C. Grainger, T. Clarke, K. Beauchemin, S. McGinn, R. Eckard
The experimental objective was to determine if whole cottonseed (WCS) could be used as a dietary supplement to reduce enteric methane emissions and profitably increase milk production from dairy cattle over the summer period when pasture is limited in quantity and has a low nutritive value. Fifty lactating cows, ~200 days in milk, were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (in the morning) and pasture silage (in the afternoon) made from a predominantly ryegrass sward in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg DM/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of untreated WCS with their grain supplement. Measurements of methane emissions (n = 12), using the SF6 tracer technique, were made in weeks 3 and 5 after the commencement of feeding treatments. Supplementation with WCS significantly reduced methane emissions by 12% (g/cow.day) and by 21% (g/cow.kg milk solids) and significantly increased yield of milk (n = 25) by 15%, milk fat by 19% and milk protein by 16%. WCS had no effect on concentration of milk fat or lactose, but resulted in a significant 3% decrease in protein concentration. WCS appears to be a promising supplement for reducing methane emissions and increasing milk production from dairy cattle when pasture is limited in quantity and has a low nutritive value.
{"title":"Supplementation with whole cottonseed reduces methane emissions and can profitably increase milk production of dairy cows offered a forage and cereal grain diet","authors":"C. Grainger, T. Clarke, K. Beauchemin, S. McGinn, R. Eckard","doi":"10.1071/EA07224","DOIUrl":"https://doi.org/10.1071/EA07224","url":null,"abstract":"The experimental objective was to determine if whole cottonseed (WCS) could be used as a dietary supplement to reduce enteric methane emissions and profitably increase milk production from dairy cattle over the summer period when pasture is limited in quantity and has a low nutritive value. Fifty lactating cows, ~200 days in milk, were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (in the morning) and pasture silage (in the afternoon) made from a predominantly ryegrass sward in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg DM/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of untreated WCS with their grain supplement. Measurements of methane emissions (n = 12), using the SF6 tracer technique, were made in weeks 3 and 5 after the commencement of feeding treatments. Supplementation with WCS significantly reduced methane emissions by 12% (g/cow.day) and by 21% (g/cow.kg milk solids) and significantly increased yield of milk (n = 25) by 15%, milk fat by 19% and milk protein by 16%. WCS had no effect on concentration of milk fat or lactose, but resulted in a significant 3% decrease in protein concentration. WCS appears to be a promising supplement for reducing methane emissions and increasing milk production from dairy cattle when pasture is limited in quantity and has a low nutritive value.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07224","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58794159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Measurements of enteric methane (CH4) emissions from individual animals have traditionally been made with indirect calorimetry techniques, which are both accurate and reliable. However, the expense and need for animal training and the extent to which calorimetric results can be extrapolated to free-ranging animals have been questioned and stimulated the development of the sulfur hexafluoride (SF6) tracer technique. The tracer technique is now widely used in New Zealand and many other countries for CH4 emission measurements on grazing and pen-fed cattle, sheep, deer and alpacas. Few studies with cattle and sheep have examined the validity of the SF6 tracer technique. Most of these studies have concluded that estimations of CH4 emission by this technique do not differ from those of calorimetric techniques, though some exceptions have been reported. There is general agreement that the tracer technique is associated with large between-animal variability in the CH4 emission estimates from animals on the same diet, but it remains unknown whether this is due to the environment, housing conditions or the technique itself. High within-animal variability has also been reported from tracer CH4 measurements. There is growing evidence that CH4 emission estimates by the tracer technique are positively influenced by the permeation rate (PR) of the SF6 gas from permeation tubes and it has been suggested that fate of the tracer in the rumen rather than unrepresentative breath sample collection is the likely reason for the latter. It is concluded that although some issues related to the tracer technique need to be clarified, using a narrow range in PR and balancing of PR between treatments should be practised in order to overcome the relationship between PR and CH4 emission estimates.
