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【目的】探讨在免耕和常耕条件下,还田稻草氮素释放特性和水稻氮素利用的差异。【方法】2006年和2007年晚稻,在田间将稻草还田,并在不同时期测定稻草中残留的氮素,同时进行桶栽试验,将15N标记稻草还田,成熟期测定水稻积累的总氮素和15N丰度。【结果】稻草中残留的氮素随还田时间延长而下降,但不同时间段下降的速度差异很大。还田后0～40d,稻草中残留的氮素下降约60%,还田后40～100d,稻草中残留的氮素下降约10%。两种耕作方式下还田稻草含氮率均呈升高趋势。无论是干稻草还是湿稻草还田,免耕条件下稻草氮素平均释放速率高于常耕。免耕方式下湿稻草的氮素释放速率较高,常耕方式下干稻草氮素释放速率较高。【结论】无论还田稻草状态相同与否,常耕水稻的氮素干物质生产效率和产量较免耕水稻高。免耕有利于还田稻草的氮素释放,但水稻从还田稻草中吸收的氮素和氮素利用效率下降。
【Objective】 The purpose of this study was to explore the differences of nitrogen release characteristics and nitrogen utilization efficiency of rice in the fields under no-till and no-till conditions. 【Method】 In late rice in 2006 and 2007, the straw was returned to field in the field, and the residual nitrogen in straw was measured at different times. At the same time, barley test was carried out, and the 15N labeled straw was returned to field. The accumulated nitrogen Su and 15N abundance. 【Result】 The results showed that the residual nitrogen in straw decreased with the prolongation of the treatment time, but the rate of decline in different periods was very different. From 0 to 40 days after returning to the field, the residual nitrogen in straw decreased by about 60% and the residual nitrogen in straw reduced by about 10% after 40 to 100 days after returning to straw. Under the two tillage methods, the nitrogen content of rice straw also increased. The average nitrogen release rate of straw under no-till condition was higher than that of normal crop, no matter it was dry straw or wet straw. Under no-tillage, the rate of nitrogen release from wet straw was higher than that from dry straw. 【Conclusion】 The nitrogen production efficiency and yield of the paddy rice were higher than those of the no-tillage rice irrespective of the status of straw returning to the field. No-tillage was beneficial to the release of nitrogen from straw, but the efficiency of nitrogen and nitrogen uptake from paddy straw decreased.