Assessing Soil Quality by Testing Organic Matter

Soil is a finite resource and interest in measuring the degradation, improvement, or preservation of soil has led to efforts in developing tests to evaluate the quality of soil. In Missouri, 50 yr of cropping to continuous com caused a 56% decline in SOM as compared with Soil organic matter (SOM) levels of virgin timber or mixed grasses. Practical evaluation of SOM change as an indicator of soil quality will require specific analysis of the dynamic SOM fractions that define SOM quality and serve as indicators of potential long-term change in the quantity of SOM. The biological factors associated with organic C are microbial biomass, respiration, enzymes and active C fractions such as carbohydrates and light fraction. Suggestions of SOM components that may be useful in soil quality evaluation and serve as early warning indicators are particulate organic matter or POM, microbial biomass and specific respiration.