The effect of land management on soil organic carbon dynamics along the soil profile in a tropical region (southern Kenya)

While the importance of soil organic carbon (SOC) in the global carbon cycle is well-established, many knowledge gaps remain related to how land management affects changes in SOC stocks, and protection mechanism of SOC. This is particularly the case for the tropics, as is clear from multiple recent meta-analyses on data related to soil biogeochemistry. In addition, while current knowledge on SOC dynamics is derived from the topsoil, studies on how land management affects subsoil OC properties are scarce.

Therefore, we studied how two types of land management affect SOC characteristics down to 1 m depth in two locations in southern Kenya. At one location (Embu), the effect of nutrient management on protection mechanisms of SOC is assessed, while at the second location (Mau Forest region) we study the effect of land use changes on soil biogeochemistry. The focus of this study is on assessing how land management affects SOC protection mechanisms (using carbon fractionation) and the contribution of microbial necromass to total SOC (using amino sugar analysis). In addition, multiple other soil properties, including microbial ecology, have been quantified to improve our understanding of the effect of land management on subsoil OC dynamics.

Using our results, we aim (i) to improve understanding of these processes and (ii) to use this knowledge to improve a mechanistic model simulating soil C and N dynamics along the soil profile.