减氮条件下基于AquaCrop模型的北疆膜下滴灌棉花水氮制度优化

Optimization of Water and Nitrogen Regime Based on AquaCrop Model for Drip Irrigation Cotton Under Nitrogen Reduction Conditions in Northern Xinjiang

[目的]为检验减氮条件下AquaCrop模型对北疆膜下滴灌棉花生长及生产的模拟适用性,探究棉花生育期最优减氮与灌水制度。[方法]通过2022年、2023年大田试验,明确4种施氮水平(常规施氮量、减氮10%、减氮20%、减氮30%)、3种灌溉定额(488,444,400 mm)对棉花产量、水氮利用效率及土壤养分含量的影响;利用各处理实测数据率定并验证模型参数,并用校正好的模型模拟6种施氮水平(常规施氮量、减氮6%、减氮12%、减氮18%、减氮24%、减氮30%)、6种灌溉水平(300,360,420,480,540,600 mm)组合下棉花产量及水氮利用效率,通过综合评价方法筛选出最优水氮组合。[结果]减氮与灌溉定额共同作用对棉花产量、水氮利用效率及土壤养分具有显著影响。减施氮肥时,可通过适当增加灌溉定额达到对产量的弥补稳定棉花产量,相同施氮量下,适当减少灌溉定额提高水分利用效率;相同灌溉定额下,适当减少施氮量提高氮肥偏生产力;常规施氮时,增加10%的常规灌溉定额(W1N1)可有效提高耕作层土壤中养分含量。模拟与实测结果表明,2年试验处理的冠层覆盖度及地上部生物量各评价指标均满足决定系数(R^(2))≥0.936,均方根误差(NRMSE)≤40.58%,纳什系数(E_(NS))≥0.72;产量与水分利用效率各评价指标均满足(R^(2))≥0.87,NRMSE≤4.29%,(E_(NS))≥0.81;该模型实现较好的模拟效果。[结论]基于36种减氮与灌水组合下的情景模拟,综合考虑产量、水氮利用效率及实际生产成本,推荐在北疆地区采用减氮12%,360 mm灌溉定额的减氮灌溉制度。可为AquaCrop模型在今后对不同施肥灌溉制度下的应用提供经验,为干旱区棉花种植过程中提升水分及氮肥利用效率提供理论依据和科学指导。

[Objective]This study was aimed to test the applicability of the AquaCrop model for simulating the growth and production of drip-irrigated cotton under nitrogen-reducing conditions in the northern border,and to investigate the optimal nitrogen-reducing and irrigation regimes during the reproductive period of cotton.[Methods]Through the field trials in 2022 and 2023,we clarified the effects of four nitrogen application levels(conventional nitrogen application,nitrogen reduction of 10%,nitrogen reduction of 20%,and nitrogen reduction of 30%),and three irrigation schedules(488,444,and 400 mm)on cotton yield,water and nitrogen use efficiency,and soil nutrient content;we used measured data from the treatments to determine and validate the parameters of the model,and then simulated the model with the calibrated model.Cotton yield and water and nitrogen use efficiencies were simulated with the calibrated model under six combinations of nitrogen application levels(conventional nitrogen application,nitrogen reduction of 6%,nitrogen reduction of 12%,nitrogen reduction of 18%,nitrogen reduction of 24%,and nitrogen reduction of 30%),and six combinations of irrigation levels(300,360,420,480,540,and 600 mm),and the optimal water and nitrogen combinations were screened out by the comprehensive evaluation method.[Results]Nitrogen reduction and irrigation quota together had a significant effect on cotton yield,water and nitrogen use efficiency and soil nutrients.Nitrogen fertilizer reduction can be achieved by appropriately increasing the irrigation quota to stabilize cotton yield;Under the same nitrogen application,appropriately reducing the irrigation quota improved water use efficiency;Under the same irrigation quota,appropriately reducing the nitrogen application improved nitrogen fertilizer bias productivity;A 10%increase in the conventional irrigation quota(W1N1)when applying conventional nitrogen effectively improved the nutrient content of the tillage layer of the soil.The simulation and measurement results showed that each evaluation index of canopy cover and above-ground biomass of the 2-years experimental treatments satisfied the coefficient of determination(R 2)≥0.936,the root mean square error(NRMSE)≤40.58%,and the Nash coefficient(E_(NS))≥0.72;And each evaluation index of yield and water-use efficiency satisfied the coefficient of determination R 2≥0.87,NRMSE≤4.29%,and E_(NS)≥0.81;The model achieved a better simulation effect.[Conclusion]Based on the scenario simulation under 36 combinations of nitrogen reduction and irrigation,and considering the yield,water and nitrogen utilization efficiency and the actual production cost,the nitrogen reduction irrigation system with 12%nitrogen reduction and 360 mm irrigation quota is recommended to be adopted in the northern border region.The study can provide experience for the application of the AquaCrop model under different fertilizer and irrigation regimes in the future and provide a theoretical basis and scientific guidance for the improvement of water and nitrogen fertilizer use efficiency during cotton cultivation in arid regions.