Proximal Soil Nutrient Sensing Using Electrochemical Sensors

Abstract

Site-specific crop management requires the collection of high spatial resolution soil property data. Currently, electromagnetic (EM) induction or soil electrical resistance sensors, which measure soil electrical conductivity, are commonly used for this purpose. From the measurements, a number of related soil properties, e.g. clay content, are inferred. Although these techniques enable rapid, low-cost measurements that are able to capture within-field soil variability, they do not provide information on soil nutrient concentrations directly. This chapter reviews research conducted towards the development of proximal soil nutrient sensors using two forms of electrochemical sensors: ion-selective electrodes (ISEs) and ion-sensitive field effect transistors (ISFETs). It provides a brief introduction to electrochemical sensors and reviews their application for rapid low-cost soil analysis and proximal sensing. Over the last three decades, electrochemical sensors have been used in the laboratory to reduce the time, cost, and complexity of soil nutrient analysis. More recent studies suggest that ISEs and ISFETs have the potential to he used for rapid in situ soil analysis. However, the technologies have some limitations, particularly for on-the-go proximal soil sensing.