Historic, archived document

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pon 4 ans

to OPE ARIMENT OF AGRICULTURE,
BUREAU OF PLANT INDUSTRY—BULLETIN NO. 190.

B. T. GALLOWAY, Chief of Bureau.

ORCHARD GREEN-MANURE CROPS
IN CALIFORNIA.

BY

ROLAND McKEE,

SCIENTIFIC ASSISTANT, OFFICE OF FORAGE-CROP
INVESTIGATIONS.

IssuED OcTOBER 27, 1910.

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WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1910.

BUREAU OF PLANT INDUSTRY.

Chief of Bureau, BEVERLY T. GALLOWAY.
Assistant Chief of Bureau, G. HAROLD POWELL.
Editor, J. E. ROCKWELL.

Chief Clerk, JAMES E. JONES.

FORAGE-CROP INVESTIGATIONS.
SCIENTIFIC STAFF.

C. V. PIPER, Agrostologist in Charge.
J. M. Westgate, Agronomist.
R. A. Oakley and H. N. Vinall. Assistant A grostologists.
8. M. Tracy, Special Agent.
A. B. Conner, A. B. Cron, M. W. Evans, Roland McKee, and W. J. Morse, Assistants.
190
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LETTER OF TRANSMITTAL.

U.S. DEPARTMENT OF AGRICULTURE,
BurEAvU OF PLANT INDUSTRY,
OFFICE OF THE CHIEF,
Washington, D. C., July 2, 1910.

Srr: [have the honor to transmit and to recommend for publication
the accompanying manuscript, entitled ‘‘ Orchard Green-Manure Crops
in California,’ by Mr. Roland McKee, Scientific Assistant in the
Office of Forage-Crop Investigations, and recommend its publication
as Bulletin No. 190 of the Bureau series.

Leguminous cover crops are now extensively used in California
citrus orchards, but only to a slight extent in deciduous orchards.
Owing to peculiar conditions certain legumes are especially adapted
for use in that State, while their usefulness elsewhere is limited.

The results presented in this bulletin are based on the investiga-
tions that have been conducted at Chico, Cal., and in cooperation
with many orchardists for the past five years.

Respectfully,
G. H. PowE tt,

Acting Chief of Bureau.

Hon. JAMES WILSON,
Secretary of Agriculture.
190 3

CON PENS:

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Rb evorchardedistricts of Calitormiag peas eee oe ne es kes
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INOREMEENECIETUS) SCCLLOMMS sie cee ee eet es See ee aS
Deciduousiorenardesecthious sac cess ee eee ee ee ee es
Conditions under which green-manure crops should not be used.....-..---.-.--
Oualitiesidesirablein a/ereen-manure Crops 4-4-2222 42-242... -+--22- 5-2-2222:
Methodsiof handling ereen-manure Crops.--224-- 42-22. - 442524225552 25552---2-
inreparationvoi the Janda. 2-2 250 58 2S Ro een

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Winter green-manure crops now used in California orchards. ...........--.-.--
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Cost of seed of green-manure crops.-.--.--------- SL hipaa feesa Rt eee ee nas ae See
Summary

BUSI IRI MOMS:

. Viewina California orange grove, showing the method employed in plow-

ing under a sreen-manure CrOpssq-o5 = ee = eee ee

. Experimental plats of horse beans at Chico, Cal., showing the striking

superiority of the noduled: plants: 3. es. s2- 5-5 se ee eee

. View in an orange orchard in southern California, showing common

vetch erown asa STeen-Manure CrOP= = - es ee a

. View in an orange orchard in southern California, showing Canada field

peas STOWn' as a) Sreen-manure Crope] =5- 42 ee ee eee eee

. An individual plant of fenugreek, showing its characteristics........--
. View in a walnut orchard in Orange County, California, showing fenu-

ereek LTOWDIAS aerTeeCD-ManuLe CLO vere retailer en

. A-field of black-purple vetch’ at Chico, Cal=2 2-3 eee
. A. field of black bitter vetchat Chicos Calves
. View in a citrus orchard in southern California, showing horse beans

eTOWD as.a, Sreen-Manure CrOP==2-e-- eee ae ee
190
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Page.

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28
29

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B. P. I.—592.

ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

INTRODUCTION.

The use of green-manure crops for the maintenance of soil fertility
is one of the oldest of agricultural practices. In California such
crops have been used in a limited way for a long time, yet it is only
within recent years that their practical value has become fully recog-
nized. The growing of these crops has attained its greatest develop-
ment in the citrus orchards of the southern part of the State, where
they have been longest used.

As far back as the early nineties some of the more progressive
orchardists were beginning to realize the necessity of some such prac-
tice as green manuring and to this end utilized the natural growth
of bur clover and other weeds, such as alfilaria,? brome-grasses, etc.
The Canada field pea was the first of the legumes to be used exten-
sively as a green-manure crop, and by 1900 it was being quite gen-
erally grown in the citrus orchards of the southern part of the State.
Common vetch and bur clover were also being utilized at this time.

In many parts of California, green-manure crops have not been used
to any extent, but not entirely without reason. That their use can
be made much more general than at present is quite certain, and as
their value is more fully appreciated and their adaptation to the
various sections demonstrated their use will be proportionately
increased.

For a number of years the Bureau of Plant Industry has been work-
ing to secure better crops for green manuring than the ones now used
and to aid in the demonstration of the adaptability of the ones now
being grown. The Agricultural Experiment Station of the Uni-
versity of California has also done extensive work in demonstrating
the value of various green-manure crops in that State.

In California the work of the Bureau of Plant Industry has been
carried on in cooperation with orchardists and farmers throughout
the various sections and at the United States Plant Introduction
Garden at Chico, where extensive tests have been made. This work
has clearly indicated the superiority of certain crops over others and
their adaptation for varying purposes and conditions.

a Known also as alfilerilla and pin-grass.

190 7

8 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA,
THE ORCHARD DISTRICTS OF CALIFORNIA.

The orchard districts of California so far as green-manure crops
are concerned at once divide themselves into the citrus and the
deciduous fruit districts. These are again readily divided into the
northern and southern citrus districts and the irrigated and nonirri-
gated deciduous sections.

The two citrus districts have a definite geographical distinction,
while with the deciduous orchards water is the differentiating factor,
without reference to any geographical distinction. The citrus dis-
tricts are quite definite in area. The southern district is confined to
what is known as southern California proper and includes the territory
south of the Sierra Madre Mountains and north along the coast to
Santa Barbara. The northern district includes a narrow strip on the
east side of the San Joaquin Valley from some distance south of
Porterville to Lemoncove, Tulare County, on the north; a similar
but smaller area in Fresno County; a small area in the Sacramento
Valley, centering about Oroville and Palermo; and various small
areas in other parts of the valleys and foothills.

Conditions with regard to water, soil, climatic or seasonal varia-
tions, etc., are quite different in these various sections, and the plant
best suited to a certain area must be carefully considered in deter-
mining the probability of success with a green-manure crop. Prac-
tices satisfactory in one locality may be unsuited to another, and the
crop best adapted to one section may not be adapted’ to another.

SOUTHERN CITRUS SECTION.

The seasonal conditions of the southern citrus section are such as
to make this the most favorable part of the State for growing green-
manure crops. The locality and climatic conditions are such that
these crops are practically never injured by frosts, and the mild
winters favor vegetative growth at that time of the year.

In contrast with the deciduous sections, where there is usually a
heavy rainfall, here the rainfall is usually light. However, as irriga-
tion is given throughout the dry season the conditions are favorable
to the sowing of a green-manure crop early in the fall, thus giving
sufficient time for considerable growth before the cold weather of
winter.

The soils vary considerably in composition and mechanical texture,
but as a general rule are of such a nature as to permit working at
almost any time during the winter, except after heavy rains, thus
favoring the turning under of a green-manure crop. Whilesome
soils in this section are a rich loam and contain considerable organic
matter, as arule they are quite deficient in this respect. That green
manures need to be more extensively used is evident.

190

alee ites ne

THE ORCHARD DISTRICTS OF CALIFORNIA. 9

NORTHERN CITRUS SECTION.

The northern citrus section, as previously stated, comprises a small
region in the San Joaquin Valley, centering about Porterville and
Exeter, and a smaller section in the Sacramento Valley, centering
about Oroville and Palermo, besides small areas in various parts of
the valleys and foothills of the State. The conditions in this district
differ very much from the conditions in the southern California dis-
trict, and in these differences is found the reason why green-manure
crops have been but little used.

The seasonal conditions at the north while favorable to the growth
of green-manure crops are less favorable for their handling. The
rainy season is quite definite, extending through January and Feb-
ruary, and sometimes into March. The soil, which is heavy, dries out
slowly during the winter season, often making it impossible to get
into the orchard to turn under a crop at the proper time. Thus, when
the season for turning under is delayed, a heavy vegetative growth is
objectionable in that it makes the land hard to work and at the same
time by shading prevents it from drying out to allow of cultivation
as early as otherwise would be the case. The soils throughout the
northern district are with few exceptions of the very heavy nature
referred to, and for this reason a heavy vegetative growth is often a
hindrance to proper handling. While the immediate effects of a
ereen-manure crop may be undesirable, there is but little question
that these lands need to be made lighter by the addition of humus,
and results that appear at the time as unfavorable can well be toler-
ated when the ultimate effect will be an improved condition.

