Soil organic matter (SOM) has a large influence on the long-term sustainability of soil systems and the ecosystems and landscapes they support (Follett et al., 1987). SOM conservation and enhancement have positive effects on plant nutrient status, soil structure, and soil water holding capacity (DeJong et al., 1983; Soane, 1990; Kern and Johnson, 1993). The beneficial impacts of these factors on plant productivity create a positive feedback loop between net primary production (NPP) and C sequestration (Fig. 5.1).