The thermodynamic efficiency of soil microbial communities subject to long-term stress is lower than those under conventional input regimes

► Thermodynamic efficiencies of soil microbial communities were determined. ► Efficiencies were different following contrasting long-term soil managements. ► Stressed communities showed lower efficiencies compared with conventional regimes. ► Differences were mirrored in microbial community structure and functional profiles. ► Micro-calorimetry provides quantification of microbial C use efficiency in soils.