Green manures have been used but little in the northern citrus
section. However, the results from a few plantings, together with
the experimental work done, clearly show that by early seeding a
good green-manure crop can be grown and in most cases can be

profitably used.
DECIDUOUS ORCHARD SECTIONS.

While the deciduous orchards are scattered throughout the State
of California they are largely in the northern part and are mostly
located on the fertile lands of the various river valleys and the low
foothills. Green-manure crops have not been used to any extent in
these orchards, and practically the only thing approaching such a crop
is the volunteer growth of bur clover, which is usually sufficient by
the time the orchards are plowed in the spring to yield considerable
humus.

The problem of growing a green-manure crop in deciduous orchards
is quite different from that of growing the same crop in citrus
orchards. This difference lies principally in the fact that the former

52810°—Bull. 190—10——2

10. ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

are not irrigated, or if water is applied it is early in the summer, and
not in the fall when it could be utilized in starting the crop.

Winter rains must be depended upon to germinate seed sown in the
fall, and only in the most favorable seasons are they early enough to
allow much growth before cold weather. When the first rains come
late, but little growth is made by fall-sown seed until the warmer
weather of the latter part of winter or early sprmg. Thus, only in
the most favorable years will the growth be sufficiently early to
allow its utilization for green manure. Where water is available for
fall irrigation the question ceases to be one of the possibility of grow-
ing a good green-manure crop and becomes one of the returns justify-
ing the expense.

CONDITIONS UNDER WHICH GREEN-MANURE CROPS SHOULD NOT
BE USED.

There are some sections in which green-manure crops can be grown
satisfactorily, but their utility nevertheless seems questionable. This
is especially true in lemon orchards having a very heavy soil, and to
a less degree in orange orchards. By a heavy soil is not meant a
heavy loam, but an adobe or a soil approaching that texture. On
such soils the discontinuance of cultivation which is necessitated by
the growing of a green-manure crop allows the soil to become quite
hard and packed, thus permitting very imperfect aeration. This is
a most undesirable soil condition to maintain during a period of sev-
eral months, and its injurious effects may be seen in the unthrifty
appearance of the trees. Where this effect is very marked it is
undoubtedly best not to use a green manure, but to use stable manure
instead, if such is available.

In the Porterville and Oroville citrus districts, where the soils are
quite generally of a heavy type, the foregoing statement does not
apply as definitely as in the southern California districts. This is
due to seasonal differences. The trees in the two former sections
have a more nearly dormant period of growth during the early win-
ter than those in the latter, in which case the effect of noncultivation
is not so marked. Where on account of heavy soils it 1s not advisable
to grow a green-manure crop, stable manure, if available, should be
used in lightening the soil.

QUALITIES DESIRABLE IN A GREEN-MANURE CROP.

No one plant possesses all the desirable qualities of an ideal green-
manure crop. However, in the various crops used for such pur-
poses, practically all the desirable qualities are represented, though
varying in degree. The conditions under which a green manure is to

be grown determine to some extent whether a certain quality is
190

METHODS OF HANDLING GREEN-MANURE CROPS. 11

desirable or objectionable and must be taken into consideration in
selecting the best crop to grow.

A green-manure crop should be a legume wherever possible, in
order to obtain the addition of nitrogen to the soil. It is also neces-
sary that a good growth be made, in order to have a large quantity of
organic matter to turn under and incorporate with the soil. Along
with good growth should be a heavy development of nodules on the
roots, as this is believed to indicate great ability to fix atmospheric
nitrogen.

The quality of being able to stand trampling with a minimum of
injury is very important where the crop will be subject to such injury,
as is the case in citrus orchards where the picking of fruit takes
place while the green-manure crop is yet growing. Uprightness and
nontwining stems are also desirable where an ordinary moldboard
plow is depended upon for turning under the crop. However, if a
disk plow is used or the crop is worked in with an ordinary disk
harrow, this does not make so much difference, and where the growth
is not allowed to become too rank little difficulty is experienced in
plowing it under.

The texture of the stem should be such as to decompose readily.
Practically all crops, however, if turned under at the right stage of
erowth decay readily. Thus, the question of decomposition is one of
turning under the crop at the right time rather than one of selecting
a crop that will decay readily.

That the cost of a green manure may not be too great, it is neces-
sary that the price of seed be reasonable as compared with the results
to be obtained.

METHODS OF HANDLING GREEN-MANURE CROPS.

The methods of handling green-manure crops in California are
quite similar throughout the various sections. However, some vari-
ation in practice exists among orchardists in the same neighborhood, as
well as among those of different localities.

The following methods are practiced in the citrus and walnut
orchards of the southern part of the State, where green manures have
been most generally grown.

PREPARATION OF THE LAND.

Since clean culture is practiced throughout the year in citrus and
walnut orchards except when a green-manure crop is being grown,
the land can be prepared at any time for the seeding of such a crop.

The general practice is to prepare the land for seeding by plowing
or disking and harrowing immediately after an irrigation. This puts
the land in good condition for the seeding.

190

12 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

SEEDING.

The most successful growers of green-manure crops sow vetch and
bur clover in the first half of September, and peas during the latter
half of the same month. Early seeding is being much more generally
practiced now than it was a few years ago, when the greater part of
the crop was sown in October. The time of irrigation of an orchard
determines to some extent when a green-manure crop shall be sown,
as water is not always available at the time desired. However,
when water is available the time mentioned is that most generally
favored for irrigation.

The seed is sown either drilled or broadcast and harrowed in.

IRRIGATION.

After the seed is sown and before it germinates, the land is prepared
for fall or winter irrigation if necessary. The furrow method is the
one most commonly used. This consists in making a number of
shallow furrows between the rows in the direction the water is to
flow, the method varying in different sections and with the lay of the
land.

The basin method is used to quite an extent in the walnut orchards
of the southern part of the State and in the orchards of the Santa
Clara Valley.¢

Nothing further is done, with the exception of irrigating if neces-
sary, until the crop is ready to turn under. When a crop is sown in
September it can be plowed under during February.

TURNING UNDER A GREEN-MANURE CROP.

In turning under a green-manure crop the common moldboard
plow (see fig. 1), the disk plow, or the disk harrow is used. In using
the first a sharp colter is attached, and where the vine growth is
heavy a chain is also used. Sometimes the land is run over once
with a disk harrow before plowing. This enables a heavy growth to
be more completely turned under. During the past few years the
disk plow has been very generally used, and for turning under a heavy
vine growth it works more satisfactorily than the moldboard plow.

After plowing under a green-manure crop the land is harrowed,
and as the crop decays cultivation is given. This at first is shallow,
so as not to bring the vines to the surface, but later a deeper cultiva-
tion is given.

In sections having a very open soil or a sandy loam the disk harrow
has been used very successfully in turning under a green-manure
crop. The use of this harrow has been taken up with the idea that
fewer surface-feeding roots of the trees are disturbed by its use than

@See Bulletin 145, Office of Experiment Stations, pp. 46-50.
190

METHODS OF HANDLING GREEN-MANURE CROPS. 13

is the case with the plow, for which reason it is thought by many to
be more desirable. In working a green-manure crop into the soil
‘with a disk harrow, four diskings are usually required, each disking,
where the planting of the orchard will permit, being made at an angle
with the previous one. On the heavier soils the disk harrow does not
work so well and the plow is used almost entirely.

After turning under a green manure the land is kept well cultivated
the remainder of the year.

For obtaining the best results a green-manure crop should be
turned under early enough in the season to allow perfect decomposi-

Fic. 1.—View in a California orange grove, showing the method employed in plowing under a green-
manure crop.

tion. In orchards this can be quite definitely designated, as the
turning under should take place before the trees start growth in the
spring. This means, for citrus orchards in southern California, not
later than February. In northern California the season is of neces-
sity a little later on account of the generally wet condition of the soil
at that time. Where the factors relating to other crops and a season
favorable to decomposition do not have to be taken into considera-
tion, it perhaps is safe to say that to obtain the best results most
legumes should be turned under about the time the first pods form,
or a little earlier.
190

14 ORCHARD GREEN-MANURE CROPS IN CALIFORNTA.

INOCULATION.

The question is often asked whether it is not advisable to inoculate
seed to be sown on land that has not previously grown that crop. In
California it has been found that the bacteria necessary to nodule
formation on the more common leguminous crops are present in most
soils. The first seeding may not, however, be as abundantly inocu-
lated as desired, and in some sections the bacteria essential to certain
crops seem to be entirely lacking in the soil.

In northern California it has been observed that horse beans are
not inoculated the first year they are grown on soil that has not pre-

Fig. 2.—Experimental plats of horse beans at Chico, Cal., showing the striking superiority of the noduled
plants.

viously grown this crop. (See fig. 2.) Thus, to obtain the best
results, it is necessary to inoculate the crop the first year. The dif-
ference between an inoculated and an uninoculated crop of horse
beans in the Sacramento Valley is very marked and is practically
the difference between success and failure. In southern California
this crop does not require artificial inoculation, the soil being inocu-
lated.

