggregates.

Oxides of iron, primarily in the ferric state, vary from yellowish brown to red- dish brown. Under aerobic (well drained) conditions these compounds are diffused throughout the soil mass (see SP-3). They coat so many of the individual soil particles that the color is uniform where it is not obscured by organic matter. Under anaerobic (poorly drained) conditions the iron compounds are in the reduced state and are more generally concentrated into concretions. It is believed that, as some soils age, mole- cules of water are lost from the iron compoiHids and the color gradually changes from yellowish brown to reddish brown.

The number, thickness, and arrangement of soil horizons, discussed at some length in SF-2, are also rather easily observed characteristics that are used in identifying soil units. Unweathered parent material is thought of as having one soil horizon, i.e., a "C" horizon. As weathering progresses, horizons de- velop one by one. In some areas in Illinois as many as six horizons have de- veloped, each having features that tend to distinguish it from adjacent horizons. The soils known to be most productive for agricultural purposes under the cli- matic conditions prevailing in Illinois are those having a few mediijun-textiired (loam, silt loam, silty clay loam) hori- zons and a thick, dark surface.

Texture is another rather easily ob- served soil characteristic. It often varies markedly from one horizon to an- other. In the field it is determined "by rubbing some soil between the thumb and fingers (see 111. Cir. 758)^ ^^"t experi- ence is needed in texturing standard samples before close correlations can be made. Laboratory analyses are sometimes needed for final comparison.

Textiore is a function of relative parti- cle size and therefore is an indicator of permeability. Coarse materials^ such as gravels and sands, have large pores through which water moves freely. As the particles become smaller and smaller, a point is eventually reached in very fine clay where the pores are so small that moisture and air movement are often seriously restricted.

The kind and arrangement of structiiral aggregates in the various soil horizons are also useful in characterizing soils. The size, shape, and arrangement of structural aggregates give some indica- tion of the moisture -absorptive capacity of a horizon, as well as some indication of its permeability. Loosely packed granular to rounded aggregates absorb water more readily and permit easier air and water movement than tightly packed angular to square or platy aggregates. But any form of aggregation tends to pro- duce cleavage planes or channels that permit freer water movement and root penetration than would otherwise be pos- sible.

Soil acidity, including the presence or absence of highly calcareous material, is used as a criterion in separating certain soil types. Tests with dilute hydrccMcric acid are used to detect areas

of high-lime (calcareous) soils. pH tests indicate the relative acidity or alkalinity of a soil, its probable re- sponse to liming materials, and its ap- proximate base saturation. A soil or any one of its horizons having a pH of 5.0 or less is considered strongly acid. It is also likely to be relatively low in exchangeable bases, such as calcium, magnesiiom, and potassium. Soils having a pH of about 6.0 are considered slightly acid, and many of them will be about 70 to 80 percent saturated with bases. Neutral soils with a pH of 7-0 are in general 90 to 100 percent saturated with bases, whereas soils of pH 8.0 usually contain free basic salts, primarily calcium carbonate and, less frequently, salts of magnesium and sodium.

The kind and amount of clay minerals are important in classification as well as in the use and management of many soils (see SP-8). Clays impart sticky or plastic properties to soils, and any in- crease in clay above a certain point increases tillage and drainage difficul- ties. On the other hand, any decrease in clay content below a certain point, especially of montmorillonitic clay, re- duces the ability of a soil to hold nutrients in a readily available form and release them to plants.

The accurate characterization of soil units consolidates past experience with those units and indicates the probable future behavior of the soils under similar conditions. Classifying soils through accurately defined characteristics is not only an attempt to better understand and interpret nature, but a means of preserv- ing in an orderly manner the facts known about the soils that produce our food.

H. L. Wascher and R. T. Odell

1^-16-56

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

CONTROLLING WILD GARLIC AND WILD ONION

W-6

It has been estimated that wild garlic and wild onion cost Illinois farmers well over a half -million dollars yearly. This loss is mainly through dockage in wheat and does not include loss of milk and meat products due to undesirable flavor caused by these weeds.

