engleski

Soil dehydrogenase activity and organic matter as affected by management system

Tillage and agrochemicals negatively affect soil organic matter (SOM) content and microbial activity. Intense cultivation of the Nadin valley began in the 1950s when land was hydro meliorated. Our objective was to assess stratification of microbial activity and SOM in order to propose the improvements in soil management. Samples were collected according to randomized stratified design from organic (O) and conventional (C) plowed agricultural soils and from natural grass vegetation soils (G). Dehydrogenases activity (DHA) and soil moisture were analyzed at 6 cm increments and C and N (total, organic and inorganic) were analyzed at 2 cm increments, both to the depth of 18 cm. DHA (nmol g-1 h-1 TPF) was higher in G (36.8±5.0) than in C (13.8±1.6) or O (7.27±0.95). DHA decreased with depth from 21.1±4.8 (0-6 cm) and 16.8±2.4 (6-12 cm) to 7.29±3.2 (12-18 cm). Water content (%w/w) was higher in O (22.1±1.3) than in C (14.2±2.2) or G (16.8±1.7). Soil bulk density in the valley decreased, from 1.28±0.05 g cm-3 in the upper part of the valley to 1.16±0.03 g cm-3 in the lower part, indicating coarser texture in upper parts. Soil C and N content were: 4.5±0.42% total carbon (organic+carbonate), 1.6±0.40% organic carbon, and 0.14±0.032% soil nitrogen (organic and inorganic). C:N ratio was 10.7. Soils were carbonate-rich with 26.0±2.0% CaCO3. Results showed that grass cover would increase microbial activity, but might decrease soil water content and increase need for water conservation measures.

agricultural management system ; C:N ; DHA ; grass cover ; microbial activity

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