A New Method for Determining Critical Irrigation Period for Large Regions Based on Precipitation-Meteorological Yield Integral Regression Relationship—A Case Study of Winter Wheat in Shaanxi Province, China

Abstract

Using the extremely limited water for deficit irrigation is a notable measure to improve crop yield in water shortage regions. Hence, determining a reasonable irrigation period in large regions is crucial. In this study, a simple and applicable process to determine the irrigation period in a large area by using the precipitation-yield integral regression method of crop growth period was proposed, and the winter wheat planting regions with a serious water shortage in Shaanxi, China were referred to as an example. According to the regional topography, soil, precipitation, temperature, and evaporation, the study area was first divided into four subregions; then, the rainfall water surplus and deficit characteristics of the subregions during the growth period of winter wheat were analyzed, and the precipitation-yield integral regression function of the subregions was calculated. In accordance with the sensitivity of rainfall to crop yield in different periods, the reasonable irrigation period of winter wheat in each subregion was determined. The results are basically consistent with irrigation habits of local farmers, and can be used to guide the irrigation of local winter wheat. They also demonstrate that the method has the advantages of requiring fewer data and being simple and reliable, and can overcome the problem that the existing method is difficult to determine the optimal irrigation period in the large-scale region, due to the lack of test points and representativeness. The proposed method application value in determining the deficit irrigation period with small water amount, in a large region lacking research materials.