Study on CO2 emissions and its kinetics of soils with different fertilization systems

CO2 emission and its kinetics of farmland soils with different fertilization systems were studied by incubation method. The results showed that CO2 emission of farmland soils is a first-order reaction in the condition of water content between 12% and 24%. CO2 emission of soils can be described quantitatively by kinetic equation y=A0(1-e-kt) of first-order reaction (r2=0.9812～0.9959). Kinetic coefficient A0(potential respiration C)was increased linearly with the increasing of water content (r2=0.9728～0.9987). Rate constant k was decreased linearly with the increasing of water content (r2=0.9356～0.9939). The kinetics and its coefficient of CO2 emission of farmland soils were affected significantly by fertilizations. Contrasted to CK (no fertilizer) soil, the potential respiration C(A0) and rate constant (k) of soils with NP fertilizer or manure +NP fertilizer were increased significantly, and A0 of soil with straw +NP fertilizer was also increased significantly, but k of soil with straw +NP fertilizer was decreased significantly. Contrasted to soil with NP chemical fertilizers, the rate constant (k) of soils fertilized with organic and inorganic fertilizer ( straw +NP, manure +NP ) was decreased significantly.