Evaluation of nitrogen fixation by bacteria in association with roots of tropical grasses.

Berkum, Peter van; Bohlool, B B

doi:10.1128/mmbr.44.3.491-517.1980

Cited by 121 publications

(32 citation statements)

References 98 publications

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“…Even with the potential capacity to fix atmospheric N, the greater accessibility of marinederived N to sea oats in the higher density nesting areas was apparent by the higher d 15 N values. Using existing soil N may be more energy efficient than fixing atmospheric N because symbiotic bacteria require carbohydrates from the plant to generate ammonia (NH 4 þ ), which is absorbed by the host (van Berkum and Bohlool 1980). In general, the overall d 15 N levels found in sea oats, even in the high density nesting areas, were relatively low compared to most (e.g., Ben-David et al 1998a, Wainright et al 1998, Anderson and Polis 1999, Farin˜a et al 2003, Ellis et al 2006) but not all (e.g., Ben-David et al 1998b, Bartz andNaiman 2005) examples of fertilization from animal transport of marine nutrients.…”

Section: Discussionmentioning

confidence: 99%

Dune Vegetation Fertilization by Nesting Sea Turtles

Hannan

Roth

Ehrhart

et al. 2007

Ecology

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Sea turtle nesting presents a potential pathway to subsidize nutrient-poor dune ecosystems, which provide the nesting habitat for sea turtles. To assess whether this positive feedback between dune plants and turtle nests exists, we measured N concentration and delta15N values in dune soils, leaves from a common dune plant (sea oats [Uniola paniculata]), and addled eggs of loggerhead (Caretta caretta) and green turtles (Chelonia mydas) across a nesting gradient (200-1050 nests/km) along a 40.5-km stretch of beach in east central Florida, USA. The delta15N levels were higher in loggerhead than green turtle eggs, denoting the higher trophic level of loggerhead turtles. Soil N concentration and delta15N values were both positively correlated to turtle nest density. Sea oat leaf tissue delta15N was also positively correlated to nest density, indicating an increased use of augmented marine-based nutrient sources. Foliar N concentration was correlated with delta15N, suggesting that increased nutrient availability from this biogenic vector may enhance the vigor of dune vegetation, promoting dune stabilization and preserving sea turtle nesting habitat.

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Section: Discussionmentioning

confidence: 99%

Dune Vegetation Fertilization by Nesting Sea Turtles

Hannan

Roth

Ehrhart

et al. 2007

Ecology

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“…We consider this phenol enhancement effect in the assessment of rhizospheric N2-fixation to be of interest, demonstrating that non-metabolized phenolic compounds which have been so far mainly considered as endogenous soil components and therefore without much effect can definitely enhance or inhibit nitrogenase activity, depending upon the concentration and the oxygen tension. This enhancement effect further complicates the possible interactions between root systems and nitrogen fixing bacteria, supply of carbon sources, cxygen supply, soil moisture, combined nitrogen sources, temperature and soil p h (van Berkum and Bohlool, 1980). Vitamin exudation from the grass roots affecting e.g.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of aerobic nitrogenase activity (acetylene reduction assay) by phenol in soils and the rhizosphere of cereals

Krotzky

Berggold

Jaeger

et al. 1983

J Plant Nutrition & Soil

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By addition of phenol at concentrations between 0.1 and 10 mmol·l−1, nitrogenase activity (acetylene reduction assay) is enhanced by a factor of 5 in the rhizosphere of Pennisetum glaucum (pearl millet) incubated under 20% O2. No increase is found under microaerobic conditions. This enhancement effect is also noticed in a soil amended with a sucrose concentration of 20 mmol·l−1. Under those conditions, however, an enhancement is found under aerobic as well as under microaerobic conditions and a further increase of the phenol added reduces the activity to almost zero. A 4‐fold increase of N2‐fixation by phenol addition under aerobic conditions was determined with homogenous sediments from a fresh water lake while anaerobic N2‐fixation was already slightly reduced by the same concentration added. Excised roots of Sorghum nutans CSH 5 failed to show any phenol enhancement of nitrogenase activity. After a preincubation of 6h, inhibition of nitrogenase activity under air by addition of 1 mmol·l−1 was much more pronounced than under microaerobic conditions.

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“…Acetylene-reduction measurements are often thought to overestimate N2 fixation because of an uncertain ratio ofC2H4 fixed to N 2 fixed (Silvester 1983). Acetylene reduction may underestimate free-living or associative N 2 fixation when roots and soil are exposed to high 0 2 concentrations or when gas diffusion into and out of intact soil cores is limited (van Berkum and Bohlool 1980). Natural abundance (' 5 N/ 14 N) and isotope dilution techniques (Binkley et al 1985, Shearer andKohl 1986) depend on a comparison with a presumed physiologically similar but non-N2-fixing species.…”

Section: Introductionmentioning

confidence: 99%

Rapid N^2 Fixation in Pines, Alder, and Locust: Evidence From the Sandbox Ecosystems Study

Bormann¹,

Bormann²,

Bowden³

et al. 1993

Ecology

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Not all nitrogen (N) inputs have been accounted for in forested ecosystems. We sought to account for N2 fixation and dry deposition using a lysimeter mass—balance approach. Large sand—filled, field lysimeters were used to construct 5—yr nitrogen budgets for two N2—fixing trees, two pines, and a nonvegetated control soil. This approach is a promising and straightforward technique for quantifying otherwise difficult—to—measure fluxes. Accurate assessment of changes in N storage combined with direct measurement of N inputs in precipitation and losses from leaching allowed as to estimate fluxes. Gains of N in pine systems were greatest in vegetation and litter, overshadowing combined losses from mineral soil and leaching by about threefold. Rapid acetylene reduction in pine rhizospheres and in cultures from washed roots suggests that unexplained gains are due to associative N2 fixation. These results provide strong evidence for N2 fixation in pine systems of °50 kg°ha—1°yr—1 N. The symbiotic N2—fixing trees black locust and black alder fixed 2 and 5 times more N2, respectively, than did pines. In all systems, input in precipitation and dry deposition were relatively unimportant to the N budget. Unexplained losses of N from the nonvegetated control suggest that denitrification is an important flux. Mineral soil organic matter declined sharply and significantly in pines (20%) and even more so in the nonvegetated control (40%). Symbiotic N2—fixing trees caused a small, nonsignificant increase in mineral soil organic matter and large, significant increases in litter layer organic matter and large, significant increases in litter layer organic matter. Bulk density (0—20 cm) declined by 5% under symbiotic N2—fixing trees and increased by 5% in one pine sandbox. Correction for soil expansion or collapse did not greatly alter estimates of unexplained N or N2 fixation. Pines with rhizospheres that fix N2 at the rates we observed might be used to restore degraded land and to create silvicultural systems that are N self sufficient. We first need to better understand the microbiology, tree genetics, and soil conditions that lead to rapid N2 fixation in pine ecosystems.

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Evaluation of nitrogen fixation by bacteria in association with roots of tropical grasses.

Cited by 121 publications

References 98 publications

Dune Vegetation Fertilization by Nesting Sea Turtles

Dune Vegetation Fertilization by Nesting Sea Turtles

Enhancement of aerobic nitrogenase activity (acetylene reduction assay) by phenol in soils and the rhizosphere of cereals

Rapid N^2 Fixation in Pines, Alder, and Locust: Evidence From the Sandbox Ecosystems Study

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