The urine patch diffusional area: An important N 2 O source?

Marsden, Karina A.; Jones, Davey L.; Chadwick, David R.

doi:10.1016/j.soilbio.2015.10.011

Cited by 27 publications

(25 citation statements)

References 55 publications

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“…Artificial urine was applied by evenly pouring onto the soil, using a fixed template as an area guide. All urine patches were smaller than the chamber basal area (2500 cm 2 ), ensuring additional room inside the chamber for the urine-patch diffusional area, which is important for accurately monitoring urine patch N 2 O emissions (Marsden et al 2016). Soil cores (0-5 cm) were taken from the area of immediate urine application, during the course of the study.…”

Section: Experimental Design and Treatment Applicationmentioning

confidence: 99%

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

2016

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Abstract. Ruminant urine nitrogen (N) concentration and volume are important parameters influencing the size and N loading rate of urine patches deposited to soil. Such parameters can influence N cycling and emissions of the greenhouse gas, nitrous oxide (N 2 O) from grazed grassland, yet, there is limited information on the effect of these parameters within typical ranges reported for sheep. We used an automated, high-frequency gas monitoring system to investigate N 2 O emissions from varying urine N application rates and patch sizes under field conditions. Using artificial sheep urine, we manipulated urine N concentration to provide two urine N application rates (4 and 16 g N/L; equivalent to 200 and 800 kg N/ha). We investigated the effect of urine patch size with equal N application rates (4 · 125 cm 2 vs 500 cm 2 , at 200 and 800 kg N/ha) and the effect of patch size with unequal N application rates, but the same total amount of N applied (62.5 mL over 125 cm 2 at 800 kg N/ha and 250 mL over 500 cm 2 at 200 kg N/ha). Cumulative emissions of N 2 O generally increased with N loading rate, whether applied as one large urine patch or four smaller ones. Cumulative N 2 O emissions increased when the N was applied in four smaller urine patches compared with one large patch; this difference was significant at 800 kg N/ha, but not at 200 kg N/ha. When the total amount of N applied was held constant (1 g of N), the amount of N 2 O released was similar when urine was applied as a high N concentration small patch (800 kg N/ha) compared with a low N concentration large patch (200 kg N/ha). Urine N 2 O emission factors in this study were, on average, 10 times lower than the IPCC default of 1% for sheep excreta. This research clearly demonstrates that the chemical and physical nature of the urine patch influences N 2 O emissions, yet further research is required to gather more data on typical sheep urine volumes (individual and daily), urination frequency, urine N concentrations and the typical volumes of soil influenced by urine deposition, to provide more accurate estimates of emissions from sheep grazed pastures.

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Section: Experimental Design and Treatment Applicationmentioning

confidence: 99%

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

2016

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“…The typical wetted area of the sheep urine patch, based on field measurements, is estimated to be between 300 and 500 cm 2 (Selbie et al, 2015;Marsden et al, 2016). Additionally, the effective area of a sheep urine deposition has been shown to not exceed 20 cm beyond the wetted area (Ducau et al, 2003).…”

Section: Image Segmentation Using K-means Algorithmmentioning

confidence: 98%

“…To avoid the detection of unwanted objects such as weed patches, small shadows and groups of denser grass, objects <300 cm 2 were discarded, which correspond at the minimal potential size of a urine patch (Selbie et al, 2015;Marsden et al, 2016). Finally, the patch characteristics such as size, centroid coordinates, patch average color values, and shape index (giving an information on the shape of the patch) were calculated and converted to square meters.…”

