Active soil organic matter (ASOM) is an important soil component, influencing
Dissolved Organic Carbon (Doc), microbial biomass
(MB), and light fraction organic matter (LOM). In particular, soil organic matter (SOM) affects short-term nutrient turnover and is responsible for temporary stability of soil structure. ASOM is a major component of biochemical cycles of nutrient elements such as N, P, S, and both its quality and quantity reflect and control primary productivity. ASOM has been proposed as a sensitive indicator of early changes in SOM under different management practices such as tillage, straw incorporation, fire, clear-cutting, or manure application. Because of its dual roles as a pool of labile nutrients and as the agent of decomposition of organic materials in soil, MB may be a sensitive indicator of changes in ASOM. This pool is important since it serves as a readily decomposable substrate for soil microorganisms, a short-term reservoir of plant nutrients, and fragments become the centre for formation of water-stable aggregates. Increases in organic matter quantity and especially quality can resulted in increased N mineralization potential and greatly increased aggregate stability. ASOM was evaluated as an index of soil quality (SQ). In this paper, the authors discuss on the relationship between soil nutrients, physical and chemical properties and SQ. The quantity and quality of ASOM were found to be influenced by soil factors such as texture, water content, temperature, cation exchange capacity, and pH value. A very significant positive correlation was found between the concentrations of DOC, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and the concentrations of soil organic carbon, total nitrogen and available nitrogen. MBC and ratio of MBC to DOC were positively correlated with soil clay and silt contents, and negatively correlated with soil sand content.