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Soil, land care and environmental research

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A simple numerical model to estimate water availability in saline soils

Mohammad Hosein Mohammadi , Mahnaz Khataar

Abstract

We develop a numerical model to predict the soil salinity from knowledge of evapotranspiration rate, crop salt tolerance, irrigation water salinity and soil hydraulic properties. By the model, we introduce a new weighting function to express limitation imposed by salinity on plant available water estimated by the integral water capacity concept (IWC). Lower and critical limits of soil water uptake by plants were also defined. We further analyzed the sensitivity of model results to underlying parameters using characteristics given for corn, cowpea and barley in the literature and two clay and sandy loam soils obtained from database as well. Results show that, between two irrigation events, soil salinity increases nonlinearly with decreasing soil water content especially when evapotranspiration and soil drainage rate are high. The salinity weighting function depends highly on the plant sensitivity to salinity and irrigation water salinity. This research confirms that both critical and lower limits (in terms of water content) of soil water uptake by plants increase with evapotranspiration rate and irrigation water salinity. Since the presented approach is based on a physical concept and well-known plant parameters, soil hydraulic characteristics, irrigation water salinity and meteorological conditions, it may be useful in spacio-temporal modeling of soil water quality and quantity and prediction of the crop yield.

SR17081  Accepted 04 October 2017

© CSIRO 2017