Abstract
To increase the nutrient release efficiency of controlled-release urea, urea granule is double coated with two different coating materials. Experimental analysis of nutrient release from the urea explains two major factors responsible for release, diffusion and erosion. It has been proposed a mathematical model involving two moving boundaries for diffusion and erosion front. The mathematical analysis presented in the paper will help in designing improved controlled-release urea to meat plant nutrient uptake requirement. The nutrient release presented in the paper are obtained for constant release rate, zero order release, time required for complete release or life time and decay release time of nutrient release of coated urea. There will be increase in time required for zero order time and total release time by double coating the urea. The model results are helpful for designing high efficiency double coated controlled release urea.