Induced N-limitation of bacterial growth in soil: Effect of carbon loading and N status in soil |
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| Institution: | 1. Microbial Ecology, Department of Biology, Ecology Building, Lund University, SE-223 62 Lund, Sweden;2. P. G. Department of Environmental Science, PVP College Pravaranagar, University of Pune, Pune, India;3. K.T.H.M. College Nashik, University of Pune, Pune, India;1. Soil Biology and Plant Nutrition, University of Kassel, Nordbahnhofstr. 1a, 37213, Witzenhausen, Germany;2. Centre of Biodiversity and Sustainable Land Use, University of Göttingen, Grisebachstr. 6, 37077, Göttingen, Germany;3. Centre for Stable Isotope Research and Analysis, University of Göttingen, Büsgenweg 2, 37077, Göttingen, Germany;1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing 100093, China;2. School of Biology, Georgia Institute of Technology, Atlanta, GA, USA;3. Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA;4. Key State Laboratory of Cotton Biology, College of Life Sciences, Henan University, Kaifeng, Henan 475004, China;1. Department of Natural Resources & the Environment, University of New Hampshire, Durham, NH 03824, USA;2. Earth Systems Research Center, University of New Hampshire, Durham, NH 03824, USA;3. School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC, Canada;1. Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, China;2. Qianjiangyuan Forest Ecosystem Research Station, National Forestry and Grassland Administration, Hangzhou, China;1. Section of Microbial Ecology, Department of Biology, Lund University, Ecology Building, 223 62, Lund, Sweden;2. School of Forestry, Northeast Forestry University, 150040, Harbin, China |
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| Abstract: | Application of C-rich plant residues can change the soil system from C-limitation for microbial growth to limitation by other nutrients. However, the initial nutrient status of the soil may interact with the added amount of residues in determining limitation. We studied this interactive effect in soils from the Harvard Forest LTER, where annual addition of N since 1988 has resulted in soils with different N-status: No N (Unfertilized), 50 (Low N) and 150 (High N) kg N ha?1. We hypothesized that adding C-rich substrate would change the soil from being C- to being N-limited for bacterial growth and that the extent of N-limitation would be higher with increasing substrate additions, while becoming less evident in soil with increasing N-status. We compared the effect of adding two C-rich substrates, starch (0, 10, 20, 40 mg g?1 soil) and straw (0, 20, 40, 80 mg g?1), incubating the soils for up to 3 and 4 weeks for starch and straw, respectively. Nutrient limitations were studied by measuring bacterial growth 3 days after adding C as glucose and N as NH4NO3 in a full factorial design. Initially bacterial growth in all soils was C-limited. As hypothesized, adding C-rich substrates removed the C-limitation, with lower amounts of starch and straw needed in the unfertilized and Low N soils than in the High N soil. Combinations of different N-status of the soil and amendment levels of starch and straw could be found, where bacterial growth appeared close to co-limited both by available C and N. However, at even higher amendment levels, presumable resulting in N-limitation, bacterial growth still responded less by adding N then C-limited soils by adding C. Thus, in a C-limited soil there appeared to be N available immediate for growth, while in an N-limited soil, easily available C was not immediately available. |
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| Keywords: | N-deposition C-rich substrate Induced-N limitation Bacterial growth Leucine incorporation Limiting factors |
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