{"title":"Reliability of the sulfur hexafluoride tracer technique for methane emission measurement from individual animals: an overview","authors":"C. Pinares-Patiño, H. Clark","doi":"10.1071/EA07297","DOIUrl":"https://doi.org/10.1071/EA07297","url":null,"abstract":"Measurements of enteric methane (CH4) emissions from individual animals have traditionally been made with indirect calorimetry techniques, which are both accurate and reliable. However, the expense and need for animal training and the extent to which calorimetric results can be extrapolated to free-ranging animals have been questioned and stimulated the development of the sulfur hexafluoride (SF6) tracer technique. The tracer technique is now widely used in New Zealand and many other countries for CH4 emission measurements on grazing and pen-fed cattle, sheep, deer and alpacas. Few studies with cattle and sheep have examined the validity of the SF6 tracer technique. Most of these studies have concluded that estimations of CH4 emission by this technique do not differ from those of calorimetric techniques, though some exceptions have been reported. There is general agreement that the tracer technique is associated with large between-animal variability in the CH4 emission estimates from animals on the same diet, but it remains unknown whether this is due to the environment, housing conditions or the technique itself. High within-animal variability has also been reported from tracer CH4 measurements. There is growing evidence that CH4 emission estimates by the tracer technique are positively influenced by the permeation rate (PR) of the SF6 gas from permeation tubes and it has been suggested that fate of the tracer in the rumen rather than unrepresentative breath sample collection is the likely reason for the latter. It is concluded that although some issues related to the tracer technique need to be clarified, using a narrow range in PR and balancing of PR between treatments should be practised in order to overcome the relationship between PR and CH4 emission estimates.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58796742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nitrous oxide (N2O) emissions account for ~10% of global greenhouse gas (GHG) emissions, with most of these emissions (~90%) deriving from agricultural practices. Animal agriculture potentially contributes up to 50% of total agricultural N2O emissions. In intensive animal agriculture, high N2O emission rates generally coincide with anaerobic soil conditions and high soil NO3–, primarily from animal urine patches. This paper provides an overview of animal, feed-based and soil or management abatement technologies for ruminant animal agriculture targeted at reducing the size of the soil NO3– pool or improving soil aeration. Direct measurements of N2O emissions from potential animal and feed-based intervention technologies are scarce. However, studies have shown that they have the potential to reduce urinary N excretion by 3–60% and thus reduce associated N2O emissions. Research on the effect of soil and water management interventions is generally further advanced and N2O reduction potentials of up to 90% have been measured in some instances. Of the currently available technologies, nitrification inhibitors, managing animal diets and fertiliser management show the best potential for reducing emissions in the short-term. However, strategies should always be evaluated in a whole-system context, to ensure that reductions in one part of the system do not stimulate higher emissions elsewhere. Current technologies reviewed here could deliver up to 50% reduction from an animal housing system, but only up to 15% from a grazing-based system. However, given that enteric methane emissions form the majority of emissions from grazing systems, a 15% abatement of N2O is likely to translate to a 2–4% decrease in total GHG emissions at a farm scale. Clearly, further research is needed to develop technologies for improving N cycling and reducing N2O emissions from grazing-based animal production systems.
{"title":"Targeted technologies for nitrous oxide abatement from animal agriculture","authors":"C. Klein, R. Eckard","doi":"10.1071/EA07217","DOIUrl":"https://doi.org/10.1071/EA07217","url":null,"abstract":"Nitrous oxide (N2O) emissions account for ~10% of global greenhouse gas (GHG) emissions, with most of these emissions (~90%) deriving from agricultural practices. Animal agriculture potentially contributes up to 50% of total agricultural N2O emissions. In intensive animal agriculture, high N2O emission rates generally coincide with anaerobic soil conditions and high soil NO3–, primarily from animal urine patches. This paper provides an overview of animal, feed-based and soil or management abatement technologies for ruminant animal agriculture targeted at reducing the size of the soil NO3– pool or improving soil aeration. Direct measurements of N2O emissions from potential animal and feed-based intervention technologies are scarce. However, studies have shown that they have the potential to reduce urinary N excretion by 3–60% and thus reduce associated N2O emissions. Research on the effect of soil and water management interventions is generally further advanced and N2O reduction potentials of up to 90% have been measured in some instances. Of the currently available technologies, nitrification inhibitors, managing animal diets and fertiliser management show the best potential for reducing emissions in the short-term. However, strategies should always be evaluated in a whole-system context, to ensure that reductions in one part of the system do not stimulate higher emissions elsewhere. Current technologies reviewed here could deliver up to 50% reduction from an animal housing system, but only up to 15% from a grazing-based system. However, given that enteric methane emissions form the majority of emissions from grazing systems, a 15% abatement of N2O is likely to translate to a 2–4% decrease in total GHG emissions at a farm scale. Clearly, further research is needed to develop technologies for improving N cycling and reducing N2O emissions from grazing-based animal production systems.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07217","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58793860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Kamra, A. Patra, P. Chatterjee, Ravindra Kumar, N. Agarwal, L. Chaudhary
Plants rich in secondary metabolites (saponins, tannins, essential oils, etc.) have antimicrobial activity which can be exploited for selective inhibition of a particular group of microbes in the rumen. We have screened a large number of plant extracts for their potential to inhibit methanogenesis and ciliate protozoa in an in vitro gas production test using buffalo rumen liquor as the inoculum. Out of 93 plant extracts tested, 11 inhibited in vitro methanogenesis to the extent of 25–50% and nine plant extracts inhibited methanogenesis more than 50%. Among 20 extracts exhibiting antimethanogenic activity, nine were ethanol extracts, 10 were methanol extracts and only one was a water extract. Some of these plant extracts inhibited ciliate protozoa as tested by microscopic examination and 14C-labelled radioisotopic technique, but the protozoa inhibition was not correlated with methane inhibition, indicating that the methanogens sensitive to plant secondary metabolites may or may not be having any symbiotic relationship with ciliate protozoa. Methane inhibition was accompanied by a drastic fall in the number of methanogens as determined by real time PCR. Plants that appeared to have some potential as feed additives to control methanogenesis by the ruminants are: (i) seed pulp of Sapindus mukorossi (rich in saponins) and Terminalia chebula (rich in tannins); (ii) leaves of Populus deltoides, Mangifera indica and Psidium guajava (rich in tannins and essential oils); and (iii) flower buds of Syzygium aromaticum and bulb of Allium sativum (rich in essential oils). Some of the plants reported in literature exhibiting antimethanogenic activity include Equisetum arvense, Lotus corniculatus, Rheum palmatum, Salvia officinalis, Sapindus saponaria, Uncaria gambir and Yucca schidigera.
