BURR CLOVER

Burr Clover (Medicago maculata) is sometimes called Spotted Medick and sometimes California clover, also Yellow clover. The name burr clover has doubtless arisen from the closely coiled seed pod, which, being covered with curved prickles, adhere to wool more or less as burrs do. The name Spotted Medick has been given because of the dark spot found in the middle of the leaflets, in conjunction with the family of plants to which it belongs. The name California clover is given because of the claim that it was much grown in California after having been introduced there from Chili, and the name yellow clover, from the color of the blossoms. After its introduction into the United States, seedsmen sell California and Southern burr clover as two varieties, but the correctness of the distinction thus made has been questioned. Many persons were wont to confuse it with alfalfa, or, as it is frequently called, lucerne, but the latter is much more upright in its habit of growth, grows to a greater height, has more blossoms, blue in color, and seed pods more loosely coiled. It is also to be distinguished from a variety (Medicago denticulata) which bears much resemblance to it, and which, growing wild over portions of the plains and foothills of the West, affords considerable pasture.

Burr clover may properly be termed a winter annual, since the seed comes up in the autumn, furnishes grazing in the winter and spring, and dies with the advent of summer. It is procumbent or spreading and branched. On good soil some of the plants radiate to the distance of several feet from the parent root. They have been known to overlap, and thus accumulate until the ground was covered 2 feet deep with this clover, thus making it very difficult to plow them under. It is only under the most favorable conditions, however, that the plants produce such a mass of foliage. The leaves are composed of three somewhat large leaflets. The flowers, as previously intimated, are yellow, and there are but two or three in each cluster, but the clusters are numerous; hence, also the pods are numerous. They are about ¼ of an inch broad, and when mature are possessed of considerable food value.

Burr clover grows chiefly during the winter, and is at its best for pasture during the months of March and April, and in the Gulf States dies down after having produced seed in May. Though it is frequently sown, it has the power of self-propagation to a marked degree, which makes it possible to grow many crops in succession without re-seeding by hand.

It is not considered a good hay plant, but its value for pasture is considerable, although, as a rule, animals do not take kindly to it at first, as they do to alfalfa or medium red clover, but later they become fond of it, but less so, probably, in the case of horses than of other animals. Being a legume, it is helpful in enriching the land, and being a free grower, it improves the soil mechanically through its root growth, and also through the stems and leaves, when these are plowed under.

Distribution.—Burr clover is said to be native to Europe and North Africa, but not to North America, although it has shown high adaptation in adapting itself to conditions as found in the latter.

Although this plant is hardy in the South, and, as previously stated, makes most of its growth in the winter, it is not sufficiently hardy to endure the winters far northward. Its highest adaptation is found in States around the Gulf of Mexico. It also grows with more or less vigor as far north as North Carolina, Tennessee and Arkansas. For these States its adaptation is, on the whole, higher than crimson clover, although where the latter will grow readily it is considered the valuable plant of the two.

For Canada, burr clover has no mission, owing to the sternness of the winter climate in that country.

Soils.—While burr clover will grow with more or less success on almost any kind of soil possessed of a reasonable amount of fertility and moisture, it is much better adapted to soils alluvial in character and moist, as, for instance, the deposit soils in the bottom of rivers. Its power to fight the battle of existence on poor lands is much less than that of Japan clover, but on soils that grow crops, such as corn or cotton, it may be made to render a service which the other cannot, since it grows chiefly in winter and early spring, whereas Japan clover grows in the summer and early autumn, when cultivated crops occupy the land.

Place in the Rotation.—Burr clover is grown more in the sense of a catch crop and for pasture than in that of a crop to be marketed directly. Since it is grown in the winter and spring, it may be made to come in between various crops. On good producing lands of the South it has given satisfaction as a pasture plant for winter for many successive years without re-sowing by hand, when sown in conjunction with crab grass (Panicum sanguinale) for hay. Dr. Phares grew it thus in Mississippi for about 20 years. In June crab grass sprang up on the ground, and being cut when in blossom, produced a good crop of hay in August. A lighter cutting was again taken in October. The clover then took possession of the land and was grazed until spring, but not so closely as to prevent re-seeding in May, after which the plants died down.

By thus allowing the plants to mature seed, any crop may follow that can be grown after May. By following burr clover with cow peas, land may be much fertilized in one year. By reversing the process on land low in fertility, that is, sowing the peas first and the clover later, a much better growth of the clover will be secured. The seed may also be sown in corn and cotton crops, with a view to enriching the land. But it is only in the Gulf States that much attention is given to growing burr clover thus, and for the reason, probably, that the winters are too cold to admit of the plants furnishing a sufficiency of grazing at that season.

Burr clover is sometimes grown with Bermuda grass. The latter furnishes summer grazing. There is some merit in the plan, if the seed of the burr clover were sown from year to year. When the re-seeding of the plants is depended on from season to season there is difficulty in adjusting the grazing so as to admit of the plants properly re-seeding for the growth that is to follow. If the Bermuda grass is not closely grazed many of the burrs which contain the seeds may not reach the ground in time to germinate.

