Soil Biology and Biochemistry, June, 2013, Vol.61, p.76(10)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2013.02.006 Byline: Susanne Kramer (a), Sven Marhan (a), Heike Haslwimmer (a), Liliane Ruess (b), Ellen Kandeler (a) Abstract: Many studies of the microbial ecology of agricultural ecosystems focus on surface soils, whereas the impacts of management practice and season on soil microbial community composition and function below the plough zone are largely neglected. Deep soils have a high potential to store carbon; therefore any management driven stimulation or repression of microorganisms in subsoil could impact biogeochemical cycling in agricultural sites. The aim of this study was to understand whether soil management affects microbial communities in the topsoil (0-10 cm), rooted zone beneath the plough layer (40-50 cm), and the unrooted zone (60-70 cm). In a field experiment with different crops [wheat (Triticum aestivum L.) and maize (Zea mays L.)] and agricultural management strategies (litter amendment) we analysed microbial biomass as phospholipid fatty acids (PLFAs) and enzyme activities involved in the C-cycle ([beta]-glucosidase, N-acetyl-[beta]-d-glucosaminidase, [beta]-xylosidase, phenol- and peroxidase) across a depth transect over a period of two years. Wheat cultivation resulted in higher bacterial and fungal biomass as well as higher enzyme activities at most sampling dates in comparison to maize cultivated plots, and this effect was visible to 50 cm depth. Litter application increased bacterial and fungal biomass as well as hydrolytic enzyme activities but effects were apparent only in the topsoil. In winter high microbial biomass and enzyme activities were measured in all soil layers, possibly due to increased mobilization and translocation of organic matter into deeper soil. Hydrolytic enzyme activities decreased with depth, whereas oxidative enzyme activities showed no decrease or even an increase with depth. This could have been due to differing sorption mechanisms of hydrolytic and oxidative enzymes. Specific enzyme activities (enzyme activity per microbial biomass) were higher in the deeper layers and possible reasons are discussed. Author Affiliation: (a) Institute of Soil Science and Land Evaluation, Soil Biology Section, University of Hohenheim, Emil-Wolff-Str. 27, 70599 Stuttgart, Germany (b) Institute of Biology, Ecology Group, Humboldt-Universitat zu Berlin, Philippstr. 13, 10115 Berlin, Germany Article History: Received 28 September 2012; Revised 20 December 2012; Accepted 12 February 2013
Agroecosystems -- Analysis ; Fatty Acids -- Analysis ; Soil Microbiology -- Analysis ; Soil Management (Agronomy) -- Analysis ; Nucleotidases -- Analysis ; Agricultural Ecology -- Analysis
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