{"title":"Effect of plant extracts on methanogenesis and microbial profile of the rumen of buffalo: a brief overview","authors":"D. Kamra, A. Patra, P. Chatterjee, Ravindra Kumar, N. Agarwal, L. Chaudhary","doi":"10.1071/EA07268","DOIUrl":"https://doi.org/10.1071/EA07268","url":null,"abstract":"Plants rich in secondary metabolites (saponins, tannins, essential oils, etc.) have antimicrobial activity which can be exploited for selective inhibition of a particular group of microbes in the rumen. We have screened a large number of plant extracts for their potential to inhibit methanogenesis and ciliate protozoa in an in vitro gas production test using buffalo rumen liquor as the inoculum. Out of 93 plant extracts tested, 11 inhibited in vitro methanogenesis to the extent of 25–50% and nine plant extracts inhibited methanogenesis more than 50%. Among 20 extracts exhibiting antimethanogenic activity, nine were ethanol extracts, 10 were methanol extracts and only one was a water extract. Some of these plant extracts inhibited ciliate protozoa as tested by microscopic examination and 14C-labelled radioisotopic technique, but the protozoa inhibition was not correlated with methane inhibition, indicating that the methanogens sensitive to plant secondary metabolites may or may not be having any symbiotic relationship with ciliate protozoa. Methane inhibition was accompanied by a drastic fall in the number of methanogens as determined by real time PCR. Plants that appeared to have some potential as feed additives to control methanogenesis by the ruminants are: (i) seed pulp of Sapindus mukorossi (rich in saponins) and Terminalia chebula (rich in tannins); (ii) leaves of Populus deltoides, Mangifera indica and Psidium guajava (rich in tannins and essential oils); and (iii) flower buds of Syzygium aromaticum and bulb of Allium sativum (rich in essential oils). Some of the plants reported in literature exhibiting antimethanogenic activity include Equisetum arvense, Lotus corniculatus, Rheum palmatum, Salvia officinalis, Sapindus saponaria, Uncaria gambir and Yucca schidigera.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07268","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58795821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. W. Groenigen, R. Schils, G. Velthof, P. Kuikman, D. Oudendag, O. Oenema
Animal production systems are large and complex sources of greenhouse gases (GHG), especially nitrous oxide (N2O) and methane (CH4). Emissions from these systems are expected to rise over the coming decades due to the increasing global population and shifting diets, unless appropriate mitigation strategies are implemented. In this paper, we argue that the main constraints for such implementation are: (i) the complex and often poorly understood controls of GHG sources in animal production systems; (ii) the lack of knowledge on the economic and social costs involved in implementing mitigation strategies; and (iii) the strong political emphasis on mitigating nitrate leaching and ammonia volatilisation, rather than GHG emissions. We further argue that overcoming these three constraints can only be achieved by initiating integrated mitigation strategies, based on modelling and experimental work at three scales. At the 'laboratory and field scale', basic causal relationships with respect to processes of GHG formation and other detrimental fluxes need to be experimentally established and modelled. As management options are considered at the 'farm scale', this is the ideal scale to evaluate the cost-effectiveness, feasibility and possible pollution swapping effects of mitigation measures. Finally, at the 'national and supra-national scales', environmental legislation is implemented, effectiveness of environmental policies and emissions abatement measures are being monitored, and the social costs of various scenarios are being weighed. We illustrate the need for integral measures and working across different scales using our own work on the relationship between nitrogen surplus and fluxes to the environment. At the field scale, a clear positive relation between nitrogen surplus and N2O emission, NO3 − leaching and NH3 volatilisation was experimentally established. At the farm scale, the model DAIRYWISE was used to evaluate effects of minimising