Crop‐Stage‐Specific Analysis of Water Use Characteristics of Summer Maize ( <scp> <i>Zea mays</i> </scp> L.) Under Different Deficit Irrigation Regimes
Annotatsiya
ABSTRACT Crop‐stage‐specific deficit irrigation (DI) has been widely applied to achieve the optimum agricultural water use in dryland farming areas. However, the water use characteristics during different crop stages have not been fully investigated, considering ET uncertainties. It may hinder the correct decisions on optimum agricultural water management. This study investigated how the root‐zone water budget components varied throughout the growing season in a summer maize field under three different irrigation regimes by using a soil water model, STEMMUS‐ET, with the indirect and direct ET methods. Two successive years of crop‐stage‐specific DI experiments were conducted on a summer maize field in Northwest China to calibrate and evaluate the STEMMUS‐ET model. Results indicate that STEMMUS‐ET simulated the soil water contents, ET , soil evaporation, and root‐zone water budgets well for all irrigation treatments. The influence of using different ET methods on soil moisture content mainly affects shallow soil layers (0–30 cm). The soil evaporation simulation was largely improved by the direct ET method due to the consideration of aerodynamic and surface resistance terms, especially after irrigation. Different irrigation amount has a significant effect on the transpiration but not on the soil evaporation. It is the frequency rather than the amount of irrigation that largely affects soil evaporation. Compared to CK treatment, the DI treatments depleted more soil water storage with less use of irrigation water throughout the growing season. T1, with the reduced irrigation water amount properly at the same irrigation frequency, can significantly improve WUE, increasing it by 9.71% compared to CK. These insights help make reasonable water management in dryland agriculture.