Greenhouse gas balance and mitigation potential of agricultural systems in Colombia: A systematic analysis

Better information on greenhouse gas (GHG) emissions and mitigation potential in the agricultural sector is necessary to manage these emissions and identify responses that are consistent with the food security and economic development priorities of countries. Critical activity data (what crops or livestock are managed in what way) are poor or lacking for many agricultural systems, especially in developing countries. In addition, the currently available methods for quantifying emissions and mitigation are often too expensive or complex or not sufficiently user friendly for widespread use.The purpose of this focus issue is to capture the state of the art in quantifying greenhouse gases from agricultural systems, with the goal of better understanding our current capabilities and near-term potential for improvement, with particular attention to quantification issues relevant to smallholders in developing countries. This work is timely in light of international discussions and negotiations around how agriculture should be included in efforts to reduce and adapt to climate change impacts, and considering that significant climate financing to developing countries in post-2012 agreements may be linked to their increased ability to identify and report GHG emissions (Murphy et al 2010, CCAFS 2011, FAO 2011).

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Globally, agriculture is directly responsible for 14% of annual greenhouse gas(GHG) emissions and induces an additional 17% through land use change, mostlyin developing countries (Vermeulen et al 2012). Agricultural intensification andexpansion in these regions is expected to catalyze the most significant relativeincreases in agricultural GHG emissions over the next decade (Smith et al 2008,Tilman et al 2011). Farms in the developing countries of sub-Saharan Africa andAsia are predominately managed by smallholders, with 80% of land holdingssmaller than ten hectares (FAO 2012). One can therefore posit that smallholderfarming significantly impacts the GHG balance of these regions today and willcontinue to do so in the near future.However, our understanding of the effect smallholder farming has on theEarth’s climate system is remarkably limited. Data quantifying existing andreduced GHG emissions and removals of smallholder production systems areavailable for only a handful of crops, livestock, and agroecosystems (Herrero et al2008, Verchot et al 2008, Palm et al 2010). For example, fewer than fifteenstudies of nitrous oxide emissions from soils have taken place in sub-SaharanAfrica, leaving the rate of emissions virtually undocumented. Due to a scarcity ofdata on GHG sources and sinks, most developing countries currently quantifyagricultural emissions and reductions using IPCC Tier 1 emissions factors.However, current Tier 1 emissions factors are either calibrated to data primarilyderived from developed countries, where agricultural production conditions aredissimilar to that in which the majority of smallholders operate, or from data thatare sparse or of mixed quality in developing countries (IPCC 2006). For the mostpart, there are insufficient emissions data characterizing smallholder agricultureto evaluate the level of accuracy or inaccuracy of current emissions estimates.Consequentially, there is no reliable information on the agricultural GHG budgetsfor developing economies. This dearth of information constrains the capacity totransition to low-carbon agricultural development, opportunities for smallholdersto capitalize on carbon markets, and the negotiating position of developingcountries in global climate policy discourse.Concerns over the poor state of information, in terms of data availability andrepresentation, have fueled appeals for new approaches to quantifying GHGemissions and removals from smallholder agriculture, for both existing conditionsand mitigation interventions (Berry and Ryan 2013, Olander et al 2013).Considering the dependence of quantification approaches on data and the currentdata deficit for smallholder systems, it is clear that in situ measurements must bea core part of initial and future strategies to improve GHG inventories and