nitrogen surplus on the nutrient flow and economic viability of an average Dutch dairy farm. Even after including trade-off effects of CH4 emissions from cattle and manure storage, there was still a clear positive relationship between farm gate nitrogen surplus and GHG emission. At this scale, the prime issue was balancing environmental gains with economic viability. Finally, at the 'national and supra-national scale' we developed the MITERRA-EUROPE model, and used it to quantify the effects on GHG emissions of environmental policies aimed at reducing NO3 − leaching and NH3 volatilisation in the 27 Member States of the European Union (EU-27). This showed the intricate relationships between different environmental goals, with both positive feedback (balanced fertilisation reduced both NO3 − leaching and N2O emission) and negative feedback ('low-emission' manure application reduced NH3 volatilisation but increased N2O emission) possible. At this scale, there is a clear need for an integral approach towards reducing e
{"title":"Mitigation strategies for greenhouse gas emissions from animal production systems: synergy between measuring and modelling at different scales","authors":"J. W. Groenigen, R. Schils, G. Velthof, P. Kuikman, D. Oudendag, O. Oenema","doi":"10.1071/EA07197","DOIUrl":"https://doi.org/10.1071/EA07197","url":null,"abstract":"Animal production systems are large and complex sources of greenhouse gases (GHG), especially nitrous oxide (N2O) and methane (CH4). Emissions from these systems are expected to rise over the coming decades due to the increasing global population and shifting diets, unless appropriate mitigation strategies are implemented. In this paper, we argue that the main constraints for such implementation are: (i) the complex and often poorly understood controls of GHG sources in animal production systems; (ii) the lack of knowledge on the economic and social costs involved in implementing mitigation strategies; and (iii) the strong political emphasis on mitigating nitrate leaching and ammonia volatilisation, rather than GHG emissions. We further argue that overcoming these three constraints can only be achieved by initiating integrated mitigation strategies, based on modelling and experimental work at three scales. At the 'laboratory and field scale', basic causal relationships with respect to processes of GHG formation and other detrimental fluxes need to be experimentally established and modelled. As management options are considered at the 'farm scale', this is the ideal scale to evaluate the cost-effectiveness, feasibility and possible pollution swapping effects of mitigation measures. Finally, at the 'national and supra-national scales', environmental legislation is implemented, effectiveness of environmental policies and emissions abatement measures are being monitored, and the social costs of various scenarios are being weighed. We illustrate the need for integral measures and working across different scales using our own work on the relationship between nitrogen surplus and fluxes to the environment. At the field scale, a clear positive relation between nitrogen surplus and N2O emission, NO3 − leaching and NH3 volatilisation was experimentally established. At the farm scale, the model DAIRYWISE was used to evaluate effects of minimising nitrogen surplus on the nutrient flow and economic viability of an average Dutch dairy farm. Even after including trade-off effects of CH4 emissions from cattle and manure storage, there was still a clear positive relationship between farm gate nitrogen surplus and GHG emission. At this scale, the prime issue was balancing environmental gains with economic viability. Finally, at the 'national and supra-national scale' we developed the MITERRA-EUROPE model, and used it to quantify the effects on GHG emissions of environmental policies aimed at reducing NO3 − leaching and NH3 volatilisation in the 27 Member States of the European Union (EU-27). This showed the intricate relationships between different environmental goals, with both positive feedback (balanced fertilisation reduced both NO3 − leaching and N2O emission) and negative feedback ('low-emission' manure application reduced NH3 volatilisation but increased N2O emission) possible. At this scale, there is a clear need