Urea is vulnerable to losses from volatilization or leaching when applied to soils. This study proposes a porous model that couples the interfacial area ratio (IAR) equation for the diffusion of nitrogen with mass transport equation in... more
Urea is vulnerable to losses from volatilization or leaching when applied to soils. This study proposes a porous model that couples the interfacial area ratio (IAR) equation for the diffusion of nitrogen with mass transport equation in porous medium (soil). The model presents the release of a single granule with an imperfect coating thickness in different environments. The model is validated with experiments in water and soil environments. In addition, it is compared to our previous model and shows an enhancement in its predictive ability because the imperfection of the coating layer has been integrated in the model. On the basis of the proposed model, the influence of coating variation and soil types also are investigated. In general, simulation results suggest that the coating layer imperfection leads to earlier and faster nitrogen release than an ideal one. Also, nitrogen release in soil depends on soil characteristics such as surface area, particle size, and density. The comparison with experimental observations taken from the literature has validated the model’s prediction of nitrogen release in different soil types. Finally, the model has an advantage that it can model the nitrogen release either in water or soil environments. By using the input from the experimental data for the release in water, the release in soil is extrapolated based on the specific soil properties, which can be obtained from experiments or the literature.
Publication Date: 2015
Publication Name: Industrial & Engineering Chemistry Research
Multi-layer diffusion and diffusion coefficient's dependence on concentration.The prediction of nitrogen release can be easily and accurately accomplished.Model was validated with a number of experimental studies on coated... more
Multi-layer diffusion and diffusion coefficient's dependence on concentration.The prediction of nitrogen release can be easily and accurately accomplished.Model was validated with a number of experimental studies on coated fertilizers.Assessment of new CRFs at lower production cost and lesser time for experiment.New finding is the delay of released nutrient within the stage of constant release.Urea, when applied to crops is vulnerable to losses from volatilisation and leaching. Controlled release urea enhances nitrogen use efficiency by plants which not only increases the crop yields but also contributes towards environmental pollution control in terms of the alleviation of hazardous gaseous emissions and water eutrophication. This study proposes a multi-diffusion model that simulates nitrogen release from coated urea particles for both the constant and decay release stages of urea. It is developed for multilayer included the coating and water zone, and integrates a Finite-element method (FEM) with 2D geometry to enhance the accuracy of simulation by introducing urea diffusivity in water domain as a function of its concentration. Results from the simulations agreed with preliminary experimental data to a standard error of estimate (SEE) that ranged from 0.0159 to 0.0567 in which the model successfully simulated and predicted nitrogen release from hours to days from smaller to larger particles. A more thorough investigation was then conducted for which the model not only predicted nitrogen release from coated urea but also described the internal release mechanism of urea from the core to urea-coated interface and into aqueous environment.
Multi-layer diffusion and diffusion coefficient's dependence on concentration.The prediction of nitrogen release can be easily and accurately accomplished.Model was validated with a number of experimental studies on coated... more
Multi-layer diffusion and diffusion coefficient's dependence on concentration.The prediction of nitrogen release can be easily and accurately accomplished.Model was validated with a number of experimental studies on coated fertilizers.Assessment of new CRFs at lower production cost and lesser time for experiment.New finding is the delay of released nutrient within the stage of constant release.Urea, when applied to crops is vulnerable to losses from volatilisation and leaching. Controlled release urea enhances nitrogen use efficiency by plants which not only increases the crop yields but also contributes towards environmental pollution control in terms of the alleviation of hazardous gaseous emissions and water eutrophication. This study proposes a multi-diffusion model that simulates nitrogen release from coated urea particles for both the constant and decay release stages of urea. It is developed for multilayer included the coating and water zone, and integrates a Finite-element method (FEM) with 2D geometry to enhance the accuracy of simulation by introducing urea diffusivity in water domain as a function of its concentration. Results from the simulations agreed with preliminary experimental data to a standard error of estimate (SEE) that ranged from 0.0159 to 0.0567 in which the model successfully simulated and predicted nitrogen release from hours to days from smaller to larger particles. A more thorough investigation was then conducted for which the model not only predicted nitrogen release from coated urea but also described the internal release mechanism of urea from the core to urea-coated interface and into aqueous environment.