Brazilian cattle production is mostly carried out in pastures, and the need to mitigate the livestock's greenhouse gas (GHG) emissions and its environmental footprint has become an important requirement. The adoption of well-suited breeds and the intensification of pasture-based livestock production systems are alternatives to optimize the sector's land use. However, further research on tropical systems is necessary. The objective of this research was to evaluate the effect of Holstein (HO) and Jersey–Holstein (JE x HO) crossbred cows in different levels of pasture intensification (continuous grazing system with low stocking rate–CLS; irrigated rotational grazing system with high stocking rate–RHS), and the interaction between these two factors on GHG mitigation. Twenty-four HO and 24 JE x HO crossbred dairy cows were used to evaluate the effect of two grazing systems on milk production and composition, soil GHG emissions, methane (CH4) emission, and soil carbon accumulation (0–100 cm). These variables were used to calculate carbon balance (CB), GHG emission intensity, the number of trees required to mitigate GHG emission, and the land-saving effect. The number of trees necessary to mitigate GHG emission was calculated, considering the C balance within the farm gate. The mitigation of GHG emissions comes from the annual growth rate and accumulation of C in eucalyptus trees' trunks. The CB of all systems and genotypes presented a deficit in carbon (C); there was no difference for genotypes, but RHS was more deficient than CLS (-4.99 to CLS and −28.72 to RHS ton CO2e..ha−1.year−1). The deficit of C on GHG emission intensity was similar between genotypes and higher for RHS (−0.480 to RHS and −0.299 to CLS kg CO2e..kg FCPCmilk−1). Lower GHG removals (0.14 to CLS higher than 0.02 to RHS kg CO2e..kg FCPCmilk−1) had the greatest influence on the GHG emission intensity of milk production. The deficit number of trees to abatement emissions was higher to HO (−46.06 to HO and −38.37 trees/cow to JE x HO) and to RHS (−51.9 to RHS and −33.05 trees/cow to CLS). However, when the results are expressed per ton of FCPCmilk, there was a difference only between pasture management, requiring −6.34 tree. ton FCPCmilk−1 for the RHS and −3.99 tree. ton FCPCmilk−1 for the CLS system. The intensification of pastures resulted in higher milk production and land-saving effect of 2.7 ha. Due to the reservation of the pasture-based dairy systems in increasing soil C sequestration to offset the GHG emissions, especially enteric CH4, planting trees can be used as a mitigation strategy. Also, the land-save effect of intensification can contribute to the issue, since the area spared through the intensification in pasture management becomes available for reforestation with commercial trees.

