Quantitation of total soil carbon (TSC) using an electrochemical impedance probe

Abstract

Soil is an essential element of Earth's ecosystem that helps regulate the nitrogen and carbon cycles while providing an adequate environment to promote plant growth. Soil carbon is one of the key elements present in soil which provides valuable information on soil health. Total soil carbon (TSC) is a combined constituent of organic and inorganic sources of carbon, and it is important to further enhance our understanding of carbon sequestration in soil. An electrochemical sensor, using a three-electrode platform, modified by EMIM[TF₂N]-calixarene-chitosan composite was used to develop a proof of concept to track total soil carbon in-situ without sample pretreatment. Computational chemistry and FTIR spectroscopy were utilized to understand the interaction chemistry between TSC and transducing elements. Based on the interaction results obtained, the sensor was calibrated in three different soil textures; sandy loam, loamy clay, and clay loam. Electrochemical impedance spectroscopy (EIS) technique was used to measure TSC across the range of 0.01 %–4 %. The dose dependent response showed excellent repeatability for all three soil types. This is a novel proof of concept for building a consolidated total soil carbon in-situ sensor, which was further field tested using standard validation principle, to obtain its real field capability.