40 results on '"Cowie, Annette"'
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2. Most root-derived carbon inputs do not contribute to long-term global soil carbon storage
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Wang, Guocheng, Xiao, Liujun, Lin, Ziqi, Zhang, Qing, Guo, Xiaowei, Cowie, Annette, Zhang, Shuai, Wang, Mingming, Chen, Songchao, Zhang, Ganlin, Shi, Zhou, Sun, Wenjuan, and Luo, Zhongkui
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Plant root-derived carbon (C) inputs (Iroot) are the primary source of C in mineral bulk soil. However, a fraction of Irootmay lose quickly (Iloss, e.g., via rhizosphere microbial respiration, leaching and fauna feeding) without contributing to long-term bulk soil C storage, yet this loss has never been quantified, particularly on a global scale. In this study we integrated three observational global data sets including soil radiocarbon content, allocation of photosynthetically assimilated C, and root biomass distribution in 2,034 soil profiles to quantify Irootand its contribution to the bulk soil C pool. We show that global average Irootin the 0–200 cm soil profile is 3.5 Mg ha−1yr−1, ∼80% of which (i.e., Iloss) is lost rather than contributing to long-term bulk soil C storage. Irootdecreases exponentially with soil depth, and the top 20 cm soil contains >60% of total Iroot. Actual C input contributing to long-term bulk soil storage (i.e., Iroot−Iloss) shows a similar depth distribution to Iroot. We also map Ilossand its depth distribution across the globe. Our results demonstrate the global significance of direct C losses which limit the contribution of Irootto bulk soil C storage; and provide spatially explicit data to facilitate reliable soil C predictions via separating direct C losses from total root-derived C inputs.
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- 2023
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3. Reducing enteric methane of ruminants in Australian grazing systems – a review of the role for temperate legumes and herbs
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Badgery, Warwick, Li, Guangdi, Simmons, Aaron, Wood, Jennifer, Smith, Rowan, Peck, David, Ingram, Lachlan, Durmic, Zoey, Cowie, Annette, Humphries, Alan, Hutton, Peter, Winslow, Emma, Vercoe, Phil, and Eckard, Richard
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In Australia, 71% of agricultural greenhouse gas (GHG) emissions are enteric methane (CH4 ), mostly produced by grazing sheep and cattle. Temperate low CH4 yielding legumes and herbs can mitigate enteric CH4 production, but system-level GHG emissions need to be considered. The aims of the study were to: (1) devise a framework to assess GHG reductions when introducing low CH4 yielding species; (2) assess mechanisms of CH4 reduction in temperate legume and herb species for Australia; (3) use a case study to demonstrate expected changes to system-level GHG emissions with the introduction of low CH4 yielding legumes; and (4) identify knowledge gaps and research priorities. Results demonstrate lowering emissions intensity (kg CO2 -equivalent/kg product) is crucial to mitigate GHG emissions, but livestock productivity is also important. Several pasture species have anti-methanogenic properties, but responses often vary considerably. Of the species investigated biserrula (Biserrula pelecinus ) has great potential to reduce enteric CH4 emissions, but in a case study its emission intensity was similar to subterranean clover (Trifolium subterraneum ) but higher than lucerne (Medicago sativa ). We conclude that there are temperate legumes and herbs with anti-methanogenic properties, and/or high productivity that could reduce total CH4 emissions and emissions intensity of ruminant livestock production. There is also great diversity in some plant genotypes that can be exploited, and this will be aided by more detailed understanding of plant secondary compounds associated with CH4 reduction. This review suggests an opportunity to formulate pasture species mixtures to achieve reduced CH4 emissions with greater or equal livestock production.
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- 2023
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4. A food-energy-water-carbon nexus framework informs region-specific optimal strategies for agricultural sustainability.
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He, Qinsi, Liu, De Li, Wang, Bin, Wang, Zikui, Cowie, Annette, Simmons, Aaron, Xu, Zhenci, Li, Linchao, Shi, Yu, Liu, Ke, Harrison, Matthew Tom, Waters, Cathy, Huete, Alfredo, and Yu, Qiang
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AGRICULTURE ,COVER crops ,ORGANIC farming ,GREENHOUSE gas mitigation ,CHICKPEA ,CROP residues ,CROP rotation - Abstract
Agricultural sustainability is threatened by pressures from water scarcity, energy crises, escalating greenhouse gas (GHG) emissions, and diminishing farm profitability. Practices that diversify crop rotations, retain crop residues, and incorporate cover crops have been widely studied for their impacts on soil organic carbon and crop production. However, their associated usage of natural resources and economic returns have been overlooked. Here, we employed a food-energy-water-carbon (FEWC) nexus framework to assess the sustainability of crop rotations plus various management strategies across three sub-regions of New South Wales (NSW) in Australia. We found that compared with residue burning and fallowing, residue retention and cover cropping contributed to GHG abatement, but the latter consumed more energy and water per hectare. The composite sustainability scores, calculated with the FEWC framework, suggested that legume-inclusive rotations were generally more sustainable. Furthermore, in northern NSW (with existing sorghum/wheat/chickpea/wheat rotation), residue retention with cover cropping was most suitable combination, while the use of residue retention with fallow yielded greater benefits in southern NSW (with existing wheat/field pea/wheat/canola rotation). Regional disparities in climate, soil, cropping systems, and on-farm costs prompted region-specific strategies to address the unbalanced distribution among FEWC domains. Our study provides assessments for identifying feasible management practices to advance agricultural sustainability. [Display omitted] [ABSTRACT FROM AUTHOR]
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- 2024
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5. Biochar in climate change mitigation
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Lehmann, Johannes, Cowie, Annette, Masiello, Caroline A., Kammann, Claudia, Woolf, Dominic, Amonette, James E., Cayuela, Maria L., Camps-Arbestain, Marta, and Whitman, Thea
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Climate change mitigation not only requires reductions of greenhouse gas emissions, but also withdrawal of carbon dioxide (CO2) from the atmosphere. Here we review the relationship between emissions reductions and CO2removal by biochar systems, which are based on pyrolysing biomass to produce biochar, used for soil application, and renewable bioenergy. Half of the emission reductions and the majority of CO2removal result from the one to two orders of magnitude longer persistence of biochar than the biomass it is made from. Globally, biochar systems could deliver emission reductions of 3.4–6.3 PgCO2e, half of which constitutes CO2removal. Relevant trade-offs exist between making and sequestering biochar in soil or producing more energy. Importantly, these trade-offs depend on what type of energy is replaced: relative to producing bioenergy, emissions of biochar systems increase by 3% when biochar replaces coal, whereas emissions decrease by 95% when biochar replaces renewable energy. The lack of a clear relationship between crop yield increases in response to fertilizer and to biochar additions suggests opportunities for biochar to increase crop yields where fertilizer alone is not effective, but also questions blanket recommendations based on known fertilizer responses. Locally specific decision support must recognize these relationships and trade-offs to establish carbon-trading mechanisms that facilitate a judicious implementation commensurate with climate change mitigation needs.
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- 2021
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6. Developing a multispecies weed competition model for high-yielding cotton
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Charles, Graham W., Sindel, Brian M., Cowie, Annette L., and Knox, Oliver G. G.
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AbstractGlyphosate-tolerant and glyphosate-resistant weeds are becoming increasingly problematic in cotton fields in Australia, necessitating a return from a glyphosate dominated system to a more integrated approach to weed management. The development of an integrated weed management system can be facilitated by identifying the critical period for weed control (CPWC), a model that enables cotton growers to optimize the timing of their weed control inputs. Using data from field studies conducted from 2003 to 2015, CPWC models using extended functions, including weed biomass in the relationships, were developed for the mimic weeds, common sunflower and Japanese millet, in high-yielding, fully irrigated cotton. A multispecies CPWC model was developed after combining these data sets with data for mungbean in irrigated cotton, using weed height and weed biomass as descriptors in the models. Comparison of observed and predicted relative cotton-lint yields from the multispecies CPWC model demonstrated that the model reasonably described the competition from these three very different mimic weeds, opening the possibility for cotton growers to use a multispecies CPWC model in their production systems.