The burning of fossil fuels in developed nations and the conversion of natural grasslands and forests to intensely managed agricultural production systems are the single most important anthropogenic sources of greenhouse gases (GHGs) contributing to global warming. Such activities do not only contribute to the accumulation of GHGs in the atmosphere, but also lead to the depletion of the global soil organic matter (SOM) pool, further impacting soil fertility and crop productivity. Climate change will likely affect the distribution and productivity of life-sustaining agricultural crops and livestock in different regions of the world, including temperate and tropical biomes. As a result, the United Nations Development Program suggested that millions of people may be facing shortages of food and continued degradation of their agricultural resources. Therefore, one of the challenges is to maintain agricultural productivity to meet current and projected trends in food production, while at the same time minimizing GHG emissions, increasing C (C) sequestration and maintaining soil fertility. This, coupled with large-scale land, soil, and water degradation, will challenge the long-term and sustainable production of agricultural resources that promote food security. Traditional coping mechanisms, such as conventional agroecosystem management practices may not be an economically feasible adaptation strategy, especially for those already experiencing socioeconomic adversity. Therefore, improvement and refinement of ecologically-based land management practices are essential. Soft-path agricultural technologies such as the complex agroecosystems, including agroforestry systems, may make a substantial contribution in the mitigation of GHGs, the sequestration of C, and other ecological services while maintaining a long-term sustainable production of agricultural products. Due to their multipart structure, complex agroecosystems are likely more resilient to climate change and provide a sustainable alternative to conventional land management practices. This special issue of the Agriculture Journal , on the role of complex agroecosystems in climate change mitigation, encapsulates research from temperate and tropical biomes, with a special focus on agroforestry systems. In tropical regions, Chesney et al. investigated the performance of cowpea ( Vigna unguiculata L.) on alley cropping agroforestry systems with Gliricidia sepium (Jacq.) Kunth ex Walp. and Leucaena leucacephala (Lam.) de Wit and a no-tree control on an infertile acidic soil in Guyana. Their goal was to evaluate the ability of fast-growing nitrogen (N 2 )-fixing trees ( G. sepium , L. leucocephala ) on cowpea yield. Such practice would maximize the cowpea crop yield but minimize the need for an external source of N fertilizers. They suggested that such practices provide a sustainable source of food, and conserve soil resources but it will also reduce the potential production of the GHGs over the long-term. They noted that these agroforestry practices would curb N 2 O emissions, which has a global warming potential 296 times greater than that of CO 2 . Smith and Oelbermann used a qualitative approach to evaluate the perception and knowledge of climate change by landowners in a remote Costa Rican agricultural community. They also evaluated the type of sustainable agricultural practices already implemented that could also serve as a strategy to climate change adaptation. Their study showed that community members were aware of climate change and already observed changes in local weather patterns over the past decade that affected the distribution of vegetation and wildlife. As a result, agricultural producers were continually striving to implement agroforestry practices which were viewed as more robust and resilient to climate change by helping to maintain agricultural productivity while also providing economic and socioecological needs. In temperate regions, Evers et al. provided an overview of the potential of tree-based intercropping (agroforestry alley cropping) systems in climate mitigation through the reduction of GHG emissions. They outlined the most recent research results from southern Ontario and Quebec and found that agroforestry systems could lower N2O emissions by 1.2 kg ha -1 y -1 compared to a conventional (monoculture) agroecosystem. They also suggested that the potential of agroforestry systems to sequester C in the soil and tree component was greater than in conventional agroecosystems, especially if fast-growing tree species for bioenergy production were used. Such practices may also provide an opportunity to receive payment for the ecological services provided by the agroforest, making these production systems a better option than conventional systems for agricultural producers in temperate regions. Isaac et al. investigated the internal accumulation and retention of nutrients in nutrient-spiked pine seedlings commonly used in temperate agroforestry systems and hypothesized that nutrient-spiking would lower seedling transplanting stress and reduce pressure on native soil resources and proposed that nutrient spiking would also lead to an increase in nutrient availability for the growing crop and also minimize competition between trees and crops. They found a favorable response in tree and crop root biomass accumulation in nutrient-spiked treatments and found that N, phosphorus (P) and potassium (K) significantly increased in the pine tissue and resulted in a steady or increased uptake of these nutrients by the crop (maize). Isaac et al. suggested that such specialized practices may be required when establishing agroforestry systems for the benefit of nutrient regulation and enhanced capacity to sequester C for the long-term mitigation of climate change. The Argentine Pampa is one of the most fertile regions in the world and natural grasslands and forests continue to be converted to intense agricultural production systems. Such practices have led to large losses in soil organic carbon (SOC) and contributed to the accumulation of GHGs in the atmosphere. The paper by Posse et al. outlines the absence of precise quantitative data on the emission and sequestration of GHG, which impedes a better understanding of the mechanisms driving CO2 emissions from agroecosystems. Although the paper by Posse et al. does not investigate CO2 fluxes from complex agroecosystems, but instead it provides vital information on the emission of this GHG in one of the most rapidly expanding agricultural frontiers in the world, which is also experiencing the effects of global warming on crop productivity. Posse et al. aim to characterize the exchange of CO 2 , using eddy covariance techniques, in a monoculture soybean system during an extreme dry summer which resulted in a high crop loss. They found that the greatest emission of CO2 occurred during premature crop senescence (due to drought) but the field became a CO 2 sink once the soil as covered by weeds. As such, changes in crop phenology and botanical composition (weeds) coincided with changes in the flux of CO 2 . The papers presented in this special issue of the Agriculture Journal provided an important insight into the potential of decreasing GHGs and maximizing C sequestration. These papers have also provided an important stepping stone by outlining the future direction of research to further understand the importance and role of complex agroecosystems in mitigating climate change. This research field is in its infancy but results are favorable by indicating that complex agroecosystems not only enhance the cycling of nutrients and the productivity of agricultural crops and show greater resilience to climate change, but they can also play an important role in the mitigation of climate change.

We assessed the economic suitability of 4 greenhouse gas (GHG) mitigation options and one GHG offset option for an improvement of the GHG balance of a representative Swiss suckler cow farm housing 35 Livestock units and cultivating 25 ha grassland. GHG emissions per kilogram meat in the economic optimum differ between the production systems and range from 18 to 21.9 kg CO2-eq./kg meat. Only GHG offset by agroforestry systems showed the potential to significantly reduce these emissions. Depending on the production system agroforestry systems could reduce net GHG emissions by 66% to 7.3 kg CO2-eq./kg meat in the most intensive system and by 100% in the most extensive system. In this calculation a carbon sequestration rate of 8 t CO2/ha/year was assumed. The potential of a combination of the addition of lipids to the diet, a cover of the slurry tank and the application of nitrification inhibitors only had the potential to reduce GHG emissions by 12% thereby marginal abatement costs are increasing much faster than for agroforestry systems. A reduction of the GHG emissions to 7.5 kg CO2-eq./kg meat—possible with agroforestry only—raised costs between 0.03 CHF/kg meat and 0.38 CHF/kg meat depending on the production system and the state of the system before the reduction. If GHG emissions were reduced maximally average costs ranged between 0.37 CHF/kg meat, if agroforestry had the potential to reduce net GHG emissions to 0 kg CO2-eq., to 1.17 CHF/kg meat if also other options had to be applied.

