Indirect effects of soil texture on organic matter mineralization through mediation of soil moisture

As the largest carbon pool in most terrestrial ecosystems, soil organic carbon (SOC) forms a critical component of the global carbon cycle and its preservation is crucial to further halt the buildup of CO2 in the atmosphere. Among many controlling factors, soil texture is a key soil trait determining SOC content. In addition, soil texture determines soil water balance, and such textural control may in turn influence organic matter (OM) mineralization indirectly. However, such indirect mechanisms induced by soil texture are often overlooked when interpreting and modeling the overall control of soil texture on SOC. In this PhD dissertation, we conducted two lab-scale experiments and two field-scale experiments to systematically investigate to what extent soil texture impacts OM mineralization indirectly through mediation of moisture. Overall, it was shown that there is a potentially significant indirect influence of soil texture on OM degradation through its impact on soil moisture balance and location of moisture in the soil matrix. These findings clearly suggest that the feedback mechanism induced by soil texture needs to be incorporated into soil C models to accurately predict future evolution of SOC stocks