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- 2021
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7. Net-zero emissions targets are vague: three ways to fix
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Rogelj, Joeri, Geden, Oliver, Cowie, Annette, and Reisinger, Andy
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To limit warming, action plans from countries and companies must be fair, rigorous and transparent.
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- 2021
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8. Soil carbon market-based instrument pilot – the sequestration of soil organic carbon for the purpose of obtaining carbon credits
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Badgery, Warwick, Murphy, Brian, Cowie, Annette, Orgill, Susan, Rawson, Andrew, Simmons, Aaron, and Crean, Jason
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Increasing soil organic carbon (SOC) in Australian farming systems has the potential to offset greenhouse gas emissions. Even though methods for soil carbon (C) sequestration have been developed under the Australian Government’s Emissions Reduction Fund, the scope for farm-scale soil C sequestration is poorly understood. A pilot scheme was developed in Central West New South Wales to trial the use of a market-based instrument to encourage farmers to change farm management to increase SOC. This paper reports changes to SOC stocks measured on farms that were successfully contracted in the pilot. The 10 contracted farms were those that submitted the lowest bid per Mg CO2-e. Four land uses were contracted in the pilot: (1) reduced tillage cropping (reference); (2) reduced tillage cropping with organic amendments (e.g. biosolids or compost); (3) conversion from cropping land to permanent pasture; and (4) conversion from cropping land to permanent pasture with organic amendments. At each site a minimum of 10 locations (sampling points) were sampled and analysed for total carbon (LECO elemental analyser) and bulk density calculated. The SOC stocks (0–0.3 m) were assessed before (2012) and after the pilot (2017; calculated on equivalent soil mass of 2012), with 60% of sites showing a significant increase. Pasture had a higher rate of SOC sequestration than reduced tillage cropping (1.2 vs 0.28 Mg C ha-1 year-1, 0–0.3 m); and organic amendments had higher rates of SOC sequestration than without (1.14 vs 0.78 Mg C ha-1 year-1, 0–0.3 m). The results of the pilot demonstrated increases in SOC, using quantification methods consistent with the current Measurement Method of the Australian Government’s Emissions Reduction Fund policy used to generate Australian Carbon Credit Units. The results require careful interpretation as rates of sequestration are likely to be lower in the longer term than initial rates of change seen in this pilot (five years), and the pilot intentionally selected sites with initially low SOC, which ensured a greater opportunity to sequester SOC.
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- 2021
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9. Determining the critical period for broadleaf weed control in high-yielding cotton using mungbean as a mimic weed
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Charles, Graham W., Sindel, Brian M., Cowie, Annette L., and Knox, Oliver G. G.
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AbstractResearch using the critical period for weed control (CPWC) has shown that high-yielding cotton crops are very sensitive to competition from grasses and large broadleaf weeds, but the CPWC has not been defined for smaller broadleaf weeds in Australian cotton. Field studies were conducted over five seasons from 2003 to 2015 to determine the CPWC for smaller broadleaf weeds, using mungbean as a mimic weed. Mungbean was planted at densities of 1, 3, 6, 15, 30, and 60 plants m−2with or after cotton emergence and added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Mungbean competed strongly with cotton, with season-long interference; 60 mungbean plants m−2resulted in an 84% reduction in cotton yield. A dynamic CPWC function was developed for densities of 1 to 60 mungbean plants m−2using extended Gompertz and exponential curves including weed density as a covariate. Using a 1% yield-loss threshold, the CPWC defined by these curves extended for the full growing season of the crop at all weed densities. The minimum yield loss from a single weed control input was 35% at the highest weed density of 60 mungbean plants m−2. The relationship for the critical time of weed removal was further improved by substituting weed biomass for weed density in the relationship.
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- 2020
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10. Determining the critical period for grass control in high-yielding cotton using Japanese millet as a mimic weed
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Charles, Graham W., Sindel, Brian M., Cowie, Annette L., and Knox, Oliver G. G.
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AbstractField studies were conducted over five seasons from 2004 to 2015 to determine the critical period for weed control (CPWC) in high-yielding, irrigated cotton using a competitive mimic grass weed, Japanese millet. Japanese millet was planted with or after cotton emergence at densities of 10, 20, 50, 100, and 200 plants m−2. Japanese millet was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Data were combined over years. Japanese millet competed strongly with cotton, with season-long interference resulting in an 84% reduction in cotton yield with 200 Japanese millet plants m−2. The data were fit to extended Gompertz and logistic curves including weed density as a covariate, allowing a dynamic CPWC to be estimated for densities of 10 to 200 Japanese millet plants m−2. Using a 1% yield-loss threshold, the CPWC commenced at 65 GDD, corresponding to 0 to 7 d after crop emergence (DAE), and ended at 803 GDD, 76 to 98 DAE with 10 Japanese millet plants m−2, and 975 GDD, 90 to 115 DAE with 200 Japanese millet plants m−2. These results highlight the high level of weed control required throughout the cropping season in high-yielding cotton to ensure crop losses do not exceed the cost of weed control.
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- 2020
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11. Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed
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Charles, Graham W., Sindel, Brian M., Cowie, Annette L., and Knox, Oliver G. G.
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AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.
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- 2019
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12. Land in balance: The scientific conceptual framework for Land Degradation Neutrality.
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Cowie, Annette L., Orr, Barron J., Castillo Sanchez, Victor M., Chasek, Pamela, Crossman, Neville D., Erlewein, Alexander, Louwagie, Geertrui, Maron, Martine, Metternicht, Graciela I., Minelli, Sara, Tengberg, Anna E., Walter, Sven, and Welton, Shelley
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LAND degradation ,UNITED Nations Convention to Combat Desertification in Those Countries Experiencing Serious Drought &/or Desertification, Particularly in Africa (1994) ,LAND use planning ,ENVIRONMENTAL protection planning ,SOCIOECONOMIC factors ,SUSTAINABLE development - Abstract
The health and productivity of global land resources are declining, while demand for those resources is increasing. The aim of land degradation neutrality (LDN) is to maintain or enhance land-based natural capital and its associated ecosystem services. The Scientific Conceptual Framework for Land Degradation Neutrality has been developed to provide a scientific approach to planning, implementing and monitoring LDN. The Science-Policy Interface of the United Nations Convention to Combat Desertification (UNCCD) led the development of the conceptual framework, drawing in expertise from a diverse range of disciplines. The LDN conceptual framework focuses on the supporting processes required to deliver LDN, including biophysical and socio-economic aspects, and their interactions. Neutrality implies no net loss of the land-based natural capital relative to a reference state, or baseline. Planning for neutrality involves projecting the likely cumulative impacts of land use and land management decisions, then counterbalancing anticipated losses with measures to achieve equivalent gains. Counterbalancing should occur only within individual land types, distinguished by land potential , to ensure “like for like” exchanges. Actions to achieve LDN include sustainable land management (SLM) practices that avoid or reduce degradation, coupled with efforts to reverse degradation through restoration or rehabilitation of degraded land. The response hierarchy of Avoid > Reduce > Reverse land degradation articulates the priorities in planning LDN interventions. The implementation of LDN is managed at the landscape level through integrated land use planning, while achievement is assessed at national level. Monitoring LDN status involves quantifying the balance between the area of gains (significant positive changes in LDN indicators) and area of losses (significant negative changes in LDN indicators), within each land type across the landscape. The LDN indicators (and associated metrics) are land cover (physical land cover class), land productivity (net primary productivity, NPP) and carbon stocks (soil organic carbon (SOC) stocks). The LDN conceptual framework comprises five modules: A: Vision of LDN describes the intended outcome of LDN; B: Frame of Reference clarifies the LDN baseline; C: Mechanism for Neutrality explains the counterbalancing mechanism; D: Achieving Neutrality presents the theory of change (logic model) articulating the impact pathway; and E: Monitoring Neutrality presents the LDN indicators. Principles that govern application of the framework provide flexibility while reducing risk of unintended outcomes. [ABSTRACT FROM AUTHOR]
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- 2018
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13. The value of using mimic weeds in competition experiments in irrigated cotton
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Charles, Graham W., Sindel, Brian M., Cowie, Annette L., and Knox, Oliver G. G.
