Effect of organic and mineral fertilizers and land management on soil enzyme activities

Sustainable and rational management of agrophytocenoses depends on various bioindices and methods of application, particularly the development and protection of soil resources (Lai et al., 2002). Among other indices, enzyme activity is proposed as a universal index of soil fertility and contamination (Dilly et al., 2003). To ascertain and to make a comparison of bioactivity variation during the vegetation period, soil (Endophypogleyi-Eutric Planasols-Ple-gln-w, artificial drainage) samples were collected from rotation fields of different fertilizing and farming systems (intensive (IF) and organic (OF)) at the Training farm of the Lithuanian University of Agriculture during 2007–2008. N application stimulated urease and saccharase activity in different farming systems (OF and IF) and fertilizing management (manure and mineral fertilizers). When comparing mean soil bioactivity values of 2 years the highest manure effect was detected in the application year (winter wheat treatment) and conditioned the highest urease (8.21 mg NH4 + –N g -1 ) and saccharase (24.52 mg CG g -1 24 h -1 ) activity but gradually decreased later. The lowest mean of urease (3.62 mg NH4 + –N g -1 ) and saccharase (22.07 mg CG g -1 24 h -1 ) activity occurred in IF soil where mineral fertilizers were applied. Soil bioactivity properties (urease and saccharase activity) were positively correlated with soil nutrients (Corg., Ntotal). Urease and saccharase activity properties reflect changes of fertilizer type and management and thus can be used as bio-indicators of soil fertility.