Preface Field Study of Greenhouse Gas Emissions and Mitigation in Cropping Systems 1. Quantifying Nitrous Oxide Emissions from Agricultural Soils and Management Impacts S. J. Del Grosso and W. J. Parton 2. Nitrogen Source Effects on Nitrous Oxide Emissions from Irrigated Cropping Systems in Colorado A. D. Halvorson and S. J. Del Grosso 3. Nitrous Oxide Emissions at the Surface of Agricultural Soils in the Red River Valley of the North, U.S.A. Rebecca L. Phillips and Cari D. Ficken 4. Exchange Fluxes of NOX, NH3, and N2O from Typical Wheat, Paddy, and Maize Fields in the Yangtze River Delta and North China Plain Yuanyuan Zhang, Shuangxi Fang, Junfeng Liu, and Yujing Mu 5. Greenhouse Gas Emissions from Rice Cropping Systems W. R. Horwath 6. Understanding Greenhouse Gas Emissions from Croplands in China Zucong Cai and Xiaoyuan Yan 7. Redox Potential Control on Cumulative Global Warming Potentials from Irrigated Rice Fields Kewei Yu 8. Fertilizer Nitrogen Management To Reduce Nitrous Oxide Emissions in the U.S. Robert L. Mikkelsen and Clifford S. Snyder 9. Physical and Chemical Manipulation of Urea Fertilizer To Limit the Emission of Reactive Nitrogen Species M. I. Khalil 10. Mitigation Options for Methane and Nitrous Oxide from Agricultural Soil: From Field Measurement to Evaluation of Overall Effectiveness Hiroko Akiyama, Yoshitaka Uchida, and Akinori Yamamoto 11. Effects of Nitrogen Fertilizer Types on Nitrous Oxide Emissions Martin Burger and Rodney T. Venterea 12. Discerning Agricultural Management Effects on Nitrous Oxide Emissions from Conventional and Alternative Cropping Systems: A California Case Study E. C. Suddick, K. Steenwerth, G. M. Garland, D. R. Smart, and J. Six 13. N2O Emissions and Water Management in California Perennial Crops David R. Smart, M. Mar Alsina, Michael W. Wolff, Michael G. Matiasek, Daniel L. Schellenberg, John P. Edstrom, Patrick H. Brown, and Kate M. Scow 14. Global Nitrous Oxide Emissions: Sources and Opportunities for Mitigation R. M. Rees 15. Climate Impacts from Agricultural Emissions: Greenhouse Species and Aerosols Jeffrey S. Gaffney, Nancy A. Marley, and John E. Frederick Modeling of Greenhouse Gas Emissions and Mitigation in Cropping Systems 16. Mitigating Greenhouse Gas Emissions from Agroecosystems: Scientific Basis and Modeling Approach Changsheng Li 17. Soil Organic Matter Cycling and Greenhouse Gas Accounting Methodologies S. J. Del Grosso, S. M. Ogle, and W. J. Parton 18. Emissions of Nitrous Oxide from Agriculture: Responses to Management and Climate Change M. Abdalla, P. Smith, and M. Williams 19. Assessing the Environmental Impact of Agriculture in Europe: The Indicator Database for European Agriculture Adrian Leip 20. Development of Spatial Inventory of Nitrous Oxide Emissions from Agricultural Land Uses in California Using Biogeochemical Modeling Lei Guo, Dongmin Luo, Changsheng Li, and Michael FitzGibbon Greenhouse Gas Emissions and Mitigation in Animal Systems 21. Greenhouse Gas Emission Sources from Beef and Dairy Production Systems in the United States Kimberly R. Stackhouse, Sara E. Place, Michelle S. Calvo, Qian Wang, and Frank M. Mitloehner 22. Greenhouse Gas Emissions from Cattle Feedlot Manure Composting and Anaerobic Digestion as a Potential Mitigation Strategy Brandon Gilroyed, Xiying Hao, Francis J. Larney, and Tim A. McAllister 23. Mitigation of Greenhouse Gas Emissions from U.S. Beef and Dairy Production Systems Sara E. Place, Kim R. Stackhouse, Qian Wang, and Frank M. Mitloehner 24. Improved Productivity Reduces Greenhouse Gas Emissions from Animal Agriculture Judith L. Capper 25. Evaluation of Poultry Litter Fertilization Practices on Greenhouse Gas Emissions Dexter B. Watts, H. Allen Torbert, and Thomas R. Way 26. Quantification and Mitigation of Greenhouse Gas Emissions from Dairy Farms Hamed M. El-Mashad and Ruihong Zhang Editors' Biographies Indexes Author Index Subject Index