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AbstractCrop plants have been used as mimic weeds to substitute for real weeds in competition studies. These mimic weeds have the advantages of availability of seed, uniform germination and growth, and the potential to confer better experimental controllability and repeatability. However, the underlying assumption that the competitive effects of mimic weeds are similar to real weeds has not been tested. We compared a range of morphological traits (plant height, node and leaf number, leaf area, leaf size, and dry weight) between the mimic weeds and real weeds: Japanese millet vs. junglerice, mungbean vs. bladder ketmia, and common sunflower vs. fierce thornapple. The impact of these mimic and real weeds on cotton was also assessed. There were similarities and differences between the mimic and real weeds, but impact on cotton lint yield was most closely associated with weed height and dry weight at mid-season. Mimic weeds may be satisfactorily substituted for real weeds in competition experiments where seasonal and environmental conditions are not limiting, such as with fully irrigated cotton, provided the plants have similar dry weight and height at mid-season. Alternatively, one can account for the differences in dry weight and height. We define here a generalized relationship estimating the yield loss of high-yielding, irrigated cotton from weed competition over a range of weed dry weights and heights, allowing extrapolation from the results with mimic weeds to the competitive effects of a range of weeds.
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- 2019
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14. Life cycle inventories for the Australian grains sector
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Simmons, Aaron T., Murray, Alexandra, Brock, Philippa M., Grant, Timothy, Cowie, Annette L., Eady, Sandra, and Sharma, Bharat
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Grain production is a key source of food globally and is an important agricultural system for the Australian economy. Environmental impacts such as the emissions of greenhouse gases (GHG) associated with grain production are well documented and the Australian grains industry has strived to ensure ongoing improvement. To facilitate this improvement, the industry funded the development of life cycle inventories to provide broad geographical coverage. Cradle-to-gate inventories for wheat were developed for each of the grains industry agro-ecological zones, and inventories were developed for minor cereal crops (e.g. barley, sorghum), oilseeds (i.e. canola) and legumes where relevant. Data for inventory development were taken from numerous sources and validated by using data collected through interviews with experts in each agro-ecological zone. Inventory data were also collected so that indicators in addition to global-warming impacts could be assessed. Global warming impacts for wheat production ranged from 193 to 567 kg carbon dioxide equivalents (CO2-e) t-1, and global warming impacts were 597–851, 333–361, 169–285 and 74–672 kg CO2-e t-1 for canola, sorghum, barley and grain-legume production, respectively. Results for eutrophication, freshwater ecotoxicity, land-use and abiotic depletion (fossil-fuel use) are also presented.
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- 2019
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15. Agroecology as a transformative approach to tackle climatic, food, and ecosystemic crises.
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Bezner Kerr, Rachel, Postigo, Julio C, Smith, Pete, Cowie, Annette, Singh, Pramod K, Rivera-Ferre, Marta, Tirado-von der Pahlen, Maria Cristina, Campbell, Donovan, and Neufeldt, Henry
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Agroecology (AE) has been proposed as a transformative approach to climate change mitigation and adaptation that reduces climate risk while supporting long-term productivity and resilience of food systems by applying ecological and humanistic principles. Agroecology is a holistic systems approach to producing food, which incorporates social, economic, and political dimensions. Agroecological practices include landscape and farm diversification, intercropping, crop and pasture rotation, adding organic amendments, cover crops, and minimizing or avoiding synthetic inputs. Social dimensions of agroecology include co-creation of knowledge with farmers, participatory processes, nonwage labor relations, collective property and management of resources, and addressing social inequities. This paper reviews the recent evidence and potential for agroecology as a transformative approach, both as climate change adaptation and mitigation strategy as well as to meet key societal goals such as healthy ecosystems, food security, and nutrition. • Agroecology is a transformative approach to food systems. • Evidence that agroecology has both adaptive and mitigative potential. • Supports human health, food security and nutrition with socio-cultural benefits. • Agroecology enhances biodiversity and ecosystem services. • To scale agroecology, need planning, policy support & further research. [ABSTRACT FROM AUTHOR]
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- 2023
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16. Quantifying the Greenhouse Gas Reduction Benefits of Utilising Straw Biochar and Enriched Biochar.
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Mohammadi, Ali, Cowie, Annette, Mai, Thi Lan Anh, de la Rosa, Ruy Anaya, Brandão, Miguel, Kristiansen, Paul, and Joseph, Stephen
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This study investigated the carbon footprint of two different biochar production systems for application to paddy fields. The impacts of using rice straw-derived biochar in raw form (System A) were compared with those arising from using rice straw biochar enriched with lime, clay, ash and manure (System B). The GHG abatement of the management of one Mg of rice straw in Systems A and B was estimated at 0.27 and 0.61 Mg CO 2 -eq, respectively, in spring season, and 0.30 and 1.22 Mg CO 2 -eq in summer. The difference is mainly due to greater reduction of soil CH 4 emissions by enriched biochar. [ABSTRACT FROM AUTHOR]
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- 2016
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17. Biochar built soil carbon over a decade by stabilizing rhizodeposits
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(Han) Weng, Zhe, Van Zwieten, Lukas, Singh, Bhupinder Pal, Tavakkoli, Ehsan, Joseph, Stephen, Macdonald, Lynne M., Rose, Terry J., Rose, Michael T., Kimber, Stephen W. L., Morris, Stephen, Cozzolino, Daniel, Araujo, Joyce R., Archanjo, Braulio S., and Cowie, Annette
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Biochar can increase the stable C content of soil. However, studies on the longer-term role of plant–soil–biochar interactions and the consequent changes to native soil organic carbon (SOC) are lacking. Periodic 13CO2pulse labelling of ryegrass was used to monitor belowground C allocation, SOC priming, and stabilization of root-derived C for a 15-month period—commencing 8.2 years after biochar (Eucalyptus saligna, 550 °C) was amended into a subtropical ferralsol. We found that field-aged biochar enhanced the belowground recovery of new root-derived C (13C) by 20%, and facilitated negative rhizosphere priming (it slowed SOC mineralization by 5.5%, that is, 46 g CO2-C m−2yr−1). Retention of root-derived 13C in the stable organo-mineral fraction (<53 μm) was also increased (6%, P < 0.05). Through synchrotron-based spectroscopic analysis of bulk soil, field-aged biochar and microaggregates (<250 μm), we demonstrate that biochar accelerates the formation of microaggregates via organo-mineral interactions, resulting in the stabilization and accumulation of SOC in a rhodic ferralsol.
