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                          FARMERS' BULLETIN 1142

                 UNITED STATES DEPARTMENT OF AGRICULTURE


                                 GROWING

                                 CRIMSON

                                  CLOVER


Crimson Clover is a handsome fall-planted annual, widely cultivated in
the Middle Atlantic and Southeastern States for forage, a cover crop, and
green manure.

Crimson clover is commonly sown in corn at the last cultivation. If the
soil is heavy, a better practice is to sow after a crop of small grain or
on other land which can be specially prepared.

Crimson clover will grow on poorer soil than most clovers and is not
particularly dependent upon lime. For this reason it has been widely used
for restoring the productivity of soils which have been abused. A more
important function is to maintain crop yields on soils which are already
moderately rich.

The most common difficulty in growing crimson clover is the killing of the
young stands by drought. This is best prevented by the preparation of a
fine, moist, and firmly compacted seed bed.

August and September are the best months for sowing crimson clover, the
exact date depending upon the condition of the soil. Either hulled or
unhulled seed may be used, the latter giving somewhat greater certainty of
a stand.

Crimson clover is often sown with a nurse crop of buckwheat or cowpeas, to
protect it from the sun. A light covering of straw is also effective.

Combinations of crimson clover with oats, hairy vetch, or other fall-sown
forage crops give somewhat higher yields and a surer stand than crimson
clover alone.

No insects trouble crimson clover seriously, and the only severe disease
is the stem-rot, or wilt.

              Contribution from the Bureau of Plant Industry
                           WM. A. TAYLOR, Chief
                      Washington, D. C. August, 1920




                       =GROWING CRIMSON CLOVER.=[1]


                  L. W. Kephart, _Scientific Assistant,
                  Office of Forage-Crop Investigations._

[1] This bulletin is a revision of Farmers' Bulletin 550, entitled
"Crimson Clover: Growing the Crop," by J. M. Westgate, formerly Agronomist
in Charge of Clover Investigations, Office of Forage-Crop Investigations.
The illustrations and some of the subject matter of the old bulletin are
retained in the present issue.




=CONTENTS.=

                                                 Page.

  History and adaptations                           4
  Varieties                                         5
  Use in the rotation                               6
    Seeding in intertilled crops                    6
    Seeding after an early-maturing crop            7
  Requirements for obtaining a stand                8
    Soils                                           9
    Preparation of the seed bed                    10
    Fertilizers                                    11
    Lime                                           12
    Inoculation                                    13
  Seeding                                          13
    Time of seeding                                13
    Rate of seeding                                14
    Methods of seeding                             14
    Choice of seed                                 16
    Unhulled seed                                  16
    Use of a nurse crop                            17
    Seed mixtures                                  18
  Treatment of the stand                           20
  Maladies                                         20


[dropcap: CRIMSON] CLOVER is an annual or winter annual true clover,
resembling common red clover in size and general appearance, the most
noticeable difference being the flower heads, which are long, narrow, and
pointed instead of short, spherical, and compact (fig. 1). The individual
flowers of this clover are commonly of a rich scarlet color, and as the
heads are borne mostly on the ends of the stems, a field of crimson clover
in full bloom presents a strikingly brilliant appearance. Because of the
color of the flowers, crimson clover is often termed "scarlet clover,"
although it is also known, less commonly, as "French clover," "Italian
clover," "German clover," "incarnate clover," and "annual clover." It is
the only annual true clover that is of more than incidental agricultural
importance in the eastern United States.

Probably the most important characteristic of crimson clover is its
ability to grow and make its crop during the fall and early spring,
when the land is not occupied by the ordinary summer-grown crops. In
sections where it succeeds, it can be sown following a grain crop or in
an intertilled crop in late summer and is ready to harvest for hay, to
pasture, or to turn under as green manure in time to plow the land for
spring-seeded crops, such as corn or cotton. South of central Delaware
it may even be cut for seed and the stubble plowed under in time for
seeding a quick-maturing strain of corn. Because it can be grown during
the offseason of the year, crimson clover is one of the most economical
legumes for green manuring, and it has been largely used for that purpose
in the regions to which it is adapted. The many uses to which this crop
may be put merit a careful study of the best methods of establishing a
stand of this clover on the farm.

[Illustration: Fig. 1.--A single plant of crimson clover.]




=HISTORY AND ADAPTATIONS.=


Crimson clover is a native of Europe, where it is cultivated as a forage
and green-manuring crop in Italy, France, Spain, Germany, Austria, and
Great Britain. Large quantities of crimson-clover seed are exported from
Europe to the United States, especially from the districts of central
France, where crimson clover is the premier leguminous forage plant.

