Field and Laboratory Tests of Soil Respiration

This chapter describes methods for assessment of soil and microbial respiration, and provides a framework for interpreting the measurements relative to soil quality. Standardization of field soil respiration determinations is based on laboratory observations for a wide range of soils that indicate maximum aerobic microbial respiration occurs when 60% of the soil pores are filled with water. The chapter also describes the use of soil respiration measurements as determined by carbon dioxide flux in the field as an indicator of the soil organic matter storage potential of the soil. It explores the use of laboratory measurements of microbial respiration as an indicator of nutrient release, specifically, the nitrogen supplying potential of soil. Some optimum soil respiration must be defined that balances the long-term detrimental aspects of soil carbon loss through respiration, and the soil nutrient turnover that respiration represents.