Dairy production systems represent a significant source of air pollutants such as greenhouse gases (GHG), that increase global warming, and ammonia (NH3), that leads to eutrophication and acidification of natural ecosystems. Greenhouse gases and ammonia are emitted both by conventional and organic dairy systems. Several studies have already been conducted to design practices that reduce greenhouse gas and ammonia emissions from dairy systems. However, those studies did not consider options specifically applied to organic farming, as well as the multiple trade-offs occurring between these air pollutants. This article reviews agricultural practices that mitigate greenhouse gas and ammonia emissions. Those practices can be applied to the most common organic dairy systems in northern Europe such as organic mixed crop-dairy systems. The following major points of mitigation options for animal production, crop production and grasslands are discussed. Animal production: the most promising options for reducing greenhouse gas emissions at the livestock management level involve either the improvement of animal production through dietary changes and genetic improvement or the reduction of the replacement rate. The control of the protein intake of animals is an effective means to reduce gaseous emissions of nitrogen, but it is difficult to implement in organic dairy farming systems. Considering the manure handling chain, mitigation options involve housing, storage and application. For housing, an increase in the amounts of straw used for bedding reduces NH3 emissions, while the limitation of CH4 emissions from deep litter is achieved by avoiding anaerobic conditions. During the storage of solid manure, composting could be an efficient mitigation option, depending on its management. Addition of straw to solid manure was shown to reduce CH4 and N2O emissions from the manure heaps. During the storage of liquid manure, emptying the slurry store before late spring is an efficient mitigation option to limit both CH4 and NH3 emissions. Addition of a wooden cover also reduces these emissions more efficiently than a natural surface crust alone, but may increase N2O emissions. Anaerobic digestion is the most promising way to reduce the overall greenhouse gas emissions from storage and land spreading, without increasing NH3 emissions. At the application stage, NH3 emissions may be reduced by spreading manure during the coolest part of the day, incorporating it quickly and in narrow bands. Crop production: the mitigation options for crop production focus on limiting CO2 and N2O emissions. The introduction of perennial crops or temporary leys of longer duration are promising options to limit CO2 emissions by storing carbon in plants or soils. Reduced tillage or no tillage as well as the incorporation of crop residues also favour carbon sequestration in soils, but these practices may enhance N2O emissions. Besides, the improvement of crop N-use efficiency through effective management of manure and slurry, by growing catch crops or by delaying the ploughing of leys, is of prime importance to reduce N2O emissions. Grassland: concerning grassland and grazing management, permanent conversion from arable to grassland provides high soil carbon sequestration while increasing or decreasing the livestock density seems not to be an appropriate mitigation option. From the study of the multiple interrelations between gases and between farm compartments, the following mitigation options are advised for organic mixed crop-dairy systems: (1) actions for increasing energy efficiency or fuel savings because they are beneficial in any case, (2) techniques improving efficiency of N management at field and farm levels because they affect not only N2O and NH3 emissions, but also nitrate leaching, and (3) biogas production through anaerobic digestion of manure because it is a promising efficient method to mitigate greenhouse gas emissions, even if the profitability of this expensive investment needs to be carefully studied. Finally, the way the farmer implements the mitigation options, i.e. his practices, will be a determining factor in the reduction of greenhouse gas and NH3 emissions.

