Toward a protocol for quantifying the greenhouse gas balance and identifying mitigation options in smallholder farming systems

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).

This book provides standards and guidelines for quantifying greenhouse gas emissions and removals in smallholder agricultural systems and comparing options for climate change mitigation based on emission reductions and livelihood trade-offs. Globally, agriculture is directly responsible for about 11% of annual greenhouse gas (GHG) emissions and induces an additional 17% through land use change, mostly in developing countries. Farms in the developing countries of sub-Saharan Africa and Asia are predominately managed by smallholders, with 80% of land holdings smaller than ten hectares. However, little to no information exists on greenhouse gas emissions and mitigation potentials in smallholder agriculture. Greenhouse gas measurements in agriculture are expensive, time consuming, and error prone, challenges only exacerbated by the heterogeneity of smallholder systems and landscapes. Concerns over methodological rigor, measurement costs, and the diversity of approaches, coupled with the demand for robust information suggest it is germane for the scientific community to establish standards of measurements for quantifying GHG emissions from smallholder agriculture. Standard guidelines for use by scientists, development organizations will help generate reliable data on emissions baselines and allow rigorous comparisons of mitigation options. The guidelines described in this book, developed by the CGIAR Research Program on Climate Change, Agriculture, and Food Security (CCAFS) and partners, are intended to inform anyone conducting field measurements of agricultural greenhouse gas sources and sinks, especially to develop IPCC Tier 2 emission factors or to compare mitigation options in smallholder systems.

Blue revolution for food security under carbon neutrality: A case from the water-saving and drought-resistance rice

Searching for solutions to mitigate greenhouse gas emissions by agricultural policy decisions — Application of system dynamics modeling for the case of Latvia

PDF HTML阅读 XML下载 导出引用 引用提醒 中国氮磷钾肥制造温室气体排放系数的估算 DOI: 10.5846/stxb201402210304 作者: 作者单位: 中国科学院生态环境研究中心,中国科学院生态环境研究中心,中国科学院生态环境研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金青年基金项目(71003092);科技部973专题项目(2010CB833504-2);中国科学院战略性先导科技专项子课题(XDA05050602, XDA05060102) Estimation of greenhouse gases emission factors for China's nitrogen, phosphate, and potash fertilizers Author: Affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,,Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:通过收集、整合国内相关数据,推算了符合中国目前情况的各种氮肥、磷肥和钾肥的制造过程中的温室气体排放系数(从原料到工厂大门)。结果显示,我国平均水平的氮肥制造碳排放系数为:合成氨(液氨)1.672 t CE/t N,尿素2.041 t CE/t N,碳铵1.928 t CE/t N,硝酸铵4.202 t CE/t N,氯化铵2.220 t CE/t N,氮肥综合系数为2.116 t CE/t N。我国一般水平的磷肥制造碳排放系数为:重钙0.467 t CE/t P2O5,磷酸二铵1.109 t CE/t P2O5,磷酸一铵0.740 t CE/t P2O5,普钙0.195 t CE/t P2O5,钙镁磷肥2.105 t CE/t P2O5,磷肥综合系数为0.636 t CE/t P2O5。我国先进水平的钾肥制造碳排放系数为:氯化钾0.168 t CE/t K2O,硫酸钾0.409 t CE/t K2O(其中罗钾法硫酸钾0.443 t CE/t K2O、曼海姆法硫酸钾0.375 t CE/t K2O),钾肥综合系数为0.180 t CE/t K2O。我国大部分氮磷钾肥的温室气体排放系数普遍为欧美平均水平的2倍左右,因此利用国外系数来估算我国的农业温室气体排放量将严重低估化肥施用的影响。 Abstract:As fossil fuel based chemical products, synthetic fertilizers are highly energy-intensive and therefore highly carbon-intensive products as well. Fertilizers are one of the most important modern agricultural materials for enhancing crop yields. The manufacture of fertilizers is also a considerable indirect greenhouse gases (GHGs) emission source related to agricultural activities. To feed its huge population, China has raised its average fertilizer application level from 86.7 kg/hm2 in 1980 to 346.1 kg/hm2 in 2010 (total N, P2O5 and K2O). China has been the largest fertilizer producer and consumer worldwide for ten years, and its fertilizer consumption has exceeded 4.76 ×107 t, almost one third of the world's total, since 2005. Thus, it is essential to evaluate the GHGs emission related to the production and consumption of synthetic fertilizers in China. However, most current Life-Cycle Analysis (LCA) studies on China's agricultural GHGs emission use foreign fertilizer emission factors (GHGs per unit of fertilizer product) because the actual domestic factors were not available, which might result in significant miscalculations and uncertainties. To solve this problem, we collected data specific to China's fertilizer manufacture and consumption, and then estimated GHGs emission factors for several types of nitrogen, phosphate, potash and compound fertilizer currently in use in China. These fertilizers were: ammonia, urea, ammonium bicarbonate(AB), ammonium nitrate(AN), ammonia chloride(AC), general nitrogen fertilizer (General-N), triple superphosphate (TSP), monoammonium phosphate (DAP), monoammonium phosphate (MAP), superphosphate (SSP), fused calcium magnesium phosphate (FCMP), general phosphate fertilizer (General-P), potassium chloride (PC), general potassium sulphate (PS), Lop-Lake-method potassium sulphate (PS-LopLake), (PS-Mannheim) and general potash fertilizer (General-K). Our emission factors accounted for CO2, CH4 and N2O released not only during manufacturing, but also from feedstock production and transportation outside factories (i.e. "from cradle to factory gate"). Due to the availability of different data, emission factors for N/P/K fertilizers were calculated using different methods, and thus represent different technological scenarios (N fertilizers: China's current average technical level. P fertilizers: China's current ordinary technological level, slightly behind the "average level", representing the nation's target for energy-saving. K fertilizers: China's current advanced technological level, representing the best potash factories with highest energy efficiency in China). China's average-level nitrogen fertilizer manufacturing GHGs emission factors were: ammonia 1.672 t CE/t N, urea 2.041 t CE/t N, AB 1.928 t CE/t N, AN 4.202 t CE/t N, AC 2.220 t CE/t N and General-N 2.116 t CE/t N. China's ordinary-level phosphate fertilizer manufacturing GHGs emission factors were: TSP 0.467 t CE/t P2O5, DAP 1.109 t CE/t P2O5, MAP 0.740 t CE/t P2O5, SSP 0.195 t CE/t P2O5, FCMP 2.105 t CE/t P2O5 and General-P 0.636 t CE/t P2O5. China's advanced-level potash fertilizer manufacturing GHGs emission factors were: PC 0.168 t CE/t K2O, PS 0.409 t CE/t K2O, PS-LopLake 0.443 t CE/t K2O, PS-Mannheim 0.375 t CE/t K2O and General-K 0.180 t CE/t K2O. As a result of the more complete LCA chain investigated in this study, different natural resource availability and distribution traits, energy structure, and technological levels, most fertilizers' GHGs emission factors in China were about 2-fold of those in western countries. Thus, the models using western factors to calculate China's agricultural GHGs emissions will significantly underestimate the impact of fertilizer application. 参考文献 相似文献 引证文献

