SWEET CLOVER

Sweet clover is so named from the sweet odor which emanates from the living plants. It is of two species. These are designated, respectively, Melilotus alba and Melilotus officinalis. The former is also called Bokhara clover, White Melilot and Tree clover. It is possibly more widely known by the name Bokhara than by any other designation. The latter is sometimes called Yellow clover. The difference between these in appearance and habits of growth does not seem to be very marked, except that the blossoms of the former are white and those of the latter are yellow.

Sweet clover is upright and branched in its habit of growth. It attains to a height of from 2 to 8 feet, according to the soil in which the plants grow. The somewhat small and truncate leaves are not so numerous, relatively, as with some other varieties of clover, and the stems are woody in character, especially as they grow older. The blossoms are small and white or yellow, according to the variety, and the seed pods are black when ripe. The roots are large and more or less branched, and go down to a great depth in the soil; especially is this true of the main, or tap root.

The plants, according to Beale, are annual or biennial, but more commonly they are biennial. They do not usually blossom the year that they are sown, but may blossom within a year from the date of sowing. For instance, when sown in the early autumn, they may bloom the following summer. They are exceedingly hardy, having much power to endure extremes of heat and cold, and to grow in poor soils and under adverse conditions. In some soils they take possession of road sides and vacant lands, and continue to grow in these for successive years. The impaction of such soils by stock treading on them seems rather to advance than to hinder the growth. They start growing early in the spring and grow quickly, especially the second year. They come into bloom in June, early or later, according to the latitude, and ordinarily only in the year following that in which they were sown. Because of the fragrant odor which is emitted from the plants as they grow, they are sometimes introduced into gardens and ornamental grounds.

The uses of the plants are at least three. It has some value as a food for live stock. It has much value as a fertilizer. It has probably even more value as a food for bees. It has also been used in binding soils. Its value as a food for stock has probably been overestimated. It is bitter, notwithstanding the fragrant odor that emanates from it; hence, it is not relished by stock, insomuch that they will not eat it when they can get other food that is more palatable. As hay, it is hard to cure and of doubtful palatability when cured. As a fertilizer, its value does not seem to have been sufficiently recognized, and the same is probably true of it as bee pasture, although many bee-keepers are alive to its great merit for such a use.

This plant does not seem to find much favor with many. The United States Department of Agriculture has spoken of it as a "weedy biennial, concerning which extravagant claims have been made." The laws of some States proscribe it as a weed, and impose penalties directed against any who allow it to grow. Legislatures should be slow to class a legume as a weed, especially one that has much power to enrich soils. The author cherishes the opinion that this plant has a mission in the economy of agriculture and of considerable importance to farmers, especially in soils that are poor and worn, as soon as they come to understand it properly.

Distribution.—Sweet clover is probably indigenous to the semi-arid regions of Asia. The name Bokhara would seem to indicate as much, but it is also found in many parts of Europe, and if the facts were known, was doubtless brought from Europe to North America by the first settlers. For many decades it has been represented in many flower gardens in all parts of the country.

The plant will endure almost any amount of cold when it is once established. It has stood well the winters of Manitoba. It can also endure extreme summer heat, since it thrives well in some parts of Texas. It grows most vigorously where the rainfall is abundant, as in Western Oregon, and it makes a strong growth in the dry areas of Western Kansas and Nebraska.

Sweet clover will grow vigorously in some part or parts of every State in the Union. Of course, it has higher adaptation for some conditions than others. In some of the Central and Southern States, it has multiplied to such an extent without cultivation as to have assumed the character of a weed; hence, the legislation against it. When it is called to mind that this plant is a legume, and when the further fact is recognized that it may be used not only in enriching soils, but at the same time improving them mechanically, in addition to other benefits that it may be made to render, surely the enactments which prohibit its growth should be repealed in any State where these exist. In the Northern States, with a normal rainfall, the mission of this plant is likely to be circumscribed, for the reason that other legumes possessed of a much higher food value may be grown in these. In the Southern States, its mission will be more important, since it may be used in some of these with decided advantage in binding soils and in renovating them, even when too poor to produce a vigorous growth of cow peas. It is likely also that it may yet be made to render good service in the semi-arid country west of the Mississippi River, where other clovers cannot be grown.

