Real-Time Soil CO2 Respiration Rate Determination and the Comparison between the Infrared Gas Analyzer and Microrespirometer (MicroRes®) Methods

Soil carbon dioxide (CO2) respiration is one of the important soil health parameters that provides a general assessment of soil microbial activity and soil quality. Soil respiration rates, however, have not been widely applied in soil testing protocols mainly because the traditional methods are either inconvenient, technically cumbersome or too expensive. Currently, only two methods are available for a true real-time soil respiration rate determination (<2h): the infrared gas analyzer (IRGA) and the microrespirometer (MR or MicroRes((R))) methods. We analyzed the real-time soil respiration rates of 20 soil samples from fifteen states after various periods of incubation using the IRGA method and the MR method. The measured soil respiration rates ranged from 0.4 mu L CO2/h/g to 9.0 mu L CO2/h/g. Both methods show precision in soil respiration determinations (CV=12.7% and 11.9%, respectively). Comparison of the results between the IRGA and MR methods indicates high degrees of agreement (r(2)=0.914). This study shows that the MR method is a simpler and more cost-effective alternative for real-time soil respiration rate determinations.