Monitoring in situ microbial activities in wet or clayey soils by a novel microbial-electrochemical technology

Measuring microbial respiration is the most common method used to determine soil biological (microbial) activities, soil organic matter content, and general soil health; however, these methods are usually time-consuming, consumables heavy, and are less sensitive to soils with excessive moisture content or low permeability (such as clay). While soil respiration methods rely on carbon dioxide (CO2) released from microbial metabolism, microbial electrochemical technologies (MET) assess soil microbial activity levels by quantifying electrons that are released from the microbial degradation of soil organic matter. An MET device was designed and constructed as an alternative tool for measuring soil microbial activities and to validate its effectiveness in clayey soil. The results indicated that the electrical potentials (voltage drops across a resistive load) measured by the MET device correlated with soil CO2 emissions and microbial activity levels. Overall, MET offers an alternative and cost-effective method for determining soil microbial activity levels without using consumables. It can also overcome the limitations associated with wet or clayey soils, further validated through ongoing and future studies and field applications. (C) 2020 Elsevier B.V. All rights reserved.