CONTROLLED UREA RELEASE EMPLOYING NANOCOMPOSITES INCREASES THE EFFICIENCY OF NITROGEN USE BY FORAGE

The rapid hydrolysis of urea applied to soil surface causes high rates of NH3 volatilization, leading to adverse environmental impacts and decreased uptake of N by crops. One approach that can be used to improve the efficiency of urea use involves strategies to control its release, such as the coating of granules with polymers. However, the effectiveness of this method can be limited by poor interaction between the coating and the granule surface. We therefore propose a novel class of nanocomposite fertilizers, based on clay exfoliation in urea matrices, with or without polymerization using formaldehyde as a strategy to increase the interaction between urea and the additives. A comparative study was performed of a set of different slow-release fertilizers, determining the amounts of volatilized ammonia, dry matter production, and efficiency of urea-N uptake by ryegrass, in a trial carried out in a greenhouse. Physicochemical characterization of the composites revealed aspects of the interaction that affec...