in any part of the United States or Canada in which moisture is sufficiently present. Japan and burr clover grow best south of parallel 37° and east of longitude 98°. Sweet clover will grow in all the States and provinces of the United States and Canada, but has highest adaptation for the Central and Southern States.

With reference to adaptation to soils, medium and mammoth clover grow best on upland clay loam soils, such as have sustained a growth of hardwood timber, and on the volcanic ash soils of the Western mountain valley. Alfalfa flourishes best on those mountain valley soils when irrigated, or when these are so underlaid with water as to furnish the plants with moisture. Alsike clover has much the same adaptation to soils as the medium and mammoth varieties, but will grow better than these on lowlying soils well stored with humus. Crimson clover has highest adaptation for sandy loam soils into which the roots can penetrate easily. Small, white clover has adaptation for soils very similar to that of alsike clover. Japan clover and burr clover will grow on almost any kind of soil, but on good soils the growth will, of course, be much more vigorous than on poor soils. Sweet clover seems to grow about equally well on sandy loams and clay loams, but it has also much power to grow in stiff clays and even in infertile sands.

Place in the Rotation.-All the varieties of clover discussed in this volume may be grown in certain rotations. Their adaptation for this use, however, differs much. This increases as the natu

ral period of the life of the plant lessens and vice versa. Consequently, the medium red variety, the mammoth, the crimson, the Japan and the burr varieties stand high in such adaptation. The alsike, living longer, is lower in its adaptation, and alfalfa, because of its long life, stands lowest in this respect. The small, white variety is almost invariably grown or found growing spontaneously along with grasses, hence no definite place has been or can be assigned to it in the rotation. Sweet clover being regarded by many as a weed has not had any place assigned to it in a regular rotation, although in certain localities it may yet be grown for purposes of soil renovation. (See page 306.)

All these crops are leguminous without any exception. This fact is of great significance where crops can be rotated. They have power to gather nitrogen from the air and store it in the soil in tubercles which form on their roots, in all soils in which they produce a vigorous growth. This fact indicates where they should come in the rotation. They should be grown with a view to gather food for other crops made to follow them, which have not the same power. They should, therefore, be made to precede such crops as the small cereals, corn, the sorghums, the millets and cotton. But since these clover plants have the power to bring nitrogen from the air, it must not be supposed that they will grow with sufficient vigor in soils destitute of this element. They must be able to appropriate enough from the seed soil to give them a good start before they can draw nitrogen from the air, hence, though they may

be made to follow almost any kind of crop, it may sometimes be necessary to apply some nitrogenous fertilizer before they will make a vigorous growth.

The clovers, unless in the case of some of the smaller varieties, are more commonly sown to provide hay than pasture in the first crops obtained from them. The value of the hay is increased or lessened in proportion as weeds are present. To insure cleanliness in the hay crop, therefore, the system which aims to sow clover seed on land to which clean cultivation has been given while growing on them a cultivated crop, as corn or field roots, meets with much favor. The mechanical condition of the soil immediately after growing these crops also favors the vigorous growth of the young clover plants, more especially when they are sown upon the surface of the land after some form of surface cultivation, rather than upon a surface made by plowing the land after cultivation has been given to it, but to this there may be some exceptions.

Clover in some of its varieties is frequently grown from year to year in orchards and for the two-fold purpose of gathering food for the trees and providing for them a cover crop in winter. The medium red and crimson varieties are preferred for such a use. The latter is the more suitable of the two, since it does not draw on soil moisture needed by the trees, owing to the season at which it is grown. Enough of the seed of these crops may be allowed to mature to re-seed the land from year to year, and thus keep it producing. The clover plants

not only gather nitrogen for the fruit trees, but in their decay they increase the power of the soil to retain moisture for the benefit of the trees.

Some varieties of clover may be grown as catch crops, that is, as crops which are grown in addition to some other crop produced the same season. When thus grown, it is usually for purposes of soil improvement rather than to furnish food. The varieties best adapted for this purpose in the Northern States and Canada are the medium red and the crimson, the latter being much more circumscribed in the area where it will grow successfully than the former. When medium red clover is thus grown, it is commonly sown along with one of the small cereal grains, and is buried in the autumn or in the following spring. (See page 75.) The extent of the advantage is dependent chiefly on the amount of the growth made, and this in turn is influenced by the character of the soil, the season and the nurse crop. In certain areas favorable to the growth of clover some good farmers sow clover along with all the small cereal grains which they grow. Crimson clover is usually sown in the late summer after some crop has been reaped and it is plowed under the following spring. (See page 250.)

In the Southern States Japan clover and burr clover will serve the purpose of catch crops better than the other varieties. The former will follow a winter crop (see page 284), and the latter a summer crop. (See page 294.)

Although alfalfa is not usually looked upon as a rotation crop in the Rocky Mountain valleys, it

may be made such a crop. In these it grows so vigorously as to fill the soil with its roots in one or two seasons, hence it may be made to rotate profitably with other crops. (See page 135.) In such instances, however, medium red clover would probably answer the purpose quite as well, and possibly better, since the labor of burying it with the plow would be less difficult.

While some varieties of clover may be grown in various rotations and with profit, one of the best of these, where the conditions are favorable, is a three years' rotation. The first year some small cereal grain is grown and clover is sown along with it or, at least, on the same land. The next year the clover is grown for hay or pasture. The third year a crop of corn, potatoes or vegetables is grown, and the following year small cereal grain and clover. The clover may thus be made to furnish nitrogen indefinitely for the other crops, but in some instances it may be necessary to add phosphoric acid and potash.

Preparing the Soil.-Clovers are usually sown with a nurse crop. The exceptions are crimson clover, and in many instances alfalfa. When thus grown, the preparation of soil for the nurse crop will usually suffice for the clovers also. But there may be instances in which it would be proper to give more attention to cleaning and pulverizing the soil to properly fit it for receiving the clover seed. The leading essentials in a seed-bed for clover are fineness, cleanness, moistness and firmness. Ordinarily black loam soils, sandy loam soils, sandy soils, humus