Indicating Soil Quality Using Urease and Saccharase Activity in Abandoned Grassland and Differently Managed Crop Fields

In order to ascertain and make a comparison of bioactivity variation during vegetation period, soil samples were collected in fields of different fertilizing and farming systems: extensive (ExF), conventional (CF) and organic (OF) in order to determine the saccharase and urease activity responses to different land management systems and main soil quality indices: soil organic carbon (SOC), total nitrogen (N), and C/N ratio. Assessed hydrolases were observed as sensitivity indicators suitable to evaluate parameters of soil quality. The highest decrease and the lowest rates of urease (1.13 mg NH4 +–N g−1) and saccharase (8.40 mg CG g−1 24 h−1) activities were observed in abandoned grassland soil where mineral fertilizers were not applied. Enzyme activity correlated stronger with SOC (r = 0.7) or C/N ratio (r = 0.6) than that with total nitrogen content (r = 0.5 − 0.6). A significantly higher 3 year mean value of saccharase (27.00 and 12.6 mg CG g−1) and urease (5.78 and 4.16 mg NH4 +–Ng−1 24 h−1) activities were observed in soil under conventional and organic management compared with abandoned grassland. Thereafter enzyme activities might be related to the different levels of soil fertilityVytauto Didžiojo universitetasŽemės ūkio akademij