Sweet clover will grow in all the provinces of Canada. For economic uses, however, it is not likely to grow to any great extent east of Lake Superior, or west of the Rocky Mountains. Other legumes more useful may be grown in these areas. But in the intervening wheat-growing region it is possible that it may come to be used for purposes of soil renovation.

Soils.—But little can be gleaned from American sources on this subject. Notwithstanding, it may be said with safety that it has greater power to grow on poor, worn and hard soils than any forage plant that has yet been introduced into America for economic uses.

It will probably be found true of it, as of other clovers, that it will thrive best on soils that have produced timber, and more especially timber of the hardwood varieties. This means, therefore, that it will grow well in probably all kinds of clay soils and also in loam soils underlaid with clay. It has high adaptation for soils abounding in lime. It can be made to succeed on hard clay subsoils from which the surface soil has been removed. But it will also grow well on sandy soils and even on gravels when a reasonable amount of moisture is present. The author succeeded in growing it in good form in 1897 and 1898 in a vacant lot in St. Paul, from which 6 to 8 feet of surface soil had been removed a short time previously. The subsoil was so sandy that it would almost have answered for building uses.

This clover will probably grow with least success on soils of the prairie so light in texture as to lift with the winds, and in which the underlying clay is several feet from the surface, also in slough soils that are much saturated with water.

Since it grows vigorously on road sides, in rocky waste places and even in brick yards when sown without a covering, the idea has gained currency that the harder the soil, the better the plants will grow, and the more surely will they be established in the soil; but this view does not seem to be in accord with the principles which usually govern plant growth. It will, however, send its roots down into hard subsoils so deeply that in certain seasons the plants could not be dug up without the aid of a pick.

Place in the Rotation.—Since sweet clover seed is more commonly scattered in byplaces, or is self-sown from plants that have run wild, it can scarcely be said that it has ever been grown as a regular crop and in a regular rotation. Nor is it ever likely to become a factor in such a rotation unless its properties shall be so modified that it can be grown acceptably as a pasture plant. In such an event it would have the same place in the rotation as other clovers; that is, it would naturally follow a cultivated, that is, a cleaning crop, and precede some crop or a succession of crops that would profit from the nitrogen and humus which it had brought to the soil, and also from the influence which the roots would exercise mechanically upon the same. But the necessity for sowing it on clean ground would not be so great as with the other clovers, since it has greater power than these to overshadow weeds when the two grow together.

In the meantime, this plant will probably continue to be grown as in the past; that is, if sown, it will be sown: 1. In byplaces to provide pasture for bees, in which case in time it will be superseded by other plants. 2. On worn lands so poor that they refuse to grow valuable food products sown, partly, at least, with a view to renovate them. And 3. In cuttings made by railroads and in gullies that have been made in fields, with a view to prevent soil movement. It may also come to be sown in grain crops in localities where other varieties of clover will not grow, to be plowed under the following spring.

Preparing the Soil.—Since sweet clover will grow on the firmest and most forbidding soils, even when self-sown, it would not seem necessary, ordinarily, to spend much time in specially preparing a seed-bed for it. The fact stated is proof of its ability to grow on a firm surface. It does not follow, however, that such a condition of the seed-bed will give a better stand of the plants than a pulverized condition of the same, as some have contended. It may be that on soils that are quite loose near the surface, and under conditions that incline to dry a seed-bed firm and even hard, may be more conductive to growth in the plants than one in which the conditions are the opposite. Much rolling of loose soils has been recommended when preparing the seed-bed with a view to firm them.

When the seed is sown along with grain, the preparation of the soil needed for grain would be ample preparation also for the clover. When sown on stubble land, in many instances no preparation by way of stirring the soil would seem necessary. And when sown on railroad embankments, road sides, rocky situations and byplaces generally no preparation of the soil would be possible.

