Effects of Silica-Biochar, Bentonite and Diatomite Ratios on Properties of Controlled Release Fertilizer

Controlled slow release fertilizer (CRF) in this study was produced by mixing Silica-Biochar (SB), Bentonite (B), and Diatomite (D) at different ratios with N, P, K form customized crystal membrane to control the dissolution of N, P, K into water. Research results show that the mixing rate of SB and B significantly affects the pelleting process, decay rate, hardness, and air hygroscopicity of CRF fertilizer. The decay rate is more than 20% after 13 and 5 days and greater than 80% after 17 and 9 days, respectively with SB mixing ratio of 30 and 40%. The maximum hardness of CRF fertilizer was 3.2 kg/cm2 and the smallest was 1.6 kg/cm2 respectively with the SB used ratio of 30 and 40%. With the mixing rate of SB at 30%, the resulting CRF fertilizer has the smallest hygroscopicity. With the mixing rate of B at 5%, the resulting decay rate of CRF was the smallest. The mixing rate of B did not affect the air hygroscopicity of CRF fertilizers. The different mixing rates of diatomite used did not affect the decay rate, hardness, and air hygroscopicity of CRF fertilizers.