Nutrient addition retards decomposition and C immobilization in two wet grasslands
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Eutrophication is one of the biggest environmental problems facing wetlands. However, its effect on soil functioning is not yet well understood. We tested the hypothesis that increased nutrient loading into wet grassland ecosystems accelerates soil C and N cycles and decreases microbial immobilization of C and N. Experimental sites were established on two wet grasslands, with either mineral or peaty soils, and fertilized by NPK fertilizer for 3 years. Soils were analyzed for soluble and microbial C and N contents and their transformations, profile of phospholipid fatty acids and number of nirK denitrifiers. Fertilization affected C more than N transformations. Opposite to what was predicted, decomposition was retarded, the soil C cycle was based more on labile C compounds, and the soil was more susceptible to C losses in fertilized versus unfertilized treatments in both soils. Fertilization resulted in lower microbial biomass C and microbial C immobilization and also decreased the activity of lignin-degrading enzymes. Shifts in the composition of the microbial communities led to decreased (1) decomposition of complex organic compounds and (2) immobilization of transformed C. Net nitrification and microbial N immobilization tended to increase in fertilized treatments indicating an acceleration of soil N cycling and losses, but only in the more vulnerable organic soil.
KeywordsWet meadows Eutrophication Lignin-degrading enzymes qPCR
This study was supported by Projects No. 526/09/1545 (awarded to Dr. Keith Edwards), No. 526/08/0751 of the Grant Agency of the Czech Republic and No. GAJU04-142/2010/P of the Grant Agency of University of South Bohemia. We also thank our technician Terezia Říhová, and our students Pavla Staňková and Veronika Špátová, for their perfect work on the project.
- Barta, J., T. Melichova, D. Vanek, T. Picek & H. Santruckova, 2010a. Effect of pH and dissolved organic matter on the abundance of nirK and nirS denitrifiers in spruce forest soil. Biogeochemistry (in press). doi: 10.1007/s10533-010-9430-9.
- European Environmental Agency, 2003. Europe’s Environment: The Third Assessment. EEA, Copenhagen, Denmark.Google Scholar
- Evans, C., C. Goodale, S. Caporn, N. Dise, B. Emmett, I. Fernandez, C. Field, S. Findlay, G. Lovett, H. Meesenburg, F. Moldan & L. Sheppard, 2008. Does elevated nitrogen deposition or ecosystem recovery from acidification drive increased dissolved organic carbon loss from upland soil? A review of evidence from field nitrogen addition experiments. Biogeochemistry 91: 13–35.CrossRefGoogle Scholar
- Fenn, M. E., M. A. Poth, J. D. Aber, J. S. Baron, B. T. Bormann, D. W. Johnson, A. D. Lemly, S. G. McNulty, D. E. Ryan & R. Stottlemyer, 1998. Nitrogen excess in North American ecosystems: predisposing factors, ecosystem responses, and management strategies. Ecological Applications 8: 706–733.CrossRefGoogle Scholar
- Hassink, J. & J. J. Neeteson, 1991. Effect of grassland management on the amount of soil organic-N and C. Netherlands Journal of Agricultural Science 39: 225–236.Google Scholar
- Henderson, S. L., C. E. Dandie, C. L. Patten, B. J. Zebarth, D. L. Burton, J. T. Trevors & C. Goyer, 2010. Changes in denitrifier abundance, denitrification gene mRNA levels, nitrous oxide emissions and denitrification in anoxic soil microcosms amended with glucose and plant residues. Applied and Environmental Microbiology 76: 2155–2164.PubMedCrossRefGoogle Scholar
- Henry, S., D. Bru, B. Stres, S. Hallet & L. Philippot, 2006. Quantitative detection of the nosZ gene, encoding nitrous oxide reductase, and comparison of the abundances of 16S rRNA, narG, nirK, and nosZ genes in soils. Applied and Environmental Microbiology 72: 5181–5189.PubMedCrossRefGoogle Scholar
- Subbarao, G. V., O. Ito, K. L. Sahrawat, W. L. Berry, K. Nakahara, T. Ishikawa, T. Watanabe, K. Suenaga, M. Rondon & I. M. Rao, 2006. Scope and strategies for regulation nitrification in agricultural systems – challenges and opportunities. Critical Reviews in Plant Science 25(4): 303–335.CrossRefGoogle Scholar
- ter Braak, C. J. F. & P. Smilauer, 1998. CANOCO Reference Manual and User’s Guide to Canoco for Windows: Software for Canonical Community Ordination (Version 4). Microcomputer Power, Ithaca, NY, USA.Google Scholar
- Tiedje, J. M., S. Simkins & P. M. Groffman, 1989. Perspectives on measurement of denitrification if the field including recommended protocols for acetylene based methods. In Clarholm, M. & L. Bergstrom (eds), Ekology of Arable Land. Kluwer, Dordrecht: 217–240.Google Scholar
- Van Oorschot, M. M. P., 1994. Plant production, nutrient uptake, and mineralization in river marginal wetlands: the impact of nutrient additions due to former land-use. In Mitsch, W. J. (ed.), Global Wetlands: Old World and New. Elsevier, Amsterdam, The Netherlands: 133–150.Google Scholar
- Yevdokimov, I., S. Saha, S. A. Blagodatsky & V. N. Kudeyanov, 2005. Nitrogen immobilization by soil microorganisms depending on nitrogen application rates. Eurasian Soil Science 38: 516–523.Google Scholar