节水灌溉与控释肥施用对太湖地区稻田土壤氮素渗漏流失的影响

在太湖流域采用田间小区试验研究了干湿交替节水灌溉与控释肥(控释BB肥与树脂包膜尿素)施用对稻田30 cm深土壤渗漏水总氮(TN)、铵态氮(NH+4-N)、硝态氮(NO-3-N)和亚硝态氮(NO-2-N)浓度的动态变化及氮素淋失的影响.结果表明:各处理渗漏水TN、NH+4-N和NO-2-N浓度均在施肥后10 d内达到高峰,然后逐渐下降.渗漏水氮素以NH+4-N(0.22~15.15 mg·L-1)为主,平均占TN 70.1%,NO-3-N(0.10~0.95 mg·L-1)占TN比例较低,平均为13.0%,NO-2-N(0~0.24 mg·L-1)平均仅占TN 1.3%.与淹灌相比,节灌对稻田渗漏水氮素浓度及各氮素占总氮的比例影响不大,但降低了14.2%的渗漏水量和9.4%的TN淋失量.施氮显著提高了渗漏水氮素浓度以及NH+4-N和NO-2-N占TN的比例.控释BB肥和树脂包膜尿素较常规尿素处理水稻全生育期渗漏水TN平均浓度分别降低10.2%和43.3%,TN淋失量分别降低26.1%和39.5%.综上,干湿交替节灌结合树脂包膜尿素施用有利于降低氮素渗漏损失,促进农田面源污染减排.

Effects of water-saving irrigation and controlled-release fertilizer application on nitrogen leaching loss of paddy soil in Taihu Lake region

A field plot experiment was conducted to study the effects of alternate wetting and drying (AWD) irrigation and controlled-release fertilizers (controlled-release bulk blending fertilizer and polymer-coated urea: BBF and PCU) application on the nitrogen (N) dynamics in percolation water at 30 cm soil depth in paddy fields in Taihu Lake region. Results showed that TN, NH₄⁺-N and NO₂^--N concentrations of the percolation water in all treatments peaked within the first 10 days after fertilization, and decreased gradually afterwards. NH₄⁺-N (0.22~15.15 mg·L^-1) was the main form of N in percolation water which accounted for 70.1% of TN, whereas NO₃^--N (0.10~0.95 mg·L^-1) and NO₂^--N (0~0.24 mg·L^-1) had lower proportions of 13.0% and 1.3%, respectively. Compared with continuous flooding (CF) irrigation, AWD irrigation did not significantly affect percolation water N concentrations, but decreased the amount of percolation water by 14.2% and the leaching loss of TN by 9.4%. N fertilization remarkably increased TN, NH₄⁺-N, NO₃^--N, and NO₂^--N concentrations as well as the proportions of NH₄⁺-N to TN and NO₂^--N to TN in percolation water. On average, BBF and PCU decreased the TN concentrations by 10.2% and 43.3% and TN leaching losses by 26.1% and 39.5%, respectively, in comparison with conventional urea. Therefore, the combination of AWD irrigation and PCU application can be helpful to decrease the leaching loss of N, and promote the reduction of agricultural non-point source pollution.