Assessment of Soil Moisture Uptake under Different Salinity Levels for Paddy Crop

The core of salinity problems starts from the fact that irrigation waters contain some amount of dissolved salts. Soil moisture salinity is dependent on soil type, climate, water use, and irrigation. The root water-uptake pattern for paddies is studied for saline as well as nonsaline conditions in the present study using a nonlinear root water uptake model. Field crop experiments are carried out using irrigation water with two different levels of salinity (4 and 6.25 dS/m) and fresh water. The effect of salinity on soil moisture uptake is studied by two approaches, i.e., effect on crop coefficient and effect on hydraulic conductivity. Based upon the experimental observations for low-saline (4 dS/m), high-saline (6.25 dS/m), and freshwater conditions, an exponential form of an equation is established for the hydraulic conductivity. The results obtained for soil moisture depletion in the crop root zone show significant improvement in prediction of soil moisture uptake for saline cases with the use of the obtained nonlinearity parameter. (C) 2016 American Society of Civil Engineers.