Microscale distribution and function of soil microorganisms in the interface between rhizosphere and detritusphere |
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| Institution: | 1. School of Agriculture, Food and Wine, Faculty of Sciences, The Waite Research Institute, University of Adelaide, Adelaide, SA, Australia;2. Soil Science and Land Evaluation, Soil Biology Section, University of Hohenheim, Stuttgart, Germany;1. Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany;2. Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen, Germany;3. Department of Soil Sciences, Vietnam National University of Forestry, Hanoi, Viet Nam;4. Institute of Physicochemical and Biological Problems in Soil Science, Pushchino, Russia;1. Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany;2. Chair of Soil Physics, University of Bayreuth, Bauyreuth D-95447, Germany;3. Institute of Physicochemical and Biological Problems in Soil Science, 142290 Pushchino, Russia;4. Department of Agroecology, University of Bayreuth, Bayreuth, Germany;5. Agro-Technology Institute, RUDN University, Moscow, Russia;1. Dept. of Soil Science of Temperate Ecosystems, University of Göttingen, Germany;2. Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino, Russia;3. Dept. of Agricultural Soil Science, University of Göttingen, Germany;4. Institute of Environmental Sciences, Kazan Federal University, Kazan, Russia;1. Department of Soil, Plant and Microbial Sciences, Michigan State University, East Lansing, MI, USA;2. Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany;3. Department of Soil Science and Plant Nutrition, University of Kiel, Kiel, Germany;4. Department of Soil Science, University of Kassel, Witzenhausen, Germany;5. Institute of Physicochemical and Biological Problems in Soil Science, 142290, Pushchino, Russia;6. RUDN University, Moscow, Russia;1. Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China;2. Changsha Research Station for Agricultural and Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China;3. Department of Agricultural Soil Science, University of Göttingen, 37077 Göttingen, Germany;4. School of Environment, Natural Resources & Geography, Bangor University, Gwynedd LL57 2UW, Wales, UK |
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| Abstract: | The rhizosphere and the detritusphere are hot spots of microbial activity, but little is known about the interface between rhizosphere and detritusphere. We used a three-compartment pot design to study microbial community structure and enzyme activity in this interface. All three compartments were filled with soil from a long-term field trial. The two outer compartments were planted with maize (root compartment) or amended with mature wheat shoot residues from a free air CO2 enrichment experiment (residue compartment) and were separated by a 50 μm mesh from the inner compartment. Soil, residues and maize differed in 13C signature (δ13C soil ?26.5‰, maize roots ?14.1‰ and wheat residues ?44.1‰) which allowed tracking of root- and residue-derived C into microbial phospholipid fatty acids (PLFA). The abundance of bacterial and fungal PLFAs showed clear gradients with highest abundance in the first 1–2 mm of the root and residue compartment, and generally higher values in the vicinity of the residue compartment. The δ13C of the PLFAs indicated that soil microorganisms incorporated more carbon from the residues than from the rhizodeposits and that the microbial use of wheat residue carbon was restricted to 1 mm from the residue compartment. Carbon incorporation into soil microorganisms in the interface was accompanied by strong microbial N immobilisation evident from the depletion of inorganic N in the rhizosphere and detritusphere. Extracellular enzyme activities involved in the degradation of organic C, N and P compounds (β-glucosidase, xylosidase, acid phosphatase and leucin peptidase) did not show distinct gradients in rhizosphere or detritusphere. Our microscale study showed that rhizosphere and detritusphere differentially influenced microbial C cycling and that the zone of influence depended on the parameter assessed. These results are highly relevant for defining the size of different microbial hot spots and understanding microbial ecology in soils. |
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