TP2-1: Soil biology

Diversity and activity of soil organism communities as indicators of sustainable land use

Summary

The evaluation of soil fertility represents a tremendous challenge, which is due to a lack of an evaluation of suitable methods applicable for a wide array of soils. Agroforestry directly affects the soil environment via changes in microclimate as well as soil water and C-input. Therefore, the presence of trees in agroecosystems has an impact on soil organisms mediating ecosystem services such as decomposition of organic matter, nutrient provision and C sequestration. Nevertheless, these effects on microbial and earthworm activity and the variation in time and space have rarely been investigated before. Furthermore, plant diversity has beneficial effects on ecosystem stability. However, the relationship between above- and belowground diversity is still under debate and the links between diversity of soil microorganisms and functioning are poorly understood. We therefore postulate that the distance of the tree line as well as plant diversity affect activity and functional diversity of soil microorganisms depending on the dynamics of abiotic (e.g. soil water content, pH) and biotic factors (e.g. quality and quantity of litter and root exudates). The objective of the study is to track spatial heterogeneity of soil microorganisms at agroforestry sites with arable cropping and grassland. Therefore soil samples taken in the upper and lower layer of top soils in agroforestry-systems with differing distances from the tree line and reference plots without trees will be analyzed for indices of microbial activity (basal respiration, community-level physiological profiling by substrate-induced respiration and enzyme activity) as well as microbial biomass (C and N), ergosterol and microbial residues (amino sugars). In addition, the effect of trees on soil fauna will be evaluated by sampling of earthworms at the different sites. Furthermore, the variation of litter decomposition and litter transformation with the distance from trees will be analyzed by soil bag experiments with 13C and 15N labelled willow leaves. Results will help to estimate the ecosystem services mediated by soil organisms as a factor of sustainable food production. It is assumed that changes in abiotic and biotic factors occurring with distance from trees are mirrored in microbial activity, earthworm activity and litter decomposition. Consequently, this study provides a comprehensive approach on soil microbial indices and earthworm activity and captures fast and slow turnover processes by combining multiple methods.

Additional Information

http://www.uni-kassel.de/fb11agrar/fachgebiete-einrichtungen/bodenbiologie-und-pflanzenernaehrung/forschung/forschungsprojekte.html

 

Contact

Prof. Dr. Rainer Georg Jörgensen

University of Kassel, Department of Soil Biology and Plant Nutrition
Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany

Phone: +49 (0)5542 98-1591
Fax: +49 (0)5542 98-1596
Email: joerge@uni-kassel.de

Dr. Christine Wachendorf

University of Kassel, Department of Soil Biology and Plant Nutrition
Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany

Phone: +49 (0)5542 98-1504
Fax: +49 (0)5542 98-1596
Email: c.wachendorf@uni-kassel.de

PD Dr. Martin Potthoff

University of Göttingen, Center of Biodiversity and sustainable Land Use
Grisebachstr. 6, D 37077 Göttingen, Germany

Phone: +49 (0)551 39 6960
Fax. +49 (0)551 39 222 95
Email: mpottho@uni-goettingen.de

M.Sc. René Beuschel

University of Kassel, Department of Soil Science and Plant Nutrition
Nordbahnhofstr. 1A, 37213 Witzenhausen, Germany

Phone: +49 (0)5542 98-1517
Email: r.beuschel@uni-kassel.de