scholarly journals Fate of N in a peatland, Whim bog: N immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

2012 ◽  
Vol 9 (7) ◽  
pp. 8141-8171 ◽  
Author(s):  
L. J. Sheppard ◽  
I. D. Leith ◽  
S. R. Leeson ◽  
N. van Dijk ◽  
C. Field ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Deposition ◽  
Soil Water ◽  
Nitrogen Availability ◽  
N Deposition ◽  
Nitrous Oxide Emissions ◽  
Ombrotrophic Peatland ◽  
Pleurocarpous Mosses ◽  
Peat Surface ◽  
Reactive N

Abstract. Peatlands' vast carbon reserves accumulated under low nitrogen availability. Carbon and nitrogen cycling are inextricably linked, so what are the consequences of increased reactive nitrogen deposition for the sustainability and functioning of peatlands, and does the form of the nitrogen deposition make a difference? We have addressed these questions for an ombrotrophic peatland, Whim bog in SE Scotland, using a globally unique field simulation of reactive N deposition as dry deposited ammonia and wet deposited reduced N, ammonium and oxidised N, nitrate, added as ammonium chloride or sodium nitrate. The effects of 10 yr of reactive N additions, 56 kg N ha−1 yr−1, depended on the N form. Ammonia-N deposition caused the keystone Sphagnum species, together with the main shrub Calluna and the pleurocarpous mosses to disappear, exposing up to 30% of the peat surface. This led to a significant increase in soil water nitrate and nitrous oxide emissions. By contrast wet deposited N, despite significantly reducing the cover of Sphagnum and Pleurozium moss, did not have a detrimental effect on Calluna cover nor did it significantly change soil water N concentrations or nitrous oxide emissions. Importantly 10 yr of wet deposited N did not bare the peat surface nor significantly disrupt the vegetation, enabling the N to be retained within the carbon rich peatland ecosystems. However, given the significant role of Sphagnum in maintaining conditions that retard decomposition this study suggests that all nitrogen forms will eventually compromise carbon sequestration by peatlands through loss of some keystone Sphagnum species.

scholarly journals Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

2013 ◽  
Vol 10 (1) ◽  
pp. 149-160 ◽  
Author(s):  
L. J. Sheppard ◽  
I. D. Leith ◽  
S. R. Leeson ◽  
N. van Dijk ◽  
C. Field ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Soil Water ◽  
Nitrogen Availability ◽  
N Deposition ◽  
Nitrous Oxide Emissions ◽  
Carbon And Nitrogen ◽  
Ombrotrophic Peatland ◽  
Pleurocarpous Mosses ◽  
Peat Surface ◽  
Reactive N

Abstract. Peatlands represent a vast carbon reserve that has accumulated under conditions of low nitrogen availability. Given the strong coupling between the carbon and nitrogen cycles, we need to establish the consequences of the increase in reactive nitrogen deposition for the sustainability of peatlands, and whether the form in which the nitrogen is deposited makes a difference. We have addressed these questions using a globally unique field simulation of reactive N deposition as dry deposited ammonia and wet deposited reduced N, ammonium and oxidised N, nitrate, added as ammonium chloride or sodium nitrate, to an ombrotrophic peatland, Whim bog in SE Scotland. Here we report the fate of 56 kg N ha−1 yr−1 additions over 10 yr and the consequences. The effects of 10 yr of reactive N additions depended on the form in which the N was applied. Ammonia-N deposition caused the keystone Sphagnum species, together with the main shrub Calluna and the pleurocarpous mosses, to disappear, exposing up to 30% of the peat surface. This led to a significant increase in soil water nitrate and nitrous oxide emissions. By contrast wet deposited N, despite significantly reducing the cover of Sphagnum and Pleurozium moss, did not have a detrimental effect on Calluna cover nor did it significantly change soil water N concentrations or nitrous oxide emissions. Importantly 10 yr of wet deposited N did not bare the peat surface nor significantly disrupt the vegetation enabling the N to be retained within the carbon rich peatland ecosystems. However, given the significant role of Sphagnum in maintaining conditions that retard decomposition, this study suggests that all nitrogen forms will eventually compromise carbon sequestration by peatlands through loss of some keystone Sphagnum species.

scholarly journals Nitrous oxide emissions from a peatbog after thirteen years of experimental nitrogen deposition

2016 ◽  
Author(s):  
Sarah R. Leeson ◽  
Peter E. Levy ◽  
Netty van Dijk ◽  
Julia Drewer ◽  
Sophie Robinson ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Deposition ◽  
Statistical Power ◽  
Automated System ◽  
Nitrous Oxide Emissions ◽  
High Doses ◽  
Experimental Treatments ◽  
Nitrogen Treatments ◽  
The Impact ◽  
Additional Nitrogen

