Modeling Approach to Simulate Water Percolation in Rice-Wheat System

Abstract

The resource conservation technologies (RCT) in the rice-wheat system are the efficient techniques for land preparation, improved crop production and conserving water. Field experiments were conducted in the rice-wheat area of Punjab, Pakistan. The assessment of percolated water below the root zone was made through the simulation from July 2001 to November 2003 in rice-wheat production system using GLEAMS (Groundwater Loading Effects of Agricultural Management System) model. Four agriculture management practices, such as 1) direct seeding of rice and zero tillage for wheat, 2) direct seeded rice and wheat on beds with 2-rows, 3) transplanting rice seedlings on beds and wheat on beds with 3-rows, and 4) random manual transplanting of rice in puddled field and traditional wheat planting on flat were used. The model was calibrated by comparing observed and simulated surface runoff, deep percolation and evapotranspiration for rice and wheat crops. The results indicated that the major component of percolation losses was observed during the period from June to November, and decreased from December to May due to the reduced irrigation application and winter rains. The average yearly percolation as a percent of inflow for agriculture management practices indicated above was 48.39, 46.68, 53.86 and 57.14, respectively. It was observed that the direct seeded rice on beds and wheat on beds with 2-rows was the best practice of water saving. The simulation study further indicated that the percolation loss increased with greater irrigation application depths and resulted in inefficient use of soil moisture storage.