Ammonia Volatilization from Exposed Soil and Tanzania Grass Pasture Fertilized with Urea and Zeolite Mixture

The aim of this study was to evaluate the effects of a zeolite and urea mixture on ammonia volatilization. Two experiments were carried out: a greenhouse pot experiment and a field trial with Tanzania grass pasture. The pot experiment used five zeolite ratios (0, 12.5, 25, 50, and 100 percent relative to the N-urea level used) mixed with 100kgha(-1) of nitrogen (N). The field trial used four treatments: 0, 12.5, 25, and 50 percent of zeolite, at the dose of 50kgha(-1). In the greenhouse experiment, the smallest losses by volatilization occurred at the proportions of 25 percent and 100 percent. During the summer, the mixture of 25 percent of zeolite in N-urea led to a reduction in ammonia volatilization from 33.5 to 7.6kgha(-1). However, in the winter, volatilization was very low, and there were no differences between the treatments. The addition of 25 percent of zeolite in urea was the most appropriate relation.