for an integral approach towards reducing e","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07197","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58793371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Greenhouse gas (GHG) emissions from New Zealand dairy farms are significant, representing nearly 35% of New Zealand’s total agricultural emissions. Although there is an urgent need for New Zealand to reduce agricultural GHG emissions in order to meet its Kyoto Protocol obligations, there are, as yet, few viable options for reducing farming related emissions while maintaining productivity. In addition to GHG emissions, dairy farms are also the source of other emissions, most importantly effluent from milking sheds and feed pads. It has been suggested that anaerobic digestion for biogas and energy production could be used to deal more effectively with dairy effluent while at the same time addressing concerns about farm energy supply. Dairy farms have a high demand for electricity, with a 300-cow farm consuming nearly 40 000 kWh per year. However, because only ~10% of the manure produced by the cows can be collected (e.g. primarily at milking times), a maximum of only ~16 000 kWh of electricity per year can be produced from the effluent alone. This means that anaerobic digestion/electricity generation schemes are currently economic only for farms with more than 1000 cows. A solution for smaller farms is to co-digest the effluent with unutilised pasture sourced on the farm, thereby increasing biogas production and making the system economically viable. A possible source of unutilised grass is the residual pasture left by the cows immediately after grazing. This residual can be substantial in the spring–early summer, when cow numbers (demand) can be less than the pasture growth rates (supply). The cutting of ungrazed grass (topping) is also a useful management tool that has been shown to increase pasture quality and milk production, especially over the late spring–summer. In this paper, we compare the energy and GHG balances of a conventional farm using a lagoon effluent system to one using anaerobic digestion supplemented by unutilised pasture collected by topping to treat effluent and generate electricity. For a hypothetical 300-cow, 100-ha farm, topping all paddocks from 1800 to 1600 kg DM/ha four times per year over the spring–summer would result in 80 tonnes of DM being collected, which when digested to biogas would yield 50 000 kWh (180 GJ) of electricity. This is in addition to the 16 000 kWh from the effluent digestion. About 90 GJ of diesel would be used to carry out the topping, emitting ~0.06 t CO2e/ha. In contrast, the anaerobic/topping system would offset/avoid 0.74 t CO2e/ha of GHG emissions: 0.6 t CO2e/ha of avoided CH4 emissions from the lagoon and 0.14 t CO2e/ha from biogas electricity offsetting grid electricity GHGs. For the average dairy farm, the net reduction in emissions of 0.68 CO2e/ha would equate to nearly 14% of the direct and indirect emissions from farming activities and if implemented on a national scale, could decrease GHG emissions nearly 1.4 million t CO2e or ~10% of New Zealand’s Kyoto Protocol obligations while at th
新西兰奶牛场的温室气体排放量很大，占新西兰农业总排放量的近35%。虽然新西兰迫切需要减少农业温室气体排放，以履行其《京都议定书》的义务，但到目前为止，在保持生产力的同时减少农业相关排放的可行选择很少。除了温室气体排放，奶牛场也是其他排放的来源，最重要的是来自挤奶棚和饲料垫的污水。有人建议，用于沼气和能源生产的厌氧消化可用于更有效地处理乳制品流出物，同时解决对农场能源供应的担忧。奶牛场对电力的需求很高，一个300头奶牛的农场每年消耗近4万千瓦时。然而，由于奶牛产生的粪便只有约10%可以被收集(例如，主要是在挤奶时)，因此仅从废水中每年最多只能产生约16000千瓦时的电力。这意味着厌氧消化/发电方案目前仅对拥有1000头以上奶牛的农场具有经济效益。小型农场的一个解决方案是将废水与农场未利用的牧场共同消化，从而增加沼气产量，使该系统在经济上可行。未利用草的一个可能来源是奶牛吃完草后留下的剩余牧草。当奶牛数量(需求)低于牧场增长率(供应)时，这一剩余量在春季-初夏可能会很大。割去未放牧的草(顶草)也是一种有用的管理工具，已被证明可以提高牧草质量和牛奶产量，特别是在春末-夏季。在本文中，我们比较了使用泻湖污水系统的传统农场与使用厌氧消化的农场的能量和温室气体平衡，并通过顶部收集未利用的牧场来处理污水和发电。假设一个300头奶牛，100公顷的农场，在春夏期间每年四次将所有围场从1800到1600千克干物质/公顷覆盖，将收集80吨干物质，当消化成沼气时将产生5万千瓦时(180吉焦)的电力。这是在污水消化产生的16000千瓦时之外的。大约90gj的柴油将用于顶顶，排放~0.06吨二氧化碳当量/公顷。相比之下，厌氧/封顶系统将抵消/避免0.74 t CO2e/公顷的温室气体排放，避免0.6 t CO2e/公顷的泻湖CH4排放，以及0.14 t CO2e/公顷的沼气电力抵消电网电力的温室气体排放。对于普通奶牛场来说，每公顷0.68二氧化碳当量的净减排相当于农业活动直接和间接排放量的近14%，如果在全国范围内实施，可以减少近140万吨二氧化碳当量的温室气体排放，或新西兰京都议定书义务的10%左右，同时更好地管理奶牛场废水，加强农场和国家能源安全，并通过优质牧场增加牛奶产量。
