YIELDS OF VEGETABLES AND PEANUT IN ROTATION PLANTINGS

Crop rotations can reduce problems that occur in monoculture planting systems. In 1990, at Lane, Okla., 0.5 ha of Bernow fine-loamy soil was planted to peanut (Arachis hypogaea L.). In the following 5 years, be ll pepper (Capsicum annuum var, annuum L.), cucumber (Cucumis sativas L.), navy bean (Phaseolus vulgaris L.), and cabbage (Brassica oleracea L. Capitata group) were planted in one of four rotations after 1, 2, or 3 years of peanut. The first vegetable planting in each annual rota tion was followed by either vegetables or peanut in following years. I n 3 of the 6 years, peanut or vegetables were planted in each rotation . Peanut yields in the first year averaged 6.6 Mg.ha(-1), but were <1. 9 Mg.ha(-1) thereafter. Yields of the first vegetable planting, which followed 1 or 2 years of peanut, were normal for this location, but we re significantly lower after 3 years of peanut. For second or third pl antings of vegetables in rotations, yields were reduced up to 50% comp ared to the first vegetable planting. For most crops, the rotation tha t had 3 years of peanut followed by 3 years of vegetables generally pr oduced the least cumulative yield. Numbers of sclerotia produced by so ilborne plant pathogenic fungi fluctuated over the years, but were the same in the spring of the second and sixth years. Rotating these crop s appears to have limited applicability for maintaining high vegetable or peanut yields.