Spatially explicit database on crop-livestock management, soil, climate, greenhouse gas emissions and mitigation potential for all of Bangladesh

A diachronic study of greenhouse gas emissions of French dairy farms according to adaptation pathways

Dairy production systems represent a significant source of air pollutants such as greenhouse gases (GHG), that increase global warming, and ammonia (NH3), that leads to eutrophication and acidification of natural ecosystems. Greenhouse gases and ammonia are emitted both by conventional and organic dairy systems. Several studies have already been conducted to design practices that reduce greenhouse gas and ammonia emissions from dairy systems. However, those studies did not consider options specifically applied to organic farming, as well as the multiple trade-offs occurring between these air pollutants. This article reviews agricultural practices that mitigate greenhouse gas and ammonia emissions. Those practices can be applied to the most common organic dairy systems in northern Europe such as organic mixed crop-dairy systems. The following major points of mitigation options for animal production, crop production and grasslands are discussed. Animal production: the most promising options for reducing greenhouse gas emissions at the livestock management level involve either the improvement of animal production through dietary changes and genetic improvement or the reduction of the replacement rate. The control of the protein intake of animals is an effective means to reduce gaseous emissions of nitrogen, but it is difficult to implement in organic dairy farming systems. Considering the manure handling chain, mitigation options involve housing, storage and application. For housing, an increase in the amounts of straw used for bedding reduces NH3 emissions, while the limitation of CH4 emissions from deep litter is achieved by avoiding anaerobic conditions. During the storage of solid manure, composting could be an efficient mitigation option, depending on its management. Addition of straw to solid manure was shown to reduce CH4 and N2O emissions from the manure heaps. During the storage of liquid manure, emptying the slurry store before late spring is an efficient mitigation option to limit both CH4 and NH3 emissions. Addition of a wooden cover also reduces these emissions more efficiently than a natural surface crust alone, but may increase N2O emissions. Anaerobic digestion is the most promising way to reduce the overall greenhouse gas emissions from storage and land spreading, without increasing NH3 emissions. At the application stage, NH3 emissions may be reduced by spreading manure during the coolest part of the day, incorporating it quickly and in narrow bands. Crop production: the mitigation options for crop production focus on limiting CO2 and N2O emissions. The introduction of perennial crops or temporary leys of longer duration are promising options to limit CO2 emissions by storing carbon in plants or soils. Reduced tillage or no tillage as well as the incorporation of crop residues also favour carbon sequestration in soils, but these practices may enhance N2O emissions. Besides, the improvement of crop N-use efficiency through effective management of manure and slurry, by growing catch crops or by delaying the ploughing of leys, is of prime importance to reduce N2O emissions. Grassland: concerning grassland and grazing management, permanent conversion from arable to grassland provides high soil carbon sequestration while increasing or decreasing the livestock density seems not to be an appropriate mitigation option. From the study of the multiple interrelations between gases and between farm compartments, the following mitigation options are advised for organic mixed crop-dairy systems: (1) actions for increasing energy efficiency or fuel savings because they are beneficial in any case, (2) techniques improving efficiency of N management at field and farm levels because they affect not only N2O and NH3 emissions, but also nitrate leaching, and (3) biogas production through anaerobic digestion of manure because it is a promising efficient method to mitigate greenhouse gas emissions, even if the profitability of this expensive investment needs to be carefully studied. Finally, the way the farmer implements the mitigation options, i.e. his practices, will be a determining factor in the reduction of greenhouse gas and NH3 emissions.KeywordsAgricultureGreenhouse gasAmmoniaAbatementMixed crop-dairy systemsOrganicLivestockManureGrasslandCarbon storageSoil carbon sequestration

For many developing countries, the land use sector, particularly agriculture and forestry, represents a large proportion of their greenhouse gas (GHG) emissions, making this sector a priority for GHG mitigation activities. Previous global surveys (e.g., IPCC 2000) as well as the most recent IPCC assessment report clearly indicate that the greatest technical potential for carbon sequestration and reductions of non-CO2 GHG emissions from the land use sector is in developing countries. Estimates that consider economic feasibility suggest that agriculture and forestry together provide among the greatest opportunities for short-term and low-cost mitigation measures across all sectors of the global economy1 (IPCC 2007). In addition, it is widely recognized that the ecosystem changes entailed by most mitigation practices, i.e., building soil organic matter, reducing losses and tightening nutrient cycles, more efficient production systems and preserving native vegetation, are well aligned with goals of increasing food security and rural development as well as buffering land use systems against climate change (Lal 2004). Hence, there is growing interest in jump-starting the capacity for broad-based engagement in agriculturally-based GHG mitigation projects in developing countries.

