Study on release characteristics of different nitrogen forms from controlled release compound fertilizer

摘要

Water dissolution, soil leaching and pot experiment methods were adopted to study the release characteristics of different forms of N (NH_4~+-N, NO_3~--N) from uncoated controlled-release compound fertilizer (CRCF) and N uptake and use efficiency of rice. Results showed that CRCF had lower release rates of total N, NH_4~+-N and NO_3~--N than common compound fertilizer (CCF). The dynamics of N release from CRCF were quantitatively described by four equations: the first-order kinetics equation (N_t=N_0(1-e~(-kt))), the Elovich equation (N_t=a + bln t), double constant equation (lnN=a+ blnt) and parabolic equation (N_t=a+bt~(0.5)). The first-order kinetics equation fittest best for describing the release of different N forms. Compared to CCF, the N release process of CRCF was better in accordance with the utrient uptake by rice. There were significant relations between the released amount of different N forms from CRCF and N uptake by rice (r=0.853~(**)—0.983~(**)).