基于DSSAT模型对豫北地区夏玉米灌溉制度的优化模拟

合理的灌溉制度是提高农业水资源利用效率、保证夏玉米高产稳产的前提。采用农业技术转化决策系统(DSSAT,Decision Support System for Agrotechno1ogy Transfer)探究了河南省北部地区夏玉米不同降水年型下的最优灌溉制度。经过参数的校正和验证,归一化均方根误差(nRMSE)、均方根误差(RMSE)和一致性指数(d)均表现出模拟值与实测值的吻合度很好,DSSAT-maize模型可以准确模拟夏玉米物候期、地上部分生物量、产量和土壤水分状况。然后基于模型模拟了不同灌溉处理下的夏玉米生产潜力,从而评估夏玉米缺水量,并对比分析不同生育时期灌水对产量的影响确定最优灌溉时期,综合考虑产量和水分利用效率确定最优灌溉制度。结果表明:夏玉米生长季的缺水量年际间差异显著,多年平均值为38.91 mm,波动范围为0—193.03 mm。在丰水年,不需要灌溉;在平水年,开花期灌水30 mm;在枯水年,开花期和灌浆期灌水50 mm;在特别干旱年,苗期、拔节期和开花期至少灌水180 mm。优化的灌溉制度下丰水年、平水年和枯水年的WUE达到最高且产量分别占其最高产量的100%、99.72%和97.89%,实现了作物高产节水协同提高的目标。

Optimizing the summer maize irrigation schedule in North Henan Province based on the DSSAT model

Henan Province is the main summer maize production area in China; however, the yield of maize in this region has been seriously threatened by water scarcity. It is important to improve maize yield and stability by appropriate irrigation allied to high water-use efficiency (WUE). In this study, we applied the Decision Support System for Agrotechnology Transfer (DSSAT) to determine the optimal irrigation schedules for summer maize in different hydrological years in the northern region of Henan Province. The GLUE procedure together with normalized root mean square errors (nRMSE), root mean square errors (RMSE), and index of agreement (d) showed that DSSAT-maize can be used to correctly predict maize yield, phenology, aboveground biomass, and soil water content. A calibrated model was used to simulate the effects of different irrigation treatments on the yield potential of summer maize in different hydrological years, and to evaluate the water shortages during the summer maize growing season. The optimal irrigation period was determined by comparing yield responses with different irrigation amounts and times, thereby enabling optimization of the irrigation schedule with yield and WUE. The results showed that water shortage in the summer maize growing season has varied significantly for the period of 1988-2017, averaging 38.91 mm, with a variation of 0 to 193.03 mm. In wet years, irrigation was unnecessary. Irrigation of 30 mm at the flowering stage should be applied in normal years and 50 mm at the flowering and grain-filling stages in dry years. In extraordinary dry years, irrigation of at least 180 mm should be applied at the emergence, jointing, and flowering stages of summer maize. Under the optimized irrigation schedule, when WUE reached the highest level in wet, normal, and dry years, the yield obtained accounted for 100%, 99.72%, and 97.89% of the maximum yield, respectively. The optimized irrigation schedule would produce a higher summer maize yield with the highest WUE.