Study of deep percolation in paddy fields using drainage-type lysimeters under varying regimes of water application

Abstract

Deep percolation in water-intensive paddy rice crop field is a major outflow and needs due attention. In this paper, field observation of deep percolation in paddy fields under varying regimes of water application has been presented. Large portion of input water is lost due to deep percolation as observed from drainage-type lysimeters and verified using physically based model. More than 80% of the input water was lost through deep percolation during continuous irrigation season, while approximately 75–80% of the input water was lost due to deep percolation during the intermittent application of irrigation season. This would be attributed to soil texture, experimental field condition and the mode of input water. The physically based model has been calibrated and validated using field-observed deep percolation. A good agreement between model simulations and field-observed deep percolation was obtained. Further, field-observed and model-simulated soil moisture content values at respective crop periods showed fairly good agreement. This shows the significance of locally constructed drainage-type lysimeters in capturing deep percolation below a crop root zone. These types of lysimeters are easy to construct, maintain, simple to operate and thus can play a significant role in agricultural water management.