Effect of root residues on the growth of upland rice

The effect of root residues of upland rice, which had been left in a field for ca. 7 months from autumn to the next spring, on the growth of succeeding upland rice was examined. The root residues incorporated into field soil inhibited the upland rice growth. This effect was considered to be caused not by toxic substances accumulating in root residues, but by aerobic detrimental organisms inhabiting root residues.