Nitrogen application rate and nitrous oxide flux from a pastoral soil

Kelliher, F. M.; Li, Z; Nobel, Adl

doi:10.1080/00288233.2014.927772

Cited by 7 publications

(8 citation statements)

References 18 publications

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“…However, de Klein et al (2014) found that the N 2 O emission factor (EF3 N 2 O-N emitted as per cent of urine-N applied) was independent of urine-N loading rate up to 1200 kg N/ha at a nearby location. Kelliher et al (2014) had a similar finding. The urine was evenly applied to the entire 24 cm diameter area of the soil chamber base.…”

Section: Methodssupporting

confidence: 62%

“…De Klein et al (2014) found that EF3 was independent of the urine-N application rate in a study conducted at the same site as this study. Kelliher et al (2014) found a linear relationship between cumulative N 2 O emissions and N application rate when applying urea to soil at rates up to 1500 kg N/ha. The emission factor for dung from the sheep fed ryegrass (0.03%) was not significantly different from that for dung from the sheep fed forage rape (0.08%; P > 0.05).…”

Section: N 2 O Emissionsmentioning

confidence: 90%

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Nitrous oxide emission factors for urine and dung from sheep fed either fresh forage rape (Brassica napus L.) or fresh perennial ryegrass (Lolium perenne L.)

Luo

Sun

Pacheco

et al. 2015

Animal

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In New Zealand, agriculture is predominantly based on pastoral grazing systems and animal excreta deposited on soil during grazing have been identified as a major source of nitrous oxide (N 2 O) emissions. Forage brassicas (Brassica spp.) have been increasingly used to improve lamb performance. Compared with conventional forage perennial ryegrass (Lolium perenne L.), a common forage in New Zealand, forage brassicas have faster growth rates, higher dry matter production and higher nutritive value. The aim of this study was to determine the partitioning of dietary nitrogen (N) between urine and dung in the excreta from sheep fed forage brassica rape (B. napus subsp. oleifera L.) or ryegrass, and then to measure N 2 O emissions when the excreta from the two different feed sources were applied to a pasture soil. A sheep metabolism study was conducted to determine urine and dung-N outputs from sheep fed forage rape or ryegrass, and N partitioning between urine and dung. Urine and dung were collected and then used in a field plot experiment for measuring N 2 O emissions. The experimental site contained a perennial ryegrass/white clover pasture on a poorly drained silt-loam soil. The treatments included urine from sheep fed forage rape or ryegrass, dung from sheep fed forage rape or ryegrass, and a control without dung or urine applied. N 2 O emission measurements were carried out using a static chamber technique. For each excreta type, the total N 2 O emissions and emission factor (EF3; N 2 O-N emitted during the 3-or 8-month measurement period as a per cent of animal urine or dung-N applied, respectively) were calculated. Our results indicate that, in terms of per unit of N intake, a similar amount of N was excreted in urine from sheep fed either forage rape or ryegrass, but less dung N was excreted from sheep fed forage rape than ryegrass. The EF3 for urine from sheep fed forage rape was lower compared with urine from sheep fed ryegrass. This may have been because of plant secondary metabolites, such as glucosinolates in forage rape and their degradation products, are transferred to urine and affect soil N transformation processes. However, the difference in the EF3 for dung from sheep fed ryegrass and forage rape was not significant.Keywords: Excreta, N partitioning, sheep, brassicas, nitrous oxide ImplicationsNitrous oxide (N 2 O) emissions from soil are one of the main components of greenhouse gases in the agricultural sector and animal excreta have been identified as a major source of these emissions. Our study showed that feeding forage rape reduced the N 2 O-N emission factor (EF3; N 2 O-N emitted during the 3-month measurement period as a per cent of animal excreta N applied) for sheep urine by about 60%, compared with feeding perennial ryegrass. This finding is significant for developing mitigation measures to reduce EF3 for animal urine. Further study needs to be conducted under different soil and climate conditions to confirm this finding. IntroductionIn New Zealand, agriculture is predominantly based on g...

