Organic carbon mineralization affected by water content and plant residues in purple paddy soil

Water content and plant residues play crucial roles in the accumulation and mineralization of soil organic carbon(SOC),and thus affect C mineralization and nutrient availability in paddy field ecosystems.In this paper,we evaluated the combined impacts of soil water content and plant residues on C mineralization in the purple paddy soil,using laboratory incubations at constant temperature(281)℃ for 62 days.Results showed that the mineralization rate of organic C in the purple paddy soil reached a steady level after 30 d incubation.The accumulative evolution amount of CO2-C in the aerobic treatments was significantly higher than those in the submergence treatments(P0.01).The kinetic rate of plant residues mineralization could be quantitatively described by the firstorder kinetics equation.The decomposition rate constants(k) of plant residues was in the order of faba bean(Vicia faba) residues maize(Zea mays) residues rice(Oryza sativa) resides in the aerobic treatments,and rice resides faba bean residues maize residues in the submergence treatments.In summary,soil water content and chemical composition of plant residues significantly affect C dynamics,and thus affect accumulative mineralized amount of CO2-C.