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in good form will also grow alfalfa in good form. This does not necessarily follow. While there is much of similarity in the soils suitable for the growth of both, alfalfa may fail on lands that grow red clover luxuriantly until the bacteria proper to alfalfa have been introduced. Soils may be tested for bacteria, and even in winter, by sowing some seed in pots and treating them like well-cared-for house plants. When the plants are 2 to 3 months old, if tubercles are found on the roots, the conclusion would seem safe that such soil does not require inoculation.
Place in the Rotation. In a certain sense it can scarcely, be said of alfalfa that it is a rotation plant, because of the long term of years for which it is grown in an unbroken succession. Nevertheless, in all places it cannot always be maintained for a long term of successive years without renewal. In the Eastern States it is frequently, though not always so crowded by various grasses, that the fields in which it grows are broken up at some period short of ten years, and not infrequently at the end of five or six years. When thus grown, it becomes a rotation plant, though grown in what may be termed long rotations. But even in the West, where, under irrigation, it may be grown for a quarter of a century or even for a longer period without renewal, it may be used when desired in short rotations. In such situations it grows so readily and becomes established so quickly, that the fields may be broken with a view to alternate with other crops at the end of the second year, or of any year subsequently from
the sowing of the seed that may be desired. Alfalfa in these soils will serve even better than medium red clover in such situations, since while it is growing, it will produce more hay or soiling food, and consequently should excel the former in the fertility which it makes available.
East of the Mississippi and north of the Ohio River, alfalfa will frequently follow cultivated crops, as corn, potatoes and field roots, and when the fields are broken, it will be followed by crops other than legumes. On many soils the influence which this crop has on relieving the surface soil from excessive moisture, through channels opened into the subsoil by the decaying roots, is so helpful as to considerably stimulate production in addition to the fertilizing influence which it exerts directly. Particularly good crops of corn, the small cereal grains, and even field roots may be grown after alfalfa.
On soils east of the Mississippi and south of the Ohio, the rotation will be somewhat similar. But on Southern soils alfalfa will frequently follow immediately crops especially grown to be plowed under as green manures for the benefit of the alfalfa. These crops include cow peas, soy beans, crimson clover, and to a limited extent, burr clover. It will also be followed frequently by crops of cotton and other non-leguminous plants, the growth of which in the United States is confined to the area now being considered.
In the area west of the Mississippi and east of the semi-arid region beside the mountains, alfalfa may follow the small cereal grains, and may in turn be
followed by them and also by millets. It may also follow and precede corn, or the non-saccharine sorghums, where the climatic conditions are suitable for growing the latter.
In the irrigated regions of the West, alfalfa may be made to serve almost any purpose in the rotation that may be desired. By growing it as a rotation crop in these valleys it may be made to furnish the soil indefinitely with supplies of nitrogen and humus. In these soils it may be made to follow directly almost any crop grown on them, and similarly it may be made to precede the growth of almost any crop for which the locality has marked adaptation. Small cereal grains, timothy, vegetables, field roots, potatoes, corn, small fruits and orchards may be profitably grown on buried alfalfa meadows. This does not imply, however, that alfalfa meadows should not, as a rule, be maintained for a long term of years.
Preparing the Soil.-In preparing the soil for alfalfa the aim should be to make a seed-bed clean, rich, fine, moist, even, and sufficiently firm or friable, according to the conditions. The subsoil should also be made sufficiently dry and open. From what has just been said, it will be apparent that in properly preparing the seed-bed, it will be necessary to study closely the requisite conditions.
The advantage from having a clean seed-bed will be apparent when it is called to mind that alfalfa is a somewhat delicate plant when young, and that because of this, it is ill able to overcome in the fight with weeds. Cleanness in the surface soil may be obtained by summerfallowing the land, by growing a root crop or a crop of corn or any of the nonsaccharine sorghums. When the seed is spring sown, this preparation must be given the year previously, but when autumn sown, it may be given the same season. In preparing the land thus, the aim should be to make the surface as clean as possible, rather than to get weed seeds out of the lower strata of the cultivated soil, in which they will likely perish before the field sown to alfalfa is broken up again. Summerfallowing makes an excellent preparation for the land, because of the fine opportunity which it furnishes for cleaning the same perfectly and leveling it off properly. The excellent condition in which it puts the seed-bed, viewed from the standpoint of the duration of the years of cropping that are likely to follow, would seem to more than justify such preparation of the land. The outcome may more than justify the loss of the crop for one season when thus summerfallowing the land. But it may not be necessary to lose the production of one season whether the seed is sown spring or autumn, as the summerfallowing in the North may follow the pasturing off of some crop, and in the South the interval for fallowing the land may be sufficiently long after the harvesting of an early winter grain crop, before sowing the seed in the autumn. (See page 136.)
When sowing the seed autumn or spring, on land that is filled with weed seeds near the surface, it is frequently better to defer sowing the seed for some weeks to give time for sprouting many of these than
to sow at once. This suggestion is specially applicable to spring sowing. It should also be mentioned that when the weeds infesting the soil are annual or even biennial in character, the harm done to the alfalfa by these will be much less than when the land is infested with perennials at the time of sowing. The former may be prevented from seeding by clipping back frequently, while the latter remain in the soil, increase from year to year, and injure the plants by crowding. Where crab grass grows abundantly, as in some parts of the South, unless the alfalfa is sown and cultivated, spring sowing ought to be avoided. But it is less objectionable to sow alfalfa on land that is weedy when the adaptation of the land for the crop is high than when it is low, as the alfalfa in the former instance has so much more power to fight its own battle. On good alfalfa soils, therefore, it may be wiser in some instances to sow alfalfa in weed-infested land than to defer sowing for a whole year in order to clean the land.
It is greatly important that the land shall be rich in available plant food on which the seed is sown. If naturally poor, it should be well fertilized before sowing. When this cannot be done, it is better not to sow. A vast preponderance of the land in the Rocky Mountain region, when first broken, would seem to possess abundantly all the essential foods required by alfalfa; hence, for a time, at least, it is not necessary to enrich these before sowing the seed. The sandy and hungry gravelly soils, which are considerable in the South, in the Atlantic States, and in some of the Central and Northern States, should be