Effects of the Nitrogen Fertilization Advance on Rice under Straw Returning Condition

Nitrogen(N) fertilizer operational experiment with straw returning in three main rice planting counties of Hubei province was conducted to find effects of nitrogen fertilization time and ratio on rice yield and partial factor productivity of nitrogen application(PFPN) under straw returning condition.The results showed that rice yield was significant(P0.05) lower in the two-split N fertilization than that in the three-split N fertilization with the same total N fertilization rate.With straw returning,rice yield was relatively lower in the three-split N fertilization than that in the two-split N fertilization.For all these three sites,two-split N fertilization with straw returning could maintain high level yield of presenting no significant difference(P0.05) with the yield in the three-split N fertilization,three-split N fertilization with straw returning and three-split of high N rate with straw returning.The PFPN value was highest in the two-split N fertilization with straw returning treatment,reaching to 41.6 ~60.8 kg/kg among the three sites.It is indicated that two-split N fertilization(i.e.,moving the panicle fertilization forward) with straw returning can be used to ensure high level of rice yield and N efficiency.