{"title":"Greenhouse gas and energy balance of dairy farms using unutilised pasture co-digested with effluent for biogas production","authors":"M. Lieffering, P. Newton, J. Thiele","doi":"10.1071/EA07252","DOIUrl":"https://doi.org/10.1071/EA07252","url":null,"abstract":"Greenhouse gas (GHG) emissions from New Zealand dairy farms are significant, representing nearly 35% of New Zealand’s total agricultural emissions. Although there is an urgent need for New Zealand to reduce agricultural GHG emissions in order to meet its Kyoto Protocol obligations, there are, as yet, few viable options for reducing farming related emissions while maintaining productivity. In addition to GHG emissions, dairy farms are also the source of other emissions, most importantly effluent from milking sheds and feed pads. It has been suggested that anaerobic digestion for biogas and energy production could be used to deal more effectively with dairy effluent while at the same time addressing concerns about farm energy supply. Dairy farms have a high demand for electricity, with a 300-cow farm consuming nearly 40 000 kWh per year. However, because only ~10% of the manure produced by the cows can be collected (e.g. primarily at milking times), a maximum of only ~16 000 kWh of electricity per year can be produced from the effluent alone. This means that anaerobic digestion/electricity generation schemes are currently economic only for farms with more than 1000 cows. A solution for smaller farms is to co-digest the effluent with unutilised pasture sourced on the farm, thereby increasing biogas production and making the system economically viable. A possible source of unutilised grass is the residual pasture left by the cows immediately after grazing. This residual can be substantial in the spring–early summer, when cow numbers (demand) can be less than the pasture growth rates (supply). The cutting of ungrazed grass (topping) is also a useful management tool that has been shown to increase pasture quality and milk production, especially over the late spring–summer. In this paper, we compare the energy and GHG balances of a conventional farm using a lagoon effluent system to one using anaerobic digestion supplemented by unutilised pasture collected by topping to treat effluent and generate electricity. For a hypothetical 300-cow, 100-ha farm, topping all paddocks from 1800 to 1600 kg DM/ha four times per year over the spring–summer would result in 80 tonnes of DM being collected, which when digested to biogas would yield 50 000 kWh (180 GJ) of electricity. This is in addition to the 16 000 kWh from the effluent digestion. About 90 GJ of diesel would be used to carry out the topping, emitting ~0.06 t CO2e/ha. In contrast, the anaerobic/topping system would offset/avoid 0.74 t CO2e/ha of GHG emissions: 0.6 t CO2e/ha of avoided CH4 emissions from the lagoon and 0.14 t CO2e/ha from biogas electricity offsetting grid electricity GHGs. For the average dairy farm, the net reduction in emissions of 0.68 CO2e/ha would equate to nearly 14% of the direct and indirect emissions from farming activities and if implemented on a national scale, could decrease GHG emissions nearly 1.4 million t CO2e or ~10% of New Zealand’s Kyoto Protocol obligations while at th","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07252","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58795305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aim of this study was to use life cycle assessment methods to determine the environmental impacts of manure utilisation by a biogas plant and by a typical manure composting system. The functional unit was defined as the average annual manure utilisation on a dairy farm with 100 cows. The environmental impact categories chosen were emissions of greenhouse gases (GHG) and acidification gases (AG). The GHG emissions were estimated as: 345.9 t CO2-equivalents (e) for solid composting (case 1), 625.4 t CO2-e for solid and liquid composting (case 2), and 86.3–90.1 t CO2-e for the biogas plant system. The AG emissions were estimated as: 10.1 t SO2-e for case 1, 18.4 t SO2-e for case 2, and 13.1–24.2 t SO2-e for the biogas plant system. These results show that a biogas plant system produces low GHG emissions, but comparatively high AG emissions with land application. It is suggested that land application using band spread or shallow injection attachments will decrease AG emissions (NH3) from biogas plant systems.
