Crimson Clover [1938]

Part 1

Transcriber Note

Emphasis is denoted as Italics and =Bold=.

=CRIMSON CLOVER=

LEAFLET No. 160

U.S.DEPARTMENT of AGRICULTURE

Issued June 1938.

=CRIMSON CLOVER=

By E. A. Hollowell, senior agronomist, Division of Forage Crops and Diseases, Bureau of Plant Industry

=Growth and Distribution=

Crimson clover (Trifolium incarnatum) is the most important winter annual legume of the central section of the Eastern States (fig. 1). Besides being an excellent hay plant and furnishing an abundance of early spring pasture, it affords protection to the soil during the fall, winter, and spring, prevents soil washing, and provides green manure for soil improvement. This legume has the distinct advantage of being a heavy producer of seed, which can be easily harvested and sown without the use of expensive machinery.

Crimson clover is a native of Europe and is widely grown in France, Hungary, and other central and southern European countries. Seed was introduced into this country as early as 1819, but it was not until 1880 that the plant became of agricultural importance. During the last 6 years the annual commercial consumption of seed in the United States has ranged from 2 to 4 million pounds. In addition, large quantities of home-grown seed are used and handled from farm to farm.

The common name of this clover is derived from the distinctive bright crimson color of the blossoms. Other common names, such as German clover and scarlet clover, are frequently heard in different localities. In general the leaves and stems of crimson clover resemble red clover, but are distinguished by the rounding of the tips of the leaves and a greater covering of hair on both leaves and steins. When it is planted in the fall the leaves develop from the crown and form a rosette, which enlarges whenever weather conditions are favorable. In late spring flower stems develop rapidly and terminate their growth with elongated flower heads. Seed forms and the plant dies with the advent of hot summer weather. The seed is yellow, slightly larger, and more rounding than red clover seed.

=Adaptation=

Crimson clover is adapted to cool, humid weather and is tolerant of winter conditions where the temperature does not become severe or too variable. In this region (fig. 1) it should be planted in late summer or early fall, since early establishment and growth are favorable to its winter survival. It will thrive on both sandy and clay soils and is tolerant of ordinary soil acidity. On extremely poor soils, stands are difficult to obtain and the growth is stunted. The use of manure and phosphate fertilizers on such soils will improve the chances of obtaining good stands.

Crimson clover may also be successfully grown as a summer annual in Maine, northern Michigan, and Minnesota. The winter culture of this clover may be extended into Kentucky, southern Missouri, and southern Indiana provided the seed is sown in fertile soil early in August. Production may be successfully extended southward with an increase of soil fertility and with seeding delayed until soil-moisture conditions are favorable.

=Seedbed Preparation=

The most important and difficult phase of successful production of crimson clover is getting a stand. Sufficient soil moisture to germinate the seed and to establish the seedlings is the greatest factor in obtaining a stand, which when established usually produces a good crop.

Seedings are usually made in late August or early September between the rows of cultivated crops. Under such conditions an ideal seedbed is difficult to prepare, therefore careful preparation is necessary. Furthermore, the crop plants in the row shade the clover seedlings and seriously compete with them for the available moisture. Increasing the distance between the rows and planting the row crop more thinly will afford better opportunity for the establishment of the clover. When planted between the rows of other crops, the seed is usually broadcast on the surface and covered by cultivating or harrowing (fig. 2). Drilling the seed after the soil surface has been stirred will usually give more complete stands than broadcasting, and it may be done with a small one-horse drill. The seed should not be planted more than one-half to three-fourths of an inch deep, respectively, in clay and sandy soils.

Crimson clover is often seeded following a grain crop, and this is a surer method of establishing a stand than planting between the rows of cultivated crops, providing the seedbed is well prepared. After the grain crop is removed the soil is plowed or disked and allowed to settle. This is followed by light harrowing or disking when necessary to kill weed seedlings. Before the clover is seeded the soil should be firmly packed, because a loose cloddy seedbed is the forerunner of failure. The seed may be either drilled or broadcast, but drilling will give more uniform stands.

=Fertilizers=

When the crop is planted on extremely poor soils, good stands and growth cannot be expected. Such soil conditions may be improved by the application of manure and phosphate fertilizers or by turning under such crops as cowpeas, soybeans, or lespedeza. In many soils of low fertility the use of 50 to 100 pounds per acre of a nitrogen fertilizer will encourage early seedling growth and establishment. On the fertile soils of this region crimson clover may be successfully grown without fertilizer, but on most soils applications of 200 pounds of phosphate fertilizer per acre are profitable in obtaining stands and vigorous growth (fig. 3). The use of potash is recommended when a deficiency is known to exist.

=Seed Sources=

Of the total amount of seed normally used approximately 60 percent is of foreign origin, coming principally from Hungary and France. Most of the domestic crimson clover seed offered on the market is produced in south-central Tennessee. While white-flowered strains and others differing in maturity have been isolated, they are little used. Claims have been made that locally grown seed is superior to seed from other sources including that of foreign origin. Further experiments are needed to determine whether such differences actually exist.

=Rate and Time of Seeding=

Under ordinary conditions 15 to 18 pounds of hulled seed will give good stands unless there is a deficiency of soil moisture. Depending upon the amount of foreign material 45 to 60 pounds of unhulled seed is comparable to a 15-pound seeding rate of hulled seed. Crimson clover may be sown from the middle of August until October 1 with the expectation of securing a good stand. The later it is seeded the less growth can be expected and the more readily winterkilling occurs. The early establishment of the plants becomes more important as plantings are extended northward. Seeding crimson clover, if possible, either immediately before or following heavy rains will increase its chances of making a stand. The spring planting of crimson clover in or south of the Corn Belt usually results in a short, stunted growth followed by meager blossoming and an unprofitable yield.

=Inoculation=

In many parts of the crimson clover region it is not necessary to inoculate the seed; but if clover has not been successfully grown on a soil, inoculation of the seed is good insurance. If the plants are not inoculated they will develop slowly, become yellow, and die. Inoculated plants are able to obtain about two-thirds of their nitrogen from the air through their root nodules. The plants may be artificially inoculated by applying pure cultures of the bacteria to the seed or by scattering soil from a field where inoculated crimson clover has been grown. Two hundred to three hundred pounds per acre of such soil evenly distributed at seeding time is sufficient.

=Unhulled Seed=

Part 2

The use of unhulled seed offers the distinct advantage of increasing the chance of obtaining thick stands. With the prevalence of dry soil conditions, light rainfall does not cause the unhulled seed to germinate, but hulled seed germinates readily and the seedlings may die from lack of moisture before they can become established.

Its bulky nature makes unhulled seed more difficult to distribute uniformly than hulled seed. It must be broadcast and may be harrowed in. It is also difficult to market and is not generally handled by the seed trade. But farmers can harvest seed for their own use and save the expense of having it hulled.

=Companion Crops=

Rye, vetch, Italian ryegrass, and fall-sown grain crops are often seeded with crimson clover. Besides making a valuable addition to the clover (fig. 4), these companion crops help bolster up a thin stand. Such crops are seeded from one-half to one-third the normal crop rate and the crimson clover is seeded at the normal rate. Planting is done at the same time, but, as a greater depth is required for most of the seed of the companion crops, two seeding operations are necessary. In Tennessee, farmers often use a mixture of 5 pounds of red clover and 10 pounds of crimson clover per acre with excellent results. The first growth of the mixture may be grazed or harvested for hay or for crimson clover seed, while the second crop is wholly red clover.

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