The Analytical solution of transport equation for linearly decreasing urea concentration in shallow water table condition in irrigated field

Abstract

Attempt has been made to develop analytical models for time dependent nitrification/ denitrification and depth dependent absorption of urea fertilizer in high water table conditions with fertigation. Laplace transformation method was used to solve the unsteady-state advection-dispersion equation. The analytical solutions that can be derived by this method assist understanding of movement of fertilizer in irrigated fields. The developed models were validated with the experimental results. They were closely predicting the fertilizer movement in one-dimension soil medium. The little deviation of result from observed values may be due to change of dispersion coefficient and velocity with moisture content. Here we have assumed these parameters as constant throughout the time under consideration. Model developed for constant degradation rate is predicting very close to observed values which shows that the soil under study have no depth dependent degradation. The developed models may be helpful for planning of drain design, nutrient management and assessment of potential hazards to groundwater in agricultural fields by the knowledge of exact transport parameters and boundary conditions universally.