化肥氮磷优化减施对水稻产量和田面水氮磷流失的影响

为探讨氮(N)、磷(P)减量对降低稻田养分地表径流损失风险的影响,以毛里湖稻区为研究对象,连续两年(2016—2017年)进行田间小区试验,研究化肥氮磷优化减施对水稻产量和生长期内田面水N、P动态变化特征及径流流失的影响。结果表明:常规施肥处理(CF)和有机替代20%化肥N处理(0.8FN+0.2ON)稻田田面水总氮(TN)、NH_4~+-N和总磷(TP)浓度在施肥后迅速达到峰值,之后逐渐下降。而控释氮肥减N处理能有效减缓N素释放速度,田面水N素流失量远低于CF处理,且磷肥减量处理TP流失量低于CF处理。与CF处理相比,控释氮肥减N 20%(0.8N)和控释氮肥+过磷酸钙减量20%(0.8NP)处理水稻两年平均分别增产5.55%、3.22%,N素累积量分别提高19.01%、13.66%,氮肥偏生产力分别显著提高31.94%、28.83%,氮肥农学利用率分别提高47.52%、33.75%,氮肥吸收利用率分别提高95.30%、73.31%。0.8NP处理较0.8N处理水稻磷肥偏生产力两年平均显著提高22.08%,而0.8FN+0.2ON处理较CF处理P素累积量和磷肥吸收利用率分别降低11.14%、36.04%。总体而言,控释氮肥与磷肥减量既保证高产稳产,又有效降低稻田施肥初期N、P径流损失风险。在综合考虑农业生产节本增效和控制农田面源污染的前提下,可采用控释氮肥减量的施肥模式。

Effects of Reducing Nitrogen and Phosphorous Fertilizers on Rice Yield, Nitrogen and Phosphorus Losses in Paddy Field

To explore the effects of reducing nitrogen (N) and phosphorus (P) fertilizers on rice yield and runoff losses of N and P in paddy fields, a field plot experiment with different fertilization was conducted from 2016 to 2017 in the rice-planting area of Maoli Lake, the yield of rice, the variation of N and P in surface water, the runoff losses of N and P, and the use efficiencies of N and P fertilizers were monitored and compared after fertilization during the rice-growing period. The results showed that the concentrations of TN, NH₄⁺-N and TP in surface water of paddy field under the treatments of conventional fertilization (CF) and organic-substitution of 20% fertilizer-N (0.8FN+0.2ON) peaked rapidly after fertilization, and then gradually decreased. However, the treatments of controlled release fertilizer with reduced N reduced effectively the release rate of N, and its N loss in surface water was much lower than that of CF treatment, and TP loss under the treatment of reduced P fertilizer was lower than that of CF treatment. Compared with CF treatment, from 2016 to 2017, the treatments of 20% reducting controlled release fertilizer-N (0.8N) and 20% reducting controlled release-N fertilizer + calcium superphosphate-P (0.8NP) increased meanly the yield of rice by 5.55% and 3.22%, N accumulation by 19.01% and 13.66%, N fertilizer partial factor productivity by 31.94% and 28.83%, N fertilizer agronomic efficiency by 47.52% and 33.75%, N fertilizer recovery efficiency by 95.30% and 73.31%, repsectively. Compared with 0.8N treatment, 0.8NP treatment increased mean P fertilizer partial factor productivity of rice significantly by 22.08%. Compared with CF treatment, 0.8FN+0.2ON treatment reduced P accumulation and P fertilizer recovery efficiency by 11.14% and 36.04%, respectively. In conclusion, reducing controlled release N fertilizer and/or P fertilizer can not only ensure high and stable rice yield, but also effectively reduce the runoff losses of N and P at the initial stage of fertilization in rice field. The fertilization mode of reducing controlled-release N fertilizer can be adopted in order to save the cost of agricultural production and control the non-point source pollution.