Intensive Cattle Grazing Affects Pasture Litter-Fall: An Unrecognized Nitrous Oxide Source

Pal, Pranoy; Clough, Tim J.; Kelliher, Francis M.; Koten, Chikako van; Sherlock, Robert R.

doi:10.2134/jeq2011.0277

Cited by 13 publications

(16 citation statements)

References 20 publications

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“…The soil at both sites was a strongly gleyed, Temuka clay loam (Typic Orthic Gley; [Hewitt 1998]) with impeded subsoil drainage. The pasture species included perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) which were regularly grazed by dairy cows as previously described (Pal et al 2012). To avoid the antecedent excreta effects of grazing animals, pasture areas (15 × 20 m) were fenced and animals excluded for six months prior to commencing the experiments.…”

Section: Methodsmentioning

confidence: 99%

“…Pasture leaf tissues may contribute to N 2 O emissions. For example, plant material harvested, but not ingested, by dairy cattle falls to the soil surface where up to 1% of the embodied N may be released as N 2 O (Pal et al 2012(Pal et al , 2013. The following study was designed to examine the potential for pasture-N to contribute to N 2 O emissions following animal treading.…”

Section: Introductionmentioning

confidence: 99%

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Sources of N₂O–N following simulated animal treading of ungrazed pastures

Pal

Clough

Kelliher

2014

New Zealand Journal of Agricultural Research

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It has been previously hypothesised that the treading of pastures by grazing animals can increase nitrous oxide (N 2 O) emissions as the result of reduced plant N uptake. In addition, grazing animals urinate and defecate on to soils which can also increase the N 2 O emissions. To avoid these additional N inputs, a treading machine was used in two field experiments where the pre-grazing dry matter (DM) was present or removed to test the above hypothesis. The N 2 O emissions were measured for 47 and 30 days afterwards, respectively. The soil nitrate (NO 3 -N) pool was 15 N labelled prior to treading in Experiment 2. Treading induced greater N 2 O emissions and reduced herbage DM yields (by 31%-41%) and soil NO 3 -N concentrations when soil gravimetric water contents ranged from 0.45 to 0.63 g water/g soil. A comparison of treading in the presence and absence of pre-grazing DM showed that reduced plant N uptake did not induce greater N 2 O emissions. Rather, the 15 N labelling of the NO 3 -N pool indicated this pool contributed to the N 2 O emissions under treading. In addition, 15 N labelling showed other soil-N pools became available as a consequence of either, (1) treading inducing soil perturbation and releasing N from the soil organic matter-N and/or plant root-N pools, or (2) as a result of simulated grazing causing the release of plant root-N. Soil water soluble carbon (C) also increased under treading in the absence of pasture, supporting the theory that organic-N was released from either the soil organic matter (OM) or plant root pools. Further research should investigate the effect of treading on the turnover and contribution of organic-N pools (roots, OM) in pasture soils in order to more fully understand the contributions these make to background N 2 O emissions and effects on N and C cycling in pasture soils.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sources of N₂O–N following simulated animal treading of ungrazed pastures

Pal

Clough

Kelliher

2014

New Zealand Journal of Agricultural Research

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“…The model assumed that cows consumed 55% of available foliage (Pal et al, 2012) at each grazing event. If grazing was spread over several consecutive days, grazing percentages on individual days were adjusted to add to a total of 55%.…”

Section: Modelling Detailsmentioning

confidence: 99%

“…During a grazing event, cows can graze paddocks from a pre-grazing pasture cover of up to 3000 kgDW ha −1 and ingest up to 1650 kgDW ha −1 (assuming 55% of available feed being ingested; Pal et al, 2012). Assuming a carbon content of 50%, this equates to an intake of up to 825 kgC ha − 1 d − 1 .…”

