Alfalfa is a legume or nitrogen gathering plant. An examination of the roots of leguminous plants reveals numerous bacteria nodules which vary in size, shape and number according to the kind and age of the plant. A very close relation has been found to exist between leguminous plants and the bacteria existing within these nodules. The plant furnishes the nourishment required by the bacteria while the bacteria in turn draw nitrogen from the air and render it available for the use of the plant. Nitrogen is essential to plant life. The plowing under and resulting decay of legume plants releases vast quantities of nitrogen into the soil where it may be absorbed and assimilated by succeeding crops.
The accompanying [illustration] shows the nodule development on the roots of a two-months-old legume plant.
Other Rotation Crops
Following the alfalfa, we sow a mixture of rye and vetch which is plowed under when the rye is in head and the vetch in bloom as at this time the vetch (which also is a legume) attains its greatest development of nitrogen nodules and the rye its greatest humus value. After this has been incorporated with the soil and a pulverized seed bed formed as before, it is seeded to a mixture of cow-peas and buckwheat.
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