Modeling root zone water and salt transport using matric flux potential based root water uptake distribution.

• A matric flux potential-based non-linear root water uptake model is developed. • The study proposed an improved objective function to estimate model's parameters. • Soil-column lysimeter experiment is conducted to calibrate model's parameters. • The compensated root water uptake reduces with increasing salinity in root zone. It is important to delineate the root water uptake (RWU) response to salt and water stress for assessing future water availability under extreme climatic conditions. The process of RWU in salt-affected soils is highly complex and not well understood. The present study proposed a matric flux potential based non-linear RWU model capable of calculating reduced RWU in water and salt stressed conditions. The study incorporates a sensitivity analysis of the model's parameters. For the inverse estimation of these parameters, an objective function has been formulated, utilizing data derived from the highly sensitive model's response. The proposed objective function provides unique estimates for these parameters. Using this objective function in an optimization process, the model is calibrated with observed data obtained from a soil column lysimeter experiment conducted on berseem crop (Trifolium alexandrium). The parameters are optimized through the coupling of the model with a genetic algorithm-based optimizer tool. Simulated data for soil moisture, electrical conductivity, and percolation are then compared to observed data. The simulated model's responses are found to be closely aligns with the experimentally observed values. The RWU under four irrigation of different salinity levels is simulated. The results highlight a reduction in RWU compensation under high-salinity irrigation treatment. [ABSTRACT FROM AUTHOR]