Modeling soil water-salt dynamics and crop response under severely saline condition using WAVES: Searching for a target irrigation volume for saline water irrigation

Abstract

Water shortage and serious soil salinization are two general features in arid regions. Crop models can provide constructive suggestions for scientific soil water-salt regulations. In the study an ecohydrological crop model WAVES (the WAter Vegetation Energy and Solute model) was employed to examine the crop responses to soil water-salt dynamics in a severely dry and saline region of southern Xinjiang, China. Observation data of film-mulched cotton with the initial soil salinity of 7.19–9.80 g kg-1 (EC1:5 of 1.56–2.12 dS m-1) were collected in 2009 and 2010 with five different irrigation water salinity treatments 0–11.05 g L-1 (EC of 0–11.85 dS m-1). Results showed that the relative absolute errors of simulated soil water and salt were less than 4.1% and 12.4% in 2010 (calibration), and 11.1% and 13.2% in 2009 (validation). The coefficient of determination of yield in calibration and validation was 0.93 and 0.74, respectively. Simulated dynamics indicated soil salt accumulation at a depth of 40 cm. Results of scenario analysis showed that crop water productivity was the highest when the total irrigation volume was 275–325 mm in all scenarios. Saline water with a certain degree of salinity can be used for irrigation without causing a severe yield reduction (20% reduction). This study provided a scientific basis for water management in areas with severe drought and salinization.