There is increasing recognition of the tension between livestock production and freshwater availability. Changes in freshwater availability can be generated by both freshwater consumptive and ...freshwater degradative use. Agriculture is a major water user, and beef cattle and sheep farming is an important agricultural activity in New Zealand (NZ). This study assessed potential environmental impacts associated with water use in beef cattle and sheep farming in NZ, following a water footprint method compliant with life cycle assessment principles with a focus on the water scarcity footprint and eutrophication potential (EP) impacts. The life cycle required for the production of beef cattle and sheep was analysed cradle-to-farm-gate, excluding animal transport or processing. Survey data from Beef and Lamb New Zealand for the year 2009/10 were used to cover a range of beef cattle and sheep farm types throughout NZ (426 farms averaged in seven farm classes), and water scarcity footprint and EP weighted averages were calculated for beef cattle and sheep. The normalised NZ weighted average water scarcity footprint of beef cattle of 0.37 L H2O-eq/kg LW was lower than the published normalised values for the water scarcity footprint of beef cattle produced in Australia (3.3–221 L H2O-eq/kg LW) and in the UK. Also, the NZ weighted average water scarcity footprint of sheep of 0.26 L H2O-eq/kg meat (assuming that 40% LW was converted into meat) was lower than the water scarcity footprint of sheep meat reported for the UK (8.4–23.1 L H2O/kg meat).
Blue water losses associated with evapotranspiration from irrigated pasture comprised the greatest proportion of the total water scarcity footprint, despite the small areas of farmland irrigated. The weighted average EP of beef cattle was 51.1 g PO4-eq/kg LW, and the weighted average EP of sheep was 26.1 g PO4-eq/kg LW. The NZ weighted average EP for beef cattle was lower than the 105 g PO4-eq/kg LW reported for European Union suckler beef cattle. On-farm nitrate leaching and phosphorus runoff dominated the EP. From an international marketing perspective, beef cattle and sheep produced in NZ have a potential advantage by having low water scarcity footprints compared to some non-NZ pastoral farming systems due to their production efficiencies and low annual water-stress levels. The impact of NZ pastoral farming on freshwater availability can potentially be reduced by practices that decrease water use, increase feed conversion efficiencies, increase the use of non-irrigated feed supplements, and reduce irrigation. The indicator EP was chosen to enable comparisons with non-NZ studies, but gaseous emissions of nitrogen compounds contributed 33–40% of the total, and their contribution to water pollution is uncertain. This study highlighted the need for a harmonised methodology and as well as to consider specific local contextual information when interpreting the absolute and relative implications of EP results, for example by developing NZ-catchment-specific characterisation factors for aquatic eutrophication in future studies.
•This is the first water footprint study of beef cattle and sheep farming in New Zealand.•Beef cattle and sheep produced in New Zealand have relatively low water scarcity footprints.•Nitrate leaching and phosphorus runoff on-farm dominated the Eutrophication Potential.•More research is needed to integrate catchment variability into water footprinting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Grazed pastures are a major contributor to emissions of the greenhouse gas nitrous oxide (N2O), and urine deposition from grazing animals is the main source of the emissions. Incorporating ...alternative forages into grazing systems could be an approach for reducing N2O emissions through mechanisms such as release of biological nitrification inhibitors from roots and increased root depth. Field plot and lysimeter (intact soil column) trials were conducted in a free draining Horotiu silt loam soil to test whether two alternative forage species, plantain (Plantago lanceolate L.) and lucerne (Medicago sativa L.), could reduce N2O emissions relative to traditional pasture species, white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.). The amounts of N2O emitted from the soil below each forage species, which all received the same cow urine at the same rates, was measured using an established static chamber method. Total N2O emissions from the plantain, lucerne and perennial ryegrass controls (without urine application) were generally very low, but emissions from the white clover control were significantly higher. When urine was applied in autumn or winter N2O emissions from plantain were lower compared with those from perennial ryegrass or white clover, but this difference was not found when urine was applied in summer. Lucerne had lower emissions in winter but not in other seasons. Incorporation of plantain into grazed pasture could be an approach to reduce N2O emissions. However, further work is required to understand the mechanisms for the reduced emissions and the effects of environmental conditions in different seasons.
