Land Use Impact on Carbon Dynamics in Soils of the Arid and Semiarid Tropics

A well known fact is soil organic carbon (SOC) levels decline when land is converted from grassland or forest ecosystems to cropland. Intensive tillage, however, was used which strongly indicates that if soil organic carbon levels are going to be maintained or enhanced, cropping systems that involve less intensive tillage practices will be necessary. In order for carbon to be retained in the soil as humus or other forms of soil organic matter (SOM), there must be sufficient nitrogen available to “hold” the carbon. The SOM is a major sink for carbon. The SOC is also significantly correlated with soil productivity and soil quality. As temperatures increase, SOM decomposition is accelerated, particularly in frequently tilled soils. Increasing carbon sequestration in soils involves increasing the quantity of organic matter returned or added to the soil, or reducing the SOC lost by oxidation or erosion, or a combination of both.