Alfalfa As A Fertilizer

Alfalfa is not considered equal to medium

red clover as a direct means of fertilizing and otherwise improving the

land on which it grows. This does not arise from less inherent power on

the part of alfalfa to draw nitrogen from the air and deposit it in the

soil, but rather from the fact that clover establishes itself more

quickly, and is much more frequently grown in the rotation. Several

crops of medium red clover can be grown in short rotations, each one

being a source of much benefit to the crops that follow, while one crop

of alfalfa occupies the land. But when the alfalfa is all fed upon the

farm on which it grew, where the plants grow freely, it then becomes a

source of fertilization without a rival, probably, among plants grown

upon the farm.

The fertility thus furnished does not consist so much in the plant food

deposited in the soil directly as in that furnished in the successive

crops that are grown and fed every year. In Farmers' Bulletin No. 133,

published by the United States Department of Agriculture, it is stated

that the Wyoming Experiment Station found 44 pounds of nitrogen, 8.27

pounds of phosphoric acid, and 50.95 pounds of potash in one ton of

alfalfa. This would mean that in the yield of alfalfa hay from a given

area, estimated at four tons per acre for the season, alfalfa would

furnish 176 pounds of nitrogen, 33.08 pounds of phosphoric acid, and

203.8 pounds of potash. If this alfalfa were fed upon the farm, it would

not only prove a cheap source of protein for feeding, but it would

furnish fertility, as stated above, without seriously diminishing the

supply of the same in the surface soil, since much of the fertilizing

material produced would come from the air and subsoil. The manure thus

made, if carefully saved and applied, would thus add materially to the

fertility of the land. If, however, the alfalfa were sold, the mineral

matter drawn from the cultivable area of the soil and from the subsoil

lying under it would be reduced to the extent of the draft made upon

these in growing the alfalfa.

The direct influence of alfalfa upon the fertility of the land on which

it grows is shown in the greatly increased production in the crops which

follow alfalfa. This increase is not only marked, but it is frequently

discernible for several successive years. But as has been intimated, the

benefit that would otherwise accrue from growing alfalfa as a direct

means of fertilizing the land is much circumscribed by the long term of

years for which it is usually grown.

The mechanical effects of alfalfa upon the land are beneficent. It

improves the tilth by means of the shade furnished, and the extent to

which the roots fill the soil. These in their decay further influence

favorably that friability which is so desirable in soils that are

cultivated, and as previously stated, the long, deep roots in their

decay exercise a salutary influence on drainage.

The work of breaking alfalfa fields is frequently laborious, owing to

the number and size of the roots. If, however, a plow is used, the share

of which has a serrated edge, the roots will be cut or broken off more

easily and more effectively.


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