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- 2017
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18. Effects of Different Biochars on Pinus elliottiiGrowth, N Use Efficiency, Soil N2O and CH4Emissions and C Storage in a Subtropical Area of China
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LIN, Zhibin, LIU, Qi, LIU, Gang, COWIE, Annette L., BEI, Qicheng, LIU, Benjuan, WANG, Xiaojie, MA, Jing, ZHU, Jianguo, and XIE, Zubin
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Intensive management of planted forests may result in soil degradation and decline in timber yield with successive rotations. Biochars may be beneficial for plant production, nutrient uptake and greenhouse gas mitigation. Biochar properties vary widely and are known to be highly dependent on feedstocks, but their effects on planted forest ecosystem are elusive. This study investigated the effects of chicken manure biochar, sawdust biochar and their feedstocks on 2-year-old Pinus elliottiigrowth, fertilizer N use efficiency (NUE), soil N2O and CH4emissions, and C storage in an acidic forest soil in a subtropical area of China for one year. The soil was mixed with materials in a total of 8 treatments: non-amended control (CK); sawdust at 2.16 kg m−2(SD); chicken manure at 1.26 kg m−2(CM); sawdust biochar at 2.4 kg m−2(SDB); chicken manure biochar at 2.4 kg m−2(CMB); 15N-fertilizer alone (10.23 atom% 15N) (NF); sawdust biochar at 2.4 kg m−2plus 15N-fertilizer (SDBN) and chicken manure biochar at 2.4 kg m−2plus 15N-fertilizer (CMBN). Results showed that the CMB treatment increased P. elliottiinet primary production (aboveground biomass plus litterfall) and annual net C fixation (ANCF) by about 180% and 157%, respectively, while the the SDB treatment had little effect on P. elliottiigrowth. The 15N stable isotope labelling technique revealed that fertilizer NUE was 22.7% in CK, 25.5% in the NF treatment, and 37.0% in the CMB treatment. Chicken manure biochar significantly increased soil pH, total N, total P, total K, available P and available K. Only 2% of the N in chicken manure biochar was available to the tree. The soil N2O emission and CH4uptake showed no significant differences among the treatments. The apparent C losses from the SD and CM treatments were 35% and 61%, respectively; while those from the CMB and SDB treatments were negligible. These demonstrated that it is crucial to consider biochar properties while evaluating their effects on plant growth and C sequestration.
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- 2017
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19. Inducing Inorganic Carbon Accrual in Subsoil through Biochar Application on Calcareous Topsoil
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Wang, Yang, Joseph, Stephen, Wang, Xiang, Weng, Zhe H., Mitchell, David R.G., Nancarrow, Mitchell, Taherymoosavi, Sarasadat, Munroe, Paul, Li, Guitong, Lin, Qimei, Chen, Qing, Flury, Markus, Cowie, Annette, Husson, Olivier, Van Zwieten, Lukas, Kuzyakov, Yakov, Lehmann, Johannes, Li, Baoguo, and Shang, Jianying
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Biochar amendments add persistent organic carbon to soil and can stabilize rhizodeposits and existing soil organic carbon (SOC), but effects of biochar on subsoil carbon stocks have been overlooked. We quantified changes in soil inorganic carbon (SIC) and SOC to 2 m depth 10 years after biochar application to calcareous soil. The total soil carbon (i.e., existing SOC, SIC, and biochar-C) increased by 71, 182, and 210% for B30, B60, and B90, respectively. Biochar application at 30, 60, and 90 t ha–1rates significantly increased SIC by 10, 38, and 68 t ha–1, respectively, with accumulation mainly occurring in the subsoil (below 1 m). This huge increase of SIC (mainly CaCO3) is ∼100 times larger than the inorganic carbon present in the added biochar (0.3, 0.6, or 0.9 t ha–1). The benzene polycarboxylic acid method showed that the biochar-amended soil contained more black carbon particles (6.8 times higher than control soil) in the depth of 1.4–1.6 m, which provided the direct quantitative evidence for biochar migration into subsoil after a decade. Spectral and energy spectrum analysis also showed an obvious biochar structure in the biochar-amended subsoil, accompanied by a Ca/Mg carbonate cluster, which provided further evidence for downward migration of biochar after a decade. To explain SIC accumulation in subsoil with biochar amendment, the interacting mechanisms are proposed: (1) biochar amendment significantly increases subsoil pH (0.3–0.5 units) 10 years after biochar application, thus forming a favorable pH environment in the subsoil to precipitate HCO3–; and (2) the transported biochar in subsoil can act as nuclei to precipitate SIC. Biochar amendment enhanced SIC by up to 80%; thus, the effects on carbon stocks in subsoil must be understood to inform strategies for carbon dioxide removal through biochar application. Our study provided critical knowledge on the impact of biochar application to topsoil on carbon stocks in subsoil in the long term.
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- 2023
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20. The climate effect of increased forest bioenergy use in Sweden: evaluation at different spatial and temporal scales
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Cintas, Olivia, Berndes, Göran, Cowie, Annette L., Egnell, Gustaf, Holmström, Hampus, and Ågren, Göran I.
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Bioenergy from boreal forests managed for productive purposes (e.g., pulp, timber) is commonly held to offer attractive options for climate change mitigation. However, this view has been challenged in recent years. Carbon balances, cumulative radiative forcing, and average global temperature change have been calculated for a variety of bioenergy management regimes in Swedish forests, and the results support the view that an increased use of forest biomass for energy in Sweden can contribute to climate change mitigation, although methodological (e.g., spatial scales) and parameter value choices influence the results significantly. We show that the climate effect of forest‐based bioenergy depends on the forest ecosystems and management, including biomass extraction for bioenergy and other products, and how this management changes in response to anticipated market demands; and on the energy system effects, which determine the fossil carbon displacement and other greenhouse gas (GHG) mitigation effects of using forest biomass for bioenergy and other purposes. The public and private sectors are advised to consider information from comprehensive analyses that provide insights about energy and forest systems in the context of evolving forest product markets, alternative policy options, and energy technology pathways in their decision‐making processes. WIREs Energy Environ2016, 5:351–369. doi: 10.1002/wene.178 This article is categorized under: Bioenergy > Climate and Environment
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- 2016
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21. Biophysical and economic limits to negative CO2emissions
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Smith, Pete, Davis, Steven J., Creutzig, Felix, Fuss, Sabine, Minx, Jan, Gabrielle, Benoit, Kato, Etsushi, Jackson, Robert B., Cowie, Annette, Kriegler, Elmar, van Vuuren, Detlef P., Rogelj, Joeri, Ciais, Philippe, Milne, Jennifer, Canadell, Josep G., McCollum, David, Peters, Glen, Andrew, Robbie, Krey, Volker, Shrestha, Gyami, Friedlingstein, Pierre, Gasser, Thomas, Grübler, Arnulf, Heidug, Wolfgang K., Jonas, Matthias, Jones, Chris D., Kraxner, Florian, Littleton, Emma, Lowe, Jason, Moreira, José Roberto, Nakicenovic, Nebojsa, Obersteiner, Michael, Patwardhan, Anand, Rogner, Mathis, Rubin, Ed, Sharifi, Ayyoob, Torvanger, Asbjørn, Yamagata, Yoshiki, Edmonds, Jae, and Yongsung, Cho
- Abstract
To have a >50% chance of limiting warming below 2 °C, most recent scenarios from integrated assessment models (IAMs) require large-scale deployment of negative emissions technologies (NETs). These are technologies that result in the net removal of greenhouse gases from the atmosphere. We quantify potential global impacts of the different NETs on various factors (such as land, greenhouse gas emissions, water, albedo, nutrients and energy) to determine the biophysical limits to, and economic costs of, their widespread application. Resource implications vary between technologies and need to be satisfactorily addressed if NETs are to have a significant role in achieving climate goals.
