Microbial and plant uptake of free amino sugars in grassland soils

► Microbial glucosamine uptake occurred via a saturable high affinity transport system. ► The annual flux of glucosamine through soil was estimated at 0.01-0.08 g C kg−1 y−1. ► This glucosamine flux equates to 0.1-1.6% of total heterotrophic soil respiration. ► Maize showed no capacity to take up or assimilate glucosamine.