Using hydrus-2D model for simulating soil water dynamics in drip-irrigated citrus. Agricultural Engineering

Abstract

The demand of water for irrigation is gradually increasing due to escalating competition for fresh water by urban, industrial, and agricultural users. To sustain or increase agricultural productivity, there is a need to adopt highly efficient irrigation technologies such as drip irrigation in crop production. Studies related to water dynamics in crop root zone is the pre-requisite for efficient and economic design of any irrigation system. In the present study, the water dynamics under drip irrigation was evaluated taking citrus as a test crop in sandy loam soil. The soil water content observed in effective root zone (0–60 cm) of the crop showed that water availability was higher in top 15 cm soil, whereas at 45–60 cm soil depth the water content remained unchanged. Drip emitter placement in tree basin had a good influence on water distribution in root zone. The soil water content was simulated using HYDRUS-2D model to compare the observed data of water distribution in the soil in root zone of the crop. The calibrated model predicted all the parameters close to observed values with root mean square (RMSE) values ranging from 0.013 to 0.015. However, lower RMSE values were observed at deeper soil layers. At fruit maturity stage, water present at 45-60 cm soil depth was predicted to be 12.5% higher in comparison to measured values. Overall, HYDRUS-2D model has proved it’s ability to predict soil water dynamics with higher accuracy in the present crop and soil condition.