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- 2016
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22. Soil carbon and inferred net primary production in high- and low-intensity grazing systems on the New England Tableland, eastern Australia
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Young, Rick, Cowie, Annette, Harden, Steven, and McLeod, Ross
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Management of grazing lands for the accumulation of soil carbon stocks (CS) has been proposed as an effective way to reduce net greenhouse gas emissions from agriculture. However, there are conflicting reports on the effects of grazing management on soil carbon. Most comparisons have involved some combination of no grazing, rotational grazing and set stocking. In the present study we compared two adjacent commercial grazing systems, distinguished on the basis of inputs and livestock productivity, located on New England basaltic landscapes experiencing a cool temperate climate. The high-intensity (H) system sustains an average stocking rate of 18 dry sheep equivalents (dse) ha-1, with a turnoff rate of 9dseha-1year-1, with high levels of investment in assets, management and fertiliser. The low-intensity (L) system, with less intensive management and half the fertiliser of the H system, sustains a stocking rate of 9dseha-1, with a turnoff rate of 3dseha-1year-1, which is slightly higher than the regional average. Pasture biomass production was inferred (back-calculated) from stocking rates and animal feed requirements using published data. From the H and L systems, seven paired landscapes from valley floor to upper hillslopes and plateaux were selected. The seventh included a forest reserve. One hundred and eighty-six undisturbed soil cores (0–0.5m depth) were assessed for bulk density, total C and N, particulate C and a range of plant nutrients. There were few differences in CS, soil pH and nutrient levels between H and L grazing systems. Average CS (0–0.3m) in pasture soils was 103Mgha-1, but was higher in the forest soil at 190Mgha-1. Regression of CS versus soil mass was a satisfactory method of dealing with the bias introduced by the higher soil bulk density in perennial pasture systems compared with the forest. The similarity of CS in H and L pasture soils was despite inferred net primary production being 1.9–3.6MgCha-1year-1 greater in H than L systems, implying higher rates of C turnover in the former. The global warming potential of the inferred annual emissions of CH4 and N2O in the H and L systems was equivalent to approximately 19% and 13% of the cycling atmospheric–plant CO2 carbon respectively.
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- 2016
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23. A global survey of stakeholder views and experiences for systems needed to effectively and efficiently govern sustainability of bioenergy
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Stupak, Inge, Joudrey, Jamie, Smith, C. Tattersall, Pelkmans, Luc, Chum, Helena, Cowie, Annette, Englund, Oskar, Goh, Chun Sheng, and Junginger, Martin
- Abstract
Different governance mechanisms have emerged to ensure biomass and bioenergy sustainability amidst a myriad of related public and private regulations that have existed for decades. We conducted a global survey with 59 questions which examined 192 stakeholders' views and experiences related to (1) the multi‐leveled governance to which they are subjected, (2) the impacts of that governance on bioenergy production and trade, and (3) the most urgent areas for improvement of certification schemes. The survey revealed significant support along the whole supply chain for new legislation which uses market‐based certification schemes to demonstrate compliance (co‐regulation). Some respondents did not see a need for new regulation, and meta‐standards is a promising approach for bridging divergent views, especially if other proof than certification will be an option. Most respondents had so far experienced positive or neutral changes to their bioenergy production or trade after the introduction of new sustainability governance. Legislative requirements and a green business profile were important motivations for getting certified, while lack of market advantages, administrative complexity and costs all were barriers of varying importance. A need to include, e.g., regular standard revision and dealing with conflicting criteria was identified by respondents associated with bioenergy schemes. Respondents associated with forestry schemes saw less need for revisions, but some were interested in supply chain sustainability criteria. Significant differences among schemes suggest it is crucial in the future to examine the tradeoffs between certification costs, schemes' inclusiveness, the quality of their substantive and procedural rules, and the subsequent effectiveness on‐the‐ground. WIREs Energy Environ2016, 5:89–118. doi: 10.1002/wene.166 This article is categorized under: Bioenergy > Climate and Environment
- Published
- 2016
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24. Biochar Carbon Stability in a Clayey Soil As a Function of Feedstock and Pyrolysis Temperature.
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Pal Singh, Bhupinder, Cowie, Annette L., and Smernik, Ronald J.
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- 2012
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25. Influence of Biochars on Nitrous Oxide Emission and Nitrogen Leaching from Two Contrasting Soils.
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Pal Singh, Bhupinder, Hatton, Blake J., Singh, Balwant, Cowie, Annette L., and Kathuria, Amrit
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NITROUS oxide ,SOIL leaching ,VERTISOLS ,ALFISOLS ,EMISSIONS (Air pollution) ,PYROLYSIS ,LEACHATE ,SOIL absorption & adsorption ,QUANTITATIVE research - Abstract
The article presents a study which evaluates the effect of biochars on nitrogen leaching and nitrous oxide emission from Vertisols and Alfisols. It states that the repacked soil columns were subdued to three wetting-drying (W-D) cycles to attain a variety of water-filled pore space (WFPS). Throughout the first two W-D cycles, wood biochar synthesized at 400 °C and 550 °C had contrasting effects on nitrous oxide emissions and the soils changed with poultry manor biochars synthesized at 400 °C generated higher nitrous oxide emissions. Throughout the third W-D cycle, all biochars consistently reduced nitrous oxide emissions. It concludes that increased biochar efficiency in decreasing nitrous oxide emissions was due to biochars' sorption capacity.
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- 2010
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26. Energy- and greenhouse gas-based LCA of biofuel and bioenergy systems: Key issues, ranges and recommendations
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Cherubini, Francesco, Bird, Neil D., Cowie, Annette, Jungmeier, Gerfried, Schlamadinger, Bernhard, and Woess-Gallasch, Susanne
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BIOMASS energy research ,BIOMASS energy & the environment ,ENERGY consumption research ,GREENHOUSE gases research ,EMISSIONS (Air pollution) ,GREENHOUSE gas mitigation ,DATA analysis ,FOSSIL fuels - Abstract
With increasing use of biomass for energy, questions arise about the validity of bioenergy as a means to reduce greenhouse gas emissions and dependence on fossil fuels. Life Cycle Assessment (LCA) is a methodology able to reveal these environmental and energy performances, but results may differ even for apparently similar bioenergy systems. Differences are due to several reasons: type and management of raw materials, conversion technologies, end-use technologies, system boundaries and reference energy system with which the bioenergy chain is compared. Based on review of published papers and elaboration of software data concerning greenhouse gas and energy balances of bioenergy, other renewable and conventional fossil systems, this paper discusses key issues in bioenergy system LCA. These issues have a strong influence on the final results but are often overlooked or mishandled in most of the studies available in literature. The article addresses the following aspects: recognition of the biomass carbon cycle, including carbon stock changes in biomass and soil over time; inclusion of nitrous oxide and methane emissions from agricultural activities; selection of the appropriate fossil reference system; homogeneity of the input parameters in Life Cycle Inventories; influence of the allocation procedure when multiple products are involved; future trends in bioenergy (i.e. second-generation biofuels and biorefineries). Because many key issues are site-specific, and many factors affect the outcome, it is not possible to give exact values for the amount of greenhouse gas emissions and fossil energy consumption saved by a certain bioenergy product, because too many uncertainties are involved. For these reasons, the results are here provided as a means of wide ranges. Despite this wide range of results, it has been possible to draw some important conclusions and devise recommendations concerning the existing bioenergy systems, and some emerging implications about the future deployment and trends of bioenergy products are pointed out. [Copyright &y& Elsevier]
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- 2009
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27. Potential synergies between existing multilateral environmental agreements in the implementation of land use, land-use change and forestry activities
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Cowie, Annette, Schneider, Uwe A., and Montanarella, Luca
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CLIMATE change ,LAND management ,ENVIRONMENTALISM -- International cooperation ,BIODIVERSITY ,GREENHOUSE gas mitigation ,ENVIRONMENTAL degradation ,SUSTAINABLE development ,MANAGEMENT - Abstract
Abstract: There is potential for synergy between the global environmental conventions on climate change, biodiversity and desertification: changes in land management and land use undertaken to reduce net greenhouse gas emissions can simultaneously deliver positive outcomes for conservation of biodiversity, and mitigation of desertification and land degradation. However, while there can be complementarities between the three environmental goals, there are often tradeoffs. Thus, the challenge lies in developing land use policies that promote optimal environmental outcomes, and in implementing these locally to promote sustainable development. The paper considers synergies and tradeoffs in implementing land use measures to address the objectives of the three global environmental conventions, both from an environmental and economic perspective. The intention is to provide environmental scientists and policy makers with a broad overview of these considerations, and the benefits of addressing the conventions simultaneously. [Copyright &y& Elsevier]
