ABSTRACT
Soil organic matter (SOM) consists of a complex array of living organisms such as bacteria and fungi, plant and animal debris in different stages of decomposition, and humus—a rather stable brown to black material showing no resemblance to the organisms from which it originates. The level of SOC in virgin soils reflects the action and interaction of the major factors of soil formation: climate, vegetation, topography, parent material, and age. These factors control SOC content by regulating the balance between carbon gains via photosynthesis and losses via autotrophic and heterotrophic respiration, as well as carbon losses in soluble and solid form.
