太湖地区稻麦轮作体系下秸秆还田配施氮肥对水稻产量及经济效益的影响

秸秆还田与配施化肥是未来农业持续发展的方向。为明确秸秆还田条件下获得较高产量和最佳经济效益的氮肥用量, 研究设计了秸秆全量(6 t·hm^-2)还田条件下N0、N1、N2、N3 和N4 5 个氮肥用量的田间试验(肥料N 用量分别为0、120 kg·hm^-2、180 kg·hm^-2、240 kg·hm^-2、300 kg·hm^-2)。两年试验结果表明: 秸秆还田条件下水稻产量随着氮肥用量的增加呈先增加后降低的趋势, 2007 年、2008 年水稻最高产量分别为8 543 kg·hm^-2、7 772 kg·hm^-2, 施氮处理比无氮处理(N0)分别增产9.6%~19.4%、13.0%~17.8%; 当氮肥用量达300 kg·hm^-2 时, 边际产量、氮肥农学利用率、结实率、千粒重、新增纯收益率以及边际成本报酬率均显著低于其余处理(N0~N3), 其中2008 年上述各指标值分别为-4.5 kg·kg^-1、3.0 kg·kg^-1(N)、69.9%、25.1 g、0.91%、1.03 元·元^-1。由水稻产量、经济效益与氮肥用量拟合方程求得最大经济收益时的氮肥用量为218~223kg·hm^-2, 水稻产量和经济收益分别为7 686~8 295 kg·hm^-2 和7 413~8 607 元·hm^-2。因此, 秸秆还田条件下合理配施氮肥, 不仅可以获得最佳经济收益, 还可以获得较高水稻产量和氮肥利用率。

Effects of different N-fertilizer rates with straw incorporation on rice yield and economic benefit of rice-wheat rotation system in Taihu Lake region

The application of fertilizers along with straw incorporation was a common practice in sustainable crop production. A field experiment under different N-fertilizer application rates with full straw incorporation was conducted to explore N application rate for optimal crop yield and economic benefit in Taihu Lake region. Five treatments were designed with 0 (N0), 120 kg(N)·hm^-2 (N1), 180 kg(N)·hm^-2 (N2), 240 kg(N)·hm^-2 (N3) and 300 kg(N)·hm^-2 (N4) N-fertilizer application rates each with 6 t·hm^-2 incorporated straw. Results showed that rice yield initially increased with increasing N-fertilizer rates and then decreased. The maximum rice yield in 2007 and 2008 was 8 543 kg·hm^-2 and 7 772 kg·hm^-2, respectively. Compared with N0 treatment, rice yield for the two years of N-fertilizer application (treatment N1~N4) increased by 9.6%~19.4% and 13.0%~17.8%, respectively. Compared with N0~N3 treatments in 2008, N4 treatment presented obviously lower marginal yield (4.5 kg·kg^-2), agronomic use efficiency of N-fertilizer 3.0 kg·kg^-1(N)], seed setting rate (69.9%), 1000-grain weight (25.1 g), additional net-income rate (0.91%), and marginal cost return rate (1.03 Yuan·Yuan^-1). A fitted rice yield, economic benefit and N-fertilizer application rate equation showed an optimal N-fertilizer rate of 218~223 kg·hm^-2, under which the optimum rice yield and maximum economic benefits were 7 686~ 8 295 kg·hm^-2 and 7 413~8 607 Yuan·hm^-2, respectively. Optimum N-fertilizer application with full straw incorporation not only achieved the best economic benefits, but also the highest rice yield and nitrogen utilization efficiency.