Simulation of nitrogen fertigation schedule for drip irrigated paddy

Abstract

A robust soil-water system is essential for achieving most of the Sustainable Development Goals of United Nations. Systems approach is essential to keep the soil-water system to derive sustainable benefits. Prevention is better than cure; hence accurate prediction of the likely results of our action on soil-water system is needed. Hydrus is one of the handy tools for simulating root zone under drip irrigation to derive best management practices for water and nutrient application. Hydrus is parameter intensive software. Hence, mostly, there is a tendency to use typical values of parameters available in the literature for modelling. In this research work, we generated data for Hydrus by intensive field experimentation to improve the reliability of modelling. The first order rate constants of urea-ammonium-nitrate reactions were obtained by field experimentation. HYDRUS was used numerically to simulate nitrogen transport for paddy crop under drip irrigation. From the simulation, various fluxes of urea, ammonium and nitrate were quantified, to develop a N fertigation schedule for entire crop duration. The fertigation schedule was implemented by raising a paddy crop and evaluation was done by estimating N assimilation of crop by plant sample analysis. The simulated values of nitrogen uptake were in good agreement with the observed values of nitrogen uptake.