Section: Algorithms Step 4: Patch Selection and Calculation Of Their mentioning

confidence: 99%

“…In our study, using these values, the amount of urine N deposited represents an equivalent of 2.0-4.8 times the annual amount of N fertilizer (225 kg N ha −1 ). This excess of applied nitrogen leads to an increased likelihood of N leaching, ammonia (NH 3 ) volatilization, and nitrous oxide (N 2 O) emission, but also increased grass growth (Hyde et al, 2016;Marsden et al, 2016), as well as increasing nitrogen and carbon pools in the soil urine depositions change soil pH, soil surface temperature, and soil moisture content (Marriott et al, 1987;Moir et al, 2011;Boon et al, 2014;Selbie et al, 2015). All factors are likely to change the N 2 O emission rate (Clough et al, 2004;Hoogendoorn et al, 2008;De Klein et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The effective area of a urine patch includes the wetted area, the diffusional area and the pasture response area. The wetted area has been distinguished from the diffusional and pasture response area which incorporates the diffusive edge of the nutrients and the plants able to access, via their roots, these nutrients (Marsden et al, 2016). Often N 2 O emission estimates of urine patches focus on the wetted area only and do not account for the diffusional areas (Williams and Haynes, 1994;Hoogendoorn et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Identifying Urine Patches on Intensively Managed Grassland Using Aerial Imagery Captured From Remotely Piloted Aircraft Systems

Maire

Gibson-poole

Cowan

et al. 2018

Front. Sustain. Food Syst.

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The deposition of livestock urine and feces in grazed fields results in a sizable input of available nitrogen (N) in these soils; therefore significantly increasing potential nitrogen pollution from agricultural areas in the form of nitrous oxide (N 2 O), ammonia (NH 3 ), and nitrate (NO 3 − ). Livestock deposition events contributes to high spatial variability within the field and generate uncertainties when assessing the contribution that animal waste has on nitrogen pollution pathways. This study investigated an innovative technique for identifying the spatial coverage of urine deposition in grasslands without the need for manual soil measurements. A Remotely Piloted Aircraft System (RPAS) using a twin camera system was used to identify urine patches in a 5 ha field, which had been grazed by sheep 3 weeks previous to measurements. The imagery was processed using Agisoft Photoscan (Agisoft LLC) to produce true and false color orthomosaic imagery of the entire field. Imagery of five areas (225 m 2 ) within the field were analyzed using a custom R script. For a total of 1,125 m 2 of grassland, 12.2% of the area consisted of what was classified as urine patch. A simple up-scaling method was applied to these data to calculate N 2 O emissions for the entire field providing an estimate of 1.3-2.0 kg N 2 O-N ha −1 emissions from urine and fertilizer inputs.

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Global Research Alliance N₂O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

et al. 2020

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Adequately estimating soil nitrous oxide (N 2 O) emissions using static chambers is challenging due to the high spatial variability and episodic nature of these fluxes. We discuss how to design experiments using static chambers to better account for this variability and reduce the uncertainty of N 2 O emission estimates. This paper is part of a series, each discussing different facets of N 2 O chamber methodology. Aspects of experimental design and sampling affected by spatial variability include site selection and chamber layout, size, and areal coverage. Where used, treatment application adds a further level of spatial variability. Time of day, frequency, and duration of sampling (both individual chamber closure and overall experiment duration) affect the temporal variability captured. We also present best practice recommendations for chamber installation and sampling protocols to reduce further uncertainty. To obtain the best N 2 O emission estimates, resources should be allocated to minimize the overall uncertainty in line with experiment objectives. Sometimes this will mean prioritizing individual flux measurements and increasing their accuracy and precision by, for example, collecting four or more headspace samples during each chamber closure. However,

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The urine patch diffusional area: An important N 2 O source?

Cited by 27 publications

References 55 publications

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

Identifying Urine Patches on Intensively Managed Grassland Using Aerial Imagery Captured From Remotely Piloted Aircraft Systems

Global Research Alliance N₂O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

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The urine patch diffusional area: An important N 2 O source?

Cited by 27 publications

References 55 publications

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

Identifying Urine Patches on Intensively Managed Grassland Using Aerial Imagery Captured From Remotely Piloted Aircraft Systems

Global Research Alliance N2O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

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Global Research Alliance N₂O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability