Abstract
To know how the effects would differ of superphosphate dressing among the varieties of paddy rice, pot experiments for a year and field experiments for 4 years were carried out. The effects on the growth, on the yield, on the amounts and the efficiencies of N_2 and P_2O_5 absorbed, and on the contents of both gredients in the straws and grains were discussed. It was found that the overdressing of superphosphate were somewhat detrimental to the earlier growth of the plant and depressed the yield of both straws and grains. The amount of the phosphate applied, temperature throughout the period of the growth and the characteristics of the variety were found to have great significances as the factors that rule the efficiency, and therefore, the limit of overdressing of the phosphate.
