Tillage disturbance influences soil microorganisms and consequently the production and decomposition of microbial residues such as amino sugars. However, our understanding is still limited with respect to the changes in amino sugars which occur in soil after tillage operations. In this study, changes in amino sugars in a clay loam soil were tracked in long-term (29 years) no tillage (NT), long-term conventional moldboard plow tillage (MP), and long-term bluegrass (Poa pratensis L.) sod (BG) as well as when long-term (13 years) NT was converted to MP, long-term MP was converted to NT, and long-term bluegrass BG was converted to MP. Soil samples were collected at depths of 0–5, 5–10, and 10–20 cm after 1, 6, 11, and 16 years following tillage conversion. The amino sugar concentrations were much higher under long-term BG than under both long-term NT and MP treatments. In the 0-5 cm depth, long-term NT significantly increased total amino sugars and fungal-derived glucosamine by 18 and 25%, respectively, compared to long-term MP. Concentrations of total amino sugars in the 0–5 cm depth were reduced significantly within the first year after converting long-term NT and BG to MP, due primarily to decreases in the glucosamine concentrations. On the other hand, soil amino sugar levels accumulated gradually after converting long-term MP to NT. The results confirmed our hypothesis that loss of soil amino sugars is rapid and substantial when MP tillage is initiated after NT and BG, while their recovery is gradual when NT tillage is initiated after MP.