Part 2

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.

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.

=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.

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

* * * * *

=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.