Research on Process of Fluvo-Aquic Soil Organic Carbon Mineralization in Initial Stage of Maize Growth Under Long-Term Different Fertilization

In a 37-day laboratory incubation study soil organic C mineralization was determined in soil samples obtained from initial stage of maize growth in an 18 year long-term field experiment which was carried out to evaluate nutrition equilibrium in a fluvo-aquic soil under different fertilization treatments. During the incubation time, cumulative CO2-C released from soil was positively correlated to soil organic carbon, total nitrogen and microbial activity, which with a general decrease order of OM1/2OM+1/2NPKNPKNPPKCKNK. A modified first-order model best described C mineralization in the soil. Potentially mineralized C (C0), easily mineralized C (C1) and the initial potential rate of C mineralization (C0k) were significantly different among the treatments with a general decline order of organic manure treatmentsmineral fertilizer treatmentscontrol, which were positively correlated to soil organic carbon, total nitrogen and microbial activity. Mineralization rate (k) and potentially mineralized C divided by organic C (C0:Organic C) were not significantly different among treatments, which were not correlated to soil organic carbon, total nitrogen and microbial activity except k was negatively correlated to organic carbon. Consequently, we conferred that long-term application of both organic manure (OM or 1/2OM+1/2NPK) and mineral fertilizers (except NK) to soil could significantly increase the mineralization of soil organic carbon, reflecting the differences in soil properties, thus increase the availability of soil mineral nutrients to crops and soil organic carbon content.