Long-term crop management effects on carbon sequestration in semi-arid soils

Abstract

The pool of organic carbon in soils (SOC) plays a key role in the global C cycle and has a large impact on the greenhouse effect (Lal et al., 1995). The levels of SOC can be managed to increase the terrestrial C pool and provide a sink for atmospheric C02. The potential of different ecoregions of the world to sequester C is climatic dependent, being high in temperate regions where crop growth conditions are favorable. Due to the droughts, arid and semi-arid regions have lower capacity to sequester C per unit area basis but due to the large extent of such areas, the total capacity may be important. Cropping practices relevant to C sequestration include tillage methods and crop rotations. However, the net change in SOC depends not only on the current management practices but also on the management history of the soil. Therefore, longterm quantification of SOC in relation to different types of soil and climates and under various soil management options is of great importance in identifying the pathways of C sequestration in soils. This paper presents results of C storage in a Calcic Haploxeralf located in the CSIC experimental farm in Toledo (central Spain) afier 12 years of maintaining various tillage and rotation combinations.