In the inoculation of horse beans the surest results are obtained by
securing soil from an inoculated plat or field and mixing this with
the seed at the time of seeding. In this way but little soil will be
required to inoculate a large area, and practically no extra time or

190

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WINTER GREEN-MANURE CROPS. 15.

labor is necessary. The inoculation of this crop may also be attained
by spreading inoculated soil over the field at the time of seeding and

’ working it in with the seed, or the seed may be inoculated with pure

cultures of the bacteria which form nodules on the roots of this plant.
Such cultures have been distributed by this Department for several
years, and the results obtained from their use have been favorable in
many cases.

COMMERCIAL FERTILIZERS.

In the citrus orchards of California commercial fertilizers are quite
generally applied, while in few deciduous orchards are fertilizers used
in any form. Where fertilizers are used they are usually applied in
connection with a green-manure crop.

The value of a green-manure crop is largely due to the part it plays
in liberating plant food in the soil. In the decay of organic matter
and the giving off of carbonic-acid gas, the action on phosphorus and
potassium compounds is such as to make them more available as
plant food. Vegetable acids, which are always more or less present
with a green-manure crop, also aid in liberating plant food. Thus,
elements present in a soil but not available as plant food may be
made so by the use of a green manure.?

From the facts just stated it will be readily seen that a green-
manure crop may serve a useful purpose when used in connection
with commercial fertilizers, especially where the various plant-food
elements are only partially available in the soil.

WINTER GREEN-MANURE CROPS NOW USED IN CALIFORNIA
ORCHARDS.

The green-manure crops now used in California, in the order of |
their importance, are as follows: Common vetch, Canada field peas,
bur clover, fenugreek, hairy vetch, and Indian melilot.

Common vetch and field peas are by far the most extensively
planted, while hairy vetch and melilot are very little used. Bur
clover and fenugreek are used to but a limited extent, although they
are of considerable importance.

COMMON VETCH.

The common or spring vetch (Vicia satwa) is the most exten-
sively grown green-manure crop in California. It is being grown
throughout the orchard sections wherever green-manure crops are
being used at all (see fig. 3). It is adapted to quite varied con-
ditions and succeeds in all sections of the State. In the coast sec-
tions, as well as inland, it makes a good growth and does well on both
the light and the heavy soils. |

$e @See E. W. Hilgard, Soils, pp. 19-21, 63, 126, and 394-396.

16 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

The qualities of common vetch are such as to make it well adapted
for green-manure purposes, especially in citrus orchards, and
orchardists in general are growing it in preference to field peas, which
were largely grown a few years since. -

Common vetch makes a vinelike growth similar to that of peas, but
the vines are less succulent and so are able to stand considerable hard
usage without much injury. Thus, in orchards when picking fruit
and doing other work, the trampling which is unavoidable interferes
but little with the growth of the vetch. The root system, which is
quite extensive, lies largely near the surface and ordinarily is well
covered with nodules.

Fic. 3.—View in an orange orchard in southern California, showing common vetch grown as a green-
manure crop.

When used for a green-manure in southern California common
vetch is usually sown during September and the first half of October.

However, better results are being secured with the earlier seedings,
and in most years to obtain the best results it is quite essential that
the crop be sown during the first half of September. When thus
sown the plants make a good growth before cold weather and continue
to grow during the winter. But if the seed is sown late and the
plants have made but a small growth before the cold weather, they
then make little or practically no growth until the warmer weather
comes in the latter part of the winter.

190

tee hehe is

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PT ET | IY I ET TT NL HT

WINTER GREEN-MANURE CROPS. 17

In February, 1908, at Redlands, Cal., which is representative of the

citrus sections, plantings of vetch made in September, 1907, were from

12 to 15 inches high and in afine condition to turn under. Plantings
made in October, 1907, from a month to six weeks later, were but
6 inches high. During the past season similar results were noted.

The rate of seeding varies from 40 to 60 pounds per acre. Forty
pounds per acre has been more generally recommended, but the
heavier seeding is giving much better crops and more than makes up
for the difference in the cost of the seed.

Early as well as heavy seeding is quite commonly recognized by
growers as necessary for obtaining the best results, and a deeper
seeding has also been found essential where the plantings are early.
In northern California under irrigation, vetches should be sown about
the first of October. They will then make sufficient growth to be
turned under in February or March. This later season of planting
in the northern part of the State is desirable in both citrus and
deciduous orchards on account of the heavy winter rainfall, which
does not permit turning under the crop as early as in the southern
section. Later planting in the deciduous-orchard sections is also

desirable on account of the possible injury from frosts when an early

succulent growth is made, as would be the case with earlier plantings.
Experiments and observations have shown that vetch will make
but little growth by February or March when sown in the fall without
irrigation.
CANADA FIELD PEAS.

The field pea was among the first crops tried in California for green
manuring and was the first one extensively used for this purpose.
Its early use was partly due to the fact that seed was readily obtain-
able. At the present time it still holds a prominent place as a green-
manure crop, and next to common vetch is most extensively used
(see fig. 4).

Like the common vetch the field pea is adapted to varied conditions
and has succeeded wherever green-manure crops have been grown.
For making a growth during cool weather there is no other crop
known that equals it; but it has other characteristics that make
it less desirable for green manuring, especially in citrus orchards.

The root system of the field pea, which is very extensive, consists
of a central or main taproot from which radiate the many finer
laterals. The roots extend quite deep, and for this reason the crop is
favored by many orchardists for breaking up ‘‘ plow sole.”

The vines, which are succulent and tender, are greatly damaged by
the trampling necessitated during the harvesting of most citrus fruits;
and on account of their making so much new growth during cold
weather they are often severely injured by frost. Usually as the

§2810°—Bull. 190—10——3

18 ORCHARD GREEN-MANURE CROPS 1N CALIFORNIA.

plants approach maturity the lower portions of the stems become
dry and wiry, making the turning under difficult.

Aphids, or plant lice, are very fond of peas and nearly every year
their attacks occasion considerable damage. In the coast sections or
those having more humid conditions, the crops also suffer severely
from the attacks of mildew. Inland, however, there has been but
little injury from this cause.

While field peas are in some ways objectionable they also have
certain qualities that make them serve special purposes. Their
ability to stand late fall planting and still produce a fair winter
growth makes them especially valuable for such use when for any

Fic. 4.—View in an orange orchard in southern California, showing Canada field peas grown as a green-
manurecrop. —

reason an earlier planting of other crops has not been accomplished,
but if sown late only a very ordinary crop can be expected. While
peas may be planted from the middle of September to the end of
November, in southern California the best results are secured from
September plantings. In the northern part of the State the middle
of October is better for planting because the winter rains prevent the
crop from being turned under until later in the winter. When planted
early, peas in the north are also likely to suffer more severely from
winter frosts.

Seventy pounds of seed per acre is the usual rate of seeding.
This in some cases gives a very good crop but a thin stand, and
therefore a light yield has been very noticeable in all orchard

190

ae ae

WINTER GREEN-MANURE CROPS. ns

sections. At least 80 pounds of seed per acre should be used, and
unless seeding conditions are very favorable more rather than less

’ is recommended.

During the past few winters the general crops of field peas and
vetch throughout the orchard sections of California have shown
that peas make a stronger individual plant growth than vetch, but
do not make as heavy a yield of green manure. When sown during
the latter part of September the peas have made a growth of from
24 to 36 inches, while common vetch made from 15 to 18 inches.
This is representative of the usual comparative stem growth of the
two crops. In the citrus orchards of southern California peas should
be turned under early in February. and in the northern part of the
State during the latter part of February or the first of March.

BUR CLOVER.

There are a number of kinds of bur clover, of which only two
are yet much grown in California, namely, the common or toothed
bur clover (JJedicago hispida denticulata) and the spotted bur clover
(Medicago arabica). The toothed bur clover is the one most com-
monly seen, being thoroughly naturalized. but the spotted bur
clover, though less abundant, grows equally well. It differs from
common bur clover in having a brown spot on each leaflet and
longer and softer spines on the burs.

Bur clover makes a decumbent growth, the stems being rather
small and quite succulent when young, but it withstands considerable
trampling. The roots are shallow but numerous and usually have
many nodules. The crop has been grown to quite an extent for green
manure, but on account of its not making a good early-winter growth
its use will always be limited. In orchards where bur clover has
been once planted it will spring up for several years. This is due
to the hard seeds that do not germinate the first year. In the citrus
orchards of southern California bur clover is sown at the same time
as vetch, which is during September and early October. To obtain
the best results, seeding as early as possible in September is advised.
Twenty pounds of seed (hulled) per acre should be used, care being
taken to plant shallow, as deeply covered seed will not germinate
but will hold over in the soil. The sowing of seed in the bur is not
recommended, because the bur delays germination and occasions
very uneven stands, to say nothing of the greater difficulty in sowing.
However, there is no longer need of using seed in the bur, as clean
seed can be secured in quantity from western seedsmen.

