| In this paper, the effect of different temperature (15℃、25℃、35℃) and moisture (40% WHC、70% WHC、100% WHC) conditions on characters and dynamics of soil organic carbon (SOC) mineralization of 3 types of soils (chestnut soil, chestnut brown soil and cinnamon soil) in Shanxi Province were investigated by homoeothermic incubation experiment. And analyze the response of SOC mineralization to the temperature and moisture changes. The final results indicate that:(1) Results under different temperatures indicate that the SOC mineralization has a short stage with the mineralization speed rising step by step rapidly. Then it’s followed by a long stage with the strong mineralization descending fast. Then it is a stable-low mineralization stage. The 3 types of the soil organic carbon mineralization rate achieves the highest rate which requires time of 35℃< 25 ℃< 15 ℃, while the time of strong mineralization rate descending phase duration was 35℃>25℃> 15℃. When the soil incubation temperature is high, the mineralization rates reaching the highest point is short, and strong mineralization stages last for a long period. The cumulative mineralization of SOC is 35℃>25℃>15℃, and has a significant differences among them (P< 0.05). The cumulative mineralization has a big difference in the temperatures of 35 ℃and 25 ℃ with the time going on while in the temperatures of 25 ℃ and 15℃, differences in earlier periods expand and decrease in later periods. On the whole, the cumulative mineralization of the soils with the variation width of temperature at higher temperatures (25℃-35℃) is greater than a lower temperature (15℃-25℃)Organic carbon mineralization of the soils has high sensitivity to temperature changes, when the temperature increases from 25℃ to the 35℃. Q10 ranges from 1.87 to 2.39, and the average rate is 2.16.When the temperature increases from 15℃to 25℃, Q10 ranges from 1.01 to 1.63, and the average rate is 1.29. The dynamics of SOC mineralization preferably follows the first-order kinetics:Ct=Cp (1-e-kt) Cp ranges from 52.70 to 300.63 mg-kg-1, and Cp/SOC ranges from 0.46% to 4.40%. Cp and Cp/SOC increase with the rise of temperature, and the increasing rate of Cp and Cp/SOC is higher in the higher temperature conditions. With the temperature increasing, the soil organic carbon sequestration ability is reduced, and the utilization of the land can increase the soil organic carbon sequestration capacity. Cp/SOC is found negatively correlated to total N content significantly (P<0.05) under 15℃, and negatively correlated to clay content significantly (P<0.01) under 25℃ or 35℃. Under the different temperature conditions, Cp/SOC have no significant correlation with total N、SOC、total P、total K、 pH and CaCO3.(2) Under the different conditions of moisture, the results show that the mineralization rate of SOC reaches the highest point in three days, declines dramatically later and it tends to be stable in 15 days. The cumulative mineralization of SOC ranges from 35.94 to 182.37 mg CO2-C·kg-1 and the cumulative mineralization of SOC under different soil moisture conditions is significantly different (P<0.05). The cumulative mineralization of SOC increases with the rise of moisture content. However, there is high increasing rate in the higher water content condition (70%-100% WHC) than in the lower water content condition (40%-70% WHC). The Cp ranges from 33.10 to 193.56 mg-kg-1, and the Cp/SOC ranges from 0.41% to 3.35%. Cp and Cp/SOC also increase with the rise of soil water content. Similarly, the increasing rate of Cp and Cp/SOC is lower in the higher water conditions. Cp/SOC is found negatively correlated to SOC content significantly (P< 0.05) under 40%WHC, and negatively correlated to SOC content and clay content significantly (P< 0.05) under 70%WHC or 100%WHC. Soil types have great influence on Cp/SOC values. The Cp/SOC values of different soils are in the following order:chestnut brown soil>chestnut soil>cinnamon soil. |
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