Pollution Research Paper

SIMULATION OF NITROGEN SCHEDULE FOR PADDY UNDER SUB SURFACE DRIP IRRIGATION

R. SHARMILADEVI AND V. RAVIKUMAR

Abstract

Growing population demand for rice and decreasing fresh water resources available for paddy cultivation leads to the adoption of water saving drip irrigation technology for paddy. Sub surface drip irrigation system (SDI) with lateral laid at 10 cm depth was selected to irrigate paddy crop.Normally under conventional irrigation fertilizer is applied in three or four equal splits without considering the plant requirement, so an attempt was made to schedule the fertilizer application for paddy under drip irrigation. Nitrogen is the important primary fertilizer required by paddy for growth, tillering and grain formation. Urea is most commonly used nitrogen fertilizer and it is highly reactive solute. Quantification of its transformation and transport are important for scheduling the fertilizer. HYDRUS 2D software was used for the purpose by simulation of water flow and nitrogen transport in the root zone. Simulation for soil water transport showed 7.14 %water lost through evaporation, 43.75% of water was consumed as root water uptake, 61.31 % of water was lost as deep percolation and change in soil moisture storage was -11.94 %. Fertigation schedule for nitrogen was done by matching the simulated nitrogen uptake with plant need of nitrogen obtained from the literature. Based on the developed schedule, 240Kg of N was given as input. Nitrogen balance within 45 cm deep soil profile indicated that volatilization, plant uptake and leaching were 159.09, 59.78 and 29.1 Kg.N/ha respectively. 0.98 Kg/ha N was left with soil at the end of the growing season. From this research it is evident that HYDRUS 2D can be used as important tool for scheduling fertilizer for any crop.