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•Urine patches in ryegrass-dominant pasture are a major contributor to N2O emissions.•Test of alternative pasture species as a novel approach to reduce N2O emissions•Compared with ryegrass, plantain had lower emissions from urine in most seasons.•Lucerne had lower emissions in winter but not in other seasons.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The carbon footprint of milk from year-round grazed-pasture dairy systems and its variability has had limited research. The objective of this study was to determine temporal, regional, and farm ...system variability in the carbon footprint of milk from New Zealand (NZ) average dairy production. Farm production and input data were collected from a national database for 2010/11 to 2017/18 across regions of NZ and weighted on relative production supplied to the major dairy cooperative Fonterra to produce an NZ-average. Total greenhouse gas emissions were calculated using a life cycle assessment methodology for the cradle-to-farm gate, covering all on- and off-farm contributing sources. The NZ-average carbon footprint of milk varied from 0.81 kg of CO2 equivalent (CO2eq)/kg of fat- and protein-corrected milk (FPCM) in 2010/11 (with widespread drought) to 0.75 to 0.78 kg of CO2eq/kg of FPCM in 2013/14 to 2017/18, with a trend for a small decrease over time. Regional variation occurred with highest carbon footprint values for the Northland region due to greatest climatic and soil limitations on pasture production. Dairy cattle diet was approximately 85% from grazed pasture with up to 15% from brought-in feeds (mainly forages and by-products). The CO2 emissions from direct fuel and electricity use constituted <2% of total CO2eq emissions, whereas enteric methane was near 70% of the total. An estimate of potential contribution from direct land use change (plantation forest to pasture) was 0.13 kg of CO2eq/kg of FPCM. This was not included because nationally there has been a net increase in forest land and a decrease in pasture land over the last 20 yr. Data used were highly representative, as evident by the same estimated carbon footprint from 368 farms (in 2017/18) from the national database compared with that from a direct survey of 7,146 farms. New Zealand-specific nitrous oxide emission factors were used, based on many validated field trials and as used in the NZ greenhouse gas inventory, resulting in an 18% lower carbon footprint than if default Intergovernmental Panel on Climate Change factors had been used. Evaluation of the upper and lower quartiles of farms based on per-cow milk production (6,044 vs. 3,542 kg of FPCM/cow) showed a 15% lower carbon footprint for the upper quartile of farms, illustrating the potential for further decrease in carbon footprint with improved farm management practices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Nitrous oxide (N
2O) emissions from grazed pastures represent a significant source of atmospheric N
2O. With an improved understanding and quantification of N sources, transformation processes, and ...soil and climatic conditions controlling N
2O emissions, a number of management options can be identified to reduce N
2O emissions from grazed pasture systems. The mitigation options discussed in this paper are: optimum soil management, limiting the amount of N fertiliser or effluent applied when soil is wet; lowering the amount of N excreted in animal urine by using low-N feed supplements as an alternative to fertiliser N-boosted grass; plant and animal selection for increased N use efficiency, using N process inhibitors that inhibit the conversion of urea to ammonium and ammonium to nitrate in soil; use of stand-off/feed pads or housing systems during high risk periods of N loss. The use of single or multiple mitigation options always needs to be evaluated in a whole farm system context and account for total greenhouse gas emissions including methane and carbon dioxide. They should focus on ensuring overall efficiency gains through decreasing N losses per unit of animal production and achieving a tighter N cycle. Whole-system life-cycle-based environmental analysis should also be conducted to assess overall environmental emissions associated the N
2O mitigation options.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Low input legume-based agriculture exists in a continuum between subsistence farming and intensive arable and pastoral systems. This review covers this range, but with most emphasis on temperate ...legume/grass pastures under grazing by livestock. Key determinants of nitrogen (N) flows in grazed legume/grass pastures are: inputs of N from symbiotic N₂ fixation which are constrained through self-regulation via grass/legume interactions; large quantities of N cycling through grazing animals with localised return in excreta; low direct conversion of pasture N into produce (typically 5-20%) but with N recycling under intensive grazing the farm efficiency of product N: fixed N can be up to 50%; and regulation of N flows by mineralisation/immobilisation reactions. Pastoral systems reliant solely on fixed N are capable of moderate-high production with modest N losses e.g. average denitrification and leaching losses from grazed pastures of 6 and 23 kg N ha⁻¹ yr⁻¹. Methods for improving efficiency of N cycling in legume-based cropping and legume/grass pasture systems are discussed. In legume/arable rotations, the utilisation of fixed N by crops is influenced greatly by the timing of management practices for synchrony of N supply via mineralisation and crop N uptake. In legume/grass pastures, the spatial return of excreta and the uptake of excreta N by pastures can potentially be improved through dietary manipulation and management strategies. Plant species selection and plant constituent modification also offer the potential to increase N efficiency through greater conversion into animal produce, improved N uptake from soil and manipulation of mineralisation/immobilisation/nitrification reactions.