Crimson clover was introduced into this country as early as 1818, and the
seed was widely distributed by the United States Patent Office in 1855.
The plant was at first regarded more for its ornamental value than as a
forage plant, however, and it was not until about 1880 that its value for
agricultural purposes began to be appreciated.

[Illustration: Fig. 2.--Map of a part of the United States, showing the
region where crimson clover is most widely grown.]

At present crimson clover is grown most widely in the lighter sandy
areas of the Atlantic Coastal Plain, where the soil is not very rich
and the winters are not severe. (Fig. 2.) The plant does not withstand
either extreme cold or extreme heat, and its culture is therefore limited
to regions which enjoy at some time during the year a long period of
relatively mild, moist weather. Ordinarily, this clover does not survive
the winter in latitudes north of southern Pennsylvania, while in some of
the Southern States it is frequently killed by dry, hot weather in the
fall or spring. It succeeds well in the humid regions near the Gulf of
Mexico and in the Pacific Northwest, but in these areas it is not widely
grown.

Normally, crimson clover is a winter annual comparable to winter wheat;
that is, it is planted in the fall, lies more or less dormant over winter,
grows rapidly in the spring, and dies, after going to seed, early in the
summer. Where the summers are not too hot it can be planted in the spring
and grown as a summer crop, but for this purpose other clovers are usually
preferred.




=VARIETIES.=


Crimson clover is exceedingly variable both in color of flower and in
time of maturity. These variations are particularly noticeable in fields
planted from a mixed lot of seed, the flowers presenting a range in color
from nearly pure white to a deep purplish red and the seeds a difference
in date of ripening of more than a month. Since crimson clover is thought
to be mainly self-pollinated, it is easy to fix these qualities by
selection and to establish definite varieties.

In Europe six or seven different varieties of crimson clover are
recognized and sold by seedsmen, varying from extra early crimson flowered
to, extra late white flowered and from very hardy to non-hardy. By the use
of a succession of these varieties the European farmer is able to spread
his harvest over six or seven weeks instead of having it concentrated
within a few days, as in America. Similarly, the culture of the plant has
been extended northward from Italy to Sweden by means of hardy strains.
A wild form of crimson clover having yellowish flowers and hairy foliage
occurs in southern and eastern Europe and in England, but it is not of
economic value.

In America no sharply defined varieties of crimson clover are recognized,
except a white-blooming variety which is sold in the South and is two
weeks later than the ordinary crimson-flowered sort. Hardy strains have
been developed and used in a small way in Massachusetts and Ohio, but
these are not commercially available.




=USE IN THE ROTATION.=


=SEEDING IN INTERTILLED CROPS.=

In former years a large percentage of the crimson-clover acreage was
seeded in corn or other intertilled crops at or shortly after the time of
the last cultivation. In most of the crimson-clover area it is possible
to make such a seeding, obtain a good growth during the fall and early
spring, and mow or plow under the clover in time, for breaking up the land
for another crop of corn. This has been the standard method of growing
this clover, and it is still the leading practice in many of the older
sections. Corn in the summer with crimson clover in the winter is a cheap
and convenient method of growing a cash crop and a restorative crop the
same year, and the reputation of crimson clover as a crop increaser is
largely based on this simple rotation. Instances are by no means rare
where the yield of corn has been gradually increased from 10 bushels per
acre to as high as 70 bushels by this means.

The difficulty with this method is the possibility of the stand of young
clover failing through drought. The growing corn makes a heavy demand on
the soil moisture, and if there is not enough moisture for both clover and
corn the latter gets the larger share and the tender clover plants are
likely to succumb. Because of the risk involved, farmers in the upland
sections are seeking other and more reliable methods of seeding, and the
sowing of crimson clover in corn is gradually decreasing.

Where the danger from fall drought is not serious, crimson clover may be
sown in corn at the time of the last cultivation or when the corn leaves
have just begun to wither. South of central Virginia there is likely to be
much hot weather after the corn is laid by, in which case it is best to
delay the seeding of the clover until after the first rain. The appearance
of a field of crimson clover seeded in corn the previous summer is shown
in figure 3.

South of southern Virginia crimson clover can be seeded in cotton,
provided the field is free from crab-grass and other weeds and the soil is
not too dry. In the extreme north of the cotton belt the seed may be sown
at the last working of the cotton; farther south this occurs too early and
it is necessary to wait for a rain, which often comes at about the time of
the first picking.

[Illustration: Fig. 3.--Crimson clover in an old cornfield. The clover
was seeded in the corn at the last cultivation. A fodder stack is to be
observed in the middle foreground. The cornstalks have been removed to
avoid difficulty in mowing the clover.]

