Conventional and organic cropping systems at Suitia III: Microbial activity in soils

Authors

• Helvi Heinonen-Tanski Department of Environmental Engineering, University of Kuopio, P.O. B. 6, SF-70211 Kuopio, Finland

DOI: https://doi.org/10.23986/afsci.72906

Abstract

From 1983 to 1988 the microbial activity of soil was measured by determining its nitrification potential, dehydrogenase activity, cellulolytic activity and respiration. The samples were Suitia silty clay soils under various types of conventional and organic cropping systems. The soil microbial activity was the highest in both organic cattle farm plots in the ley phase and conventional cattle farm plots in the ley phase. The difference between these two ley soils was not clear, partly because of the considerable statistical variance, but the microbial activity of organic cattle farm plots in clover leys tended to be higher than in conventionally cultivated grass leys. This favourable effect on dehydrogenase activity was not detected after poor overwintering in organic cattle farm plots in annual clover in 1984 and Persian clover in 1985, but some effect on nitrification was found in 1984. In many cases, soil microbial activity was still increased two to three years after the leys. The soil nitrification activities were often higher in organic plant production plots than in conventional plant production plots, but the dehydrogenase activities and cellulose decompositions of organic plant production plots were similar to those in conventional diverse plant production or barley monoculture plots.