Development of a portable sensor for monitoring soil biological activity

Abstract

Human health and well-being are inseparably linked to the health of other ecosystem components, such as soil, plants, and animals. Soil is a living, dynamic, and vital resource for diverse ecosystems and the maintenance of environmental quality. In recent years, soil characterization has been largely restricted to physicochemical analysis, with biological indicators being rarely included. Among the latter, fluorescein diacetate hydrolysis stands out as a method to determine the activity of various enzymes, serving as a key indicator of soil microbiological activity. In this project, an analytical methodology was developed to monitor soil biological quality directly in the field by simplifying this reference method, which until now could only be conducted under laboratory conditions. This system continuously monitors the progress of an enzymatic reaction, assisted by a smartphone that photographically records the interior of a dark box for subsequent digital analysis. Proof-of-concept tests demonstrate its capability to semi-quantitatively estimate soil biological quality in a robust, portable, and rapid manner, thereby contributing to the communication and understanding of soil biological processes and land management.