ABSTRACT
Agricultural practices (row crop, orchard, forest management, and rangeland management) that disrupt the soil proŸle with aggressive tillage for crop production or weed control or structural rehabilitation, remove crops and their stubble on a regular basis, or rely on inorganic fertilizers tend to promote declines in natural SOM reserves (Six et al., 2000; Coleman et al., 2004; Wang and Dalal, 2006). Ways to ameliorate the losses of SOM pools in croplands and forested lands are being explored by scientists in several countries (Elliott and Coleman, 1988; Grace et al., 1998; Six et al., 2000, 2004). These efforts were initially promoted to sustain croplands for food production but more recently are seen as mechanisms for the sequestration of C in soil due to the concern over global warming and rising levels of atmospheric CO2 and the fact that soils represent the largest terrestrial pool of C, containing 1500 pg, twice that of the atmosphere (Schlesinger, 1996).
