Soil Organic Sulphur and its Turnover

This chapter focuses on the schematic description of sulfur (S) cycle at global level and in soil–plant–atmosphere systems. Knowledge of this cycle helps in understanding the accumulation and turnover of organic S in soils. The chapter also summarizes the knowledge concerning the quantity, forms, distribution, and turnover of organic S in soils. Chemical fractionation provides information about the nature of organic S, yet it does not provide a true reflection of the biological reactivity of the different forms of S in soil where the whole system is heterogenous and complex. The method that fractionates soil organic S into different pools according to their biological and biochemical lability is very informative. Microbial biomass-S is the most active component of soil organic S. The relationships and interactions between organic C, N, and S cycles in soil are examined through the perspective of microbial activity.