For use in deciduous orchards bur clover is of considerable import-
ance and if properly handled will serve a very useful purpose. At the
present time it.is utilized only where it volunteers as a weed and
can be turned under at the regular spring plowing of the orchard.

190

20 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

On account of the light growth usually made by a green-manure
crop sown in the fall without irrigation, the expense of seeding a
crop each year in this way is hardly justified. Through the use of
bur clover this objection can be overcome by allowing the crop to
reseed itself from year to year. In this way with a little care bur
clover can be maintained in an orchard at small expense. If an
occasional late season prevents the crop from ripening its seed before
the orchard must be plowed, narrow strips can be left between the
rows to mature, and
in this way reseed-
ing be accomplished.
The fact that the
seeds of bur clover do
not all germinate the
first year but hold
over in the soil until
the second or third
year, or even longer,
lends to the ease
of maintaining the
stand. ;

Bur clover is at
present most com-
monly introduced
and maintained in
orchards by the use
of manure from old
sheep corrals, which
usually contains large
quantities of theseed.

FENUGREEK.

Fenugreek (Trigo-
nella foenum-graecum)
is an upright-growing
plant having acentral
stem which is more or less branched. A somewhat open top is formed
when fenugreek is grown as an individual plant (see fig. 5). When
grown in plats with little chance for individual development, but
few branches are formed. The plants attain a height of 20 to 30
inches. The leaves, of which there is a medium number, are trifoliate,
with cuneate or obovate thickish leaflets. The seeds, which are borne
in long, pointed pods, are quite small (one or two lines long) and of
a brownish-yellow color. The pods dehisce, or break open, tardily,

making the crop one that can be handled easily for seed.
190

Fie. 5.—An individual plant of fenugreek, showing its characteristics.

diate coast influ-

WINTER GREEN-MANURE CROPS. 21

ADAPTATION.

Fenugreek is grown in quantity in California only in Ventura and
Orange counties. The recognition of its value as a green-manure
crop dates back to 1903, it having been distributed the previous
year by the California experiment station. Since that time its use
has gradually increased, and while it is only in Orange and Ventura
counties that it has been used as a regular crop it has been tested
and grown in a small way in all the citrus sections of the State
(see fig. 6).

From. tests and observations made during the past three years it
seems quite evident
that fenugreek is best
adapted to the citrus
sections of the State
having the imme-

ences. The climatic
conditions of such lo-
calities are very
favorable for fenu-
ereek, and it is there-
fore in those sections
that it has attained
its best development.
In sections farther
from the coast, such
as at Riverside and

- Redlands, and in the

Fig. 6.—View in a walnut orchard in Orange County, California,
showing fenugreek grown as a green-manure crop.

interior valleys of the
State, quite good
crops have been grown, but in such localities the crop is more exacting
in its requirements as to time of planting, ete.

COMPARATIVE VALUE.

In comparative tests made at Redlands, Cal., fenugreek sown
October 7, 1907, by the middle of February, 1908, had attained a
height of 10 inches. Common vetch made but 6 inches of growth in
the same time. At Pomona, Cal., fenugreek sown November 4,
1907, by the middle of February, 1908, had made a growth of
18 to 24 inches. Common vetch in comparison made but 8 inches
of growth during the same time. At Chico, in northern California,
fenugreek sown October 5, 1908, with irrigation, by the first of
March, 1909, had made a growth of 12 to 15 inches, and of 16 to
20 inches by the middle of March. In other tests the fenugreek did

190

22 ORCHARD GREEN-MANURE GROPS IN CALIFORNIA.

not make so good a showing, yet wherever sown early it has done
quite well.

As to the quantity of green manure produced by fenugreek in
comparison with other crops there are but limited data. At Santa
Paula, Cal., weights of vetch and fenugreek were taken the middle
of February, 1909, to determine the quantity of green manure pro-
duced. The plants growing in the space between four trees were
cut and weighed green, and the yield per acre was computed from these
weights. The fenugreek yielded 11,745 pounds per acre solid area,
or 8,432 pounds orchard area, while the common vetch yielded
19,140 pounds per acre solid area, or 13,742 pounds orchard area.
However, these figures do not justly represent the comparative yield
of organic matter, as the moisture content of the vetch was undoubt-
edly much greater than that of the fenugreek, and the yield of dry
matter of the two crops would have been much more nearly equal
than is indicated by the figures given. At Chico, in northern Cali-
fornia, fenugreek weighed green March 16, 1909, yielded at the rate
of 13,721 pounds per acre. This was from plantings made October 5,
1908. In comparison, at Chico, common vetch produced but 2,831
pounds per acre.

Considering the convenience and cost of handling, fenugreek is
superior to any other green-manure crop now being used. The
upright habit of the plant makes the crop easy to turn under. The
roots have many nodules and form a system similar to that of the
field pea.

Fenugreek is especially desirable for an orchard green-manure
crop, owing to the fact that no insect pests seem to be harbored by

it. This point has been especially noticeable in sections where the |

army worm, harbored in such crops as vetch, bur clover, and field
peas, has done considerable damage to fruit. During the season of
1907, orchards in which fenugreek was being grown were noted as
being free from the army worm, while other orchards in the same
section were quite badly infested. |

PLANTING.

No special preparation of the land is necessary for planting fenu-
greek. A seed bed such as is desirable for ordinary field crops is
all that is required. The best time for seeding varies somewhat in
the different parts of the State. For a winter green-manure crop in
southern California, in sections away from the coast, such as Pomona
and Redlands, plantings should be made as early in September as
possible. In sections near the coast plantings may be made later
with good results, but September planting is to be advised. In
northern California plantings for green manure should: be made the
first of October.

190

WINTER GREEN-MANURE CROPS. 23

Fenugreek does best on a good, deep loamy soil, but such a soil is
not necessary for success, as the plant does quite well on a gravelly
or asandy soil. It is not adapted, however, to a soil that will become
hard, like heavy clay or adobe. The crop should be sown either
broadcast or in close drills. Thirty pounds of seed per acre is neces-
sary for a green-manure crop, while less is best for a seed crop. Care
should be taken not to plant the seed too deep.

SEED PRODUCTION.

The fenugreek seed handled by American seedsmen is almost
entirely imported. The demand for it has been so slight that only
small stocks are handled. The imported seed comes from the Medi-
terranean countries, chiefly from Egypt and Palestine. The seed
of fenugreek used in the orchard green-manure work in California is
grown almost entirely in Orange and Ventura counties, in which
localities a good crop of fine seed can be produced.

Possibly the only sections where fenugreek can be grown profitably
as a seed crop are where the winters are very mild, having at most light
frosts, so that with late fall seeding there will be a sufficient growth
made during the winter months. An ordinary grain drill is the best
implement to use in seeding. From 15 to 20 pounds of seed per acre
are sufficient. After seeding, nothing is done with the crop until it
is harvested. In the interior valleys an irrigation at the time of
seeding is necessary.

The crop can be cut with an ordinary mower, and after a short time
should be raked into windrows. Here it should be allowed to cure
for several days before thrashing, which can be done with an ordinary
thrashing machine. In so far as possible the crop should be taken
from the windrows in the early morning, there being less shattering
of the seed when handled at this time. The pods when very dry
drop from the stem and dehisce, or break open slightly, although
the loss of seed from this cause is not great.

The quantity of seed produced per acre varies as with any other
crop, and while there are few definite figures as to yields, in Ventura
and Orange counties, where the best fenugreek seed crops are produced,
probably 1,500 pounds per acre is an average yield. At Chico, in
northern California, plantings in ;';-acre plats yielded at the rate
of 490 pounds of seed per acre, while one smaller plat yielded at the
rate of 1,315 pounds per acre. The Chico plantings were made with
irrigation the first half of October, 1908. The crop was harvested

the Ist of June, 1909.
HAIRY VETCH.

The hairy or winter vetch ( Vicia villosa) is not so well adapted for
green-manure purposes as is the common vetch, and it has not been
used except in a very limited way. Under California conditions it

190

24 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

makes less growth during the winter season than the common vetch,
and this has prevented its larger use for green manuring. Extensive
experimental tests in comparison with common vetch, as well as
practical tests made by orchardists, show the same results.

While hairy vetch does not make a good winter growth, when the
warmer weather of the latter part of winter and early spring comes,
it makes a very vigorous start and,if left to develop fully, a heavier
growth than common vetch. It also stands more dry weather without
injury, and where a late spring crop is wanted it is very desirable.
The handling of the crop is the same as with common vetch. From
45 to 50 pounds of seed per acre should be used in seeding.

INDIAN MELILOT.

Indian melilot (Melilotus indica) is quite common in waste places
throughout the orchard sections of southern California and for a
number of years has received some attention as a green-manure
crop. However, it has never been used except in a very limited or
experimental way, and this experience indicates that it has but
very little value in orchard work in California. .

The winter growth of melilot is about like that of bur clover, and,
like that crop, its best growth is not made until too late in the
winter to be turned under in February. The only place in California
where melilot seems likely to prove at all valuable is on the very
sandy soils, to which it is quite well adapted and on which it is often
hard to get a stand of other green-manure crops.

SUMMER GREEN-MANURE CROPS.

