Study on the release property of nitrogen in sustained-release fertilizer with carrier of bentonite

The research took the natural, cheap and porous mineral bentonite as the carrier of raw fertilizer NH4H2PO4, added urea-formaldehyde resin to bond and mixed them, then made the bentonite carrier slow release nitrogen fertilizer by electric tablet press machine. Through the method of water dissolution rate to exam the cumulative release property of nitrogen element in bentonite carrier slow release nitrogen fertilizer. By single-factor experiments, the article studied the impact on release property of nitrogen element caused by bentonite type, the amount of urea-formaldehyde resin, magnesium carbonate, and the ratio between bentonite and ammonium dihydrogen phosphate in order to determine the relationship between those factors and the release property of nitrogen element. The experiment have gotten the following main conclusions: Compared with calcium bentonite and purification of calcium bentonite, sodium bentonite has a better slow release effect. The rate of nitrogen accumulation release of slow release nitrogen fertilizer tablets increased with the ratio between bentonite and fertilizer while decreased with the increasing of the amount of urine aldehyde resin, but when the amount of resin increased to a certain degree, the difference was not significant. As the addition ratio of magnesium increased, the sustained release effect became better. However, adding too much (10%) magnesium would produce too many by-products, which led a negative effect to the release property of nitrogen element in fertilizer.