Evaluation of the Nitrogen Release Properties of Chitosan-Bentonite Beads

Abstract

In this study, chitosan-bentonite beads were prepared by using bentonite and chitosan as fertilizer carrier materials and urea as fertilizer components. The prepared samples were named BUC0.2, BUC0.4 and BUC0.6 based on the bentonite ratios of 0.2%, 0.4% and 0.6% (weight/volume). In the FT-IR and XRD results, it was seen that the characteristic peaks of the bentonite structure became evident in the BUC0.6 sample, while chitosan peaks were dominant in the BUC0.2 sample, as expected. As the amount of bentonite increased, the swelling ratio generally increased from 31.6% to 48.6. In the nitrogen release experiments, a very rapid nitrogen release occurred in the first hours of release. It was thought to be due to the rapid dissolution of urea in water. The cumulative release percentage showed a slightly decreasing trend in the days following the release experiment. When nitrogen release profiles of the samples containing different amounts of bentonite were compared, it was observed that the nitrogen release curves were quite close to each other due to the lower bentonite ratio. Release percentages of the samples containing different amounts of bentonite were obtained between 61.2-67.7. Observations supported the efficient degradation of fertilizers in the soil environment. As a result, it was evaluated that the prepared materials were promising as environmentally friendly nitrogen fertilizer.