Effects of the Interruption of Alternating Cropping of Corn and Italian Ryegrass with Soybean or White Radish Cropping or Fallowing on the Growth and Yield of the Crops in Succeeding Seasons

Abstract

The effects of interruption of alternating cropping of corn and Italian ryegrass with one or two years of soybean or white radish cropping or fallowing on the growth and yield of these crops in succeeding seasons were examined. Experiments were conducted in the fi eld of andosol in Ibaraki, Japan, where corn and Italian ryegrass were alternately cultivated for a long period. The effects of the interruption for one year and that for two years were not distinguishable. The corn yield in the first season after the interruption with soybean cropping was higher than that in continuous alternating corn / Italian ryegrass cropping. However, the corn yield after interruption with white radish cropping or fallowing was similar to that in continuous alternating cropping, although it depressed the early growth of corn and the colonization of arbuscular mycorrhizal fungi. Such effect of interruption was observed only in the fi rst season after the interruption. The interruption of sequential cropping did not affect the yield of Italian ryegrass in the second season; neither did it affect the yield of maize in the third season. Our results indicated that the effect of short-term interruption of sequential cropping of corn / Italian ryegrass was observed only in the fi rst season after the interruption.