FOOD RESERVES IN RELATION TO OTHER FACTORS LIMITING THE GROWTH OF GRASSES

Abstract

The immediate applied significance of the pronouncements of LIEBIG (1840) with reference to mineral nutrition of plants, not only gave rise to profound changes in soil culture and crop husbandry, but also furnished the basis of the present fertilizer industry. The classic work of SACHS, PFEFFER, KLEBS and others on the organic nutrition of plants, however, has not been utilized to full advantage. Fairly recently (1918) KRAUS and KRAYBILL (12) have attempted to redirect attention to such studies, and many important contributions have been made by such workers as HARVEY (9), MURNEEK (14), NIGHTINGALE (17), ROBERTS (25), JANSSEN (11), LEUKEL (13), TIEDJENS (28), ALBERT (1), NELSON ( Unlike mineral nutrients, the carbohydrates and other organic foods cannot at present be supplied to green plants in a com- mercial way. They must be elaborated by the living plant itself. The plant producer can vary cultural procedures, however, so that the formation, utilization, storage and destruction of such materials may be con- trolled or directed and crop production be more or less precisely regulated with reference to quality and yields. Such cultural practices include defoliations by cuttings, pruning and grazing; fertilization, especially with nitrogenous fertilizers; etiolation by shading or other limitations of light; irrigation and combinations of these treatments.