Isotopic Labeling of Soil Nitrate Pools Using Nitrogen‐15‐Nitric Oxide Gas

Stark, John; Firestone, Mary K.

doi:10.2136/sssaj1995.03615995005900030030x

Cited by 21 publications

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“…As elevated ammonification has increased the availability of NH 4 ? in the surface soil, this has decreased substrate limitation for nitrifying bacteria and accelerated nitrification (Stark and Firestone 1995). The positive relationships we report between with IERB NH 4 ?…”

Section: Forest Succession and Indicators Of Surface Soil N Cyclingmentioning

confidence: 50%

Changes in soil nitrogen cycling in a northern temperate forest ecosystem during succession

et al. 2014

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Nitrogen (N) transformations in forest soils are fundamentally important to plant and microbial N nutrition and the N balance of forest ecosystems, but changes in the patterns and rates of N transformations during forest succession are poorly understood. In order to better understand how soil N cycling changes during ecosystem succession, we analyzed four years of soil N cycling measurements in a 90-year-old secondary forest undergoing dieback of early-successional, dominant canopy trees. We expected that tree mortality would decrease root biomass, leading to increased soil NH 4? availability, and that these changes would prompt fundamental shifts in the N cycle such as the initiation of significant nitrification and increased cycling of oxidized N compounds in gas phase and soil solution. As expected, indices of soil NH 4 ? and NO 3 -availability increased with successional stage (defined as the proportion of dead trees), and were negatively correlated with the amount of fine root biomass. However, the standing amount of fine root biomass was not affected by tree mortality; increased soil NH 4 ? and NO 3 -availability therefore more likely resulted from successional increases in N-mineralization than decreases in root N uptake. Nitrification (as indicated by NO efflux as a proxy) increased due to elevated substrate (NH 4 ? ) availability, and the soil solution NO 3 -concentration increased as a result. Soil N 2 O efflux was not affected by succession, nor was it related to other N cycling parameters. Collectively, these results indicate that recent successional advancement has accelerated soil N cycling and shifted the N economy of this ecosystem towards greater importance of NO 3 -.

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Section: Forest Succession and Indicators Of Surface Soil N Cyclingmentioning

confidence: 50%

Changes in soil nitrogen cycling in a northern temperate forest ecosystem during succession

et al. 2014

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“…Previous measurements of gross nitrification rates in dry California grassland soils suggest that nitrification is negligible under these extremely dry conditions (41) and little nitrate is present in these soils before wet-up (Fig. 3).…”

Section: Discussionmentioning

confidence: 80%

Transcriptional Response of Nitrifying Communities to Wetting of Dry Soil

Placella

Firestone

2013

Appl Environ Microbiol

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114

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The first rainfall following a severe dry period provides an abrupt water potential change that is both an acute physiological stress and a defined stimulus for the reawakening of soil microbial communities. We followed the responses of indigenous communities of ammonia-oxidizing bacteria, ammonia-oxidizing archaea, and nitrite-oxidizing bacteria to the addition of water to laboratory incubations of soils taken from two California annual grasslands following a typically dry Mediterranean summer. By quantifying transcripts for a subunit of bacterial and archaeal ammonia monooxygenases (amoA) and a bacterial nitrite oxidoreductase (nxrA) in soil from 15 min to 72 h after water addition, we identified transcriptional response patterns for each of these three groups of nitrifiers. An increase in quantity of bacterial amoA transcripts was detectable within 1 h of wet-up and continued until the size of the ammonium pool began to decrease, reflecting a possible role of transcription in upregulation of nitrification after drought-induced stasis. In one soil, the pulse of amoA transcription lasted for less than 24 h, demonstrating the transience of transcriptional pools and the tight coupling of transcription to the local soil environment. Analysis of 16S rRNA using a high-density microarray suggested that nitrite-oxidizing Nitrobacter spp. respond in tandem with ammonia-oxidizing bacteria while nitrite-oxidizing Nitrospina spp. and Nitrospira bacteria may not. Archaeal ammonia oxidizers may respond slightly later than bacterial ammonia oxidizers but may maintain elevated transcription longer. Despite months of desiccation-induced inactivation, we found rapid transcriptional response by all three groups of soil nitrifiers.

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“…1994). Some of this NO consumption results from abiotic oxidation and dissolution of NO in soil solution forming NO 2 Ϫ and NO 3 Ϫ (Stark and Firestone 1995); however, NO oxidation by heterotrophic microorganisms has also been identified as an important consumptive fate for NO in soils receiving organic C additions (Baumgartner et al 1996, Dunfield andKnowles 1997). Dunfield and Knowles (1998) concluded that NO consumption was a function of heterotrophic microbial activity; thus, CO 2 flux and soil organic matter contents should be good predictors of net NO uptake by soils exposed to high NO concentrations.…”

Section: Discussionmentioning

confidence: 99%

Regulation of Nitric Oxide Emissions from Forest and Rangeland Soils of Western North America

Stark

Hart

Haubensak

2002

Ecology

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Nitric oxide (NO) is a relatively short-lived trace gas that reacts with oxygen in the troposphere to produce the air pollutant ozone. It also reacts with water vapor to form nitric and nitrous acids, which acidify precipitation and increase N deposition. Models currently used to predict soil NO fluxes are based on the assumption that NO flux is proportional to the gross rate of nitrification or N mineralization; however, this assumption has not been tested because of the difficulty in measuring gross N-cycling rates in situ. We measured soil NO fluxes, gross and net N-cycling rates, and a variety of other soil characteristics in the forest floor and intact soil cores at nine undisturbed forest and rangeland ecosystems of New Mexico, Utah, and Oregon, USA, to determine which soil variables were most closely related to soil NO flux. Soil NO fluxes ranged from a low of 0.02 ng N·m Ϫ2 ·s Ϫ1 , prior to wetting in a western hemlock-sitka spruce forest on the Oregon coast, to a high of 6.74 ng N·m Ϫ2 ·s Ϫ1 , one hour after soil wetting in a juniper woodland of central Oregon. In contrast to our expectations, neither gross nitrification nor gross mineralization was correlated with soil NO flux. Fluxes were positively correlated with net rates of mineralization and nitrification, soil NO 3 Ϫ concentrations, bulk density, and pH, and negatively correlated with gross rates of NO 3 Ϫ consumption in the forest floor, soil organic carbon (SOC), soil C:N, and soil water content. Principal-component analysis showed that NO flux after water addition (2 cm of water) had a strong negative correlation with microbial demand for N (as indicated by net mineralization, net nitrification, SOC, and C:N). Our results suggest that, even in well-drained soils, NO efflux is limited more by NO consumption than by NO production. As a result, models utilizing the more easily measured net rates, rather than gross rates, may be better predictors of soil NO fluxes across a range of ecosystems.

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Isotopic Labeling of Soil Nitrate Pools Using Nitrogen‐15‐Nitric Oxide Gas

Cited by 21 publications

References 0 publications

Changes in soil nitrogen cycling in a northern temperate forest ecosystem during succession

Changes in soil nitrogen cycling in a northern temperate forest ecosystem during succession

Transcriptional Response of Nitrifying Communities to Wetting of Dry Soil

Regulation of Nitric Oxide Emissions from Forest and Rangeland Soils of Western North America

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