Sowing.—In the North sweet clover is best sown in the spring. In fact, it can only be sown then with the assurance that it will survive the winter north of a certain limit. That limit will vary with altitude, but it will probably run irregularly across the Middle States, from the Atlantic westward to the Cascade Mountains, beyond which it will veer away to the North. In the Southern States, it may be sown fall or spring, but if sown late in the fall the young plants will in some instances succumb to the frost of winter. Early fall sowing, therefore, is much to be preferred to sowing late.

The method of sowing may be the same as in sowing medium red clover (see page 78); that is, when the seed is sown with grain crops. When sown in byplaces, it will ordinarily be sown by hand. In such places it will re-seed itself and will likely grow in these for successive seasons. On railroad embankments, the seed is scattered more commonly on the upper portion, and from the plants which grow there the seeds produced scatter downward. The plants not only lessen washing in the soil, but they prepare the same for the growth of grasses. They also aid thus in the introduction of grasses into rocky and very hard soils.

Sweet clover may be sown with almost any kind of a nurse crop desired, which does not destroy it with an over-abundant shade. Or it may be sown alone where such a necessity exists. But the instances are not numerous in which it would be desirable or necessary to sow it alone on arable soils. There may be conditions when it could be sown successfully at the time of the last cultivation given to corn and with a view to soil enrichment.

Since sweet clover is seldom sown for the purpose of providing food for live stock, it is not sown in mixtures, nor is it well adapted for being sown thus, because of the large and luxuriant character of the growth, which would tend to smother other plants sown along with it.

The amount of seed to sow has been variously stated at from 15 to 20 pounds per acre. The smaller amount should be enough for almost any purpose, and a much smaller amount should suffice for sowing in byplaces and along road sides, where the plants retain possession of the ground through self-seeding.

Pasturing.—Because of the bitter aromatic principle which it contains, known as commarin, stock dislike it, especially at the first. And it is questionable if they can be educated to like it in areas where other food, which is more palatable, grows abundantly. In an experiment directed by the author at the Minnesota University Experiment Station, sheep pastured upon it, and did not take kindly to it; but by turning them in to graze upon it in the morning, they cropped it down. In localities where good grazing is not plentiful, if live stock have access to it, especially when the plants are young, they will so crop it down that in a few years it will entirely disappear. But where other pastures are abundant, it will continue to grow indefinitely. It would not seem wise to sow it for the purpose of providing grazing, unless where the conditions for growing other and better grazing are unfavorable.

Some have spoken favorably of sweet clover for soiling uses. It makes a very rapid growth quite early in the season, and when cut and wilted more or less before being fed, the palatability is thereby considerably increased. Small plots of this plant near the outbuildings may in this way be utilized with some advantage in the absence of better soiling plants.

Harvesting for Hay.—Sweet clover is not a really good hay plant under any conditions, and if not cut until it becomes woody, is practically valueless for hay. It ought to be cut for hay a little before the stage of bloom. If cutting is longer deferred, the plants become woody. Such early cutting, however, adds much to the difficulty of curing the crop, since, while naturally succulent, its succulence is then, of course, considerably more than at a later period. It should be cured like medium red clover. (See page 96.) If not cut sufficiently early, and cured with as much care as is exercised in curing alfalfa, there will be considerable loss from the shedding of the leaves.

More commonly the plants are not cut for hay the year that they are sown, but some seasons such harvesting is entirely practicable in certain situations. The hay crop or crops are usually taken the second year. Sometimes the crop is cut twice. It is entirely practicable to obtain two cuttings under ordinary conditions, because of the vigor in the growth, and because of the early season at which it must be harvested for hay. From 3 to 4 or 5 tons may thus be obtained in many instances from the two cuttings.

Securing Seed.—Nearly all of the seed sown in this country is imported. The author has not been able to obtain information with reference to growing seed within the United States; hence, the inference is fair that but little of it has been grown for that purpose up to the present time. Since, however, it seeds freely, and since the price of seed is high, seed crops, more especially when the plants are also utilized as bee pasture, ought to prove remunerative in the hands of judicious growers.

The seed crop is obtained usually, if not always, the second year after the sowing. If cut for hay before coming into bloom, it will grow up again and bear seed profusely. This would seem preferable on strong soils, as it would prevent that rankness in growth which would militate against abundant seed production, and which would add much to the labor of handling the crop.

