TOWARDS A MINIMUM DATA SET TO ASSESS SOIL ORGANIC-MATTER QUALITY IN AGRICULTURAL SOILS

Soil quality is a composite measure of both a soil's ability to functi on and how well it functions, relative to a specific use. Soil quality can be assessed using a minimum data set comprising soil attributes s uch as texture, organic matter, pH, bulk density, and rooting depth. S oil organic matter has particular significance for soil quality as it can influence many different soil properties including other attribute s of the minimum data set. Assessment of soil organic matter is a valu able step towards identifying the overall quality of a soil and may be so informative as to be included in minimum data sets used to evaluat e the world's soils. In this review, soil organic matter is considered to encompass a set of attributes rather than being a single entity. I ncluded among the attributes and discussed here are total soil organic carbon and nitrogen, light fraction and macroorganic (particulate) ma tter, mineralizable carbon and nitrogen, microbial biomass, soil carbo hydrates and enzymes. These attributes are involved in various soil pr ocesses, such as those related to nutrient storage, biological activit y, and soil structure, and can be used to establish different minimum data sets for the evaluation of soil organic matter quality.