•Dicyandiamide (DCD) degradation rate and mean soil temperature were linearly related.•At 8 and 16°C, estimated DCD half-lives were 39±6 and 25±3 days, respectively.•At a temperature, DCD degraded ...faster in soils in the field than in incubated samples.
Data were analysed from five trials begun in autumn at a field site and a relationship between time for concentration of the nitrification inhibitor dicyandiamide (DCD) in soil to halve (t½, days) and the mean soil temperature (T, °C) was developed: t½=54–1.8T. For example, when T was 8 and 16°C, t½ was 39±6 and 25±3 days (±95% confidence limit), respectively. Previously, under laboratory conditions at equivalent temperatures, the corresponding values of t½ were 86±31 and 44±24days. Thus, the proportional responses of t½ to increasing T from 8 to 16°C were similar, but under field conditions t½ was about half that under laboratory conditions.
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•Dairy heifers were orally administered with dicyandiamide (DCD) at 3 rates over a 90-day continuous dosing period.•DCD did not affect heifer growth or measured blood metabolites.•Prolonged daily ...administration of DCD resulted in the sustained excretion of DCD in urine and inhibited nitrification in soil.•A 3-fold increase in the rate administered resulted in a similar increase in the level of DCD in urine and deposited in urine patches.•DCD application rate onto soils varied widely, and the variability increased with increasing dose rate administered.
Oral administration of the nitrification inhibitor dicyandiamide (DCD) to grazing ruminants for excretion in urine represents a targeted mitigation strategy to reduce nitrogen (N) losses from grazed pastures. A field trial and allied laboratory incubation study were conducted to examine the effects of oral administration of DCD to non-lactating Friesian dairy heifers on excretion of DCD in urine and efficacy in soil. Dairy heifers were orally administered DCD daily at three treatment levels (low, medium and high; 12, 24 and 36gDCDheifer−1day−1, respectively) and compared to a nil-DCD control group over a 90-day continuous dosing period. There were no adverse effects of DCD administration on heifer health or growth, as inferred by live-weight gain and measured blood metabolite levels. Prolonged administration of DCD to dairy heifers resulted in the sustained excretion of DCD in the urine over 90 days and inhibition of nitrification of urinary-N in the silty peat soil for up to 56 days (incubated at 20°C; P<0.001). Field soil sampling (0–75mm depth) of individual urine patches for DCD analysis revealed that a 3-fold increase in the rate of DCD administered resulted in a similar increase in the concentration of DCD voided in the urine and subsequently deposited in urine patches (median equivalent DCD application rates of 22, 36 and 59kgha−1 for the low, medium and high DCD treatment levels, respectively; P<0.001). However, large differences (up to 40-fold) existed between individual urine patches in the rate of DCD deposited at each treatment level, which showed a positively skewed distribution. This study highlights the viability of prolonged daily administration of DCD to ruminants for sustained excretion in urine and effective inhibition of nitrification in soil as a practical targeted mitigation technology to reduce urinary-N losses from grazed pastures.
