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 the vegetation period, soil (Hapli–Epihypogleyic Luvisol (LVg-p-w-ha), Albi–Epihypogleyic Luvisol (LVg-p-w-ab), and Hapli–Albic Luvisol (LVA-Ha), artificial drainage) samples were collected in fields of different fertilization and farming systems, namely extensive (ExF), conventional (CF) and organic (OF), at the Lithuanian University of Agriculture during 2007–2009. The aim of this study was to determine the soil bioactivity responses (saccharase and urease activity) to different land management systems and main soil quality indices. The trial comprised eight experimental plots (three land management systems and two crop groups: legumes and grasses). Assessed hydrolases were sensitive 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 was more strongly correlated with SOC (r = 0.7) or C/N ratio (r = 0.6) than that with total nitrogen content (r = 0.5–0.6). Significantly higher 3-year mean values of saccharase (27.00 and 12.6 mg of conventional glucose, CG g–1) and urease (5.78 and 4.16 mg NH4 +–N g–1 24 h–1) were observed in soil under conventional and organic management in comparison with abandoned grassland. Consequently, it can be concluded that enzyme activities might be responsible for the different levels of soil fertilityVytauto Didžiojo universitetasŽemės ūkio akademij