Preparing the Soil.—Since burr clover has much power to re-seed the land without preparation, it is more commonly reproduced thus. But, as with all other plants, it will grow more quickly and more luxuriantly on a well-prepared seed-bed, where it may be thought worth while to thus prepare the land. The cultivation given to such crops as corn, cotton or cow peas makes an excellent preparation of the soil on which to sow burr clover.

Sowing.—Usually, burr clover is allowed to re-seed itself after it has once become established in the soil. In this respect it is not unlike small white clover and Japan clover, but it does not grow so well as these on poor soil. Where not yet established, it must, of course, be sown where it is desired to grow it.

The seed is commonly sown in September or early October, but some growers recommend sowing in the burrs as early as June or July, that the tough surrounding which encloses the seed may have time to decay. When seed separate from the burr is used, it is sown in the months named. When sown on well-prepared soil, grazing should be plentiful from February onward.

Burr clover is more commonly sown in the burr. The burrs are usually scattered by hand and on land that has been pulverized, but it is easily possible, when the conditions are favorable, to obtain a stand on land that has not been plowed. Where seed is scarce, the burrs are sometimes planted in squares 3 feet apart each way, a limited number of burrs being dropped at one time. When thus planted, 1 bushel of burrs will plant several acres. The plants will soon possess all the ground, but to enable them to do so, pasturing must be deferred for one season. Whether sown in the burr or otherwise, it is better to cover the seed with the harrow.

One bushel of burrs weighs from 10 to 12 pounds. It has been stated 1 bushel of clean seed weighs 60 pounds. When sown in the burr, it is usual to sow 3 to 5 bushels per acre, but in some instances less is sown and in some more. When seed apart from the burr is sown 12 pounds per acre should suffice. In some instances it is sown on Bermuda sod, but the attempts to grow it thus have not always proved satisfactory. At the Louisiana Experiment Station it was found that the burr clover remained long enough and grew large enough to injure the Bermuda. Possibly closer grazing would have prevented such injury. When sown on Bermuda grass, June, July or August are the months chosen for scattering the seed.

Burr clover is also sometimes sown in corn and cotton to provide winter grazing, but when thus sown the object more frequently sought is to enrich the land. Both ends may be accomplished in some degree.

Pasturing.—Opinions differ as to the palatability of this grass. All are agreed that stock do not take kindly to it at first, but that they come to relish it at least reasonably well when accustomed to it. It is said to be relished less by horses and mules than by other domestic animals. It has been praised as a pasture for swine. It is more palatable in the early stages of its growth, and will bear close grazing, and also severe tramping. It will provide pasture for six months, but not so bountifully in the first months of growing as later.

Harvesting for Hay.—Burr clover is not a good hay plant. Owing to the recumbent character of the growth it is not easily mowed, nor has it much palatability in the cured form. The yield is said to be from ½ to 1 ton per acre.

Securing Seed.—In the Gulf States the seed matures in April and May. The plants grow seed profusely. Sown in October, stock may usually be allowed free access to it until March, and if then removed, it will spring up quickly and mature seed so profusely that when the plants die and partially decay seed may sometimes be collected in hollows, into which it has been driven by the wind. It is more commonly sown in the burr form, the form in which it is usually gathered. The more common method of saving the seed, as given by Mr. A. H. Beattie of Starkville, Mississippi, is to first rake off the dead vines so as to leave the burrs on the ground and then sweep them together with a suitable wire or street broom. It is then lifted and run through two sets of sifters of suitable mesh by hand to remove the trash swept up in gathering the seed. It is probable that other methods more economical of labor are yet to be devised when harvesting the seed crop. As much as 100 bushels of burrs have been obtained from an acre, but that is considerably more than the average yield of seed.

Renewing.—Since this plant is an annual, it cannot be renewed in the sense in which renewal is possible with a perennial. But as has been shown above (see page 294), it may be grown annually for an indefinite period in the same land and without re-sowing by hand. It has also been shown that by sowing the seed in certain crops at the proper season, from year to year, it may be made to grow from year to year where the rotation will admit of this. (See page 295.) When the ground is well stored with seed, the plants will continue to come up freely in the soil for at least two or three years, even without any re-seeding of the land.

As a Fertilizer.—The growing of burr clover exercises a beneficial influence on the land. Its value for this purpose, since it can be grown as a catch crop, is probably greater than its value in providing food for stock. Like all plants that are more or less creeping in their habit of growth, it shades the soil and keeps it moist, which, in conjunction with the influence of the roots, puts it in a friable condition. When the plants grow rankly, it is not easy to bury them properly with the ordinary plow, but in such instances, if cut up with a disk harrow, the work is facilitated. The plants quickly die down so as to make plowing easily possible, but the aim should be to have such decay take place within the soil rather than above it.