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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 (N₂O) ...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 N₂O 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 N₂O 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. N₂O emission measurements were carried out using a static chamber technique. For each excreta type, the total N₂O emissions and emission factor (EF3; N₂O–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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Metabolism stall studies investigated fate of administering DCD to cattle.•Recovery of DCD in urine was 61–82% with 10–19% in faeces and 1.2% in milk.•Rapid depletion of DCD in milk and excreta ...occurred after ceasing administration.•Provision of DCD in silage is a viable delivery method to cattle.•Administration of DCD to lactating dairy cows results in low amounts in milk.
A metabolism stall study examined the fate of dicyandiamide (DCD) administered to dairy cows by either oral drenching or via a supplementary feed source (pasture silage) as a practical method to achieve targeted DCD excretion in individual urinations to reduce nitrogen (N) losses from grazed pasture systems. The study consisted of two experiments; firstly, lactating dairy cows were orally administered an aqueous solution of DCD at two rates (3 or 30gcow−1day−1) to examine the output in urine, faeces and milk, and secondly, non-lactating dairy cows were fed pasture silage amended with fine-crystalline DCD powder (30g DCD cow−1day−1) to investigate concentrations of DCD in excreta (urine and faeces) and the subsequent inhibition of nitrification of urinary-N in soil. Administration of DCD to lactating dairy cows in solution resulted in DCD being predominantly recovered in urine at 61% relative to 19% in faeces and 1.2% in milk (SEM 2.3, 1.0 and 0.08, respectively). Increased DCD administration rate led to higher (P<0.01) concentrations of DCD in urine, faeces and milk, but had no significant effect on the total daily proportion recovered (percentage of that administered). After ceasing administration, concentrations of DCD in milk and excreta (urine and faeces) declined to undetectable levels after 5 days. In the second experiment, recovery of DCD in urine from cows fed DCD-treated pasture silage was higher at 82%, with 10% in faeces (SEM 1.9 and 0.6, respectively) and markedly inhibited nitrification of urine-N in soil. This study highlights that oral administration of an aqueous DCD solution to lactating dairy cows is predominantly eliminated in urine with relatively low amounts voided in milk. Furthermore, provision of fine-crystalline DCD powder in supplementary feed is also a viable delivery method for excretion in urine to potentially reduce environmental N losses from grazed pasture systems.
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•Feeding DCD to cows was tested to mitigate N2O losses from urine patches.•Soil was heavy-textured and climate was temperate.•DCD fed and then excreted was as effective as powdered DCD mixed with ...urine.•DCD application rate of 30kgDCDha−1 was more effective than 10kgDCDha−1.•Feeding DCD to cows is potentially more effective than DCD broadcasting.
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Nitrate (NO3−) leaching and nitrous oxide (N2O) emission from urine patches in grazed pastures are key sources of water and air pollution, respectively. Broadcast spraying of the nitrification inhibitor dicyandiamide (DCD) has been shown to reduce these losses, but it is expensive. As an alternative, it had been demonstrated that feeding DCD to cattle (after manual mixing with supplementary feeds) was a practical, effective and cheaper method to deliver high DCD rates within urine patches. This two-year study carried out on simulated urine patches in three application seasons (spring, summer, autumn) explored the efficacy of DCD feeding to cattle to reduce N losses from grazed pasture soil in a heavy-textured soil under temperate climatic conditions. In each application season, DCD fed to cows, then excreted with urine and applied at a rate of 30kgDCDha−1 (treatment U+DCD30-f) was as effective as powdered DCD mixed with normal urine and applied at the same rate (treatment U+DCD30) at reducing cumulative N2O-N emissions and the N2O-N emission factor (EF3, expressed as % of N applied). Increasing DCD loading within urine patches from 10 to 30kgDCDha−1 improved efficacy by significantly reducing the EF3 from 34% to 64%, which highlights that under local conditions, 10kgDCDha−1 (the recommended rate for commercial use in New Zealand) was not the optimum DCD rate to curb N2O emissions. The modelling of EF3 in this study also suggests that N mitigation should be given more attention when soil moisture is going to be high, which can be predicted with short-term weather forecasting. DCD feeding, for instance in autumn when cows are not lactating and the risk of N losses is high, could then be reduced by focusing mainly on those forecasted wet periods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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