ABSTRACT
Chemical transformations of the carbon (C) and its close association with the mineral phase, which provides physical protection, have been proposed as general mechanisms to explain the sequestration of C in the soil. The actual distribution of soil organic matter (SOM) relative to soil architecture is highly heterogenous and can be studied at different scales varying from whole soil profile to the microscopic level. The chapter aims to examine the location of SOM relative to the soil aggregate structure and to illustrate some mechanisms by which SOM, and in particular fresh plant residues, contribute to the formation and stabilization of soil aggregates. It discusses the possible role of aggregation on the decomposition and fate of SOM. In plant residue-mediated aggregation, the microorganisms are the active binding agents through both physical enmeshment, and adhesion of mineral particles to microorganisms surfaces and their associated by-products.
