Human health and well-being are intrinsically linked to the state of ecosystems, including soil, which acts as a key reservoir of biodiversity. Its biological activity is essential for the stability and functioning of both natural ecosystems and agroecosystems. Anthropogenic intervention in soils has consequences that must be estimated in order to link soil health with soil use and management. In recent years, soil characterization has been largely limited to physico-chemical analysis, with biological indicators being scarcely considered. In this context, a methodology was developed to allow for a semi-quantitative estimation of soil biological quality in a simple, inexpensive and fast way, avoiding the need for sample transport and laboratory processing as required by standard reference methods. A setup was designed to monitor the enzymatic hydrolysis of fluorescein diacetate (FDA) through image capture using a mobile phone. The kinetic profiles of each soil sample are calculated based on the time-lapse recording of reaction tubes assisted by a smartphone and subsequent digital processing. From proof-of-concept trials, it is concluded that the methodology currently developed allows a semi-quantitative estimation of soil biological quality in a robust, portable and fast way, collaborating in the communication and understanding of soil biological processes and soil uses. The proposed approach offers a robust, portable, and adaptable alternative, with potential for application in other environmental or clinical diagnostics based on photometric reactions.