Understanding and analysing spatial variability of nitrous oxide emissions from a grazed pasture

SUMMARYChamber sampling is a common method for measuring nitrous oxide (N2O) emissions from agricultural soils. However, for grazed pastures, the patchy nature of urine deposition results in very high levels of spatial variability in N2O emissions. In the present study, the behaviour of the sample mean was examined by simulating a large number (9999) of random N2O chamber samples under different assumptions regarding the underlying N2O distribution. Using sample sizes of up to 100 chambers, the Central Limit Theorem did not apply. The distribution of the sample mean was always right-skewed with a standard deviation varying between 12·5 and 135% of the true mean. However, the arithmetic mean was an unbiased estimator and the mean of the sample mean distribution was close to the true mean of the simulated N2O distribution. The properties of the sample mean distribution (variance, skewness) were affected significantly by the assumed distribution of the emission factor, but not by distribution of the urine patch concentration. The geometric mean was also investigated as a potential alternative estimator. However, although its distribution had lower variance, it was also biased. Two methods for bias correcting the mean were investigated. These methods reduced the bias, but at the cost of increasing the variance. Neither of the bias-corrected estimators were consistently better than the arithmetic mean in terms of skewness and variance. To improve the estimation of N2O emissions from a grazed pasture using chambers, techniques need to be developed to identify urine patch and non-urine patch areas before sampling.

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Spatial variability of nitrous oxide emissions in an unmanaged old-growth beech forest

Journal of Plant Nutrition and Soil Science ◽

10.1002/jpln.201100412 ◽

2012 ◽

Vol 175 (5) ◽

pp. 739-749 ◽

Cited By ~ 8

Author(s):

Hermann F. Jungkunst ◽

Anika Bargsten ◽

Marc Timme ◽

Stephan Glatzel

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Beech Forest ◽

Nitrous Oxide Emissions ◽

Old Growth

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Nitrous Oxide Emissions from an Open-Lot Beef Cattle Feedyard in Texas

Transactions of the ASABE ◽

10.13031/trans.13396 ◽

2019 ◽

Vol 62 (5) ◽

pp. 1173-1183

Author(s):

David B. Parker ◽

Kenneth D. Casey ◽

Heidi M. Waldrip ◽

Byeng R. Min ◽

Bryan L. Woodbury ◽

...

Keyword(s):

Nitrous Oxide ◽

Beef Cattle ◽

Spatial Variability ◽

Greenhouse Gas ◽

Field Research ◽

Background Level ◽

Nitrous Oxide Emissions ◽

Simulated Rainfall ◽

Flux Chamber ◽

Arithmetic Means

Abstract. Nitrous oxide (N2O) is a greenhouse gas (GHG) with a global warming potential much greater than that of carbon dioxide (CO2). Nitrous oxide is emitted from the manure-covered pen surfaces of open-lot beef cattle feedyards, and more than six million beef cattle are fed in the Southern Great Plains. A field research project was conducted to determine the temporal and spatial variability of N2O emissions from the pen surfaces of a commercial feedyard before and after simulated rainfall. Two week-long monitoring cycles were conducted in April and August 2018 in the Texas Panhandle. Temporal variability was assessed using six continuous automated flux chambers per pen, and spatial variability was assessed using a portable chamber at up to 61 locations in a single pen. Diurnal fluxes varied 5-fold to 10-fold over a 24 h period. Flux varied seasonally, with arithmetic means of 0.56 mg N2O-N m-2 h-1 in April and 3.21 mg N2O-N m-2 h-1 in August. Fluxes measured spatially across the pen surface over a 2 h period at midday were lognormally distributed, with April geometric and arithmetic means of -0.81 and 0.80 mg N2O-N m-2 h-1, respectively, and August geometric and arithmetic means of 0.095 and 2.6 mg N2O-N m-2 h-1, respectively. Fluxes peaked shortly after simulated rainfall. Arithmetic mean N2O-N flux for the 2 d after rainfall increased over the background level by 4.6-fold in April and 1.7-fold in August. Manure properties measured at the time of flux measurement were poorly correlated with N2O emissions and were of little value for predicting N2O emissions, which confirmed that further work is warranted on the biochemistry of feedyard manure. The results of this field research will help refine models for predicting N2O emissions from open-lot beef cattle feedyards and help to develop effective mitigation methods to conserve feedyard N. Keywords: Beef cattle, Flux chamber, Greenhouse gas, Manure, Nitrous oxide, Rainfall.

