STUDY ON NITROGEN MIGRATION IN PURPLE SOIL AND NITROGEN UPTAKE BY RICE

The effect of nitrogen fertilizer kind and dose on nitrogen migration, leaching loss and nitrogen utilization rate by rice in purple soil was studied in percolating pools. The results showed that during flooding period nitrogen leached basically as NH4+-N which mainly distributed in soil surface layer and moved downward with time prolonging. The amount of NH4+-N leaching loss was positively correlated with the amount of rainfall significantly. NH4Cl promoted NH4+-N leaching loss while its utilization rate was 8 percent points higher than of urea. So chlorine contained fertilizer can be used on rice at a judicial discretion. The increase of nitrogen dose increased the amount of NH4+-N leaching loss and decreased nitrogen fertilizer utilization rate. It was also suggested that the dose of nitrogen fertilized on rice be controlled at 150kg/hm2.