苏南麦田基施包膜尿素的农学和环境效应评价

为验证包膜尿素一次性基施、速效矿质氮肥分次施用在南方冬小麦系统中的可替代性,在江苏江宁麦田建立田间试验,通过连续3 a的3个作物季观测,比较了0、160 kg N·hm~(-2)(低量)和240 kg N·hm~(-2)(习惯用量)施氮量下树脂包膜尿素一次基施(PU)和非包膜尿素分次施用(U)对小麦产量、氮肥利用率及NH_3挥发与N_2O排放的影响,并从经济效益和气态活性氮减排两方面评估了包膜尿素施用的农学和环境效应。结果表明:U和PU处理小麦产量均随施氮量增加而提高,但PU下增产更显著。习惯施氮量下,PU比U平均增加小麦产量16.6%,提高氮肥偏生产力和农学利用效率16.7%和26.6%。等氮量下PU虽不能提高氮肥生理效率,但却显著提高氮肥利用率35.7%～65.2%。同时,PU较U处理能有效削减NH_3和N_2O排放峰,习惯施氮量下可降低NH_3和N_2O季节累积排放量43.3%和37.6%。综合分析产量、肥料和其他管理成本的产投收益结果表明,施用160 kg N·hm~(-2)PU即可近似达到U习惯施氮量下小麦产量水平和净收益;且当PU施氮量增至240 kg N·hm~(-2)时,可在不显著增加NH_3和N_2O排放情况下,显著增加小麦产量,近而大幅提高农户净收益41.8%。研究表明,与农户习惯施氮相比,供试聚氨酯包膜尿素一次基施不仅能够获得高产,而且也有利于农户增收和环境保护。

Effects of a single basal application of polymer-coated urea to a wheat field on crop yield, nitrogen use efficiency and NH3 and N2O emissions in eastern China

The purpose of this study was to verify the subrogation of one-time base application of coated urea and multiple application of quick mineral nitrogen fertilizer in winter wheat system in southern China. A field experiment was established in Jiangning wheat field in Jiangsu Province. The effects of polyurethane resin coated urea(PU) with single application and non-coated urea(U) with three split application on wheat yield, nitrogen use efficiency, NH₃ volatilization and N₂O emission were compared at 0, 160 kg N·hm^-2(the lower application rate) and 240 kg N·hm^-2(the conventional application rate). The agronomic and environmental effects of coated urea application were evaluated from two aspects of economic benefit and reduction of gaseous active nitrogen. The wheat yield of U and PU treatments increased with the increase of nitrogen application rate, but the effect of increasing yield was more significant with PU treatments. At the conventional application rate, the amount of PU to U increased wheat yield by 16.6%, the N partial factor productivity and agronomic efficiency by 16.7% and 26.6%. Although PU treatments could not improve the physiological efficiency, it significantly increased nitrogen use efficiency by 35.7%~65.2% at the same application.The results showed that PU had better effect on wheat yield increase because of the promotion of above-ground nitrogen absorption and the improvement of apparent nitrogen use efficiency. Meanwhile, PU can effectively reduce the emission peaks of NH₃ and N₂O compared with U treatment, and the seasonal cumulative emission of NH₃ and N₂O can be reduced by 43.3% and 37.6% at the conventional application rate. The results of comprehensive analysis of yield, fertilizer and other management costs showed that 160 kg N·hm^-2 PU could approximately reach the yield level and net economic benefits of wheat at the conventional application rate. When the nitrogen application rate of PU increased to 240 kg N·hm^-2, the wheat yield was significantly increased and the net economic benefits of farmers was significantly increased by 41.8% with no significant increase in NH₃ and N₂O emissions. Compared with farmers'' conventional practice with three split application, a single application of polyurethane coated urea in the test could not only obtain high yield, but also benefit farmers'' incomes increase and environmental protection.