LAUSR

Abstract The pressure of the water supply is controlled to a negative value relying on soil matric suction and is called negative‐pressure irrigation (NPI), a subsurface irrigation method used to improve water use efficiency; however, the impacts of initial soil water conditions and emitter hydraulic conductivity on water movement under NPI remain unknown. To study the effects of irrigation management parameters on water movement under NPI, 300 scenarios using different soil textures, initial soil matric potentials, emitter hydraulic conductivities, negative pressure inside emitter and time were simulated using the Hydrus-2D software package. The effects of these variables on water movement under NPI were analyzed following the simulations, and a empirical model was created to quantify the cumulative water supply based on initial soil matric potential, emitter hydraulic conductivity, negative pressure inside emitter, and time. The results showed that the cumulative water supply increased as the emitter hydraulic conductivity increased or initial soil matric potential decreased. The relationships between the cumulative water supply and both the hydraulic conductivity of the emitter wall and the absolute value of the initial soil matric potential were logarithmic. Cumulative water supply had exponential and linear relationships with the absolute value of the negative pressure inside emitter and time, respectively. The empirical model created to quantify the cumulative water supply under NPI yielded estimations that were in good agreement with the measured values. Therefore, this model can be applied to calculate water supply under NPI, providing a smiple and reliable tool for future NPI applications and management.