Crimson clover may be seeded in practically any of the cultivated truck
crops which receive their last cultivation from 8 to 12 weeks before
the first frost. It is not practicable to seed the clover in late
potatoes, sweet potatoes, or other root crops, as the digging in the fall
practically destroys the clover.

Ordinarily, crimson clover does not succeed when sown in cowpeas, sorghum,
or watermelons, owing to the heavy shade cast by these crops. It can,
however, be seeded in tobacco, tomatoes, cultivated soy beans, and
cantaloupes.


=SEEDING AFTER AN EARLY-MATURING CROP.=

Seeding crimson clover in an intertilled crop is successful mostly on
sandy soils, which can easily be prepared for seeding even in mid-summer.
On clay soils and in weedy fields this method of seeding is likely to be
unsatisfactory. Such soils are usually hard and dry in August and can with
difficulty be brought into condition for a seed bed, with the result that
a large percentage of such seedings fail. A better plan on clay soils, and
on sandy soils in many cases, is to seed the crimson clover on specially
prepared ground from which all other crops have been removed. Such ground
can be made as fine and firm as desired. Furthermore, the clover after
planting does not have to compete with another crop for the soil moisture.
This method is somewhat more troublesome than planting in intertilled
crops, but the greater certainty of getting a stand more than offsets the
greater cost. Planting crimson clover on specially prepared ground has
extended the culture of the plant to regions where it was not hitherto
grown and is increasing the reliability of the crop in sections where it
has been long established.

In the ordinary rotation, crimson clover follows a crop of small grain.
However, it may follow any crop that is removed 8 to 10 weeks before
frost, or it may be seeded on fallow ground. Ground from which early
potatoes have been removed is especially favorable for the establishment
of a stand of this clover. The residual effect of the fertilizers used on
potatoes is partially responsible for this, while the well-settled seed
bed, which requires only leveling and harrowing, also presents favorable
conditions for the crimson-clover seedlings.

In many parts of the South crimson clover can be seeded in corn stubble if
an early variety of corn has been used. Although there is some risk that
the clover may not make enough growth before winter if seeding is delayed
until the corn is harvested, the danger of losing the stand is not as
great as if the clover were seeded earlier, while the corn was standing.

Crimson clover is sometimes seeded after a grass or clover crop if the
rainfall in July is sufficient to cause the sod to decay. In the far South
it can be planted after peanuts, while in all sections it can be sown as
a catch crop on land where cotton or other crops have died early in the
season.




=REQUIREMENTS FOR OBTAINING A STAND.=


Probably the difficulty most commonly experienced in growing crimson
clover is failure to obtain a satisfactory stand. Sometimes the seed does
not germinate well; more commonly good germination is secured, but the
seedlings wither and die before they can become established. Frequently
not more than 50 per cent of the plants survive the first three weeks,
while a complete failure of the crop is a common risk even in the sections
where crimson clover is most widely grown.

The most common cause of failure to obtain a stand is hot, dry
weather after planting. The seedlings of crimson clover are tender,
succulent, and shallow rooted and are easily killed by lack of moisture.
Unfortunately, in most of the crimson-clover area the weather during late
August and early September is very likely to be hot and droughty, making
the planting of the clover at that time rather hazardous. Some farmers
attempt to avoid this difficulty by planting either in early summer or in
October, after the fall rains; there is danger, however, that the plants
will make too much or too little growth to survive the winter. In the
long run it is probably better to plant at the regular time and depend
upon thorough preparation of the seed bed to offset any deficiency in the
rainfall.


=SOILS.=

Crimson clover can be grown successfully on almost any type of soil if it
is reasonably rich, well drained, and supplied with organic matter and the
proper inoculating bacteria. Probably two-thirds of the crimson-clover
acreage is found on the sandy soils of the Atlantic Coastal Plain, but
the crop is not necessarily restricted to sandy soils and is in fact
increasing in importance on the red-clay soils of the Piedmont region and
in the limestone valleys of Virginia and Tennessee.

[Illustration: Fig. 4.--a crimson-clover failure on ground too poor in
humus.]

Crimson clover has been an important factor in increasing yields on soils
that have been abused, but it is not a crop for land which is naturally
very poor. It does not do well on rough, newly cleared areas, raw
subsoil, Hard, dry clay, or sterile sand. (Fig. 4.) For such soils soy
beans, cowpeas, and velvet beans are better suited and should be used for
the first three or four years until crimson clover can be successfully
grown. Crimson clover can be made to grow on poor soils, provided they
are specially prepared by liming, manuring, and inoculating. In general,
however, crimson clover is a crop for maintaining soils which are already
fairly productive rather than one for inducing productivity in soils where
it is quite lacking. If there is any doubt whether the soil is suitable
for crimson clover, a small plat should be prepared under field conditions
and planted one year for trial.


