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

Abstract

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 fertility.