<p> It has been widely reported that although IPCC methodologies appropriate for national-level accounting purposes, they lack the farm level resolution and holistic approach required for whole-farm systems analysis. The importance of evaluating greenhouse gas (GHG) emissions from crop production, animal farming and agroforestry within the whole farm setting is being realized as more important than evaluating these emissions in isolation. Thus, whole-farm systems modelling is widely used for farm-level analysis. Here we compare three whole-farm models e.g. FarmSim, Holos and IFSM to simulate the effect of management practices on GHG emissions at the whole farm level and evaluate the carbon sequestration and methane oxidation potential of afforestation as a compensation mechanism for the mitigation of farm-level GHG emissions. Ideally, we would also want information on model performance in predicting GHG emissions in future climatic scenarios. Initial results indicate that these models can accurately predict CO<sub>2</sub> emissions but the accuracy of these models for predicting methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O) emissions is quite low. We found that the most prominent drivers for GHG emissions in a whole farm setting were the enteric CH<sub>4</sub> from animal farming and N<sub>2</sub>O emissions from soil management in cropland.  Thus, the low prediction accuracy for CH<sub>4</sub> and N<sub>2</sub>O emissions in whole-farm models may introduce substantial errors into GHG inventories and lead to incorrect mitigation recommendations, which necessitates further fine-tuning of these models. Efforts are ongoing to integrate carbon sequestration and soil methane oxidation potential of farm-level afforestation in the whole farm models. There are indications that afforestation can be an effective mitigation strategy. The variation we found in farm system parameters, and the inherent uncertainties associated with emissions of CH<sub>4</sub> and N<sub>2</sub>O can have substantial implications for reported agricultural emissions requiring uncertainty or sensitivity analysis in any modelling approach. Although there is considerable variation among the quality of farm data, boundary assumptions, the emission factors used we suggest that whole-farm systems models are an appropriate tool to develop and measure GHG mitigation strategies for the European farmed landscape.</p>

Smallholder dairy farms face enormous challenges in increasing milk production while mitigating greenhouse gas (GHG) emissions, thereby enhancing climate resilience. The carbon footprint (CF) of smallholder milk production is expected to increase with increasing demand for dairy products under the business-as-usual scenario. This study estimates the carbon footprint of smallholder milk production and examines variation across farms using data from 480 households to identify viable options for mitigating GHG emissions. We applied a cradle to farm-gate life cycle assessment (LCA) approach to examine the effects of farming systems on GHG emission intensities across intensification gradients of smallholder farms (SHF) from four potential dairy districts in the central highlands of Ethiopia. According to our findings, enteric fermentation was the primary source of GHG emissions, and methane(CH4) emissions from enteric fermentation and manure management accounted for the majority of total emissions across farms. The estimated average CF varies depending on farming systems, global warming potential (GWP), and allocation methods used. When GHG emissions were allocated to multiple products using economic allocation and based on IPCC (2007)and IPCC (2014)GWPs, the overall average CF of milk production was 1.91 and 2.35kg CO2e/kg fat and protein-corrected milk (FPCM), respectively. On average, milk accounted for 72% of total greenhouse gas emissions. In terms of farm typology, rural SHF systems produced significantly more CF per kg of milk than urban and peri-urban SHF systems. Variations in milk yield explained more than half of the variation in GHG emissions intensity at the farm level. Feed digestibility and feed efficiency had a negative and significant (P < 0.01) association with CF of SHF. Our findings suggested that improving feed digestibility and feed efficiency by increasing the proportion of concentrate and improved forage as well as chemically upgrading straw and crop residue could provide an opportunity to both increase milk yield and reduce the CF of milk production of SHF in the study area. Supporting SHF to realize strategies contributing to climate-resilient dairy development require interventions at several levels in the dairy value chain.

Greenhouse gas emissions during storage of manure and digestates: Key role of methane for prediction and mitigation