CO2 emission pattern of eroded sloping croplands after simulated rainfall in subtropical China

Abstract

Soil water erosion can profoundly affect soil properties, especially their integration with serious cultivation. The mobilization and depletion of soil organic carbon (SOC) are likely to respond to this disturbance, which may profoundly change the patterns of ecosystem carbon cycles. The effects of water erosion on SOC mineralization within tillage (TT) and no-tillage (NT) sloping lands were examined in this study through the simulation of one-hour rainfall and field observation of CO2 emission. During the rainfall, the estimated soil loss rates induced by erosion in NT and TT amounted to 0.72 and 0.05×103gm−2 respectively, and the corresponding SOC loss rates amounted to 10.83 and 0.84gm−2. Most of the measured soil properties showed significant difference between NT and TT after erosion. The cumulative CO2 productions of the three sub-plots in NT were lower than that of the control plot, while this observation was not detected in TT. NT also had larger variability in CO2 evolution rate than TT. The potentially mineralizable C showed a pattern of increase from up slope to down slope in both NT and TT. Redundancy analysis results illustrate that soil bulk density, moisture and dissolved organic carbon were the major physical factors controlling erosion-induced carbon mineralization among the measured soil properties, and that a complex interplay between the above three factors and silt content could best explain the variability of the cumulative CO2 productions. Together, these results suggest that patterns of CO2 emission from sloping croplands are closely related to the changes of soil properties induced by erosion, and tillage practices may profoundly affect those patterns by inducing shifts in the erosion-resistance response of soil texture to rainfall. Moreover, tillage practices could slow SOC mineralization under the influence of a single rainfall event more than no-tillage practices in the hilly red soil region of subtropical China.