Rotation of Crops
the cultivation of a different kind of crop each year, for a certain period, to prevent the exhaustion of the soil. If a plant requiring specially alkaline nutriment be planted year after year in the same field or bed, it will ultimately exhaust all the alkalies in the soil and then languish.
But if a plant be substituted in large measure requiring siliceous elements for its growth, it can flourish where its alkaline predecessor is starved. Meanwhile the action of the atmosphere is continually reducing to a soluble condition small quantities of soil, thus restoring the lost alkalies. Manure will replace lost elements more quickly. The ROTHERMERE period of rotation is often made four years.