Comparison of Soil Microbial Activity Measurement Techniques.

Soil respiration is the emission of soil carbon dioxide (CO₂) by microbes in the soil. Measurement of CO₂ evolution is one of the best indicators of microbial activity and serves as an important tool to assess the biological potential of the soil. In order to standardize the measurement techniques of soil respiration in a laboratory set-up and to identify the most economic and efficient method, we compared five different types of existing methodologies: 1) Titration, 2) Electro-conductivity (EC), 3) Solvita, 4) CO₂ flow injection analyzer and 5) Modified pressure calcimeter (MPC). Soil samples from 5 soil types (Alfisols, Histosols, Inceptisols, Mollisols, and Spodosols) in the Mid-Western region, USA were analyzed in this study. The hypothesis is that all five methods will correlate with each other, but the level of accuracy, ease of use, and time and effort required to perform the tests will change among the procedures allowing us to determine what method will be the most accurate, rapid and cost-effective.