=PREPARATION OF THE SEED BED.=

To secure a full, even stand of crimson clover with any degree of
regularity the seed bed should be well and thoroughly prepared. The soil
should be firm, moist, well settled, and fine on top. Only indifferent
success can possibly be expected if the seed is scattered on land which
is loose, dry, and full of hard lumps and trash. A loose seed bed dries
out quickly, heaves during the winter, and on some soils blows and washes
badly.

[Illustration: Fig. 5.--A corrugated roller or pulverizer, an excellent
implement for preparing the seed bed for crimson clover.]

On the other hand, the seed bed should not be too hard, for although this
clover often grows successfully on soil which would be too solid for
corn, there must be at| least enough loose soil on the surface to cover
the seed. Thorough preparation is the very best insurance against failure
of the stand through drought or winterkilling, and the most successful
growers sow crimson clover on land as well prepared as that for wheat.

To secure a fine, firm seed bed without drying out the surface soil, the
land should be prepared with as few operations as possible. A single
working when the soil is in a moist, crumbly condition is better than half
a dozen workings when the soil is too wet or too dry. In very sandy soils,
or soils which do not form a crust, the only preparation needed is to keep
down the weeds.

An excellent tool for making the seed bed is the corrugated roller or
pulverizer (fig. 5). This implement is an improvement over the old plain
roller for breaking clods and is unexcelled for keeping the surface soil
moist. It can be used after plowing and again before planting, and even
after planting if the soil needs to be compacted. Rolling of some kind to
firm the soil is especially important on sandy soils, but it is equally
beneficial on clay soils if they are cloddy.

When clover is seeded in an intertilled crop, such as corn, cotton, or
tomatoes, the customary cultivation received by these crops is ordinarily
sufficient preparation for crimson clover. In sandy soil the clover is
often seeded without any immediate preparation, but a light stirring with
a harrow-toothed cultivator is desirable if the ground is hard. If the
clover is to be used for hay or seed, the preceding crop should be laid by
level rather than in ridges. This will facilitate cutting the clover.

Where crimson clover is seeded after a crop of small grain, the stubble
should be plowed or disked as soon as possible after the grain is cut.
Stubble land dries out quickly, partly because the soil is suddenly left
bare and partly because of the drain on the soil moisture by the crops of
ragweed and other coarse-growing weeds which always follow a grain crop.
Unless the soil is cultivated at once it becomes very difficult to obtain
anything like an ideal seed bed for crimson clover. This difficulty is
usually more pronounced after oats and barley than after rye and wheat.
Ordinarily the best practice is to disk the grain stubble within a week
after harvest and harrow every week, or at least after every rain, in
order to settle the ground, destroy the weeds, and assist in holding the
moisture pending the time of seeding the clover. Plowing the stubble
is more expensive than disking and requires that the ground be allowed
to settle for a month or six weeks in order to secure a firm seed bed.
Plowing is an advantage in a wet season, because plowed ground dries
readily; it is a disadvantage in a dry season for the same reason.


=FERTILIZERS.=

On moderately rich soil the fertilizer applied to the preceding crop is
sufficient to produce a good crop of crimson clover. This is especially
true where the clover follows such crops as potatoes or tomatoes, which
ordinarily are heavily treated with fertilizers. It is important to
realize, however, that crimson clover has a very short period of growth,
and that to make a vigorous growth it must have a good supply of plant
food. On sandy soils where fertilizers have not recently been applied it
is often the practice to apply from 150 to 200 pounds of acid phosphate,
with some potash fertilizer if it can be afforded. On clay soils 200 or
300 pounds per acre of acid phosphate ordinarily are sufficient. On many
soils a light application of nitrate of soda will assist materially in
giving the young clover plants a good start and often will enable them to
withstand the effects of a late drought or severe winter which otherwise
might have injured the stand. If the seeding has been delayed, as by
waiting for suitable rains, an application of not more than 75 pounds of
nitrate of soda per acre will stimulate the young plants and enable them
to make a better growth before winter.

Fertilizer is usually applied at seeding time, but a few farmers have been
found who apply it as a top-dressing very early the following summer,
giving as a reason that there is then no loss from winter leaching and
that by this method the plants are nourished at the time they are making
their most vigorous growth. Such top-dressings of fertilizer should not
be made while the leaves are wet with rain or dew. Where stable manure is
applied to crimson clover very marked results follow. It may be spread
just before seeding when the clover is not grown in an intertilled crop,
or it may be applied as a top-dressing in winter or very early spring.

