采用田间试验比较研究了在水稻秸秆还田环境下不同施氮模式对土壤N素供应、氮肥利用率及其对水稻生产力的影响。结果表明,稻草还田改善了土壤的供氮能力,不论在背景氮较低的砂性土壤上还是在背景氮较高的粘性土壤上,稻草还田配施减量氮肥(N1、N3处理全年施氮量180kg.hm-2,其中桃江主试验中N1处理早稻施氮80kg.hm-2,60%为基肥,40%为分蘖肥施用;晚稻施氮105kg.hm-2,50%为基肥,40%为分蘖肥,10%为穗肥施用;桃源氮替代试验中N1、N3处理早稻施氮81kg.hm-2,晚稻施氮99kg.hm-2,N1处理早、晚稻氮肥施用分配比例为基肥30%,分蘖肥30%,穗肥40%,N3处理早稻氮肥50%为基肥,50%为分蘖肥施用,晚稻氮肥50%为基肥,40%为分蘖肥,10%为穗肥施用)处理,相对于移走稻草+高量氮肥(N2处理其中桃江主试验早稻施氮量115kg.hm-2,晚稻施氮量为150kg.hm-2,分别以60%为基肥,40%为分蘖肥施用;桃源氮替代试验早稻施氮量为108kg.hm-2,50%为基肥,50%为分蘖肥施用,晚稻施氮量为132kg.hm-2,50%为基肥,40%为分蘖肥,10%为穗肥施用)处理之间稻田系统生产力无显著差异,但每年节约60～80kg纯氮化肥的投入,提高了其边际成本报酬率。分次施氮的效果表明,稻草还田下等量氮肥不同施氮模式(N1、N3)处理之间,水稻产量差异不显著,但水稻吸氮高峰集中在分蘖旗至孕穗期,N1模式减少了基肥施氮量,防止了因作物未能及时吸收导致的土壤速效氮的损失,而适当增加作物后期施氮量又能有效缓减作物后期生长大量吸氮的要求与微生物分解稻草固持矿质氮之间的矛盾,改善了土壤的供氮状况,其效果最优。因此,在全年稻草还田量为7500kg.hm-2的红壤稻田系统,根据投入氮肥的边际收益,全年适宜配施氮量为180kg.hm-2,且各时期施氮量优化比例为基肥30%、分蘖肥30%、穗肥40%。 A field experiment was conducted to compare the effects of different N application modes on soil N availability, nitrogen use efficiency and rice productivity in paddy field with rice straw. The results showed that the straw returning to the soil improved the ability of supplying nitrogen to the soil. The straw returning to the field with reducing nitrogen fertilizer (N1, N3 treatment) was the best under the condition of sandy soil with lower background nitrogen or cohesive soil with higher background nitrogen The annual nitrogen application rate was 180kg.hm-2. Among them, N1 treatment in the main experiment N1 in Taojiang applied N 80kg.hm-2, 60% in basic rice and 40% in tillering fertilizer; Base fertilizer, 40% of tillering fertilizer, 10% of the panicle fertilizer application; Taoyuan nitrogen substitution test N1, N3 treatment of early rice nitrogen 81kg.hm-2, late rice nitrogen 99kg.hm-2, N1 treatment of early and late rice nitrogen application allocation The proportion of basal fertilizer is 30%, tillering fertilizer is 30%, panicle fertilizer is 40%, N3 is 50% of base fertilizer, 50% is tillering fertilizer, 50% of late rice is basal fertilizer, 40% is tillering fertilizer and 10% is panicle fertilizer Compared with the treatment of nitrogen removal (straw treatment + N2 treatment), the nitrogen content of early rice in the Taojiang experiment was 115kg.hm-2 and that of the late rice was 150kg.hm-2, with 60% as the basal fertilizer and 40% The results showed that N application rate was 108kg.hm-2 in early rice, 50% was basal fertilizer, 50% was tillering fertilizer, 132kg.hm-2 in late rice, 50% basal fertilizer, 40% For tillering fertilizer, 10% for panicle fertilizer application) to deal with paddy lines There is no significant difference in total productivity, but the annual saving of 60 ~ 80kg of pure nitrogen fertilizer investment, increased marginal cost rate of return. The effect of nitrogen application at different times showed that there was no significant difference in the yield of rice between the different nitrogen application rates (N1, N3), but the peak of nitrogen uptake was concentrated in the tillering flag to the booting stage, and the N1 mode decreased The amount of nitrogen applied to the basal fertilizer should be used to prevent the loss of available nitrogen in the soil due to the failure of the crop to absorb in time and to increase the amount of nitrogen applied at the late stage of the crop and effectively reduce the amount of nitrogen uptake required by late crop growth. The contradiction between the two has improved the status of nitrogen supply to the soil and its effect is optimal. Therefore, according to the marginal benefit of inputting nitrogen fertilizers, the annual nitrogen application rate was 180kg.hm-2 in the red paddy field system with 7500kg.hm-2 straw returning all year, and the optimum proportion of nitrogen application rate in each period was Basal fertilizer 30%, tillering fertilizer 30%, spike 40%.