Nonlinear Root-Water Uptake Model

Abstract

Sound irrigation management requires information about root-water uptake patterns of different crops. In the existing literature, the extraction rate of soil moisture by the roots is assumed to be either constant or varying linearly with the root depth, during the crop period. However, both these models have limited application. With this in view, an empirical root-water uptake model in which the extraction rate varies nonlinearly with the root depth is proposed. Using experimentally obtained soil-moisture depletion values for nonlimiting soil-moisture conditions, it is found that the proposed model performs better than the constant rate models and linearly varying rate models of root-water uptake. Also, constant as well as linear extraction-rate models are found to be particular cases of the proposed model. Based on simulations for limited soil-moisture conditions, it is also found that the frequency of irrigation is sensitive to the use of root-water uptake models.