Abstract:

Soil organic carbon mineralization was the major pathway of carbon dioxide released from soil into atmosphere. The key point to estimate the carbon source or carbon sequestration of ecosystem was the difference between soil organic carbon mineralization and vegetation net primary productivity. By laboratory simulated experiment, the effects of nitrogen treatments on the soil organic carbon mineralization of the citrus orchard soil were investigated under 10℃, 20℃, 30℃. The results showed that the mineralization rate decreased quickly at the beginning of the experiment but remained stable at the late period under three temperature treatments. The amounts of CO2 ranged from 1328.25-2219.42 mg/kg under three temperature condition, the amount of soil organic carbon mineralization of 100 mg/kg (N4) treatment was the greatest and that of CK was the lowest, meanwhile, The high level nitrogen treatment (N4 and N3) were significant higher than the lower level nitrogen treatment (N2 and N1). The soil organic carbon mineralization rate increased with the temperature from 10℃ to 30℃. The dependence of soil carbon mineralization to temperature (Q10) was different under different nitrogen treatments. The Q10 value of N2 treatment was the lowest and that of the N4 treatment was the greatest.. The soil organic carbon mineralization in Citrus orange orchard soil was affected significantly by high level nitrogen treatment, but with no significance under lower nitrogen treatment. The dependence of soil carbon mineralization to temperature (Q10) increased with the increasing nitrogen input. Nitrogen combined with temperature may increase there lease of CO2 from Citrus orchard soil.