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- 2007
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28. Options for including all lands in a future greenhouse gas accounting framework
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Cowie, Annette L., Kirschbaum, Miko U.F., and Ward, Murray
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GREENHOUSE gas mitigation ,LAND management ,UNITED Nations Framework Convention on Climate Change (1992). Protocols, etc., 1997 December 11 ,CLIMATE change ,CARBON & the environment ,CARBON dioxide mitigation ,CARBON cycle - Abstract
Abstract: The current framework through which greenhouse gas emissions and removals in the land use sector are accounted under the Kyoto Protocol has several problems. They include a complex structure, onerous monitoring and reporting requirements, and potential for omission of some important fluxes. One solution that may overcome some of these problems is to include all lands and associated processes within a country''s jurisdiction, rather than restrict accounting to specific nominated land categories or activities. Ideally, the accounting approach should cover all significant biospheric sources and sinks, avoid biased or unbalanced accounting, avoid leakage and require no arbitrary adjustments to remedy unintended consequences. Furthermore, accounting should focus on the direct human-induced component of biospheric emissions/removals so that debits/credits can be allocated equitably and provide appropriate incentives to adopt land-use management options with beneficial outcomes for the atmosphere. This paper focuses on biospheric emissions and removals resulting from carbon stock changes. It considers four alternative accounting options that include all land areas: Gross-Net Accounting, Net-Net Accounting, Net Accounting with Negotiated Baselines and the Average Carbon Stocks approach. Each option is described, and assessed with respect to defined criteria for effectiveness. Gross-Net Accounting and Net-Net Accounting do not adequately distinguish the anthropogenic component of carbon-stock changes from indirect and natural effects, so large undeserved credits or debits could be created. Under Net Accounting with Negotiated Baselines, countries’ projected emissions and removals during the commitment period would be taken into account in the negotiation of emissions targets. In the commitment period, countries would then gain credits/debits for biospheric removals/emissions. Difficulties with this approach would lie in reaching agreed baselines for emissions and removals for individual countries, and, if desired, in factoring out residual effects of natural variability on emissions/removals. Under the Average Carbon Stocks approach, debits/credits for changes in land use or management practices would be based on the changes in long-term average carbon stocks associated with changes in specific land use and management regimes. This approach thereby directly identifies the anthropogenic component, and assigns debits and credits accordingly. It may prove problematic, however, for countries to accept long-term averages rather than observable realised carbon-stock changes as the basis for accounting. Thus, none of the options is without its drawbacks, but Net Accounting with Negotiated Baselines and the Average Carbon Stocks approach could potentially be used as the basis of developing a future ‘all lands’ accounting framework. [Copyright &y& Elsevier]
- Published
- 2007
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29. Carbon allocation in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii.
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Forrester, David I., Bauhus, Jürgen, and Cowie, Annette L.
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BIOMASS ,ACACIA ,RIVERS - Abstract
Abstract: Aboveground biomass was twice as high in mixtures of Eucalyptus globulus and Acacia mearnsii when compared to E. globulus monocultures after 11 years. This was attributed to increased nutrient availability and accelerated rates of N and P cycling in mixtures. This study examined whether the increase in aboveground biomass production was associated with an increase in total productivity (both above- and belowground), a change in C partitioning (from below to aboveground) or both. Total annual belowground C allocation (TBCA) was determined during year 11 in a mixed-species trial near Cann River, southeastern Australia. Monocultures of E. globulus (100%E) and A. mearnsii (100%A) and mixtures of these species (50%E:50%A) were planted in a replacement series. Using a conservation of mass approach, TBCA was estimated as soil carbon dioxide (CO
2 ) efflux C minus the C input from aboveground litter plus changes in the C stored in soil, roots and the forest floor litter layer. Aboveground net primary production (ANPP) was also estimated to enable comparison of ratios of above and belowground fluxes between treatments. TBCA ranged from 14.6 to 16.3MgCha−1 year−1 and was not significantly different in 100%E, 50%E:50%A and 100%A. Higher ratios of ANPP:TBCA in the mixtures (0.41) than in either monoculture (100%A:0.28 100%E:0.31) indicated that trees in mixture partitioned a lower proportion of assimilated C belowground than those in monocultures. Since the mixture was as productive as monocultures belowground but more productive aboveground, it appears to be more productive overall and thus have the potential to increase C sequestration above that of monocultures. [Copyright &y& Elsevier]- Published
- 2006
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30. Mixed-species plantations of Eucalyptus with nitrogen-fixing trees: A review.
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Forrester, David I., Bauhus, Jürgen, Cowie, Annette L., and Vanclay, Jerome K.
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EUCALYPTUS ,PLANTATIONS ,SOIL fertility ,SOIL productivity - Abstract
Abstract: Mixed-species plantations of Eucalyptus with a nitrogen (N
2 ) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shade-tolerant species. Successful mixtures also have significantly higher rates of N and P cycling than Eucalyptus monocultures. It is therefore important to select N2 -fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2 -fixation. While the dynamics of N2 -fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly (P <0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series. [Copyright &y& Elsevier]- Published
- 2006
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31. On the success and failure of mixed-species tree plantations: lessons learned from a model system of Eucalyptus globulus and Acacia mearnsii.
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Forrester, David I., Bauhus, Jürgen, and Cowie, Annette L.
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PLANTATIONS ,ACACIA mearnsii ,EUCALYPTUS globulus ,NUTRIENT cycles - Abstract
Abstract: Mixed plantations of a Eucalyptus species with a nitrogen-fixing tree species can produce significantly higher quantities of aboveground biomass than monocultures. However, if species or sites are not chosen correctly, one species may suppress the growth of the other and mixtures may be less productive than monocultures. Based on a study of Eucalyptus globulus and Acacia mearnsii, this paper discusses the species attributes and site factors that should be considered to improve the probability of increasing biomass production using mixed-species plantations. In an 11-year-old mixed-species trial of E. globulus and A. mearnsii in southeastern Australia aboveground biomass production was twice as high in mixtures containing 50% E. globulus and 50% A. mearnsii than in E. globulus monocultures. There are three main types of interactions that led to this growth outcome: competition, competitive reduction and facilitation. Facilitation occurred as A. mearnsii fixed significant quantities of N, both in monoculture and when mixed with E. globulus. In addition, not only rates of N but also those of P cycling through litterfall were significantly higher in mixed stands than E. globulus monocultures, pointing to the importance of selecting a nitrogen-fixing species that is capable of N fixation and subsequent fast nutrient cycling through litterfall. Mixed stands developed stratified canopies, such that E. globulus eventually overtopped A. mearnsii after 9 years. This resulted in an increase in light capture at the stand level and a reduction in competition for light for E. globulus, a relatively shade intolerant species. This illustrates the importance of selecting species based on their height growth dynamics and relative shade tolerances, to ensure that neither species is suppressed by the other and that the less tolerant species is not overtopped by the more shade tolerant species. In addition to species attributes, site factors, such as soil nitrogen, phosphorus and water availability, play an important role in the interactions and processes occurring in mixtures. In a pot trial containing monocultures and mixtures of E. globulus and A. mearnsii, mixtures produced more biomass than monocultures of either species at low levels of N fertiliser. However, at high levels of N fertiliser E. globulus suppressed A. mearnsii and the biomass production of mixtures was not significantly different to that of E. globulus monocultures. This suggests that mixtures should only be planted on sites where the processes and interactions between species will increase the availability of, or reduce competition for, a major limiting resource for growth at that site. The accurate prediction of successful mixed-species combinations and sites is difficult due to the limited number of studies on mixtures. A mechanistic approach is required to examine the interactions and processes that occur in mixtures and to demonstrate why certain combinations are successful on some sites and not others. [Copyright &y& Elsevier]
- Published
- 2005
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32. Bioenergy and land use change—state of the art
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Berndes, Göran, Ahlgren, Serina, Börjesson, Pål, and Cowie, Annette L.