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Spatial variability of nitrous oxide emissions from an Australian irrigated dairy pasture

Plant and Soil ◽

10.1007/s11104-008-9639-8 ◽

2008 ◽

Vol 309 (1-2) ◽

pp. 77-88 ◽

Cited By ~ 57

Author(s):

D. A. Turner ◽

D. Chen ◽

I. E. Galbally ◽

R. Leuning ◽

R. B. Edis ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Nitrous Oxide Emissions

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

Soil Research ◽

10.1071/sr9950341 ◽

1995 ◽

Vol 33 (2) ◽

pp. 341 ◽

Cited By ~ 54

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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Effects of short-term freezing on nitrous oxide emissions and enzyme activities in a grazed pasture soil after bovine-urine application

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.140006 ◽

2020 ◽

Vol 740 ◽

pp. 140006

Author(s):

Toru Hamamoto ◽

Yoshitaka Uchida ◽

Isabell von Rein ◽

Ikabongo Mukumbuta

Keyword(s):

Nitrous Oxide ◽

Enzyme Activities ◽

Nitrous Oxide Emissions ◽

Short Term ◽

Bovine Urine ◽

Grazed Pasture ◽

Pasture Soil

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Spatial Variability of Nitrous Oxide Emissions and Their Soil-Related Determining Factors in an Agricultural Field

Journal of Environmental Quality ◽

10.2134/jeq2003.1965 ◽

2003 ◽

Vol 32 (6) ◽

pp. 1965-1977 ◽

Cited By ~ 87

Author(s):

Junta Yanai ◽

Takuji Sawamoto ◽

Taku Oe ◽

Kanako Kusa ◽

Keisuke Yamakawa ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Nitrous Oxide Emissions ◽

Agricultural Field ◽

Determining Factors

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Management and implications of using nitrification inhibitors to reduce nitrous oxide emissions from urine patches on grazed pasture soils – a review

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.148099 ◽

2021 ◽

pp. 148099

Author(s):

Kamal P. Adhikari ◽

Grace Chibuike ◽

Surinder Saggar ◽

Priscila L. Simon ◽

Jiafa Luo ◽

...

Keyword(s):

Nitrous Oxide ◽

Nitrous Oxide Emissions ◽

Nitrification Inhibitors ◽

Grazed Pasture

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Nitrous oxide emissions from a beech forest floor measured by eddy covariance and soil enclosure techniques

Biogeosciences ◽

10.5194/bg-2-377-2005 ◽

2005 ◽

Vol 2 (4) ◽

pp. 377-387 ◽

Cited By ~ 49

Author(s):

M. Pihlatie ◽

J. Rinne ◽

P. Ambus ◽

K. Pilegaard ◽

J. R. Dorsey ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Eddy Covariance ◽

Temporal Variability ◽

Nitrous Oxide Emissions ◽

Small Scale ◽

N2o Emissions ◽

Ecosystem Level ◽

N2o Fluxes ◽

Trunk Space

Abstract. Spring time nitrous oxide (N2O) emissions from an old beech (Fagus sylvatica L.) forest were measured with eddy covariance (EC) and chamber techniques. The aim was to obtain information on the spatial and temporal variability in N2O emissions and link the emissions to soil environmental parameters. Mean N2O fluxes over the five week measurement period were 5.6±1.1, 10±1 and 16±11 μg N m−2 h−1 from EC, automatic chamber and manual chambers, respectively. High temporal variability characterized the EC fluxes in the trunk-space. To reduce this variability, resulting mostly from random uncertainty due to measuring fluxes close to the detection limit, we averaged the fluxes over one day periods. The variability in the chamber measurements was much smaller and dominated by high small scale spatial variability. The highest emissions measured by the EC method occurred during the first week of May when the trees were leafing and the soil moisture content was at its highest. If chamber techniques are used to estimate ecosystem level N2O emissions from forest soils, placement of the chambers should be considered carefully to cover the spatial variability in the soil N2O emissions. The EC technique, applied in this study, is a promising alternative tool to measure ecosystem level N2O fluxes in forest ecosystems. To our knowledge, this is the first study to demonstrate that the EC technique can be used to measure N2O fluxes in the trunk-space of a forest.

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