不同降水年型下水氮调控对小麦产量及生物量的影响

水和氮是影响西北黄土高原雨养农业区粮食生产的主要因素,但其增产效应受降水年型影响明显。本水氮调控试验利用APSIM模型在甘肃省定西市安定区1971—2018年气象数据,分析了不同降水年型下水氮管理对小麦产量和生物量的变异系数、可持续性指数的影响,明确了各年型产量与施氮量、降水量之间的关系。结果表明,模型模拟的小麦产量和生物量的决定系数R2均在0.90以上,一致性指标D均在0.95以上,归一化均方根误差(NRMSE)均在15%以下,表明该模型在研究区具有较好的模型拟合度和适应性。通过二元二次回归方程探讨了其最优产量下的水氮优化组合,在当年年降水总量的基础上,干旱年小麦达潜在最优产量时(3492.6kghm–2),降水需增加39.73%,应施氮182.73 kg hm–2;平水年小麦达潜在最优产量时(4514.5 kg hm–2),降水需增加45.26%,应施氮208.26 kg hm–2;湿润年小麦达潜在最优产量时(4890.3 kg hm–2),降水需增加46.31%,应施氮211.15 kg hm–2。研究结果可为研究区不同降水年型下缓解小麦干旱和养分胁迫,节约化肥资源和农业可持续性发展提供理论依据。

Regulation effects of water and nitrogen on wheat yield and biomass in different precipitation years

Water and nitrogen are the main factors affecting grain production in the rain-fed agriculture area of the Loess Plateau in Northwest China, but their yield-increasing effects will be affected by the type of precipitation. In this paper, the APSIM model was used to conduct water-nitrogen coupling test based on the meteorological data of the experimental area from 1971 to 2018. The effects of different precipitation years on the variation coefficient and sustainability index of wheat yield and biomass were analyzed. In addition, the relationship between annual yield and nitrogen application rate and precipitation was also discussed. According to the model the wheat yield and biomass determination coefficient R ² was above 0.90, the D index was above 0.95, and the normalized root mean square error (NRMSE) was below 15%, indicating that the model has good model fitting and adaptability in the study area. Based on natural conventional rainfall in each year, we explored the optimized combination of water and nitrogen for the three types of annual yields using the binary quadratic regression equation. When the potential yield of wheat in drought year reached 3492.6 kg hm ^-2, the precipitation increased by 39.73% and the nitrogen consumption was 182.73 kg hm ^-2; when the potential yield of wheat in flat water year reached 4514.5 kg hm ^-2, the precipitation increased by 45.26%, the nitrogen consumption was 208.26 kg hm ^-2; and when the potential yield in wet year reached 4890.3 kg hm ^-2, the precipitation increased by 46.31%, the amount of nitrogen was 211.15 kg hm ^-2. Among them, precipitation increased on the basis of the total annual precipitation in that year. The research results can provide a theoretical basis for alleviating wheat drought and nutrient stresses in different precipitation years in the study area, saving fertilizer resources and keeping sustainable development of agriculture.