This work is a ‘historical’ revision of the evolution of an experimental procedure developed by Prof. Lisardo Nez and his research group TERBIPROMAT to study the sustainability and the soil health state. From the very beginning, in 1993, the microbial activity was the main bioindicator selected to analyse the ‘soil health state’. For this reason, a microcalorimetric technique was used lately to analyse the influence of different human activities such as reforestations, agricultural exploitation or pollution on the microbial activity in different soils. Microcalorimetry is the main scientific technique used in this research to follow the stimulation of the microbial activity by addition of glucose. The data obtained were complemented by a study of physical, chemical and biological parameters of soil and allowed to follow the microbial activity in soils of Galicia (Spain) along the year. The final results, still in revision, will be helpful in establishing a data basis for real maps of the ‘health state’ of different soils. Such maps could be used to design processes that help us to decide how we should exploit soils ensuring their sustainability.