Abstract. Nitrogen deposition was experimentally increased on a Scottish peat bog over a period of thirteen years (2002–2015). Nitrogen was applied in three forms, NH3 gas, NH4+ solution, and NO3− solution, at rates ranging from ambient (8) to 64 kg N ha−1 y−1, and higher near the NH3 fumigation source. An automated system was used to apply the nitrogen, such that the deposition was realistic in terms of rates and high frequency of deposition events. We measured the response of nitrous oxide (N2O) flux to the increased nitrogen input. Prior expectations, based on the IPCC default emission factor, were that 1 % of the added nitrogen would be emitted as N2O. In the plots treated with NH4+ and NO3− solution, no response was seen, and there was a tendency for N2O fluxes to be reduced by additional nitrogen, though this was not significant. Areas subjected to high NH3 emitted more N2O than expected, up to 8.5 % of the added nitrogen. Differences in the response are related to the impact of the nitrogen treatments on the vegetation. In the NH4+ and NO3− treatments, all the additional nitrogen is effectively immobilised in the vegetation and top 10 cm of peat. In the NH3 treatment, much of the vegetation was killed off by high doses of NH3, and the nitrogen was presumably more available to denitrifying bacteria. The design of the wet and dry experimental treatments meant that they differed in statistical power, and we are less likely to detect an effect of the the NH4+ and NO3− treatments, though they avoid issues of pseudo-replication.

The effect of urinary nitrogen loading rate and a nitrification inhibitor on nitrous oxide emissions from a temperate grassland soil

2014 ◽  
Vol 152 (S1) ◽  
pp. 159-171 ◽  
Author(s):  
D. R. SELBIE ◽  
K. C. CAMERON ◽  
H. J. DI ◽  
J. L. MOIR ◽  
G. J. LANIGAN ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Loading Rate ◽  
Nitrification Inhibitor ◽  
N Deposition ◽  
Nitrogen Loading ◽  
Nitrous Oxide Emissions ◽  
Curvilinear Relationship ◽  
Grassland Soil ◽  
Domestic Livestock ◽  
N Loading

SUMMARYNitrous oxide (N2O) emissions associated with urine nitrogen (N) deposition during grazing are a major component of greenhouse gas emissions from domestic livestock. The present study investigated the relationship between urine N loading rate and the efficacy of a nitrification inhibitor, dicyandiamide (DCD), on cumulative N2O emissions from a grassland soil in Ireland over 80 and 360-day periods in 2009/10 and 2010/11. A diminishing curvilinear relationship between urine N rate and cumulative N2O emissions was observed in both years. Despite this increase in cumulative N2O emissions, the emission factor (EF3) for N2O decreased with increasing urine N rate from, on average, 0·24 to 0·10% (urine applied at 300 and 1000 kg N/ha, respectively), during an 80-day measurement period. This was probably the result of a factor other than N, such as carbon (C), limiting the production of N2O. The efficacy of DCD varied with urine N loading rate, and inter-annual variability in efficacy was also observed. Dicyandiamide was effective at reducing N2O production for 50–80 days after urine application, which accounted for the major period of elevated daily flux. However, DCD was ineffective at reducing N2O production after this period, which was likely a result of its removal from the soil via degradation and leaching.

Effect of the soil water dynamics on nitrous oxide emissions

Geoderma ◽  
2016 ◽  
Vol 280 ◽  
pp. 38-46 ◽  
Author(s):  
E. Rabot ◽  
C. Hénault ◽  
I. Cousin
Keyword(s):  
Nitrous Oxide ◽  
Soil Water ◽  
Water Dynamics ◽  
Nitrous Oxide Emissions ◽  
Soil Water Dynamics

Emission of nitrous-oxide from some grazed pasture soils in New Zealand

Soil Research ◽  
1995 ◽  
Vol 33 (2) ◽  
pp. 341 ◽  
Author(s):  
RA Carran ◽  
PW Theobald ◽  
JP Evans
Keyword(s):  
Nitrous Oxide ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Capacity ◽  
Low Fertility ◽  
Nitrous Oxide Emissions ◽  
Drainage Class ◽  
Grazed Pasture ◽  
Low Emission

Nitrous oxide emissions from grazed pastures were measured at four sites for a 2 year period. Sites differed in drainage class and N cycle characteristics. At two intensively farmed sites on Kairanga silt loam, which is poorly drained, daily emissions ranged from 0 to 100 g N ha-1 day-1 and annual emission was in the range 3-5 kg N2O-N ha-1. Emissions occurred when the soil was near or above field capacity indicating denitrification is the probable source of N2O. Multiple regression analysis, using soil water content, NO3-, NH4+ and temperature, gave r2 = 0.44 and 0.57 at sites 1 and 2 respectively. Soil water content and NH4+ were significant variables. Emissions at a low fertility hillside site were very low and an annual emission of 0.5 kg N2O-N yr-1, or less, was indicated. The highly fertile hillside site also showed low emission values. It is suggested that grazing animals may have a large impact on emissions through hoof damage on wet soils.

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