Section: Ecosystem Respiration-challenges Posed By Grazing Eventsmentioning

confidence: 99%

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Kirschbaum

Rutledge

Kuijper

et al. 2015

Science of The Total Environment

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We used two years of eddy covariance (EC) measurements collected over an intensively grazed dairy pasture to better understand the key drivers of changes in soil organic carbon stocks. Analysing grazing systems with EC measurements poses significant challenges as the respiration from grazing animals can result in large short-term CO2 fluxes. As paddocks are grazed only periodically, EC observations derive from a mosaic of paddocks with very different exchange rates. This violates the assumptions implicit in the use of EC methodology. To test whether these challenges could be overcome, and to develop a tool for wider scenario testing, we compared EC measurements with simulation runs with the detailed ecosystem model CenW 4.1. Simulations were run separately for 26 paddocks around the EC tower and coupled to a footprint analysis to estimate net fluxes at the EC tower. Overall, we obtained good agreement between modelled and measured fluxes, especially for the comparison of evapotranspiration rates, with model efficiency of 0.96 for weekly averaged values of the validation data. For net ecosystem productivity (NEP) comparisons, observations were omitted when cattle grazed the paddocks immediately around the tower. With those points omitted, model efficiencies for weekly averaged values of the validation data were 0.78, 0.67 and 0.54 for daytime, night-time and 24-hour NEP, respectively. While not included for model parameterisation, simulated gross primary production also agreed closely with values inferred from eddy covariance measurements (model efficiency of 0.84 for weekly averages). The study confirmed that CenW simulations could adequately model carbon and water exchange in grazed pastures. It highlighted the critical role of animal respiration for net CO2 fluxes, and showed that EC studies of grazed pastures need to consider the best approach of accounting for this important flux to avoid unbalanced accounting.

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“…Previous results using 15 N to apportion N 2 O sources have shown that emissions from plant residue applications can be short-lived (Frimpong and Baggs, 2010;Frimpong et al, 2011). Ruminant grazing of pasture and forage crops causes fresh litterfall, as animals fail to ingest all harvested herbage (Lodge et al, 2006;Campanella and Bisigato, 2010;Pal et al, 2012). One study, replicating a grazing-induced litterfall event, used 15 N tracer to show that fresh litter deposition contributed to the N 2 O flux (1% of N applied) from the soil surface and enriched the soil inorganic-N pool (Pal et al, 2013).…”

Section: Stable Isotopes Of Nitrogenmentioning

confidence: 99%

Using stable isotopes to follow excreta N dynamics and N2O emissions in animal production systems

Clough

Müller

Laughlin

2013

Animal

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Nitrous oxide (N 2 O) is a potent greenhouse gas and the dominant anthropogenic stratospheric ozone-depleting emission. The tropospheric concentration of N 2 O continues to increase, with animal production systems constituting the largest anthropogenic source. Stable isotopes of nitrogen (N) provide tools for constraining emission sources and, following the temporal dynamics of N 2 O, providing additional insight and unequivocal proof of N 2 O source, production pathways and consumption. The potential for using stable isotopes of N is underutilised. The intent of this article is to provide an overview of what these tools are and demonstrate where and how these tools could be applied to advance the mitigation of N 2 O emissions from animal production systems. Nitrogen inputs and outputs are dominated by fertiliser and excreta, respectively, both of which are substrates for N 2 O production. These substrates can be labelled with 15 N to enable the substrate-N to be traced and linked to N 2 O emissions. Thus, the effects of changes to animal production systems to reduce feed-N wastage by animals and fertiliser wastage, aimed at N 2 O mitigation and/or improved animal or economic performance, can be traced. Further 15 N-tracer studies are required to fully understand the dynamics and N 2 O fluxes associated with excreta, and the biological contribution to these fluxes. These data are also essential for the new generation of 15 N models. Recent technique developments in isotopomer science along with stable isotope probing using multiple isotopes also offer exciting capability for addressing the N 2 O mitigation quest.

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Intensive Cattle Grazing Affects Pasture Litter-Fall: An Unrecognized Nitrous Oxide Source

Cited by 13 publications

References 20 publications

Sources of N₂O–N following simulated animal treading of ungrazed pastures

Sources of N₂O–N following simulated animal treading of ungrazed pastures

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Using stable isotopes to follow excreta N dynamics and N2O emissions in animal production systems

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Intensive Cattle Grazing Affects Pasture Litter-Fall: An Unrecognized Nitrous Oxide Source

Cited by 13 publications

References 20 publications

Sources of N2O–N following simulated animal treading of ungrazed pastures

Sources of N2O–N following simulated animal treading of ungrazed pastures

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Using stable isotopes to follow excreta N dynamics and N2O emissions in animal production systems

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Sources of N₂O–N following simulated animal treading of ungrazed pastures

Sources of N₂O–N following simulated animal treading of ungrazed pastures