STUDY ON THE GROWTH AND UTILIZATION OF NITROGEN FOR RICE UNDER THE DIFFERENT WATER MANAGEMENTS

The differences in the growth of rice and the absorption and distribution of N in rice plant under long-term flooded and water leakage conditions were quantitatively inverstigated using 15N-urea in greenhouse imitative soil column experiment. The results indicated that the growth of root and accumulation of dry matter of rice plant were obviously different under two kinds of soil water managements. The accumulation of N in rice plant after elongation stage became lower under the long-term flooded condition,while the rice grew, under water leakage condition, still maintained high N absorption ability up to booting stage. The utilization rate of N fertilizer of the former was significantly lower than that of the later, and the contribution of soil mineralizable N was relatively higher in the former, compared with the later. This is related to the growth status of rice and the characteristics of nitrogen transformation in soil under two kinds of water managements. In the experiment. the absorbing rate of soil mineralizable N increased greatly after the elongation stage, it was assumed that the rice had a fertilizer deficiency phenomenon during the later period. Therefore,application of booting fertilizer should be recommended.