Organic farming is supposed to be environmentally friendly due to abandonment of external inputs such
as mineral fertilizers or pesticides. Albeit conversion to organic farming frequently comes along with a
decline in crop yields, proponents of organic farming emphasize the sustainability of that system particularly
because of improving organic matter-related soil quality. Based on recent research on mechanisms
driving soil organic matter turnover, however, it rather appears that low-input agro ecosystems may
convert to smaller efficiency in terms of substrate use by heterotrophs which may affect soil organic
matter storage in the long run. A compilation of field data confirms an inferior use efficiency in some
organic soils and thus questions the claim of an overall sustainable use of the soil resource in organic
farming systems.