Root Water Uptake Model Considering Soil Temperature

Abstract

A field experiment was carried out to research the effect of soil temperature distribution on root water uptake in soil water simulation. Soil temperature distribution patterns under border irrigation and surface drip irrigation were researched. The root water uptake model was modified based on the effect of soil temperature on root water uptake. Results showed soil temperature profile distribution was greatly influenced by irrigation method. The range of temperature was larger under border irrigation, with the temperature being 3–6°C higher in 0–20 cm depth than in 20–100 cm depth. Except for the top layer under surface drip irrigation, mean soil temperature showed the trend of exponential decay throughout the soil profile. The relationship between temperature and water uptake rate was expressed in exponential function. With the modification of the root water uptake model as affected by temperature profile distribution, the value of the root mean square error between the simulated and observed soil water decreased from approximately 0.04 to 0.02 in the top layer under border irrigation, but showed no obvious difference under surface drip irrigation. When soil temperature differed greatly in the top layer from the deep layer, the root water uptake model considering soil temperature could improve the precision of soil water simulation. The results indicated that the modified root water uptake model could be used to simulate soil water dynamics.