The more vigorous the growth that can be induced by the application of
suitable fertilizers the more marked will be the increase in the yield of
the succeeding crops. On soil in a low state of productivity the use of
a reasonable amount of fertilizer will often enable a successful crop of
clover and succeeding crops to be produced, where had not the fertilizers
been applied the clover would have failed. Furthermore, the following
crop, particularly if it be corn, would also fail to give the increased
yield which follows a successful stand of crimson clover.

An application of barnyard manure will be found to be especially effective
in obtaining a stand of crimson clover on any thin, galled spots in the
field. The manure should be worked into the ground before seeding, and,
if possible, a second application as a top-dressing should be given a day
or two after planting. The top-dressing stimulates the seedlings and if
strawy helps to protect them from the August sun.


=LIME.=

Crimson clover is not as dependent on lime as red clover and alfalfa,
being more like alsike clover in this respect. It does not thrive on soils
which are very "sour," but on well-drained soils in a productive condition
crimson clover frequently makes a vigorous growth, even though the soil
may show a high lime requirement. The stands are usually more uniformly
good over the limed parts of such fields than on the unlimed parts,
although it is sometimes questionable whether the benefit derived from
liming is profitable. Liming is more often desirable on clay soils than
on sandy soils, and usually gives better results when used in conjunction
with fertilizers than when used alone. On light sandy soils deficient
in humus burnt lime may be actually injurious. In considering the
advisability of applying lime one must not lose sight of the need of lime
on the part of such other crops as corn, cantaloupes, or peaches, which
are either grown with or follow the clover. Inasmuch as the effect of
liming varies greatly in different localities, it is suggested that small
plats be treated experimentally at different rates before any considerable
areas are limed.


=INOCULATION.=

A large part of the value of all clovers lies in their ability to utilize
the nitrogen of the air and add it to the soil. When grown on rich land,
the clovers, like many other plants, use the nitrogen already present in
the soil and are not stimulated to contribute any to their own support or
to the support of other crops. To enable the clover to use the nitrogen in
the air the presence of the proper nodule-forming bacteria in the soil is
necessary.

Fortunately, most of the soils in the crimson-clover sections appear to
be already inoculated, and artificial inoculation is not often necessary,
except on soils new to the crop. Crimson clover is inoculated by the same
strain of bacteria which occurs on the roots of the other true clovers;
consequently, a field which has produced a good stand of red, mammoth,
alsike, white, hop, Carolina, rabbit's-foot, or buffalo clover is usually
inoculated sufficiently for crimson clover. Sweet clover, Japan clover,
and bur clover are not true clovers and are inoculated by a different
strain of bacteria.

The importance of inoculation is well shown by an experiment conducted by
the Alabama Agricultural Experiment Station. In this experiment yields of
4,057 and 6,100 pounds of crimson-clover hay were secured on inoculated
soils, while on corresponding areas which were not inoculated the yields
were 761 pounds on one area and nothing on the other.

The soil can be inoculated artificially by means of pure cultures of the
bacteria or by the transfer of a small quantity of soil from another
clover field.[2] The latter method is the more certain, but is open to
the danger of introducing noxious weeds, insects, and plant diseases,
especially if the soil is brought from a distance. The presence of
stem-rot in many sections makes the use of soil especially dangerous. This
disease can, be carried with the soil from field to field.

[2] Sufficient pure culture for inoculating seed for 1 acre can be secured
free from the United States Department of Agriculture. Full directions for
using the culture accompany each bottle. Directions for inoculating by the
soil-transfer method can also be obtained from this Department.




=SEEDING.=


=TIME OF SEEDING.=

Crimson clover is usually sown between August 15 and October 1, the
general rule being to plant about 60 days before the first killing frost
is expected. South of Virginia crimson clover can be seeded as late as
November 1, although if planted late more seed should be used and a light
dressing of nitrate of soda applied, in order to stimulate the young
plants. Seeding earlier than August 1 is seldom advisable unless the crop
is sown with some other crop the shade of which will hold it back.

The exact date of planting depends almost entirely upon the moisture
content of the soil. The principal condition to avoid is planting when the
soil contains just enough moisture to germinate the seeds, but not enough
to keep the plants growing. Usually it is better to plant when the soil is
quite dry than when it is slightly moist, for in dry soil the seeds, if
properly buried, lie without germinating and are ready to grow vigorously
at the first rainfall. The most favorable time for seeding is just before
or just after a good rain, when the soil is moist enough to form a ball in
the hand.


