Numerical modeling of the coupled mechanisms underlying salt accumulation in agricultural soils

Abstract

Sodicity is a widespread significant threat to agricultural soils with adverse impact on soil properties and crop yields. The main processes underlying this environmental hazard is the excessive accumulation of sodium ions within the soil due to the use of saline groundwater for irrigation along with high rates of evaporation. This situation naturally puts agricultural soils in arid and semi-arid regions into that risk and therefore understanding the mechanisms behind it gains importance. Although, there have been numerous studies to understand and model the problem, a detailed modeling of the coupled processes can provide further insight into the different mechanisms and their interactions. The main processes included in the model include liquid and vapor water flow, solute transport and sorption, heat transport, and evapotranspiration assess, and according to that, a numerical 1D model code is developed using an explicit finite difference method. The model is applied to a series of different cases with crop and meteorological data adopted from the Konya Closed Basin a significant agricultural region of Turkey and under the risk of sodicity with increasing drought in recent years. The factors tested in assessing soil sodicity are irrigation water quality, crop type and climate change. The importance of including heat and vapor transport during such calculations are presented and discussed.