本研究的目的是使用生命周期评估方法来确定沼气厂和典型粪肥堆肥系统利用粪肥的环境影响。功能单位定义为拥有100头奶牛的奶牛场的年平均粪便利用率。所选择的环境影响类别是温室气体(GHG)和酸化气体(AG)的排放。温室气体排放量估计为:固体堆肥(案例1)的345.9 t co2当量(e)，固体和液体堆肥(案例2)的625.4 t co2当量(e)，沼气厂系统的86.3-90.1 t co2当量(e)。估算的AG排放量为:案例1为10.1 t SO2-e，案例2为18.4 t SO2-e，沼气厂系统为13.1-24.2 t SO2-e。综上所述，随着土地利用的增加，沼气厂系统产生的温室气体排放量较低，但AG排放量相对较高。结果表明，采用带状铺展或浅层注入附着物可减少沼气厂系统氨氮的排放。
{"title":"Using a life cycle assessment method to determine the environmental impacts of manure utilisation: biogas plant and composting systems","authors":"T. Hishinuma, H. Kurishima, C. Yang, Y. Genchi","doi":"10.1071/EA07246","DOIUrl":"https://doi.org/10.1071/EA07246","url":null,"abstract":"The aim of this study was to use life cycle assessment methods to determine the environmental impacts of manure utilisation by a biogas plant and by a typical manure composting system. The functional unit was defined as the average annual manure utilisation on a dairy farm with 100 cows. The environmental impact categories chosen were emissions of greenhouse gases (GHG) and acidification gases (AG). The GHG emissions were estimated as: 345.9 t CO2-equivalents (e) for solid composting (case 1), 625.4 t CO2-e for solid and liquid composting (case 2), and 86.3–90.1 t CO2-e for the biogas plant system. The AG emissions were estimated as: 10.1 t SO2-e for case 1, 18.4 t SO2-e for case 2, and 13.1–24.2 t SO2-e for the biogas plant system. These results show that a biogas plant system produces low GHG emissions, but comparatively high AG emissions with land application. It is suggested that land application using band spread or shallow injection attachments will decrease AG emissions (NH3) from biogas plant systems.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07246","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58795446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gas emissions from enteric fermentation of the domestic livestock contribute to greenhouse gas inventories. Farming activities in Bolivia have nearly doubled methane emissions during the past decade. Methane was the second most important greenhouse gas emitted from human activities in Bolivia according the 1990–2000 GHG inventory. Emissions of methane from enteric fermentation of three regions of Bolivia, highland, valley and lowland, were studied. Atmospheric methane concentrations have increased by a factor of 1.1 to 1.3 in response to this increase and continue to rise. The projection of fermentation enteric gas emissions depends on the increase of the livestock, which was assumed for this study to be linear for 2001–2015 with an increment of 2.27%. In this overview, we examine past trends in the emission of methane due to the enteric fermentation and the sources and sinks that determine its growth rate.
{"title":"Greenhouse gas emissions from enteric fermentation of livestock in Bolivia: values for 1990-2000 and future projections","authors":"E. Garcia-Apaza, O. Paz, I. Arana","doi":"10.1071/EA07247","DOIUrl":"https://doi.org/10.1071/EA07247","url":null,"abstract":"Gas emissions from enteric fermentation of the domestic livestock contribute to greenhouse gas inventories. Farming activities in Bolivia have nearly doubled methane emissions during the past decade. Methane was the second most important greenhouse gas emitted from human activities in Bolivia according the 1990–2000 GHG inventory. Emissions of methane from enteric fermentation of three regions of Bolivia, highland, valley and lowland, were studied. Atmospheric methane concentrations have increased by a factor of 1.1 to 1.3 in response to this increase and continue to rise. The projection of fermentation enteric gas emissions depends on the increase of the livestock, which was assumed for this study to be linear for 2001–2015 with an increment of 2.27%. In this overview, we examine past trends in the emission of methane due to the enteric fermentation and the sources and sinks that determine its growth rate.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07247","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58795535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Cavanagh, L. McNaughton, H. Clark, C. Greaves, J. M. Gowan, C. Pinares-Patiño, D. Dalley, B. Vlaming, G. Molano
As part of a large quantitative trait loci trial, methane emissions were measured on 698 second and third lactation dairy cows which were the progeny of six bulls. The trial ran over two 4-week periods in January 2004 and 2005. Methane samples were collected over 24 h on each of four consecutive days in 2004 and three consecutive days in 2005. Methane emissions were measured using the sulfur hexafluoride (SF6) tracer dilution technique. During measurement periods, all cows grazed grass–clover pasture with ad libitum herbage allowances. Herbage dry matter intakes (DMI) were calculated using Australian Feeding Standards based on individual cow data of milk yield, liveweight, liveweight change and cow body condition. The average DMI was estimated to be 17.1 kg/day (s.d. = 2.0). Daily methane emissions ranged from 151 to 497 g/day with an average of 311 g/day (s.d. = 43.8) or 18.2 g/kg DMI (s.d. = 2.8); this is 15.7% lower than the figure currently used in the New Zealand national inventory. This study also indicates that there are large differences between cows in methane emissions per kg DMI when estimated using the SF6 tracer technique.