=RATE OF SEEDING.=

The ordinary rate of seeding crimson clover is 15 pounds per acre,
although the rate varies according to conditions. From 12 to 15 pounds per
acre are usually sufficient when growing the crop for seed or when the
soil is unusually rich. On poor soil, dry soil, or on soil which has not
previously produced crimson clover 18 to 22 pounds of seed give better
assurance of a stand. Heavy seeding is also desirable when planting late
in the season or when a heavy crop is wanted for green manure early in the
spring.

Theoretically, 2 pounds of seed per acre would provide six plants
for every square foot, which is a satisfactory stand. Under ordinary
circumstances, however, it is necessary to allow for some of the seed
being too deep, or too shallow, or failing to germinate, and for a certain
percentage of winterkilling. It is also well to have a fairly thick stand
of the young plants, so that the ground may be well covered during the
early fall and thus prevent soil washing and the growth of winter weeds.


=METHODS OF SEEDING.=

The most common method of seeding crimson clover in intertilled crops
is to scatter the seed broadcast with a rotary seeder or by hand. (Fig.
6.) In order to place the seed on a fresh, moist seed bed it is commonly
broadcasted immediately behind the cultivator at the last cultivation and
is covered 'at once by a second cultivator. In tall corn the seed may be
sown from horseback, the ears of the horse being covered with small bags
to prevent the entrance of the flying seed. Slightly more seed is required
when seeding in tall corn, as some seed catches in the corn plants. When
seeding in cotton care must be taken to avoid injury to the opening bolls,
which are easily knocked off or torn. This is best done by seeding by
hand, covering the seed with a piece of brush dragged down the rows.

In low-growing truck crops and on fallow ground crimson clover can be
seeded with a wheelbarrow seeder. This implement distributes the seed more
evenly than can be done by hand or with the rotary seeder, especially
when planting a mixture of crops. The wheelbarrow seeder being somewhat
awkward to handle is better adapted to smooth, level fields than to
hillsides.

Probably the very best method of seeding crimson clover is with the
special clover or alfalfa drill. Where enough clover is grown to warrant
its use this implement is to be highly recommended. The seed is sown in
4-inch rows at just the proper depth and with the right pressure, and the
fertilizer is placed exactly under each row, where it will be immediately
available to the seedlings. Drilled clover requires less seed than
broadcasted clover and produces a more even and certain stand.

In place of the special clover drill an ordinary grain drill equipped with
a clover-seed attachment can be used with good results. Special spouts
should be arranged to lead from the clover-seed box back of the shoes or
disks, in order to deposit the seed directly in the furrow. Chain furrow
closers are best for covering the seed, as they leave the furrows broad
and flat instead of =V= shaped and lessen the danger of the seedlings
being covered with soil during a hard rain.

[Illustration: Fig. 6.--Seeding crimson clover in corn at the last
cultivation.]

For use in intertilled crops there are several types of 1-row drills, the
best for this purpose being the 5-hoe drill equipped with press wheels.

Crimson-clover seed must be covered, but not too deeply. In most soils it
is not enough to depend on rain to effect a covering. An inch in sandy
soils and half an inch in clay soils appear to be about the right depth.
Shallow planting gives the best results in wet seasons and deep planting
in time of drought. Broadcasted seed should be covered with a spike-tooth
harrow or a weeder rather than a heavy harrow or a shovel cultivator. A
harrow made of fairly stiff brush is often useful in loose soil.


=CHOICE OF SEED.=

As a rule, fresh crimson-clover seed is of good viability, and failure
to secure a stand is not often caused by failure of the seed to grow.
Unlike most clovers, crimson-clover seed absorbs water readily and sprouts
quickly. There are practically none of the hard seeds which are so
frequent in red clover and sweet clover, and a germination of 90 per cent
in 48 hour's is not uncommon. The seed deteriorates rapidly, however, and
when more than 2 years old rarely shows a germination in excess of 50 per
cent. Sometimes, when stocks of commercial seed are low, old seed finds
its way to the market, and this, when planted, gives poor results. Old
seed can usually be detected by the dull-brown appearance of the seed coat
as contrasted with the bright, shiny, pinkish or greenish yellow color of
fresh seed. Brown seed, however, is sometimes caused by weathering during
harvest, and such seed is not objectionable unless the weathering has been
excessive.

A common impurity in crimson-clover seed is green, shrunken, and immature
seed, caused by harvesting the crop before it is ripe. Crimson-clover seed
does not germinate readily until it takes on a yellowish tinge; therefore,
green seed should be rejected.

