EFFECT OF ALFALFA AND GRASSES ON YIELD OF SUBSEQUENT WHEAT CROPS AND SOME CHEMICAL PROPERTIES OF A GRAY WOODED SOIL

Abstract

Wheat was grown continuously after forage crops or fallow of a fallow-wheat rotation, with fertilizer being applied to only the fifth wheat crop. Yields of the first, second, fourth and fifth wheat crops succeeding alfalfa were greater than those succeeding fallow by 71, 82, 75 and 68%, respectively. The third crop was frozen. Yields were slightly less after a bromegrass-alfalfa mixture than after alfalfa alone. Yields after red fescue or bromegrass were similar to those after fallow. Age of the forage swards, two to six years, did not affect subsequent wheat yields. Total N and organic matter in the surface soil changed only slightly under the forage swards. Mineralizable N and chlorophyll units were in much greater amounts in the first year following alfalfa, alone or in mixture with bromegrass, than following the other crops, but the differences had diminished somewhat by the fifth year.