Chapter II: Part 2

The methods used for seeding red clover or alfalfa in any particular region will be suitable for seeding sweet clover. Good results have been obtained by broadcasting the seed on winter grain in the spring when the ground is in a honeycombed condition. Perhaps a better method is to wait until the ground can be worked and then to broadcast and cover the seed with a harrow or to sow it with a drill. Unhulled seed is usually broadcasted, since it is necessary to sow it before the ground is in condition to be worked. Unless the hulls have been rubbed smooth, some difficulty may be experienced in seeding it evenly with a drill.

When sweet clover is to be sown with spring-seeded grain or when it is to lie sown without a nurse crop it may be drilled in or sown broadcast and covered with a harrow. Better stands are generally obtained with a smaller quantity of seed when it is sown with the drill than when it is broadcasted on honeycombed ground. When the seed is sown at the time the grain is planted, the grass-seeder attachment of the drill commonly is used. In some sections the end-gate seeder is used almost entirely. When the seed is sown by either of these methods it may be seeded alone or mixed with the grain. When only the clover seed is sown with a drill, the alfalfa and clover seed drills are to be preferred.

Sweet-clover seed may be mixed with some inert substance of approximately the same size and weight and sown with an ordinary grain drill. Finely cracked corn, cracked wheat, or coarse bran often are used for this purpose. When one portion of sweet clover is mixed with two portions of a filler find the drill is set to sow one-half bushel of wheat, it will usually sow from 15 to 20 pounds of sweet clover to the acre. As this quantity will vary with the different types of drills, it is necessary to test each drill, so that the seed may be mixed with the filler in such proportions that the desired quantity will be sown. The drill may be tested by blocking it up, so that the geared wheel is off the ground, and this wheel may be turned a sufficient number of times to establish a definite portion of an acre. The seed that runs through can then be weighed and the rate per acre determined. The rate may be determined more accurately by plugging up the grain tubes or by tying a small sack on each tube and pulling the drill for a specific distance over the field to be sown. The jar of the drill will cause it to drop more seed than when it is blocked up and run by hand.

It is often desired to seed sweet clover on land which can not be cultivated. When sown on such land it is recommended that unhulled seed or seed that contains a large percentage of hard seed be used and that it be broadcasted during the winter. The subsequent freezing and thawing will cover many of the seeds and cause them to germinate. It is a good plan to scatter in deep gulleys mature plants that have not shattered all their seed. The branches of these plants will help to hold the seed in place until it germinates and the young plants become established.

Seed may be scattered on native prairie ground in the late winter, but unless it is trampled into the ground by live stock disappointing results are likely to be obtained at first. Fair results have been secured by planting seed with disk drills on prairie sod after it had been double-disked in the early spring. This method should be used in preference to broadcasting the seed and depending on cattle to trample it in. Mr. George Hummer, of Prairie Point, Miss., reports good success in his locality by simply broadcasting 1 peck of unhulled seed on Bermuda-grass sod not later than January 1.

INOCULATION.

Excepting soil acidity, lack of inoculation probably is responsible for more failures with sweet clover than any other one cause. When sweet-clover plants are not inoculated they must depend upon the available nitrogen in the soil for their supply, and as the crop is grown for the most part on soils low in nitrogen the plants can not be expected to make more than a small growth. (Fig. 9.)

Arny and Thatcher, at the Minnesota Agricultural Experiment Station, obtained 10 times as much dry matter in the tops and seven times as much in the roots of sweet-clover plants which had been grown on thoroughly inoculated soil as from plants Which had been grown on soil not inoculated. Moreover, the plants grown on the inoculated soil contained 117 pounds more nitrogen to the acre than those grown on the uninoculated soil.

Experiments in many other sections of the country, and especially in the northeastern quarter of the United States, where but little sweet clover or alfalfa has thus far been grown, show that inoculation is very essential to success. Ordinarily it is not necessary to inoculate sweet clover when it is to be planted on land where alfalfa, bur-clover, or black medic thrives, because the same strain of inoculating germs inoculates all of these plants. However, when this closer is to be planted on land where none of the plants inoculated by this strain of the organism have been grown, inoculation should be provided. In localities where sweet clover or other plants inoculated by the same strain of bacteria thrive, the early growth has at times been made much more vigorous by inoculating the soil or seed thoroughly.

