长期不同施肥条件下红壤性水稻土双季稻氮肥回收率的变化特征

在江西进贤红壤性水稻土上连续种植双季水稻26年，分析了在化肥氮用量相同条件下，不施肥（CK）， 单施氮肥（N）， 施用氮、 磷化肥（NP）， 氮、 钾化肥（NK）， 氮、 磷、 钾化肥（NPK）和氮磷钾配施有机肥（NPKM）处理的水稻氮肥回收率的演变特征及其增产效应。结果表明，不同施肥条件下的化肥氮回收率差异显著，26年的平均氮肥回收率 N 处理为 9.4%~11.6%、 NP为13.0%~18.5%、 NPK为19.8%~26.1%， NPKM为14.1%~22.9%。磷、 钾肥混施和与有机肥配施可显著提高水稻氮肥回收率，且对早稻的贡献大于晚稻，NPK和NPKM处理的早稻氮肥回收率比晚稻平均高6.3和8.8个百分点。N和NK处理的早稻和晚稻氮肥回收率均随年度增加而显著降低，平均每年下降约0.6个百分点，而NPK、 NPKM处理的氮肥回收率基本保持稳定。与NPK相比，NPKM处理早稻和晚稻籽粒产量分别增加19.0%和21.7%。因此，NPKM处理在提高化肥氮的回收率和高产稳产方面都是红壤性水稻土上可持续的施肥模式。

The inter-annual characteristics of nitrogen recovery efficiency of double cropping rice system on paddy soil under long-term fertilization

A 26 year different fertilization experiment was conducted to investigate rice yields and dynamics of nitrogen recovery efficiency (NRE) of double rice cropping system in red paddy soil at Jinxian,Jiangxi province. There were six treatments, unfertilized control (CK), inorganic fertilizer nitrogen (N), N and P (NP), N and K (NK), NPK, and NPK with manure (NPKM). The results show that there are significant differences of NREs in the six treatments, and the average values of NRE in 26 years are 9.4%-11.6%, 13.0%-18.5%, 19.8%-26.1% and 14.1%-22.9% for the N, NP, NPK and NPKM treatments, respectively. The NREs of double cropping rice are significantly improved under the application of PK combined fertilizer and manure, and the NRE of early rice is higher than that of late rice. The NREs of early rice under the NPK and NPKM treatments are 6.3 and 8.8 percentage point higher than those of late rice, respectively. The NREs of both early rice and late rice are significantly decreased at a rate of about 0.6 percentage point/a under the N and NK treatmentsover the 26 years. There are no significant changes in the NREs of rice under the NPK and NPKM treatments over the 26 years. Compared with the NPK fertilization, the NPKMfertilization resulted in 19.0% and 21.7% grain yield increases of early rice and late rice, respectively. We conclude that chemical fertilizer in combination with manure is amore effective fertilization to improve grain yield and maintain NRE for red paddy soil.