Crimson-clover seed is larger and plumper than red-clover seed and if
properly cleaned should not contain seeds of dodder or the smaller
seeded weeds. Frequently, however, it does contain the seeds of field
peppergrass, yellow trefoil, evening primrose, sheep sorrel, wild
geranium, buttercups, mustards, and other weeds which blossom in early
summer.


=UNHULLED SEED.=

There is a growing belief among farmers that they are less likely to lose
a stand of crimson clover through drought if they sow the seed in the hull
rather than use the hulled seed as it ordinarily appears on the market.
It is claimed that the hulls hold the moisture to some extent and carry
the seedlings over the critical day or two following germination, while
some farmers assert that the unhulled seeds require more moisture for
germination, and the seeds therefore do not sprout until there is enough
moisture in the soil to keep the plants growing. Unhulled seed is bulky
and is not often handled by commercial seedsmen, although one large grower
sells the unhulled seed in compressed, bales similar to small cotton
bales. It usually can be secured from neighboring farmers, however, or is
easily saved at home. The seed can be harvested with a stripper from the
standing crop in the field or the mature crop can be cut and thrashed like
an ordinary grain crop. For local planting on a small scale unhulled seed
is the cheapest and most accessible form of crimson-clover seed.

Unhulled seed is somewhat difficult to sow, because the hairy hulls stick
together in masses and can not be scattered uniformly. To avoid this
trouble the seed may be mixed with moistened earth or with lime, or may be
sown with a blower similar to those used on small forges. A better plan
is to sow on a windy day, throwing the seed vertically into the air and
allowing the wind to scatter it.

Of unhulled seed of the best quality, 100 pounds contains about 1 bushel
(60 pounds) of clean seed. The common grades, however, are usually more
chaffy and require 120 to 180 pounds to make a bushel. From 2 to 3 pounds
of unhulled seed are therefore regarded as equivalent to 1 pound of hulled
seed. A bushel of unhulled seed, even when well packed down, weighs only 6
to 10 pounds and contains about 4 pounds of seed. The appearance of both
hulled and unhulled crimson-clover seed is shown in figure 7.

[Illustration: Fig. 7.--Hulled seed of crimson clover of a common
commercial grade and unhulled seed gathered with a homemade stripper.
(Natural size.)]


=USE OF A NURSE CROP.=

In order to protect the crimson-clover seedlings from the hot sun of late
August it is a common practice in some sections to plant with the clover a
small quantity of some quick-growing crop like buckwheat, cowpeas, rape,
or turnips. A thin stand of these heavier leaved plants furnishes an ideal
shade for the young clover, and on soils which are inclined to bake it
prevents the formation of a crust. The nurse crop must be seeded lightly,
usually not more than half the regular rate, as the ordinary stand shades
the ground so completely as to destroy the crimson clover. On hot clay
soil in the Piedmont region the chances of obtaining a stand of clover are
about twice as good with a nurse crop as without one.

Buckwheat is the principal nurse crop northward from Washington, D. C.
A common rate of seeding is 2 to 3 pecks of buckwheat in 15 pounds of
crimson clover. If the planting can be made in July the buckwheat usually
has time to ripen before frost and thus pay the cost of starting both
stands.

In the cotton belt cowpeas have been used successfully, especially
when seeding on fallow ground. They are seeded broadcast at the rate
of one-half bushel per acre. There is ordinarily not enough time for
the cowpeas to mature, but they add to the value of the stand for fall
pasturage and protect the clover from severe weather in the winter. Both
cowpeas and buckwheat have the merit of being able to grow on poor soil.

Dwarf Essex rape has been used as a nurse crop in a few cases where the
clover was to be pastured by hogs or sheep in the fall. From 2 to 3 pounds
of rape, sown in August, furnishes sufficient cover for a nurse crop.
Cowhorn turnips, winter kale, and mustard are also satisfactory nurse
crops if planted at a rate not exceeding 1 pound of seed per acre. If the
clover is to be saved for seed these latter crops are objectionable, as a
few plants will live over winter and ripen at the same time as the clover.

Where a nurse crop can not be grown conveniently, the crimson-clover
seedlings can be protected from the sun by a light top-dressing of straw,
spread just after the seed is sown.


SEED MIXTURES.

Crimson clover is frequently grown in combination with winter grain, hairy
vetch, or other forage crops having a similar period of growth. The mixed
crop is less liable to lodge than the single crop, cures more readily in
damp weather, and usually furnishes a heavier yield. Another advantage of
the mixed crop is that if either should fail the other will serve as a
cover crop during the winter and bring some return the following spring.
Mixed crops are not desirable if the clover is to be saved for seed.

