Microbiological indicators are key to assessing soil organic quality and fertility. Microbial biomass reflects the abundance of living organisms (bacteria, fungi, protozoa) and represents the living fraction of soil organic carbon. It responds quickly to changes in practices and is proportional to total carbon, offering insight into microbial activity. A high value indicates strong microbial presence, promoting organic matter mineralisation and soil structure. ABM (Anaerobic Mineralisation of Nitrogen) measures nitrogen release under controlled conditions (40?°C, 7 days), offering a quick estimate of mineralisable nitrogen. It complements the 28-day aerobic test and is easier to implement. High ABM values suggest strong nitrogen supply potential, but also risk of nitrogen losses through volatilisation. Together, these indicators help interpret soil biological health and guide fertilisation strategies. Good soil fertility requires balancing biological, chemical, and physical parameters.