- Abstract
Bioenergy projects can lead to direct and indirect land use change (LUC), which can substantially affect greenhouse gas balances with both beneficial and adverse outcomes for bioenergy's contribution to climate change mitigation. The causes behind LUC are multiple, complex, interlinked, and change over time. This makes quantification uncertain and sensitive to many factors that can develop in different directions—including land use productivity, trade patterns, prices and elasticities, and use of by‐products associated with biofuels production. Quantifications reported so far vary substantially and do not support the ranking of bioenergy options with regard to LUC and associated emissions. There are however several options for mitigating these emissions, which can be implemented despite the uncertainties. Long‐rotation forest management is associated with carbon emissions and sequestration that are not in temporal balance with each other and this leads to mitigation trade‐offs between biomass extraction for energy use and the alternative to leave the biomass in the forest. Bioenergy's contribution to climate change mitigation needs to reflect a balance between near‐term targets and the long‐term objective to hold the increase in global temperature below 2°C (Copenhagen Accord). Although emissions from LUC can be significant in some circumstances, the reality of such emissions is not sufficient reason to exclude bioenergy from the list of worthwhile technologies for climate change mitigation. Policy measures to minimize the negative impacts of LUC should be based on a holistic perspective recognizing the multiple drivers and effects of LUC. This article is categorized under: Bioenergy > Economics and PolicyBioenergy > Climate and Environment
- Published
- 2013
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33. Impact of carbon farming practices on soil carbon in northern New South Wales
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Cowie, Annette L., Lonergan, Vanessa E., Rabbi, S. M. Fazle, Fornasier, Flavio, Macdonald, Catriona, Harden, Steven, Kawasaki, Akitomo, and Singh, Brajesh K.
- Abstract
This study sought to quantify the influence of ‘carbon farming’ practices on soil carbon stocks, in comparison with conventional grazing and cropping, in northern New South Wales. The study had two components: assessment of impacts of organic amendments on soil carbon and biological indicators in croplands on Vertosols of the Liverpool Plains; and assessment of the impact of grazing management on soil carbon in Chromosols of the Northern Tablelands. The organic amendment sites identified for the survey had been treated with manures, composts, or microbial treatments, while the conventional management sites had received only chemical fertilisers. The rotational grazing sites had been managed so that grazing was restricted to short periods of several days, followed by long rest periods (generally several months) governed by pasture growth. These were compared with sites that were grazed continuously. No differences in total soil carbon stock, or soil carbon fractions, were observed between sites treated with organic amendments and those treated with chemical fertiliser. There was some evidence of increased soil carbon stock under rotational compared with continuous grazing, but the difference was not statistically significant. Similarly, double-stranded DNA (dsDNA) stocks were not significantly different in either of the management contrasts, but tended to show higher values in organic treatments and rotational grazing. The enzymatic activities of β-glucosidase and leucine-aminopeptidase were significantly higher in rotational than continuous grazing but statistically similar for the cropping site treatments. Relative abundance and community structure, measured on a subset of the cropping sites, showed a higher bacteria:fungi ratio and provided evidence that microbial process rates were significantly higher in chemically fertilised sites than organic amendment sites, suggesting enhanced mineralisation of organic matter under conventional management. The higher enzyme activity and indication of greater efficiency of microbial populations on carbon farming sites suggests a greater potential to build soil carbon under these practices. Further research is required to investigate whether the indicative trends observed reflect real effects of management.
- Published
- 2013
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34. Greenhouse gas accounting for inventory, emissions trading and life cycle assessment in the land-based sector: a review
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Cowie, Annette, Eckard, Richard, and Eady, Sandra
- Abstract
Governments, organisations and individuals have recognised the need to reduce their greenhouse gas (GHG) emissions. To identify where savings can be made, and to monitor progress in reducing emissions, we need methodologies to quantify GHG emissions and sequestration. Through the Australian Government’s Carbon Farming Initiative (CFI) landholders may generate credits for reducing emissions and/or sequestering carbon (C). National GHG inventories for the United Nations Framework Convention on Climate Change, and accounting under the Kyoto Protocol use a sectoral approach. For example, fuel use in agriculture is reported in the transport component of the energy sector; energy use in producing herbicide and fertiliser is included in the manufacturing section of the energy sector; sequestration in farm forestry is reported in the land use, land-use change and forestry sector, while emissions reported in the agriculture sector include methane (CH4) from ruminant livestock, nitrous oxide (N2O) from soils, and non-carbon dioxide (CO2) GHG from stubble and savannah burning. In contrast, project-level accounting for CFI includes land-use change, forestry and agricultural sector emissions, and significant direct inputs such as diesel and electricity. A C footprint calculation uses a life cycle approach, including all the emissions associated with an organisation, activity or product. The C footprint of a food product includes the upstream emissions from manufacturing fertiliser and other inputs, fuel use in farming operations, transport, processing and packaging, distribution to consumers, electricity use in refrigeration and food preparation, and waste disposal. Methods used to estimate emissions range from simple empirical emissions factors, to complex process-based models. Methods developed for inventory and emissions trading must balance the need for sufficient accuracy to give confidence to the market, with practical aspects such as ease and expense of data collection. Requirements for frequent on-ground monitoring and third party verification of soil C or livestock CH4 estimates, for example, may incur costs that would negate the financial benefit of credits earned, and could also generate additional GHG emissions. Research is required to develop practical on-farm measures of CH4 and N2O, and methods to quantify C in environmental plantings, agricultural soils and rangeland ecosystems, to improve models for estimation and prediction of GHG emissions, and enable baseline assessment. There is a need for whole-farm level estimation tools that accommodate regional and management differences in emissions and sequestration to support landholders in managing net emissions from their farming enterprises. These on-farm ‘bottom-up’ accounting tools must align with the ‘top-down’ national account. To facilitate assessment of C footprints for food and fibre products, Australia also needs a comprehensive life cycle inventory database. This paper reviews current methods and approaches used for quantifying GHG emissions for the land-based sectors in the context of emissions reporting, emissions trading and C footprinting, and proposes possible improvements. We emphasise that cost-effective yet credible GHG estimation methods are needed to encourage participation in voluntary offset schemes such as the CFI, and thereby achieve maximum mitigation in the land-based sector.