South of central Virginia crimson clover is usually grown in combination
with winter oats. An early variety of oats, such as the Fulghum, or a late
variety of clover, such as the white blooming, is usually the best, as
the oat crop matures somewhat later than the ordinary crimson clover. The
customary rate of seeding is 15 pounds of the clover and 2½ bushels of
oats per acre. In Delaware and eastern Maryland the most popular companion
crop for crimson clover is winter wheat, although barley makes a desirable
hay crop and is sometimes used. Eye is not desirable for hay, but it
is probably the best of the grains for green manure, as it is hardy,
vigorous, and starts growth early in the spring. Rye and wheat are seeded
at the rate of 1 bushel per acre with the customary quantity of crimson
clover. The accompanying illustration (fig. 8) shows a field seeded to a
mixture of crimson clover and wheat. Usually the grain is well headed,
but in the milk or soft-dough stage, when the clover is ready to cut, the
yield of the mixed crimson clover and grain is often 25 to 50 per cent
greater than that of the clover alone.

[Illustration: Fig. 8.--Crimson clover and wheat in mixture. In the
foreground the crop has been cut and fed green to stock. The remainder
was cut the next day for hay. The grain prevents the crimson clover from
lodging.]

Hairy vetch and crimson clover are sometimes grown together, seeding at
the rate of 20 pounds and 10 pounds per acre, respectively. As both these
plants are likely to lodge in good soil, however, one of the grains is
usually included, a common seeding mixture being oats 2 bushels, hairy
vetch 12 to 15 pounds, and crimson clover 5 pounds. Bur clover, black
medic, and other winter-growing legumes are sometimes found in mixtures
with crimson clover, although such mixtures generally occur by accident
rather than intent. Black medic and crimson clover make' a particularly
good combination on rich soil.

In most of the crimson-clover area the cultivated grasses, such as
timothy, redtop, and orchard grass, are not commonly grown. However,
where these grasses flourish they may well be seeded at the same time
as the crimson clover, provided the latter is planted not earlier than
September 15. In some sections Johnson grass and Bermuda grass make useful
combinations with crimson clover, the grasses making most of their growth
in the summer and the clover in the fall and spring.




=TREATMENT OF THE STAND.=


Ordinarily no special treatment is required after seeding and the clover
goes into the winter without any further handling. If the growth is so
rank that there is danger of the plants being too succulent to survive the
winter, the tops can be reduced by light grazing with small animals, such
as calves, sheep, or chickens, or by mowing with the cutter bar of the
mowing machine set high. If the stand is backward, it may be stimulated
by a light application of nitrate of soda. It is said that a thin stand
can be thickened by grazing lightly with sheep, as the grazing induces
heavier stooling. The aim should be to carry the clover into the winter
with well-hardened leafy stems and with a well-established root system to
withstand heaving out in the spring.

In fields which are to be saved for seed a wise precaution is to go over
them early in the spring and chop out the weeds. If wild onion and other
weeds are chopped off in April, they do not make enough growth by May to
contaminate the seed crop.




=MALADIES.=


The only disease seriously affecting crimson clover is the clover
stem-rot, root-rot, or wilt, a disease resembling the stem-rot, or wilt,
of lettuce and other plants. This disease is prevalent in nearly all
the crimson-clover States and sometimes does considerable damage. The
stem-rot affects the clover at all seasons, but is more noticeable in the
spring, when it sometimes causes large spots of clover suddenly to wilt
and fall. Occasionally an entire field is affected, but the disease is
most prevalent in low, rich spots. Examination of the plants discloses
a rotting off or decay of the stems close to the ground, followed
immediately by the appearance on the stems of small black lumps, or
sclerotia, about the size of clover seed. These sclerotia are a means of
spreading the disease and are often harvested in the hay or in the seed
crop. The only known remedy for the stem-rot is to cease growing clover or
alfalfa on an infested field for three or four years, substituting cowpeas
or soy beans. Seed from fields known to be infested should, of course, be
avoided.

No insects are known to affect crimson clover seriously, nor are weeds
of great importance in clover planted on clean fields. When planted in
cultivated crops or in poorly prepared ground crimson clover is often
seriously damaged by a rank growth of chickweed, knawel (moss weed),
winter cress, and other winter-growing annuals.


WASHINGTON : GOVERNMENT PRINTING OFFICE : 1920


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=Transcriber Note=

Minor typos have been corrected. Illustrations were moved to prevent
splitting paragraphs. Produced from files generously made available by
USDA through The Internet Archive. All resultant materials are placed in
the Public Domain.