It is not safe to assume that a certain piece of soil is inoculated because any one of the plants inoculated by the same strain of the organism is growing or has been grown on other fields in the same vicinity. Many fields have come under observation where sweet clover was a failure because the plants were not inoculated, when plats or fields of alfalfa growing near by were abundantly inoculated.

There are several methods of inoculating sweet clover, any one of which when properly applied should give good results.

THE SOIL-TRANSFER METHOD.

The soil-transfer method of inoculation consists in scattering over the field to be seeded 200 to 400 pounds to the acre of soil collected from sweet-clover, alfalfa, or bur-clover fields where the healthy plants show an abundance of tubercles on the roots. It is strongly recommended that this soil be scattered on a cloudy day or in the early morning or in the evening and immediately harrowed or disked into the ground, as the sun's rays are very injurious to the inoculating germs. It is a good plan for the person scattering the soil to walk directly in front of the harrow. When this practice is followed little harm can be done by the light. To facilitate even scattering, the soil may be mixed thoroughly with two or three times its weight of other soil, preferably from the field where the sweet clover is to be sown. Soil used for inoculating sweet clover does not necessarily have to be scattered on the land just previous to sowing the seed. It may be scattered a few months or a year in advance of the time the sweet clover is to be seeded and be just as effective as if it were scattered at a later time. In general, where sweet clover is to be seeded in the spring on winter grain, the inoculation should be applied before the grain is sown.

Good success has been obtained by drying in a dark place soil containing the inoculating germs, sifting it, and running it through the fertilizer compartment of a grain drill. When this method is employed it is not necessary to use as much soil as when it is scattered broadcast.

A comparatively new method which has given successful results calls for dampening each bushel of seed and spreading it on a cloth, paper, or cement floor, where half a gallon of throughly inoculated soil from sweet-clover or alfalfa plants may be sifted over it. Some people prefer to add a trace of glue or sugar to water, so that more of the soil will adhere to the seed, although some soil will remain on the seed if the glue or sugar is not used. When only this quantity of soil is used it should be collected from around the roots of sweet-clover plants which are abundantly inoculated. Such soil may be collected in the fall and kept until spring in a cool, dry, dark place with no injury to the inoculating organisms. Seed treated in this manner should be kept in the dark and should be sown as soon as possible after treating.

THE PURE-CULTURE METHOD.

The pure-culture method has the advantage of greater case of transportation and freedom from danger of introducing harmful pests upon the farm. Inoculation by pure cultures may be carried out in either of two ways:

(1) A bottle of pure culture of the proper kind of bacteria is opened and the culture mixed with a convenient quantity of water; this diluted culture now is mixed thoroughly with a considerable quantity of soil, preferably from the field where the legume is to be sown; the treated soil is then distributed in the same manner as when inoculation is made by the soil-transfer method.

(2) A pure culture of the proper kind of bacteria should be applied to the seeds in such a way that they will all be moistened. The seed should then be permitted to dry in a shady or dark place and should be planted as soon as possible after it is dry. Drying may be facilitated by adding dry, sifted soil, preferably from the field where the seed is to be sown. Inoculating organisms very often die within a week after the seed is inoculated. It is highly desirable, therefore that the inoculation be made the day the seed is sown. Inoculated seed never should be dried in the sun.

The question is often asked whether it is advisable to inoculate seed with pure-culture method and sow it on honeycombed ground in the spring. No experiments have thus far been completed to determine the advisability of this procedure. Some inoculation would probably result from this practice, because the bacteria on that portion of the seed next to the ground would be protected from the sunlight and would in a short time under ordinary conditions be covered by the freezing and thawing of the soil. While it is hardly possible to obtain as complete inoculation by this practice as by other methods, it is to be preferred to no inoculation.

TREATMENT OF THE STAND.

The manner in which a stand of sweet clover is handled should depend somewhat upon the method and date of seeding and the purpose for which it is sown. Climatic conditions should also be taken into consideration and the handling of the crop governed accordingly.

TREATMENT THE FIRST SEASON.