Wild garlic (Allium vineale) is much more common than wild onion. VJild onion (Allium canadense ) is found in the same areas as wild garlic but usually pre- sents a small problem compared with its neighbor.

How to Tell the Plants Apart

Wild garlic

Wild onion

leaves

Form Base	Cylindrical Sometimes above- ground on stems
Bulbs (undergrovind) Number Clusters at base of each plant Covering Fibrous Kind Hard- shelled (brown) and soft-shelled
Flavor and odor	Strong

Both of these weeds begin to grow in the fall from the old plants as well as from the bulblets. Fall growth starts any time from September to November, depend- ing on fall rains. Both weeds seemingly "grow under the snow" during the winter. Wild garlic begins to form undergro\and bulblets in March. In May the aerial bulblets begin to form on both wild gar- lic and wild onion.

Both plants have matured by small grain harvest, and the aerial biolblets are harvested with the small grain. By mid- July they become dormant, and plowing or disking during the summer has little effect on them. The old plants and the new bulblets are ready to start their life cycle again with the fall rains of September and October,

Both wild garlic and wild onion can be controlled and eliminated by growing crops that can be plowed in either late fall or early spring. If such crops can be combined with one that can be culti- vated during the growing season, such

Flat

At ground level, rising out of the bulb

One at base of each

plant Ketlike All soft-shelled

Moderate

as corn or soybeans, both weeds can be eliminated in three to four years.

Plowing in late fall or early spring is particularly effective because it smothers the plants that have germinated and fall plowing usually prevents the underground garlic bulblets from form- ing. The cultivated crop then destroys any seedlings that may appear with rains during the growing season. Three or four years of this program will practi- cally exhaust all seeds or bulblets that are in the soil,

2,^-D is also effective in destroying wild garlic. Experiments conducted from 19^8 to 1950 by the Agronomy Department showed that 1 l/2 to 2 pounds of 2,U-D ester in late fall destroyed both the old plants and the newly germinated seed- lings. The same rates in early April were only slightly less effective than the late fall spraying.

Unfortunately, winter wheat will not tolerate these rates of 2,i|— D. Only pastures or stubblefields can be sprayed with these amounts.

The folloving table on wheat yields in- dicates that winter wheat will not tolerate a rate of 2,k-'D that will effec-

tively control aerial bulblets without seriously reducing yields.

		Percent
Rate of	Yield of	control of
2,l^-D ester/A	wheat aerial bulhlets
Fall Applica	ticn, November 22, 1948
Check	32.0	0
1/8	28.0	20
lA	31.1	40
1/2	25.3	65
1	23.5	100
1 1/2	20.9	ICO
Spring Appli	cation, April, 5^	1949
Check	21.4	0
1/k	18.8	25
1/2	19.1	50
1	16.4	70
2	lo.o	eo
Spring Application, April 29,	, 1949
Check	16.8	0
l/,3	16.3	0
2/3	14.4	10
11/3	12.0	30
2 2/3	13.0	40

Applications made about the first week in April at I/2 pound of 2,4-D ester per acre have had very little effect on wheat yields but have reduced aerial bulblet formation an average of 50 per- cent. In addition, the remaining plants have been so deformed that the combine has picked up very few of them. Appli- cations in late April have not been ef- fective in controlling garlic in winter wheat .

The best way to control both wild garlic and wild onion is to change the cropping

sequence so that ctiltivated crops are grown continuously for three to four years. If this program cannot be car- ried out, then applications of l/2 pc\and of 2,4-D ester applied to winter wheat about the first week in April will ma- terially reduce aerial biilblet formation and will gradually thin out stands of wild garlic. One and a half to 2 pounds of 2,4-D acid in the ester form is high- ly effective in eliminating garlic either in pastures without legumes or in stub- blefields. The application can be made either in late fall or in early spring.