{"title":"Methane emissions from grazing Jersey × Friesian dairy cows in mid lactation","authors":"A. Cavanagh, L. McNaughton, H. Clark, C. Greaves, J. M. Gowan, C. Pinares-Patiño, D. Dalley, B. Vlaming, G. Molano","doi":"10.1071/EA07277","DOIUrl":"https://doi.org/10.1071/EA07277","url":null,"abstract":"As part of a large quantitative trait loci trial, methane emissions were measured on 698 second and third lactation dairy cows which were the progeny of six bulls. The trial ran over two 4-week periods in January 2004 and 2005. Methane samples were collected over 24 h on each of four consecutive days in 2004 and three consecutive days in 2005. Methane emissions were measured using the sulfur hexafluoride (SF6) tracer dilution technique. During measurement periods, all cows grazed grass–clover pasture with ad libitum herbage allowances. Herbage dry matter intakes (DMI) were calculated using Australian Feeding Standards based on individual cow data of milk yield, liveweight, liveweight change and cow body condition. The average DMI was estimated to be 17.1 kg/day (s.d. = 2.0). Daily methane emissions ranged from 151 to 497 g/day with an average of 311 g/day (s.d. = 43.8) or 18.2 g/kg DMI (s.d. = 2.8); this is 15.7% lower than the figure currently used in the New Zealand national inventory. This study also indicates that there are large differences between cows in methane emissions per kg DMI when estimated using the SF6 tracer technique.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07277","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58796403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. B. Liang, S. Suzuki, A. Kawamura, A. Habasaki, T. Kato
To meet the rapid and increased demand for animal protein, intensive poultry and livestock farming units are growing quickly in many developing countries in Asia. To access the markets, such production units are primarily located in peri-urban areas where available land for manure treatment and/or recycling back to the soil is limited, thus leading to serious environmental pollution. Although poultry manure from these farms is readily used as organic fertiliser for the production of cash crops, pig manure is usually washed and discharged, with or without treatment, into nearby streams and rivers. Efficient treatment of wastewater from pig farms with limited land is very expensive as it normally requires some degree of artificial aeration. Although it has long been proven that the biogas produced from the anaerobic lagoons can be converted to reusable fuel for heating and/or the generation of electricity for the farm, the technology has not been well received by farmers because they have easy access to other cheap energy sources. However, due to the opportunity of gaining extra monetary return from carbon credit trading under the initiative of the Kyoto Protocol, many pig farmers are beginning to show interest in this technology. From a recent feasibility study conducted in Malaysia to assess the technical and economic viabilities of converting biogas from pig farms into electricity, the following challenges were identified: (i) the organic content of the wastewater generated from the pig farm was far below that required for the efficient production of biogas; (ii) the high costs required for the modification of the existing farm infrastructures and additional equipment made the project economically unattractive; (iii) the potential amount of electricity generated from such a project does not match the daily fluctuating electricity demand on-farm; (iv) current governmental policies and infrastructural supports to buy back the extra electricity generated from such a project are inadequate; (v) the misconception by farmers that recovery of biogas from an anaerobic lagoon will enhance the efficiency of wastewater treatment and thus improve the quality of their wastewater at endpoint to meet the governmental requirements for discharge; and (vi) the quantum sharing of the carbon fund by farmers and the carbon credit trading company.
{"title":"Opportunities and challenges of converting biogas from pig farms into renewable energy in developing countries in Asia – a Malaysian experience","authors":"J. B. Liang, S. Suzuki, A. Kawamura, A. Habasaki, T. Kato","doi":"10.1071/EA07200","DOIUrl":"https://doi.org/10.1071/EA07200","url":null,"abstract":"To meet the rapid and increased demand for animal protein, intensive poultry and livestock farming units are growing quickly in many developing countries in Asia. To access the markets, such production units are primarily located in peri-urban areas where available land for manure treatment and/or recycling back to the soil is limited, thus leading to serious environmental pollution. Although poultry manure from these farms is readily used as organic fertiliser for the production of cash crops, pig manure is usually washed and discharged, with or without treatment, into nearby streams and rivers. Efficient treatment of wastewater from pig farms with limited land is very expensive as it normally requires some degree of artificial aeration. Although it has long been proven that the biogas produced from the anaerobic lagoons can be converted to reusable fuel for heating and/or the generation of electricity for the farm, the technology has not been well received by farmers because they have easy access to other cheap energy sources. However, due to the opportunity of gaining extra monetary return from carbon credit trading under the initiative of the Kyoto Protocol, many pig farmers are beginning to show interest in this technology. From a recent feasibility study conducted in Malaysia to assess the technical and economic viabilities of converting biogas from pig farms into electricity, the following challenges were identified: (i) the organic content of the wastewater generated from the pig farm was far below that required for the efficient production of biogas; (ii) the high costs required for the modification of the existing farm infrastructures and additional equipment made the project economically unattractive; (iii) the potential amount of electricity generated from such a project does not match the daily fluctuating electricity demand on-farm; (iv) current governmental policies and infrastructural supports to buy back the extra electricity generated from such a project are inadequate; (v) the misconception by farmers that recovery of biogas from an anaerobic lagoon will enhance the efficiency of wastewater treatment and thus improve the quality of their wastewater at endpoint to meet the governmental requirements for discharge; and (vi) the quantum sharing of the carbon fund by farmers and the carbon credit trading company.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07200","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58793499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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