The question is sometimes asked whether it is advisable to grow a
summer green-manure crop as well as a winter crop, thus enabling
one to add two crops a year to the soil instead of one. Where water
for irrigation is available there is no difficulty in doing this. How-
ever, the practice is not to be advised except under very exceptional
conditions. The enormous quantity of water used by a green-manure
crop in its growth makes it decidedly objectionable for summer use
in an orchard, where all the water available is usually needed for the
orchard crop. | :

The growing of a summer green-manure crop also necessitates the
discontinuance of cultivation of the soil, which except on the most
open soils would be more or less detrimental if continued for a long
period. There may be instances, however, where it is desirable to
build a soil up as rapidly as possible. In such cases a summer green-
manure crop may be used to advantage. For this purpose the
Whippoorwill variety of cowpea has been found the best of any crop
tested.

190

RESULTS OF TESTS WITH VARIOUS LEGUMES. 25

RESULTS OF GREEN MANURING IN CALIFORNIA.

There have been no definite tests made in California to determine
the results in an increased yield of fruit or improved quality of the
same from the use of green manures. The only evidence available
is that of general observation and the experience of the orchardists.

While orchardists differ to some extent in conclusions, they gener-
ally are favorable to the practice, as its continued and growing use
attests. Careful observations also show the beneficial results of
ereen-manure crops in a more thrifty appearance of the trees, an
improved condition of the soil, and a better quality of the fruit.
The belief is quite general that the yield, also, is increased. Orchards
in which a few years ago there were unthrifty trees with yellowish-
colored leaves now, after several years’ use of green-manure crops,
show a decided improvement in color and general appearance. The
work of the California experiment station has demonstrated that
eummosis of citrus trees is brought on by unfavorable soil conditions
and that in remedying such conditions green manures serve a very
useful purpose.“ Orchards in which green manures have been used
for a long time are but little affected by this disease.

The improved condition of the soil when green manures have been
used for some time has been readily noticeable to those handling an
orchard. The heavier soils have become quite open and friable and
the sandier soils more loamy. Beneficial results in the conserving
of rainfall and the prevention of washing of the soil have also been
very apparent. Most soils that wash badly do so because they are
deficient in organic matter. Green manuring, by the improvement
of the mechanical condition of the soil, not only prevents washing,
but the presence of the growing crop on the land prevents gullying
during the rainy season. This is of particular importance on sloping
lands.

RESULTS OF TESTS WITH VARIOUS LEGUMES.

From the fact that the addition of humus to the soil is one of the
main objects in using a green manure, it necessarily follows that,
other things being equal, the crop producing the heaviest vegetative
growth is the most desirable. To determine the comparative
amount of vegetative growth made by various crops the green weight
per acre has been determined, as shown in Tables I, I, and III.
However, these figures can be taken only as indicating in a general
way the amount of organic matter returned to the soil, as no correc-
tions were made for the varying moisture content of the different
crops.

@ Bulletin 200, California Agricultural Experiment Station. 1908.
190

26 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

In Table II the weight of the green material produced per acre is

presented, together with the weight of the same when dry. The
green material was weighed at the time of cutting, and for estimates
of the yield of dry matter was weighed again in thirty days. During
this period the various crops had become nearly dry, but undoubt-
edly the moisture content, even at this time, would vary to some
extent, although not nearly so much as in the green state. ;

That the yield of green material as shown by its weight may be
misleading without proper correction for the moisture it contains is
shown in Table IT in the case of the two lots of black-purple vetch. The
first lot was quite succulent at the time of cutting, and consequently
was very heavy in the green state, while the other was a little older and
less succulent, and so was much lighter. The latter did not show the
heavy loss in drying that the former did, however, and thus the dif-
ference in the amount of organic matter of the two is not nearly so
ereat as the difference in the weights of the green matter would indi-
cate. In this connection it should also be noted that varying yields
are often due to a difference in the stands rather than to differences
in the growth of the crop. In the comparative data presented in
the tables this has been reduced to a minimum by selecting for this
purpose crops with as nearly uniform stands as possible.

From all data available it seems clear that of the commonly grown
ereen-manure crops, vetch, peas, bur clover, and fenugreek, the
vetch returns the most organic matter to the soil and the peas the
least. The light yield of peas is not due to a lack of stem growth,
which on the contrary is always good, but to the generally poorer
stand and more open habit of growth. Bur clover, while weighing
heavy green, is very succulent when young, and when compared with
an equal weight of green vetch represents much less organic matter.
Fenugreek yields well, but not so much as vetch.

In securing the yield of green manure per acre, as presented in
Table I, the plants growing on a plat 6 by 20 feet were cut and
weighed green and the yield per acre computed from these weights.
In Table II a plat 10 by 10 feet square of each crop was cut and
weighed green and the yield per acre thus calculated. The same
was weighed again in thirty days, as shown in the table, giving the
yields of the dry matter. In Table III the weights shown were
taken from crops being grown by orchardists during the winter of

1908-9 at the places mentioned in the table and are representative _

of these crops as grown under actual orchard conditions. To obtain
the results the plants growing on a space between four trees were cut
and the yield per acre calculated from such weights.

190

cm la a icc Ls

PROMISING GREEN-MANURE CROPS.

27

TaBLE I.—Growth of plants and weight per acre of green-manure crops sown with arriga-
tion October 19, 1907, at Chico, Cal.

; Height of} Weight of
Rate o plants, | green ma-
Name. seeding. | March 18,/nure, March
1908. 28, 1908.

1 ae ee ee, oe

Pounds. | Inches. Pounds.

: 2

Bilvekabithenveccha wes 1) Scr eee ace Ole een eee 2 Nita ee 33/056
Blaekepinplenvieten: = soi. s non. e ee Uae ee een ee ea Se { s a ae a
Wioollysnoddedivetch eae). 50 25 Seem eee a eer ae Asian eee 17 28 18, 876
FLAT VRV CLC Mey estes a es rae is | yen Soe ore we eam cv ger pagea eaaca 56 15 11, 616
COMMIT OTR VC LCM ee ra a ey oe te Se aN a Hae ge AE ope ere Ma) = Joe 39 12 7,623
Gerbil StSeuGI WU ees se a eee cle ate se ee rere ree aee Sits eee eaiace 56 16 19, 239
WEMRIG WED s oo badese sede seduce cadens seeacobe coecosocesdocessecconeccuee 56 18 13,794
IMIG VER. - os cobb ode ca donsee ace Janes teanses Saddoss Hoes sob eseceyoesanee 159 26 15, 944
FEVORS@ YD CAINE aa eee tigre eee Sie Se Ss ee Ee ESSE Ee Oe Dae aisfonet citer 164 28 10, 890

TaBLE II.—Growth of plants and weight per acre of green-manure crops sown with irriga-

tion October 5, 1908, at Chico, Cal.

Height of | Weight of/ Weight of, PTOP0"-
Rate of | plants, | dry mat-| dry mat- adeate
Name. seeding. | March 15, ter, March! ter, April ore on
1909. 16, 1909. | 16, 1909. Eaten
Pounds. | Inches. | Pounds. | Pounds. | Per cent.
62 32-36 40, 565 3, 675 9.
Black-purple vetch............--------+++-+++++++--- { 45 36-40 | 14,374 2) 394 16.8
Nioolly=poddedavetch ees =a eee ae 48 ees 25, 047 2,933 Tale 2
eae 76 20-2 27, 660 3,776 13.6
Black bitter vetch............--....---+--+--+++++--- { 49 | 20-22 14,3741 2'130 14.8
ELOTSey Deals sees BS carers ie epee AS EE SS ere 149 30-36 21, 130 2, 634 12.4
TCV aN We Ree bee eS oe Bie tre tees UE 29 16 13,721 1,783 12.9
PRAM PIOLAD Came sare eee or eee soe eee 72 17 | 12,840 1, 646 12.8
[Bi Obe CONS Soe open es tok ae Ge one ee Sn ae 21 14-16 | 11,980 735 6.1
JELENA. AMOUC cues BOE SOU eee tae ame amen tu ay! 3l 8-15 5, 880 871 14.8
GomimOneyvie Ge tare eyes Se eee Se eee 33 10-18 7a toes eee eect | aude nis 2

TaBLE III.— Weight of green-manure crops growing in orange

i
i

orchards in California.

Name. Place.
4 NAVA OCR BS Sneed nics ae ce ee ee vedi and sierra ser eee
Commnrongycicheey esas ae eo cers eee cee clseeee (OKO ea SB oe ARC Eee
MalVvOrro hinGito linet too eee | nee GOR sae ee ae ie ual
ES UTA OVC Te ae ee nena ne ork Ns Se a ee CG Kayes iN a Ses Seehrtas SeE aee
TO TICGE TOYS SPE a ae a | Ore ee a Raed |
emirenee kes tare ee orca aes cee cis cane hes SantarPaulaae nese seers)
Commoneviel chesney ee ee ee OE Fes eas Se ene

| Weight of

green mat-
ter per acre.

Pounds.
29,093
13, 578
19, 800
16, 347

7,260
11,745
19,140

Weight of

green mat-

ter per 0.718
acre.@

Pounds.
20, 888
9,749
14, 216
UAB YL
5, 212
8, 432
13, 742

@ This equals the part of an acre usually covered by a green-manure crop in an orchard.

