Abiotic nitrate incorporation in 45 U.S. soils.
Colman, Benjamin*,1, Fierer, Noah2, Schimel, Joshua1, 1 University of California, Santa Barbara, CA2 Duke University, Durham, NC
ABSTRACT- Increasingly, the fate of N deposited on natural ecosystems has become an issue of concern. In forests, the fertilization effect of high anthropogenic N deposition is fairly limited while retention of added N in soil is high. It was thought that microbes incorporate the N into soil organic matter, but recent work has shown that it may in fact be chemistry, not biology, that is leading to high rates of N retention and low N availability. In this study we examined the factors that regulate abiotic NO3- incorporation in 45 different soils collected as part of a nationwide soil survey. We found that the extent of incorporation was strongly positively correlated with the concentration of iron and phenolics in the soil extract, and negatively correlated with pH. This process appears to be important in shrubland and grassland soils with pH <5.5, as well as in coniferous and deciduous forests. This study suggests that these processes may be widespread and may play a substantial role in the fate of NO3- in ecosystems with acid soils.
Key words: nitrogen cycle, nitrate immobilization, abiotic incorporation
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