Document Detail


Factors influencing spatial variability in nitrogen processing in nitrogen-saturated soils.
MedLine Citation:
PMID:  12805879     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and nitrification in N-saturated soils from FEF, and how these effects varied between high N-processing vs. low N-processing soils collected from two watersheds, WS3 (fertilized with [NH4]2SO4) and WS4 (untreated control). Samples of forest floor material (O1 horizon) and mineral soil (to a 5-cm depth) were taken from three subplots within each of four plots that represented the extremes of highest and lowest rates of net N mineralization and nitrification (hereafter, high N and low N, respectively) of untreated WS4 and N-treated WS3: control/low N, control/high N, N-treated/low N, N-treated/high N. Forest floor material was analyzed for carbon (C), lignin, and N. Subsamples of mineral soil were extracted immediately with 1 N KCl and analyzed for NH4+ and NO3- to determine preincubation levels. Extracts were also analyzed for Mg, Ca, Al, and pH. To test the hypothesis that the lack of net nitrification observed in field incubations on the untreated/low N plot was the result of absence of nitrifier populations, we characterized the bacterial community involved in N cycling by amplification of amoA genes. Remaining soil was incubated for 28 d at three temperatures (10, 20, and 30 degrees C), followed by 1 N KCl extraction and analysis for NH4+ and NO3-. Net nitrification was essentially 100% of net N mineralization for all samples combined. Nitrification rates from lab incubations at all temperatures supported earlier observations based on field incubations. At 30 degrees C, rates from N-treated/high N were three times those of N-treated/low N. Highest rates were found for untreated/high N (two times greater than those of N-treated/high N), whereas untreated/low N exhibited no net nitrification. However, soils exhibiting no net nitrification tested positive for presence of nitrifying bacteria, causing us to reject our initial hypothesis. We hypothesize that nitrifier populations in such soil are being inhibited by a combination of low Ca to Al ratios in mineral soil and allelopathic interactions with mycorrhizae of ericaceous species in the herbaceous layer.
Authors:
F S Gilliam; C C Somerville; N L Lyttle; M B Adams
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Publication Detail:
Type:  Journal Article     Date:  2001-10-16
Journal Detail:
Title:  TheScientificWorldJournal     Volume:  1 Suppl 2     ISSN:  1537-744X     ISO Abbreviation:  ScientificWorldJournal     Publication Date:  2001 Oct 
Date Detail:
Created Date:  2003-06-13     Completed Date:  2004-04-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  101131163     Medline TA:  ScientificWorldJournal     Country:  United States    
Other Details:
Languages:  eng     Pagination:  505-13     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, Marshall University, Huntington, WV 25755-2510, USA. gilliam@Marshall.edu
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MeSH Terms
Descriptor/Qualifier:
DNA, Bacterial / genetics
Ecosystem
Environmental Monitoring / methods
Fertilizers / analysis
Fresh Water / analysis,  microbiology
Genes, Bacterial / genetics
Lignin / analysis
Minerals / analysis,  metabolism
Nitrates / analysis,  metabolism
Nitrites / analysis,  metabolism
Nitrogen / analysis,  metabolism*
Nitrogen Compounds / analysis,  metabolism
Nitrosomonas / enzymology,  genetics,  isolation & purification
Nucleic Acid Amplification Techniques / methods
Oxidation-Reduction
Oxidoreductases / genetics
Soil / analysis*
Soil Microbiology
West Virginia
Chemical
Reg. No./Substance:
0/DNA, Bacterial; 0/Fertilizers; 0/Minerals; 0/Nitrates; 0/Nitrites; 0/Nitrogen Compounds; 0/Soil; 7727-37-9/Nitrogen; 9005-53-2/Lignin; EC 1.-/Oxidoreductases; EC 1.7.3.-/ammonia monooxygenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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