PROMISING GREEN-MANURE CROPS.

As shown by Tables I and II, giving comparative yields, there
are several plants very promising for green-manure purposes as com-

pared with common vetch and field peas.

The claim of superiority

for these plants is largely due to their ability to make more growth

190

28 ORCHARD GREEN-MANURE GROPS IN CALIFORNIA.

during the cool weather of the winter, thus affording a heavier growth
to be turned under. This is an especially strong point where it is
desirable to turn the crop under as early as possible, as is the case in
the citrus orchards of southern California. The plants referred to
are the black-purple vetch, the black bitter vetch, the woolly-podded
vetch, the horse bean, and the Tangier pea.

BLACK-PURPLE VETCH.

The black-purple vetch (Vicia atropurpurea) is one of the most
promising green-manure crops tested for California. Its general

Fic. 7.—A field of black-purple vetch at Chico, Cal.

appearance and habit of growth are about like those of the com-
mon vetch (fig. 7), although it is very distinct from that species.
The superior value of black-purple vetch when compared with com-
mon vetch lies in its ability to make a much stronger growth during
the cool weather of early winter. This, as noted elsewhere, is an
especially desirable quality in a green manure to be turned under in
February.

The root system of black-purple vetch, which is similar to that of
common vetch, is well covered with medium large nodules. The
stems, aside from making a strong growth, are of such a texture as

190

PROMISING GREEN-MANURE CROPS. 29

to enable them to stand much trampling or other hard usage without
injury.

The time and manner of seeding this crop are much the same as
with common vetch. As the seed is a little smaller, however, a
smaller quantity may be used inseeding. From 50 to 60 pounds per

acre is advised.
BLACK BITTER VETCH.

Black bitter vetch (Vicia ervilia), another very promising green-
manure crop for California, is different from most other vetches in
that it is upright inits habit of growth, rather than vinelike. Like

Fic. 8.—A field of black bitter vetch at Chico, Cal.

the black-purple vetch, it possesses the desirable quality of making a
good growth during the cool weather of early winter and is much
superior to common vetch in this respect. (See fig. 8.) In this
connection it should be noted that different strains of this vetch
have given different yields, so that some will doubtless be found
superior to others.

Its upright habit of growth makes this crop very easy to turn under
with an ordinary moldboard plow. The viny growth of common
vetch makes it objectionable to some orchardists. The root system,
while quite well covered with nodules, is perhaps not so extensive as
that of some of the other vetches. The plant has a more definite

190

30 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

central root, or taproot, than common vetch, and the fibrous roots
tend to penetrate more deeply. The seeding habits are much better
than those of other vetches. “The pods shatter but very little, which
much facilitates the harvesting of the seed.

Black bitter vetch is grown very extensively in the Mediterranean
region, where the seed is a commercial product. The fact that the
seed of this plant can be imported at a reasonable cost makes it pos-
sible to supply the trade at once. On account of the plant branch-
ing but little it is necessary to use a slightly larger quantity of seed
in seeding than with common vetch. Seventy pounds per acre is
recommended. Aside from the quantity of seed per acre used, the
crop should be handled ike common vetch.

WOOLLY-PODDED VETCH.

Woolly-podded vetch (Vicia dasycarpa) resembles hairy vetch
quite closely, both in appearance and in agricultural value.

In comparative tests the woolly-podded vetch has made a stronger
erowth during the cool weather of early winter than the common or
the hairy vetch, but not so strong as the black-purple vetch or the
black bitter vetch. As soon as the warmer weather of the latter part
of winter comes it is one of the most vigorous growers and its ultimate
yield is very heavy. Thus, while it will serve very well as a crop to
be turned under in early winter its special value 1s for conditions where
the crop can be allowed to remain a little later in the spring. For
sowing without irrigation in deciduous orchards it may be of special
value.

Woolly-podded vetch stands trampling well and for orchard use
is in this respect equal, if not superior, to common vetch. The root
system is about like that of common vetch and is well covered with
medium large nodules.

In growing woolly-podded vetch it should be handled as common
vetch, except that a little less seed may be used in seeding. Fifty
pounds per acre is sufficient.

HORSE BEAN.

The horse bean (Vicia faba) has been but little grown in California.
The broad bean, however, which differs from the horse bean only in
having larger and broader seeds and pods, has been grown as a vege-
table for a number of years in a few localities.

Experimental tests in California during the past few years indicate
that the horse bean has considerable value as a green-manure crop,
especially in the southern part of the State. (See fig. 9.)

The plant has an upright stem which is quite leafy, but little
branched. The leaves, as well as the stems, are quite large, but com-

190

\

PROMISING GREEN-MANURE CROPS. 31

paratively soft and succulent until well matured. The root system
consists of a strong taproot, with a fairly well-developed fibrous sys-
tem radiating from this. The roots penetrate quite deeply into ordi-
nary soils and aid in overcoming ‘‘plow sole.” The taproot, as well
as the smaller roots, when well inoculated has many large nodules,
indicating that it is a good nitrogen gatherer. In southern California
horse beans are usually well inoculated and have many large nodules.
In northern California, thus far, they have had very few or no nodules
the first year they have been grown. Consequently, when grown
without artificial inoculation they amount to but little, although when
inoculated they succeed quite well.

Fic. 9.—View in a citrus orchard in southern California, showing horse beans grown as a green-manure crop.

Although the stems of the horse bean are quite large they decom-
pose readily when turned under for green manure. In comparison
with other green-manure crops horse beans make a good growth, but
in an orchard will not withstand trampling like the vetches. As the
seeds are large a considerable quantity is required in seeding, unless
the field is planted in drills more than the ordinary distance apart. As
the individual plants make a comparatively large growth they will
stand this method of planting, and if sown in drills 18 or 24 inches
apart a good yield will be secured. The season for planting is the
same as that of vetch.

190

52, ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

TANGIER PEA.

The Tangier pea (Lathyrus tingitanus) was originally introduced into
this country from northern Africa. It is an annual legume resembling
in general the garden sweet pea, to which it is related.

During the past few years considerable attention has been given to
the Tangier pea to determine its value as a green-manure crop, and
results thus far indicate that it 1s of considerable value for this pur-
pose. It makes a strong growth, yielding a heavier tonnage per acre
than the common vetch (see Tables I, IJ, and III). Its dense growth
enables it to overrun and smother out weeds, which is one of the very
noticeable qualities of this crop. Though the stems are quite large
they are not very succulent and stand considerable rough usage,
being well adapted for orchard use in this respect. The large growth
made by Tangier peas makes them somewhat difficult to turn under
with an ordinary moldboard plow; with a disk plow but little trouble
in this respect will be experienced.

The root system is well developed. It has a more nearly definite
central root than vetch, and the roots penetrate the soil more deeply.
The nodules are large and numerous, indicating that the plant is a
good nitrogen gatherer.

For a green-manure crop Tangier peas should be handled like com-
mon vetch, except that the seeding should be heavier, from 70 to 75
pounds of seed per acre being required for obtaining the best results.

COST OF SEED OF GREEN-MANURE CROPS.

The cost of seed of green-manure crops is a factor of considerable
importance in determining their relative value. The high price of
seed may be the cause of the elimination from use of an otherwise
good crop. In most orchard sections it is hardly practicable for the
orchardist to attempt to raise his own seed, though with crops having
good seeding habits this could be readily done. The commercial seed
grower will very likely be depended upon for the supply of seed needed.
The price that growers will pay for any new crop will probably be
largely determined by the price of seed of common vetch and of field
peas. A slightly higher price for a superior crop would undoubtedly
be paid. However, a superior crop and cheap seed are what is
desired.

The practice of allowing enough seed to ripen in the orchard to
volunteer a crop from year to year is the cheapest method of seeding
a green-manure crop, but this is practicable only in deciduous orchards
without irrigation, where the returns will justify but very little
expense in connection with such a crop. Under such conditions bur
clover in particular can be effectively used.

190

COST OF SEED OF GREEN-MANURE CROPS. 33

TaBLE I[V.—Seed production per acre of various legumes at Chico, Cal., 1909. Plats
one-twentieth acre.

: Rate of Yield

~ Name. | seeding. | of seed.

