A study on Corp absorption and utilization of nitrogen and phosphorus using isotopes 15N and 32P

The results of the study on adsorption and utilization of nitrogen and phosphorus from fertilizers by crops with istopes 15N and 32P in 1983 ∼ 1986 were described. The experiment showed that in paddy field, the rates of utilization of ammonium nitrogen by rice from (15NH4)2SO4 and 15NH4NO3 are 40.58% and 33.80%, respectively, and that of nitrate nitrogen from NH415NO3 and K15NO3, 15.99% and 15.30%, respectively. The raes of utilization of ammonium nitrogen by rice is significantly higher than that of nitrate nitrogen. In upland field, the rates of utilization of nitrate nitrogen by millet from NH415NO3 and K15NO3 are 71.6% and 59.5%, respectively, and that of ammonium nitrogen from (15NH4)2SO4 and 15NH4NO3, 52.4% and 42.2%, respectively; the rates of utilization of nitrate nitrogen by milliet is significantly higher than that of ammonium nitrogen. Uptake and utilization of nitrogen and phosphorus by rice were studied with 15N and 32P as tracers. Efficiencies of utilization of nitrogen are as follows: for urea-ammoonium phosphate, 44.65%; for ammonium phosphate-chloride, 45.54%; for urea, 44.12%; and for nitric phosphate, 36.65%. Efficiencies of utilization of phophorus are as follows: 22.5% for nitric phosphate, 22.36% for ammonium phosphate-chloride, 21.08% for urea-ammonium phosphate, 20.74% for urea+superphosphate, and 11.80% for superphosphate. The determination of radioactive scanning and autoradiography method show that after 20 days the vertical moving distances of the 32P of fertilizers in the soil, in the order, are as follows: 4.21 cm for nitric phosphate, 4.20 cm for urea-ammonium phosphate, 4.01 cm for ammonium phophate-chloride, 3.50 cm for urea+superphosphate, 3.12 cm for ammonium phophate-sulfate, and 3.00 cm for superphosphate+superphosphate, 11.80% for superphosphate. The determination of radioactive scanning and autoradioraphy method show that the vertical moving distances of the 32P of fertiliz