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Confirmation of co-denitrification in grazed grassland.

Selbie DR, Lanigan GJ, Laughlin RJ, Di HJ, Moir JL, Cameron KC, Clough TJ, Watson CJ, Grant J, Somers C, Richards KG - Sci Rep (2015)

Bottom Line: Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment.We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification.This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland.

ABSTRACT
Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high (15)N isotopic enrichment of applied N with a high precision of determination of (15)N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

No MeSH data available.


Related in: MedlinePlus

Conceptual model of co-denitrification under urine patches in grassland soils, commencing with urea, the dominant N substrate found in ruminant urine.
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f1: Conceptual model of co-denitrification under urine patches in grassland soils, commencing with urea, the dominant N substrate found in ruminant urine.

Mentions: A process rarely considered in determining gaseous contributions to 15N mass balances is that of co-denitrification. Whilst hybrid N2 production is recognized in microbiology20, it has seldom been quantified in soil N process studies. Co-denitrification produces N2O (N2OCO) and N2 (N2CO) when, during sequential binding, a side reaction occurs between the initial electrophilic enzyme/N species complex and a nucleophile2122. As a result, co-denitrification results in hybrid N2 and/or N2O molecules that are formed from isotopically non-uniform pools, with one N atom of NO/NO2 derived from an inorganic N source (NO3−, NO2− or NO−) and another nucleophilic N atom from a co-substrate1722 (usually N3, NH3 or a monomeric organic N source such as an amine) (Fig. 1). Whereas abiotic N2 production has been shown to occur at low pH (<5.2)2324, N2 from co-denitrification is recognized as a biotic process occurring under intermediate to high pH conditions (>6)22.


Confirmation of co-denitrification in grazed grassland.

Selbie DR, Lanigan GJ, Laughlin RJ, Di HJ, Moir JL, Cameron KC, Clough TJ, Watson CJ, Grant J, Somers C, Richards KG - Sci Rep (2015)

Conceptual model of co-denitrification under urine patches in grassland soils, commencing with urea, the dominant N substrate found in ruminant urine.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663629&req=5

f1: Conceptual model of co-denitrification under urine patches in grassland soils, commencing with urea, the dominant N substrate found in ruminant urine.
Mentions: A process rarely considered in determining gaseous contributions to 15N mass balances is that of co-denitrification. Whilst hybrid N2 production is recognized in microbiology20, it has seldom been quantified in soil N process studies. Co-denitrification produces N2O (N2OCO) and N2 (N2CO) when, during sequential binding, a side reaction occurs between the initial electrophilic enzyme/N species complex and a nucleophile2122. As a result, co-denitrification results in hybrid N2 and/or N2O molecules that are formed from isotopically non-uniform pools, with one N atom of NO/NO2 derived from an inorganic N source (NO3−, NO2− or NO−) and another nucleophilic N atom from a co-substrate1722 (usually N3, NH3 or a monomeric organic N source such as an amine) (Fig. 1). Whereas abiotic N2 production has been shown to occur at low pH (<5.2)2324, N2 from co-denitrification is recognized as a biotic process occurring under intermediate to high pH conditions (>6)22.

Bottom Line: Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment.We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification.This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland.

ABSTRACT
Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high (15)N isotopic enrichment of applied N with a high precision of determination of (15)N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m(-2) (95%, CI 38 to 77 g m(-2)) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m(-2)), compared to only 1.1 g N m(-2) (0.4 to 2.8 g m(-2)) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.

No MeSH data available.


Related in: MedlinePlus