生物炭配施缓控释肥对稻田田面水氮素动态变化及径流流失的影响

在太湖流域,通过田间试验研究了控释肥(CRF)、生物炭配施控释肥(BC+CRF)、生物炭配施稳定性肥(BC+SF)、生物炭配施控释肥和稳定性肥(BC+CRF+SF)4种施肥处理对稻田田面水p H、氮素动态变化、氮素径流流失的影响.结果表明,田面水平均p H介于5.64~8.15,生物炭配施控释肥和稳定性肥田面水p H降低3.16%~4.48%.田面水平均全氮(TN)质量浓度介于19.05~25.23 mg·L~(-1),生物炭配施控释肥和稳定性肥田面水TN质量浓度显著降低4.75%~6.58%.田面水无机氮素以铵态氮(NH_4~+-N)为主,NH_4~+-N和硝态氮(NO_3~--N)平均质量浓度分别介于0.01~17.26 mg·L~(-1)和0.24~3.11mg·L~(-1).与单施控释肥相比,各处理田面水NH_4~+-N和NO_3~--N质量浓度分别显著降低35.89%~48.78%和20.54%~37.01%.生物炭配施稳定性肥显著降低了田面水NH_4~+-N和NO_3~--N质量浓度,有效减少无机氮素径流流失风险.TN、NH_4~+-N、NO_3~--N径流流失量分别介于16.24~18.09、1.76~2.22、0.76~1.38 kg·hm~(-2).与单施控释肥相比,各处理TN、NH_4~+-N、NO_3~--N径流流失均有不同程度削减.生物炭配施控释肥和稳定性肥显著削减了氮素径流流失,有效降低区域稻田氮素面源污染风险.

Dynamics and Runoff Losses of Nitrogen in Paddy Field Surface Water Under Combined Application of Biochar and Slow/Controlled-Release Fertilizer

Field experiments were conducted to investigate the effects of four fertilization treatments, that is, controlled-release fertilizer (CRF), biochar combined with controlled-release fertilizer (BC+ CRF), biochar combined with stabilized fertilizer (BC+ SF), and biochar combined with controlled-release fertilizer and stabilized fertilizer (BC+ CRF+ SF), on the dynamics of the pH and nitrogen mass concentration and runoff losses of nitrogen in paddy field surface water in the Taihu Lake Basin. The results show that the average pH of the surface water decreases by 3.16%-4.48% for BC+ CRF+ SF and is in the range of 5.64-8.15. The average total nitrogen (TN) mass concentration of surface water ranges from 19.05 to 25.23 mg·L^-1. A significant decrease of 4.75%-6.58% in the TN mass concentration of surface water was observed for BC+ CRF+ SF. The average ammonium (NH₄⁺-N) and nitrate (NO₃^--N) mass concentration of the surface water vary from 0.01-17.26 mg·L^-1 and from 0.24-3.11 mg·L^-1, respectively. Inorganic nitrogen is dominated by NH₄⁺-N in surface water. Compared with individual CRF, other treatments significantly reduce the NH₄⁺-N mass concentration of surface water by 35.89%-48.78% and the NO₃^--N mass concentration of surface water by 20.54%-37.01%. The BC+ SF combination shows a significant reduction in the NH₄⁺-N and NO₃^--N mass concentration of the surface water, which greatly lowers the risk of inorganic nitrogen loss via runoff. The runoff losses of TN, NH₄⁺-N, and NO₃^--N are in the range of 16.24-18.09, 1.76-2.22 and 0.76-1.38 kg·hm^-2, respectively. Compared with the individual CRF, the runoff loss of TN, NH₄⁺-N, and NO₃^--N of other treatments is reduced. The BC+ CRF+ SF combination shows a significant reduction in the runoff losses of nitrogen, which greatly lowers the risk of nitrogen nonpoint source pollution from paddy fields.