The seed crop may be cut and handled in substantially the same way as medium red clover when grown for seed. It may also be cured and thrashed essentially in the same way. (See page 105.) The author has not been able to obtain information with reference to the average yield of the seed crop under American conditions. The seed, like that of the medium red variety, should weigh 60 pounds per bushel.

Renewing.—In the sense of a pasture or hay crop, it would not seem necessary to try to renew this crop, because of the relatively low value which it possesses for these uses. When grown for bee pasture, it will renew itself for an indefinite period when the plants are not cut for seed and where the conditions are favorable to growth. When grown to keep soils from washing or railroad embankments from breaking down, it will, of course, renew itself in the same way. In time, however, it is usually superseded by some kind of grass, for which it has prepared the way by the ameliorating and renewing influence which it exerts upon the soil.

Value for Bee Pasture.—All authorities are agreed as to the high value of this plant as a honey producer. The claim has been made for it that for such a use it is more valuable acre for acre than any ordinary grain crop. By cutting a part of the crop before it comes into bloom, the season of honey production may be prolonged from, say, July 1st until some time in the autumn, as the part thus cut will come into bloom after the blooms have left the plants that were cut. When not disturbed, sweet clover yields honey in the interval between the blooming of the basswood and the golden rod. The honey is of excellent quality. There should be no good reasons, therefore, why bee-keepers should not sow the seed in by and waste places. But the wisdom of growing it as a honey-producing crop on valuable land where other honey crops, as alsike and white clover, can be grown in good form may be questioned.

Value as a Fertilizer.—The high value of this plant as a fertilizer and soil improver cannot be questioned. But whether it should ever be sown for such a use will depend on the capacity of the soil to produce other crops valuable for fertilizing and also more valuable for producing forage or fodder. Where other clovers more useful can be grown, also cow peas, soy beans and other legumes valuable for food uses, it would seem unwise to sow sweet clover. This would restrict its use, therefore, as a soil renovator; first, to soils too poor to grow those useful legumes; second, to areas where the climate conditions will not admit of the growth of these; and third, to areas from which the surface soil has been removed, and which it is desirable to so ameliorate and improve the soil thus laid bare that it could later be covered with some more valuable cover crop. Under present conditions this would restrict its growth for the purpose named to sandy and gravelly soils, to certain areas in the semi-arid region east of the Rocky Mountains, and to such small areas as the surface soil had been removed from.

In the semi-arid region where crops of grain and also some varieties of field corn can be grown successfully, but where the clovers are not successful; it would seem practicable to sow a few pounds of sweet clover seed per acre at the same time as the grains, and to plow under the plants produced some time in the month of May the next season. The clover thus buried could be at once followed by corn or potatoes, or, indeed, by any kind of a cleaning crop. The high price of seed at present practically forbids growing clover thus.

Whether sweet clover grown for renovating uses should be turned under the season in which it has been sown will depend largely on the growth that has been made. In many instances, the growth made is so rank as to justify plowing it under the following autumn. In other instances, better results will follow plowing it under the next season. It frequently happens that the growth made is so rank that a strong plow and also a strong team are necessary to do the work properly.

Value on Alkali soils.—This plant has been grown to some extent to aid in removing alkali from soils superabundantly impregnated with the same. It will grow, it is claimed, under certain conditions on such soils so surcharged with alkali as to prohibit almost every other form of vegetable growth. The extent to which it may be thus used profitably had not yet been fully demonstrated. But where it can be grown on such soils, the fact that it takes up and removes relatively large quantities of alkali would appear to be well established.

Destroying the Plants.—Should the conditions be found so favorable to the growth of the plant that it persists in growing where it is not wanted, it will soon cease to appear, if prevented from going to seed. Ordinarily, the blossoms appear only during the second year of growth. If, therefore, the plants are cut off when in bloom, seed forming will not only be prevented, but since sweet clover is a biennial, the plants will die. When thus dealt with, the only source from which other plants may come while extermination is being thus sought is from seed lodged in the soil and still capable of germinating.