Pounds. | Pounds.
INEYOVES (E07 1G aE ey SEE CHC S Ne RP Sar SR ER ERE gee et BE ad Ae a eR 72 210
PRAT PICEA Cate etree asaya ee as Se EA rine Soles gate Rae Rope i a ae ee UN 17 | 630
CMU RER eee n sen eiee ces anes 5 ane EE eee anne era se se Sac ae Cae a 28 | 490
IBC EIU RCC Keer ee een ala rea 8, ae PN ena NSS U2 Sedan 2 APL Yu 21 490
TEUBYES SSS RARNETE Vi IDA ac ee le Re alr ni ea Cen gee Aaa ea ie ee Re 48 600
BIC ka LGLCraVeLGh ea ates fase ie Gl He an are eee ae ne ere ees 45 1, 800
IBIACKsbIGGeRVeLChe. ssmrs Shek 2 Sie OS ee a eee a ede Dee ea Bee Stain 76 1, 980
Black-purple vetch...--..--5.-=-4-.- adecboneslccfercococeescgeagsesslees seces ee seneee|| 58 300
IBlack=punplecvelch sass. ssa) Se Soa eee eee Sp cduCCadeE ee ieee ee | 36 | 380
IBIACK= Up leave t@ hier ees- per copay ete a eg eg ee Ee IE | 36 580
EIACK=PUnDICMMeLC eee aioe ae ae a a ee ern ee ee enya Rene Seo 48 400
Nioolly=nod deduvetchs sect sha. Secs eiare o5e e ce ee aha caps eee eae cy eas has Ces | 45 290

In Table IV is presented the seed yield of various new green-manure
crops discussed in this bulletin. These yields were taken from 5-acre
plats that had been sown primarily for a green-manure crop test
and not for seed production. So the yields in some instances are
much lighter than would have been the case had the crop been sown -
for seed.

It is quite probable that at Chico, where these crops were grown,
conditions are not so favorable for the seed production of such plants
as the woolly-podded vetch and the black-purple vetch as are the
conditions in western Oregon, where seed of common vetch and hairy
vetch is grown commercially. This is probably also true of the Tan-
gier pea, though not so much so of the black bitter vetch, which
does well at Chico. The yields presented in the table and the gen-
eral character of the crops indicate that seed should be produced
as cheaply as that of common and of hairy vetch, and in the case of
black bitter vetch somewhat more cheaply. The seeding habits of
black bitter vetch are such that an orchardist could easily raise his
own seed if necessary, and where it is desirable to grow some crop
in a young orchard he might raise the seed with profit.

Of the crops mentioned, the production of seed will cost most
with the Tangier pea and the woolly-podded vetch, and least with
the black bitter vetch. The cost of seed of common vetch and field
peas varies from year to year. Seed of common vetch during the
past few years has varied from 34 to 5 cents per pound. When
seeding at the rate of 60 pounds to the acre this would make the
cost of seed from $2.10 to $3 per acre.

Seed of field peas has been about the same price per pound as
that of common vetch, but as 80 pounds of seed per acre are needed
in seeding, this makes the cost from $2.80 to $4 per acre.

Bur clover seed is advertised at from 25 to 30 cents per pound,
hulled. When seeding at the rate of 20 pounds of seed per acre this
makes the cost of seed from $5 to $6 per acre.

190

34 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

The wholesale price of fenugreek seed in the European market is
from 24 to 3 cents per pound. The price to the grower would of
course be somewhat in advance of this, but should not exceed 5 or
6 cents. When 30 pounds of seed per acre are used, this would make
the cost of seeding from $1.50 to $1.80 per acre.

Black bitter vetch seed, though not handled in quantity by Ameri-

can seedsmen, can be secured in foreign markets and imported at a.

cost that should make the price to the grower about the same or
less than that of common vetch. When seeding at the rate of 70
pounds of seed per acre, this would make the cost of seeding from
$2.40 to $3.50 per acre. As stated elsewhere, the fact that black
bitter vetch yields a heavy crop of seed in California and has excep-
tionally good seeding habits should make it possible to place Cali-
fornia-grown seed on the market at a much less cost than that of

common vetch.
SUMMARY.

California soils, though often very fertile, are generally deficient in

humus.

Within recent years green-manure crops in California have been
given special attention.

The only places where green manures are being used extensively
are the citrus and walnut orchards of the southern part of the State.

Deciduous orchard sections of the State are using practically no
oreen-manure crop.

By the use of green manures a generally improved condition of
orchards has been secured, as shown by a more healthy appearance
of the trees and more and better fruit.

The early seeding of green-manure crops 1s desirable for obtaining
the best results.

Green manures should be turned under before the trees start new
erowth in the spring.

Heavier seeding than is ordinarily practiced is advised.

Common vetch and field peas are the most generally used green-
manure crops, the vetch being the most popular.

Peas or common vetch sown in the fall without irrigation will not,
except in the most favorable years, make sufficient growth to be
turned under early as a green manure, but when thus sown will
make a good growth later in the spring.

Field peas, common vetch, and bur clover are adapted to quite
varied conditions, and are being grown in a limited way throughout
the State.

In any part of the State having a mild winter a green-manure
crop of peas or common vetch will succeed if sown early in the fall
with irrigation. ;

190

SUMMARY. 35

Bur clover seems to be of most value for deciduous orchard con-
ditions, while the woolly-podded vetch promises to be of value for
the same conditions. ;

Fenugreek and bur clover are used to a limited extent, fenugreek
being especially adapted to the region near the coast.

Hairy vetch is not well adapted for use as a green-manure crop in
California.

Black bitter vetch, black-purple vetch, woolly-podded vetch, horse
beans, and the Tangier pea are promising new green-manure crops
in comparison with common vetch.

Green-manure crops need no inoculation in California, horse beans
in the northern portion being the only known exception.

The growing of a summer green-manure crop in California orchards
is not advisable.

Local as well as sectional conditions in the various parts of the
State vary considerably, and must be taken into consideration in
determining the best crop for green manure as we ell as the best method
of handling the same.

190

Pag.

Pe eR Pe

as et i ile cae “See. cet al oon ee ed

\
INDEX.
an Page.
Acids, vegetable, relation to availability of plant food......................- 15
Alhlaniasuseas Sree MAMUTC. 21s ss emer EN IN ahem Se at, Dae AE 7
Mlnlerillas synonym of¢e til artis jee see eee ee dee Ss el if
Aphids adamage-tO: skeen aMUre CLOpsey Meese soe he ee eee el 18
Army worm. See Worm, army.
iBean: horse inoculation im green manurine=- 22245522. 2- 2-228. 25. 6242s ne ook 14, 35
iitropen-catherine statis esten wee hs kha ts 8 ee on
USC FAS CLEC N-IMATULC CLO) sets eee eee eee eee 26, 27, 30-31, 35
Black bitter vetch. See Vetch, black bitter.
purple vetch. See Vetch, black-purple.
Srome-cTAsses; Mse/as| CTECMLMANUTO «cet eye es eee eee ae nee eee 7
Bur clover. See Clover, bur.
Waliforniaeorehardeaistrictsms cscs ee = oe eee ee ere ea etre la 8-10
southern, inoculation with nitrogen-gathering bacteria. ..........- 31
SUMMaAnye CreeM Ma MUt ClCEOPSxsas Seer re oper seen coats yet vars reel a rene 34-35
University, work with green-manure crops..-...-----.-..----...-- 7
Canada field peas. See Peas, Canada field.
Chicos Calz~ lant ImtroductiomiGardeny testss-4.-- 406-524-2055 05.0 022 eee 7
FEsllis tor oTeen-IManureClLOpsa= oqo seo. Se sais Se ZA 222352 coe
Citrus orchards. See Orchards, citrus.
trees. See Trees, citrus.
Clov.ers bur nitroren-rathenm oe, stacusi).=/-( sks See ese aee se eee ae 19
Use) as/STeen-mManure erOp-2---.- -2-= == -< 7, 9, 12, 15, 19-20, 26, 27, 32, 34, 35
Commercial fertilizers. See Fertilizers.
Cowpea, Whippoorwill, use as green-manure crop..-.....---..--..---.-+--- 24
Crops, stechiomanure-.conditions Of USE «52S os abcee sos es see eo Saat
nitrogen-gathering status.........--. 16219522528, 29, o0noleae
PLOMMSIMSA CIS CUSSIOMm a saa eee cya eee ee 27-32
qualitrestand’ methods: ies see Nac see an cee 10-15
PESUES TOI CTO WANE ah oe etiage (eta tee ny sh ee 25-27
SuMmmanyaton@alitornaorchardses: 6555) eee eee 34-35
summer, objections and suggestions.................... 24, 35
(ideas ihre (Seyeaie aad am mak cereal ee Meena Me nS A 12-13
Winter Wsellmne Calnorniayorenards 24a eee 15-24
Deciduous orchard sections. See Orchards, deciduous.
Proushiewendurance by, hairy: vetehs 23... tt eee eee ee 24
Dry weather. See Drought.
Erosion. See Soil, erosion.
HectoMg comeacenter Ol ClirUus-IMilt ATCA es 5 e.5 6 faeces en ick Ss Sisto oee meee Bee 9
Fenugreek, freedom from insects harmful to orchards. .........------------- 22”
MALTOPeN- PA LCL Stat Mn tec ae ets ete ere aoe a ee ae 22
SEC eg eee Bea ge enc yet LR nee es Seale SC Pelle Sane be fat cs che nN ee 22, 23, 00, o4
USCHAGIOTCEN-MAMULE) CEOP ears ose cis es iors misters setaereeie oe 15, 20-28, 27, 35

