"Burn-leaf" rice soils derived from Quaternary clay deposits give a slightly acid reaction of about pH 6.6, and contain many small iron concretions in the surface layer. An abundance of large clods is appeared in soil profile after water-logging. Rice plants grown on these soils usually exhibit a characteristic symptom of phosphorus deficiency of "burn-leaf" and are stunted in growth. It was found that the formation of soil clods has markedly reduced the availability of phosphorus nutrient to plant. Further, the fractionation of soil phosphorus revealed that they are largely occluded by iron oxide. The normal growth of the rice plant can be effectively restored by the application of superphosphate. Proper measures of tilling break down the soil clods and consequently also improve the status of phosphorus nutrient.