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Section: Methodssupporting

confidence: 62%

Section: N 2 O Emissionsmentioning

confidence: 90%

Nitrous oxide emission factors for urine and dung from sheep fed either fresh forage rape (Brassica napus L.) or fresh perennial ryegrass (Lolium perenne L.)

Luo

Sun

Pacheco

et al. 2015

Animal

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“…The lack of any difference between the two N-addition rates for urine and urea, with respect to N 2 O emissions, is consistent with the reports of a non-significant effect of the amount of urine-N on N 2 O emissions in an incubation study by van Groenigen et al (2005b). However, both these studies contradict another previous laboratory study by Kelliher et al (2014), who found increased N 2 O emissions with increasing urea-N-application rate. Additionally, denitrification has been found to increase with increasing DOC concentration in sandy soils when NO À 3 is not limiting (Strong andFillery 2002), andde Klein andVanlogtestijn (1994) further demonstrated that urine significantly enhanced denitrification and N 2 O emission from a sandy grassland soil.…”

Section: Discussionsupporting

confidence: 88%

Greater stimulation of greenhouse gas emissions by stored yak urine than urea in an alpine steppe soil from the Qinghai‐Tibetan Plateau: A laboratory study

Cai

Yan

et al. 2017

Grassland Science

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Urine deposition by grazing animals, with urea as the major constituent, is an important nitrogen (N) source in grassland ecosystems and may affect the production of three potent greenhouse gases (GHGs): nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2). However, owing to the greater chemical complexity of urine, the effect of urine on GHG emissions may differ from that of urea, and this difference has not been well reported. A short‐term laboratory study was conducted to examine the influence of stored yak urine and urea at addition rates of 350 and 700 mg N m−1 soil on GHG emissions at 20 and 60% water holding capacity (WHC) in an alpine steppe soil from the Qinghai‐Tibetan Plateau. Compared with no N addition, urea led to greater increases in soil ammonium N (NH4+–N) concentrations, while yak urine resulted in a greater increase in soil dissolved organic carbon concentrations. Greater (P < 0.05) cumulative N2O and CH4 emissions occurred under 60% than 20% WHC, but soil moisture content did not affect CO2 emissions (P > 0.05). There were no statistically significant (P > 0.05) differences in N2O or CH4 emissions between the two N‐addition rates, regardless of N type. The increases in N2O and CH4 emissions after N addition were greater in the urine than in the urea treatments, particularly under 60% WHC. The average CO2 emissions for the two soil moisture contents in the urine treatments increased with increasing N‐addition rate, but the two urea treatments showed similar values to the control. The greater GHG emissions in the stored yak urine treatments were probably due to the existence of intrinsic organic carbon. Our results suggest that fresh yak urine may also possibly cause more GHG losses than urea under equivalent N application rates in alpine steppe soil on the Qinghai‐Tibetan Plateau.

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“…This formulation assumed that EF and U were independent. Some studies have suggested that EF may increase with increasing N concentration (Kim et al 2013); however, de Klein et al (2014) suggested that this dependency only occurs at low values, while Kelliher et al (2014) found no dependency.…”

Section: Nitrous Oxide Emission Modelmentioning

confidence: 98%

The effects of spatial variability of nitrous oxide emissions from grazed pastures on the sampling distribution of chamber measurements

Giltrap

Godfrey

2015

J. Agric. Sci.

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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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Nitrogen application rate and nitrous oxide flux from a pastoral soil

Cited by 7 publications

References 18 publications

Nitrous oxide emission factors for urine and dung from sheep fed either fresh forage rape (Brassica napus L.) or fresh perennial ryegrass (Lolium perenne L.)

Nitrous oxide emission factors for urine and dung from sheep fed either fresh forage rape (Brassica napus L.) or fresh perennial ryegrass (Lolium perenne L.)

Greater stimulation of greenhouse gas emissions by stored yak urine than urea in an alpine steppe soil from the Qinghai‐Tibetan Plateau: A laboratory study

The effects of spatial variability of nitrous oxide emissions from grazed pastures on the sampling distribution of chamber measurements

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