F. W. Slife 10-24-55

UNIVERSITY OF ILLINOIS • COLLEGE OF AGRICULTURE

AGRONOMY FACTS

W-7

REACTION OF VARIOUS V/EEDS AND BRUSH TO 2,4-D AND 2,4,5-T

Many veeds and woody plants are not killed when sprayed with 2^i4--D and 2,k,'^-T, while others are easily con-

trolled. Following is a listing of various weeds and woody plants and their reactions to 2,U-Dand 2,h,^-1! herbicides.

Annuals

Weeds and Their Reaction to 2,4-E Susceptible Perennials & Biennials - Susceptible (Cont.)

Beggar-ticks

Bitter wintercress

Black medic

Carpet weed

Cocklebur

False flax

Flower-of -the -hour

Hemp

Hemp -nettle

Henbit

Jewelweed

Kochia

Lambsquarters

Marsh elder

Morning glory, annual

Mustards

Peppergrasses

Pigweeds

Plantain, annual

Prostrate verbain

Radish, wild

Ragweeds

Rape, annual

Rough cinquefoil

Sow thistle, annual

Stinkweed

Sunflower

Vetch

Yellow star thistle

Annuals - less Susceptible (plants may recover under seme conditions,

Bedstraw

Buckwheat, wild

Chickweed

Dodder

Dog-fennel

Fleabane

Goosefoot

Jimsonweed

Khotweed Lettuce, wild Mallow, roundleaved Purslane Russian thistle Shepherd's purse Smartweeds Speedwells Velvet weed

Annuals - Not Susceptible

Annual grasses Black nightshade Buffalo bur Catchfly

Corn cockle Cow cockle Wild cucumber Wood sorrel

Perennials and Biennials - Susceptible (Frequently killed by one application)

Artichoke Broadleaf plantain Buckhorn

Bull thistle

Burdock

Catnip

Chicory

Cinquefoils

Coneflowers

Creeping charley

Dandelion

Dragonhead

Evening primrose

False ragweed

Figwort

Four-o-clock

Gummweed

Heal-all

Hedge bindweed

Hedge nettle Hoary alyssum Horsetail Licorice, wild Moonseed Kettle, stinging Poppy, mallow Roadside thistle Rosin weed Skelton weed Slender rush Verbains Water hemlock VJild parsnip

Perennials & Biennials - Less Susceptible (Tops are killed but regrowth may occur)

Bouncing Bett

Buttercups

Canda thistle

Carrot, wild

Docks

Dogbane

Field bindweed

Goatsbeard Goldenrod Lettuce, blue Poke weed Poverty weed Sorrel, red Teasel Yarrow

Perennials & Biennials - Wot Susceptible

Asters

Bittersweet

Bracken

Catchfly

Cattail

Chickweed, mouse-ear

Climbing milkweed

Ferns

Foxglove

Goatweed

Ground cherry

Hoary verbain

Milkweeds

Mullen, ccmmon Nettles, horse Ox-eye daisy Russian knapweed Smartweed, swamp Sorrel, yellow Spurges

Strawberry, wild Tansy rag\rort Tick-trefoils Toadflax Violets White cockle

Woody Plants

Woody Plants - Susceptible (Cont.

A mixture of 2,U-D and 2,k,'^-1 or straight 2.,h,^-']l is more effective than 2,4-D alone on most of these plants.

Vfoody Plants - Susceptible (Current growth killed but retreatment may be required. )

Alder

Apple ^ crab Aspen Barberry Birch^ black Blackberry Boxelder Buckbrush

Cherry, wild

Cottonwood

Currant

Dogwood

Elderberry

Elm

Gooseberry

Grape, wild

Hackberry Hazelnut Honeysuckle Locust, black Mulberry Osage orange Persimmon Plum, wild

Poison ivy Sassafras Sumac Tamarisk Trumpet vine Virginia creeper Walnut, black Willows

Woody Plants - Not Susceptible

Ash

Basswood Bittersweet Lead plant Locust, honey

Oak

Raspberries Red cedar Rose, wild

Earl C. Spurrier U-30-56

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