- Published
- 2012
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35. Influence of Biochars on Nitrous Oxide Emission and Nitrogen Leaching from Two Contrasting Soils
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Singh, Bhupinder Pal, Hatton, Blake J., Singh, Balwant, Cowie, Annette L., and Kathuria, Amrit
- Abstract
The influence of biochar on nitrogen (N) transformation processes in soil is not fully understood. This study assessed the influence of four biochars (wood and poultry manure biochars synthesized at 400°C, nonactivated, and at 550°C, activated, abbreviated as: W400, PM400, W550, PM550, respectively) on nitrous oxide (N2O) emission and N leaching from an Alfisol and a Vertisol. Repacked soil columns were subjected to three wetting–drying (W–D) cycles to achieve a range of water‐filled pore space (WFPS) over a 5‐mo period. During the first two W–D cycles, W400 and W550 had inconsistent effects on N2O emissions and the soils amended with PM400 produced higher N2O emissions relative to the control. The initially greater N2O emission from the PM400 soils was ascribed to its higher labile intrinsic N content than the other biochars. During the third W–D cycle, all biochar treatments consistently decreased N2O emissions, cumulatively by 14 to 73% from the Alfisol and by 23 to 52% from the Vertisol, relative to their controls. In the first leaching event, higher nitrate leaching occurred from the PM400‐amended soils compared with the other treatments. In the second event, the leaching of ammonium was reduced by 55 to 93% from the W550‐ and PM550‐Alfisol and Vertisol, and by 87 to 94% from the W400‐ and PM400‐Vertisol only (cf. control). We propose that the increased effectiveness of biochars in reducing N2O emissions and ammonium leaching over time was due to increased sorption capacity of biochars through oxidative reactions on the biochar surfaces with ageing.
- Published
- 2010
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36. Characterisation and evaluation of biochars for their application as a soil amendment
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Singh, Balwant, Singh, Bhupinder Pal, and Cowie, Annette L.
- Abstract
Biochar properties can be significantly influenced by feedstock source and pyrolysis conditions; this warrants detailed characterisation of biochars for their application to improve soil fertility and sequester carbon. We characterised 11 biochars, made from 5 feedstocks [Eucalyptus salignawood (at 400°C and 550°C both with and without steam activation); E. salignaleaves (at 400°C and 550°C with activation); papermill sludge (at 550°C with activation); poultry litter and cow manure (each at 400°C without activation and at 550°C with activation)] using standard or modified soil chemical procedures. Biochar pH values varied from near neutral to highly alkaline. In general, wood biochars had higher total C, lower ash content, lower total N, P, K, S, Ca, Mg, Al, Na, and Cu contents, and lower potential cation exchange capacity (CEC) and exchangeable cations than the manure-based biochars, and the leaf biochars were generally in-between. Papermill sludge biochar had the highest total and exchangeable Ca, CaCO3equivalence, total Cu, and potential CEC, and the lowest total and exchangeable K. Water-soluble salts were higher in the manure-based biochars, followed by leaf, papermill sludge, and wood biochars. Total As, Cd, Pb, and polycyclic aromatic hydrocarbons in the biochars were either very low or below detection limits. In general, increase in pyrolysis temperature increased the ash content, pH, and surface basicity and decreased surface acidity. The activation treatment had a little effect on most of the biochar properties. X-ray diffraction analysis showed the presence of whewellite in E. salignabiochars produced at 400°C, and the whewellite was converted to calcite in biochars formed at 550°C. Papermill sludge biochar contained the largest amount of calcite. Water-soluble salts and calcite interfered with surface charge measurements and should be removed before the surface charge measurements of biochar. The biochars used in the study ranged from C-rich to nutrient-rich to lime-rich soil amendment, and these properties could be optimised through feedstock formulation and pyrolysis temperature for tailored soil application.
- Published
- 2010
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37. The modelling approach determines the carbon footprint of biofuels: The role of LCA in informing decision makers in government and industry
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Brandão, Miguel, Azzi, Elias, Novaes, Renan.M.L., and Cowie, Annette
- Abstract
Concerns over climate change have led to the promotion of biofuels for transport, particularly biodiesel from oilseed crops and ethanol from sugar and starch crops. However, the climate-change mitigation potential of the various biofuels estimated in published studies tends to vary significantly, questioning the reliability of the methods used to quantify potential impacts. We investigated the values published in the European Commission's Renewable Energy Directive (RED), and recalculated the climate-change impacts of a range of biofuels using internally-consistent attributional and consequential modelling approaches to enable comparison of these approaches. We conclude that the estimated results are highly dependent on the modelling approach adopted, to the detriment of the perception of the robustness of life cycle assessment as a tool for estimating the climate-change impacts of biofuels. Land use change emissions are a determining parameter which should not be omitted, even if modelling it introduces a large variability in the results and makes interpretation complex. Clearer guidelines and standardization efforts would be helpful in the harmonization of LCA practice, so that the results can be more useful, robust and reproducible.
- Published
- 2021
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38. Promoting co-benefits of carbon farming in Oceania: Applying and adapting approaches and metrics from existing market-based schemes.
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Baumber, Alex, Metternicht, Graciela, Cross, Rebecca, Ruoso, Laure-Elise, Cowie, Annette L., and Waters, Cathleen
- Abstract
• Current availability of data on co-benefits of carbon farming is low. • Spatial models, indirect indicators and benchmarks can assist with decision support. • Indices could be employed in new or adapted market-based co-benefit schemes. • Activity-based indicators can be used to link actions and proxies to predicted outcomes. • Outcome-based indicators can be linked to payments and used to verify policy effectiveness. Carbon farming in its various forms has the potential to deliver a range of ecosystem services in addition to climate regulation. In Australia, the main public 'co-benefits' that could result from carbon farming are conservation of biodiversity, increases in soil and water quality, productivity increases, and economic and cultural services for Indigenous communities. While there is a lack of empirical evidence that carbon farming is delivering these ecosystem services to date, various metrics have been developed by researchers and through other payment for ecosystem services schemes that may enable effective targeting of these co-benefits. In this article, we review previous studies and schemes and identify four main approaches for metrics that could be applied to carbon farming in Australia: (1) spatial modelling, (2) benchmarks; (3) environmental benefit indices; and (4) indicators. The relative value of each of these approaches varies, depending on the objectives of policy-makers. Spatial modelling and benchmarks can play a key role in decision support systems for landholders who may be interested in carbon farming. Indices are valuable for the development of new or modified market-based schemes that weigh up different co-benefits. Indicators are critical for outcome-based payment schemes and for verifying the effectiveness of co-benefit policies overall. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
39. Meta-analysis quantifying the potential of dietary additives and rumen modifiers for methane mitigation in ruminant production systems
- Author
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Almeida, Amelia K., Hegarty, Roger S., and Cowie, Annette
- Abstract
Increasingly countries are seeking to reduce emission of greenhouse gases from the agricultural industries, and livestock production in particular, as part of their climate change management. While many reviews update progress in mitigation research, a quantitative assessment of the efficacy and performance-consequences of nutritional strategies to mitigate enteric methane (CH4) emissions from ruminants has been lacking. A meta-analysis was conducted based on 108 refereed papers from recent animal studies (2000–2020) to report effects on CH4production, CH4yield and CH4emission intensity from 8 dietary interventions. The interventions (oils, microalgae, nitrate, ionophores, protozoal control, phytochemicals, essential oils and 3-nitrooxypropanol). Of these, macroalgae and 3-Nitroxypropanol showed greatest efficacy in reducing CH4yield (g CH4/kg of dry matter intake) at the doses trialled. The confidence intervals derived for the mitigation efficacies could be applied to estimate the potential to reduce national livestock emissions through the implementation of these dietary interventions.
- Published
- 2021
- Full Text
- View/download PDF
40. Policy institutions and forest carbon
- Author
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Cowie, Annette, Ximenes, Fabiano, Berndes, Göran, Brandão, Miguel, Lamers, Patrick, and Marland, Gregg
- Published
- 2016
- Full Text
- View/download PDF
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