The most serious objection to seeding sweet clover in the spring without a nurse crop is weeds. In many sections of the country seeds will take as much water from the soil and make as much or more shade than a crop of grain. In spite of the fact that sweet clover will withstand more adverse conditions than red clover or alfalfa, a heavy growth of weeds will greatly retard the growth of the plants and in some cases kill most of them. (Fig. 10.) On plats sown in April without a nurse crop at Arlington, Va., it was necessary to mow weeds five times during the summer of 1915 in order to keep them partly checked. Where it is necessary to mow a field so many times the plants are not only checked or killed, but as much time is required for this work as would be necessary to harvest a crop of grain. This trouble may be overcome in part by pasturing the sweet clover the first season, but even then during wet weather it may be necessary to cut the weeds at least once before the plants become well enough established to turn live stock on the field. The plants should at no time be clipped closer than 5 inches from the ground.

After a field of sweet clover has become well established, it may be pastured throughout the summer and fall. Close grazing should be avoided during the summer, or the plants may be killed, but they may be pastured fairly close to the ground in the autumn, as it does not appear as necessary to provide a winter covering as is the case with red clover. Close pasturing or clipping late in the fall has had a marked effect on the growth of the plants the following spring on some fields and no apparent effect on the stand and growth of the plants on other fields. A portion of a field in Livingston County, Ill., was clipped close to the ground in the late fall of 1915. On June 1, 1916, the stand was somewhat heavier on the unclipped part of the field. More noticeable than the thickness of the stand was the fact that the plants on the unclipped portion were 8 to 10 inches higher than those on the clipped area. It is reasonable to believe that plants going into the winter with no protection are more likely to be injured than those having some protection.

On the other hand, many fields in different parts of the country have been closely clipped or pastured in the late fall with no noticeable injury. Because of the value of the hay or pasturage in the late summer and autumn of the year of seeding, it is strongly recommended that the first year's growth be utilized. If the field be cut for hay it is well to leave a 4-inch or 5-inch stubble, as this will serve to catch drifting snow during the winter, thereby adding to the protection against winterkilling. If the field is not pastured the first season and weeds are not troublesome, a cutting of hay may be made when growth ceases in the fall.

When sweet clover is seeded with grain, moisture conditions should serve to determine whether the grain should be permitted to ripen or be cut for hay. When untimely droughts appear the plants may be killed if the grain is not cut as early as possible.

In the South and in some sections of the Eastern and North-Central States where the soil contains an abundance of limestone and is well inoculated, a cutting of hay may usually be obtained after a grain crop has been harvested. In other sections of the North in only exceptionally favorable weather will more than pasturage be obtained after the grain is cut.

TREATMENT THE SECOND SEASON.

One of the special advantages of sweet clover is that it produces good pasturage somewhat earlier in the spring than most forage crops. In the North, with the exception of the extreme northern portion of the United States, it will furnish a cutting of hay in June or excellent pasturage until that time and a crop of hay or seed in late summer. In the South two cuttings of hay and a seed crop may be harvested. After maturing seed the plants die. It is a common practice in many sections to pasture the crop until about June 10, when the stock is removed and the plants are permitted to mature seed. If the plants have not been grazed closely they should be clipped at this time, so that the seed crop will ripen more evenly. Sweet clover may be pastured during the entire second season's growth, provided sufficient stock is kept on the field to prevent the growth from becoming woody. If the plants become coarse the pasture may be clipped, leaving an 8-inch stubble, so as to induce a new growth which will be more palatable. If it is desired to have the pasture reseed itself stock should be removed at least eight weeks before heavy frosts are expected, or only sufficient stock should be permitted to remain on the pasture to keep some of the plants in check.

SWEET CLOVER IN MIXTURES.

Very little sweet clover thus far has been grown in mixtures with other crops. A few farmers have sown red clover and sweet clover together, but such a mixture has no advantage over sweet clover seeded alone for hay, as sweet clover should be cut at least two Weeks before the red clover is ready to harvest. Sweet clover is being seeded to some extent on native prairie sod in the Northwest, where it is claimed it adds greatly to the value of the native grasses for pasturage. A thin seeding of sweet clover is often desired in bluegrass pastures on this account. One of the best pastures in eastern Iowa consists of a mixture of bluegrass, timothy, and sweet clover. The Mississippi Agricultural Experiment Station recommends a mixture of Johnson grass and sweet clover. In this mixture the first cutting will consist of almost pure sweet clover, while the second and third cutting's will be a mixture of those plants. A number of southern farmer have had good success in seeding sweet clover on Bermuda-grass sod.

