SOME EFFECTS OF ALFALFA, FERTILIZER AND LIME ON CORN YIELD IN ROTATIONS ON CLAY SOIL DURING A RANGE OF SEASONAL MOISTURE CONDITIONS

Abstract

The yields of corn (Zea mays L.) grown in rotation with alfalfa (Medicago sativa L.) and oats (Avena sativa L.) were compared with continuous corn on Brookston clay soil. Yields were measured in the presence and absence of fertilizer, alone or combined with lime, and covered a period of 13 yr, commencing in 1961. The 2-yr alfalfa sod system produced a significant yield increase over continuous corn and, also, over the 1-yr alfalfa sod system. Yields of corn varied widely from season to season, according to moisture conditions, but always responded to alfalfa in the rotation, particularly where no fertilizer had been applied. The effect of 2 yr of alfalfa sod every 4 yr in the cropping system was equivalent to 110 kg N/ha/yr on continuous corn in producing corn yield. Lime application was most beneficial on rotations where fertilizer was not applied and was associated with alfalfa and/or oat rotations.