A dynamic model for salinity and sodicity management on agricultural lands: Interactive simulation approach

Abstract

In this research, a dynamic simulation model, SAMIMI (Salinity/Sodicity Management with an Interactive Model Interface), is developed for managing the effects of agricultural water use and crop choices on soil salinization and sodification, and their impacts on crop yields. SAMIMI integrates the vertical hydraulic flow, solute transport, and crop processes in feedback by a compartmental, non-linear model architecture. With its holistic integrated approach to salinity /sodicity processes, it adopts a system dynamics approach. Though it is simplified in spatial resolution, the model credibility is sufficiently evaluated with indirect structure tests and against the data by Hydrus-1D, and soil-column experiments that were conducted as part of the SAMIMI (Salinity/Sodicity Management Interdisciplinary Multi-Institutional Network) project conducted in the semi-arid Konya Closed Basin of Turkey. Model analysis provide valuable insights to the role of irrigation efficiency, water quality and crop choices on soil degradation and yield losses, which are important for learning about and management of salinity/sodicity related problems: Although irrigation efficiency is desirable for water conservation purposes, it may result in higher salinity /sodicity levels because of insufficient leaching in well drained soil profiles. Salinity and sodicity have opposite effects on soil hydraulic conductivity, and while low saline irrigation water is desirable for agricultural production, under relatively high sodic conditions, it can lead to reduced hydraulic conductivity which can degrade soil characteristics to the detriment of crops. Salinity is not simply correlated with relative irrigation water consumption but with the crop salt tolerance as well. Hence, low water consuming crops with high salt tolerance can lead to over salinization, rendering the soil profiles inappropriate for cultivation of salt vulnerable crops, if not sufficiently leached before by precipitation and/or good-quality irrigation water. The model is published as a publicly available online interactive simulation tool with a fast-simulating user-friendly interface targeting researchers, students, experts, farmers and policy makers.