Achieving high-yield and high-efficient management strategy based on optimized irrigation and nitrogen fertilization management and planting structure

Abstract: The Hexi Corridor is an important production base of maize seed and commodity grain in China. The ample sunshine and temperature greatly contribute to crop production in sustainable agriculture. However, the shortage of water resources has posed a serious threat to the efficiency of resource utilization. An adaption strategy can be expected to promote crop yield and resource use efficiency in changing environments, including the optimization of management measures and the adjustment of planting structure. Taking the seed maize, field maize, and wheat as the research objects, this study aimed to optimize the irrigation and nitrogen fertilization in the crop planting structure, in order to comprehensively improve the crop yield, irrigation Water Productivity (WPI), and Nitrogen Use Efficiency (NUE). An Agricultural Production Systems sIMulator (APSIM) model was also calibrated to evaluate the optimization using the simulations. The field experimental data was collected from the different stations over several years. The profile of seed maize was established for the crop type. The key parameters of field maize and wheat were calibrated in the APSIM. There was the high accuracy of calibrated APSIM model (0.80 < R2 < 0.85, 11.0% < normalized Root Mean Square Error (nRMSE) < 15.6%), indicating the better applicability of APSIM simulation for the seed maize, field maize, and wheat. The optimization module of irrigation was taken the single crop coefficient as the key component, considering the precipitation during the crop growth period. The optimization module of nitrogen fertilization selected the crop nitrogen concentration and biomass accumulation curve as the important components, in order to jointly constitute the irrigation nitrogen application for the optimization framework. The optimal inputs of irrigation water and nitrogen fertilization were reduced evidently. The irrigation water amount of seed maize, field maize, and wheat was saved by 22.1%-22.3%, 9.1%-17.0%, and 22.9%-27.3%, respectively, and the nitrogen application amount was saved by 32.2%-50.0%, 37.5%-44.0%, and 26.6%-33.6%, respectively, compared with the present. The objective functions included the maximum crop yield, WPI, and NUE in the optimization of crop planting structure. The boundary constraints included the total crop planting area, crop yield demand, as well as irrigation water and nitrogen fertilization input. The planting areas of seed maize and wheat after optimization were reduced by 1 095.1 and 4 472.1 hm2, respectively. By contrast, the planting area of field maize increased by 692.4 hm2. The total planting area was reduced by 4 874.8 hm2. There was a significant difference in the spatial distribution of crop planting after optimization. The total crop production, WPI, and NUE increased by 0.12×109 kg, 0.54 kg/m3, and 17.35 kg/kg, respectively, whereas, the irrigation water and nitrogen fertilization inputs decreased by 0.27×109 m3 and 3.26×107 kg, respectively, under the optimization of the irrigation and nitrogen fertilization. After the optimization of irrigation, nitrogen fertilization, and the crop planting structure, the total crop production, WPI, and NUE increased by 0.16×109 kg, 0.62 kg/m3, and 18.97 kg/kg, respectively, whereas, the irrigation water and nitrogen fertilization inputs decreased by 0.29×109 m3 and 3.36×107 kg, respectively. The finding can provide scientific guidance and reference for the high-efficient and high-yield crop production in sustainable agriculture in areas with the major grain-producing and water shortages.