190 oll

38 ORCHARD GREEN-MANURE CROPS IN CALIFORNIA.

Page
Fertilizers, commercial, use with green manuring- = =-225-5-5-5..-2- 522-2. 506: 15
Field peas, Canada. See Peas, Canada field.
Hresno County; Cal, area in’ northernseitrus districia=s see ee 8
Krosts; danger. Loigreen-manure\Cro PS sem see sere ae ee Selig
Green-manure crops. See Crops, green manure.
Gummosis, citrus disease, remedy by green manuring......................- 25
Hairy vetch. See Vetch, hairy.
Harrow, disk, use with créen-manure Cropsss-- eco. nee eee ie
Horse beans. See Beans, horse.
Indian melilot. See Melilot, Indian.
Inoculation;use in Sreen mManUTing fesse ee eee eee 14-15, 31, 35
Insects, injurious, harbored in green-manure crops ...:...........-..----.--- 22
Introduction ‘to bullle times p55 Soe ee oes errs eae ee 7
lnrigation, use:with ereen-manuure Cropss=22 264455 — see eerie 8, 9-10, 12, 17, 23, 27, 34
Land, preparation, green manuring in southern California...................- Me
Lathyrus sativus, comparison as green-manure crop....-..........--.-.------ PAT
tingitanus. See Pea, Tangier.
iesumes; seed production at Chico, Cale tablesasss- ses. eee ee 33
USe.as STEEN-MANMULS CLO PSiwe are saeis sere ee eee LSS 25. 2ieae
Lemon, orchard conditions unfavorable to green manuring.................... 10
iemoncove; Cal.: relation to northern citrus district... ---— 2464 8
Malva rotundifolia, yield ofereen: manures .— e245 2 oe eee 27
Manure ereen, use:in Caliiormia its. oce2.42 452) aos ee ae ee ee 10-35
stable, usefulness on heavy soil..................- ee bi eee er en 10
Medicago arabica. See Clover, bur.
hispida denticulata. See Clover, bur.
Melilot,-Indian® use:as:a)ereen-manure Crop: 445 2se sere eee ee 15, 24
Melilotus indica. See Melilot, Indian.
Noldew, damage to/green-manure crops-2-- ose eee eee eee eee 18

Nitrogen gathering. See Nodules. ;
Nodules, occurrence, on roots of nitrogen-gathering plants.. 16, 19, 22, 28, 29, 30, 31, 32
Northern citrus section. See Orchards, citrus.

Orange County, Cal., fenugreek as green-manure crop -.......-..--.--.-:-... 21,23
sTeen-manure crops, results im’ orchards) .-= = eee eee Pat
Orchards, California, increasing use of green manure...............--.-..-.-- 25
Citrus, green-manlire Crops ics ee agec etek aoe Ce eee ee 7, 34

southern Section]. 22425 cee eye eae eee ee 8-9, 11-15, 34

deciduous, bur‘clover/as ereen manure: 2: ee- soe es Se ee 19, 35
California, discussion 2-5: eae ee ee 9-10, 34

geographic districts; Californian = =5 ss eeneee eee eee ee sae 8-10

walnut, southern California, green-manuring methods.............. 11-15

Oroville; Cal-, center of citrus truit-orowimgarea 2eese-) see eee eee 8
Palermo, ‘Cal., center of citrus:ituit-crowine areas. -oes5- 2s cee ee 8
Pea, Canada field, use as sreen-manure crop!-2-)- 455-2 eee e ne eee 7, 15, 17-19, 34
field,“ comparison:as ereen-manure Clops. see. see see eee eee ae 26, 27, 34
peed, prices. |... celice Pec oe yee re oe mere ee 33

time and rate of seeding for green manuressss-2 3-222 -)ee 18-19

Manger, nitrogen-cathering statuse--).455- 422 oe eee eee eee 32

Use! as STECN-ManuUrelCroOpsassee ee eee ee 27, 32, 33, a0

Pin-erass; synonym of-alfilariaz..2.c22 2... ee 7
Plant*food, availability, remarks. 552-554. eee ee eee 15

lice. See Aphids,
190

INDEX. 39
Page

‘‘Plow sole.’’ See Roots, deeply penetrating.
Plow, use in turning under green-manure crops.......-.---:-.-------..--+------ ARES,
Homona Cala tenucreek. Comparative testsss. 2562 60.0.5. 2 le ee oe nee se 21
Hontenville Cale srelation to southern citrus district. 2 -425-2-....5520 922eee- 8
Rainfall, California orchard districts, relation to green manuring......... 8-9, 10, 17

Rainy season. See Rainfall.

edlands-2Calk plantings tor ereememanure seem hee eo st os oe ee ae 1174, PAL
Roots. deeply penetrating, remedy for “plow soles: 22... ...2.-.-2---22223 Aero
orchard tree, danger of disturbance in green-manure plowing........... 12
Sacramento Valley, area in northern California citrus district. .............-. 8
San Joaquin Valley, relation to California citrus districts. .................-- 8
Santa Clara Valley, irrigation for green-manure crops. .............-...---.-- 2
Raulaw@ale fenugreek, comparathvertestas seen 2-222. - o-oo ee 22
Deedee Cost LOMmereen-MaNUre Crops aso ete eo See See He ee oo ee eee 32-34
SRECM=IMAMUTe LOPS.) PLOGUCLIOME eee mee pee oe 23, 32-34
Seedincaibumclover timer and Tabese eons ss eee eee eee eee sale 19
fenuercek.s time and Tabescc2) a. 2 aps set ar ce LS Lene ap Ds
Me ld peasauime) ancy raters aye, aie eee a PPR a epee ee A cece 18-19
Mme LNod Sans Cala torn ae ner ae ome rape en eee ee OA At Sekar 12532
HEC O MAMIE MC A CIOS -teeiapey setae ress ee eee ee peer sO 34
Mangierpeasiimac an diratetrcis ma: eters ee ern ae ce IA Lae 32
VELC Mma GII CCAM GE TAGE ws see ioe hee en anes Siero eters Apes Ls 17, 29, 30
Sierra Madre Mountains, relation to California citrus districts. ............-.--- 8
Soul mC alii onniarstae kao elms eee ees epee Be ip eee sd eo 34
ORE Hardest Cts see ey ter re teehee pe ones ES SRN A 8-9
Erosione prevention oyeereen MmanUring 5520 eeee eee eee ee See 25
PET OTE keprgeage erete hoy Ve Ata ey ae ee Ua ren, sihoel in Sienna a Ae cee Wi ke nee 23
eamyA Ua Oral eso CneCeMeImMaAMUnIM Oe a22 seem at ke ee eevee eres oe 10
IIMPLOVEMEeN ty OiyelTeeNemMAMUPIMN Ose sas ant oe ob sea see nee ots ees 25
sanchye tonmlindiamemelnlocee ser ets ites bat ee sede ape cen nate 24

Southern citrus section. See Orchards, citrus.

Spring vetch. See Vetch, common.

Stable manure. See Manure, stable.

SMM AVE eLe eM -MaaTUNE CLOPS a 21s tic <crilore oe icie ae oe ice els SK ee ee eee 34-35
Summer green manure. See Crops, green manure.

Tangier pea. See Pea, Tangier.

iramplune-relation:to green manuring:......-..:-2---.5--2-2:5-2-2 1 17, 19529530
Trees, citrus, cultivation, need, and effect of cessation...........-----..------ 10
Trigonella foenum-graecum. See Fenugreek.
Minmmenimeer time for sreen-manure Crops: .....2.- 52-25-2222 ses 2bce sence 34
Vegetable acids. See Acids, vegetable.
Ventura County, Cal., fenugreek as green-manure crop...........-..--------- 21523
Meten plackabiiter, mitrocen-gathering status ...-.---..2.2---+--.+-.2-2----4- 29
UsSerasiGrLeen Manure CLOp sas as see eee eee 26-27, 29-30, 33, 34, 35
puLple mitrogen-cathering status-+---s5-o2- 5-2-2 cs asses see 28
use: as PTreen-manure CroOp-=..-+------+-----.- 20-21, 28-29) daa0
commons mtrozen-catherine stabuss..-.-s-+4.-2---- sess. essen eee es 16
use AS ereen-Manure ClLope = =e eee eee 12, 15-17, 22, 26-27, 34, 35
haliyedseras CTeCN-MANUTC CLOP). ssc 250 seo eens esse eS 15, 23-24, 26-27, 35
spring. See Vetch, common.
woolly-podded; nitrogen-cathering status.-.....-22...5...22..-+----2- 30
USC as ORCC IMAMULC CLOPesai- sacra ies 26-27, 30, 33, 35

190

ORCHARD GREEN-MANURE CROPS IN CALIFORNIA,

Vicia atropurpurea. See Vetch, black purple.
dasycarpa. See Vetch, woolly podded.
ervilia. See Vetch, black bitter.
faba. See Bean, horse.
sativa, use as '/sTeen-Manure CrOps.- 2: 255. eae ee eee
villosa. See Vetch, hairy.
Walnut orchards. See Orchards, walnut.
Weather, southern citrus section, notess2: a= ss.) 2-5 ee ee war
Weeds, use in:green manuring? 0208.22.52 Geos 2) oon ee ee
Winter green-manure crops. See Crops, green manure, winter.
relation to vetch and peas for green manuring.....................-.-
Worm, army, harbored 1in/ereen-manure crops 2-=--- 22 = =e eee
190

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