The New Jersey Agricultural Experiment Station has obtained excellent results from a mixture of Dwarf Essex rape and sweet clover, and also by the addition of soy beans to this mixture. It was found that by seeding 6 pounds of rape and 10 pounds of sweet clover per acre an abundance of nutritious pasturage was produced and that pigs preferred this mixture to alfalfa. When soy beans were added it was seeded at the rate of 1 bushel of soy beans, 6 pounds of Dwarf Essex rape, and 18 pounds of sweet clover. The soy beans were drilled by themselves, and the rape and sweet clover were mixed and seeded with a press drill. Brood sows made a gain of from three-fourths to 1 pound a day during July on this mixture without additional feed and gave unusual evidence of thrift and vigor.

ERADICATION OF SWEET CLOVER.

Some farmers hesitate to plant sweet clover on their farms for fear they will have difficulty in eradicating it when the fields are planted to other crops. The results obtained annually by hundreds of farmers are sufficient proof that there is no foundation for such fear; in fact, farmers are experiencing much difficulty in cutting the first crop the second season so high that the plants will not be killed. The new crop of sweet clover, unlike that of red clover and alfalfa, must come from the buds left on the stubble, so when the plants are cut below these buds they will be killed. As sweet clover is a biennial, the plants die as soon as the seed crop is produced.

When the first year's growth of sweet clover is to be turned under for green-manure it is recommended that the field be plowed after the plants have made some growth the following spring rather than in the fall of the year of seeding. When the first year's growth is plowed under the same fall many of the plants will not be entirely covered, and these will made a vigorous growth the following spring. When the plowing is delayed until the plants have made some growth the following spring no trouble will be experienced in eradicating them. (Fig. 11.)

* * * * *

PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE RELATING TO FORAGE CROPS.

AVAILABLE FOR FREE DISTRIBUTION BY THE DEPARTMENT.

Cowpeas. (Farmers' Bulletin 318.)
Alfalfa. (Farmers' Bulletin 339.)
Soy Beans. (Farmers' Bulletin 372.)
Red Clover. (Farmers' Bulletin 455.)
Alfalfa Seed Production. (Farmers' Bulletin 495.)
Forage Crops for the Cotton Region. (Farmers' Bulletin 509. )
Vetches. (Farmers' Bulletin 515.)
Vetch Growing In the South Atlantic States. (Farmers' Bulletin 529.)
Crimson Clover: Growing the Crop. (Farmers' Bulletin 550.)
Crimson Clover: Seed Production. (Farmers' Bulletin 646.)
The Field Pen as a Forage Crop. (Farmers' Bulletin 690.)
Bur Clover. (Farmers' Bulletin 693.)
Button Clover. (Farmers' Bulletin 730.)
The Clover leafhopper and Its Control in the Central States.
(Farmers' Bulletin 737.)

FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING OFFICE, WASHINGTON, D. C.

Leguminous Crops for Green Manuring. (Farmers' Bulletin 278.) Price,
5 cents.
Lespedeza, or Japan clover. (Farmers' Bulletin 441.) Price, 5 cents.
Crimson Clover: Utilization. (Farmers' Bulletin 579.) Price, 5 cents.
Alfalfa Production: Pollination Studies. (Department Bulletin 75.)
Price, 5 cents.
Red-Clover Seed Production: Pollination Studies. (Department Bulletin
289.) Price, 5 cents.
Variegated Alfalfa. (Bureau of Plant Industry Bulletin 169.) Price,
10 cents.
Leguminous Crops for Hawaii. (Hawaii Agricultural Experiment Station
Bulletin 23.) Price, 10 cents.

WASHINGTON : GOVERNMENT PRINTING OFFICE : 1917

* * * * *

Transcribers Note

All illustrations moved to avoid splitting paragraphs. Sweet clover and sweet-clover variants retained.