The impact of uncertainties on predicted greenhouse gas emissions of dairy cow production systems

Greenhouse gas (GHG) emissions from agriculture contribute to climate change. The consequences of unsustainable agricultural activity are polluted water, soil, air, and food. The agricultural sector has become one of the major contributors to global GHG emissions and is the world’s second largest emitter after the energy sector, which includes emissions from power generation and transport. Latvian and Lithuanian agriculture generates about one fifth of GHG emissions, while Estonia generates only about one tenth of the country’s GHG emissions. This paper investigates the GHG trends in agriculture from 1995 to 2019 and the driving forces of changes in GHG emissions from the agricultural sectors in the Baltic States (Lithuania, Latvia, and Estonia), which are helpful for formulating effective carbon reduction policies and strategies. The impact factors have on GHG emissions was analysed by using the Logarithmic Mean Divisia Index (LMDI) method based on Kaya identity. The aim of this study is to assess the dynamics of GHG emissions in agriculture and to identify the factors that have had the greatest impact on emissions. The analysis of the research data showed that in all three Baltic States GHG emissions from agriculture from 1995 to 2001–2002 decreased but later exceeded the level of 1995 (except for Lithuania). The analysis of the research data also revealed that the pollution caused by animal husbandry activities decreased. GHG intensity declined by 2–3% annually, but the structure of agriculture remained relatively stable. The decomposition of GHG emissions in agriculture showed very large temporary changes in the analysed factors and the agriculture of the Baltic States. GHG emissions are mainly increased by pollution due to the growing economy of the sector, and their decrease is mainly influenced by two factors—the decrease in the number of people employed in the agriculture sector and the decreasing intensity of GHGs in agriculture. The dependence of the result on the factors used for the decomposition analysis was investigated by the method of multivariate regression analysis. Regression analysis showed that the highest coefficient of determination (R2 = 0.93) was obtained for Estonian data and the lowest (R2 = 0.54) for Lithuanian data. In the case of Estonia, all factors were statistically significant; in the case of Latvia and Lithuania, one of the factors was statistically insignificant. The identified GHG emission factors allowed us to submit our insights for the reduction of emissions in the agriculture of the Baltic States.

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.

Policy and technological constraints to implementation of greenhouse gas mitigation options in agriculture

This monograph is concerned with different aspects of green house gas (GHG) emissions in agriculture. The first part summarizes the total amount of GHG emissions and analyses them regarding their composition. A differentiation is made between the emissions which are already linked to agriculture (source group agriculture: digestion , manure-management and agricultural soils ) within the National Report on GHG Emissions and those which can be counted primarily in addition to agriculture ( energy and land use and land use change ). Depending on which database is used, agriculture is participating in emitting green house gases with 6.3% or 11.1% of total German GHG emissions in 2004. This means that agriculture is an important polluter. The development of GHG emissions in agriculture compared to the year 1990 is -18.5% for the source group agriculture. This means that the source group has reduced more emissions than the average (-17.5%) over all domains published within the National Report. Regarding the sources energy and land use and land use change in addition emission reduction is -16.4% in the same period and thus worse than the average. Moreover, realized emission reductions are predominantly based on structural changes, less on systematical measures. This fact raises the question how agriculture can make a contribution to the reduction of GHG emissions in future particularly with regard to higher aims in climate politics.For this reason the second part of the monograph identifies capacities for the reduction of GHG emissions by using available agricultural biomass for energetic purposes. Due to the heterogeneity of biomass and the variety of its possible products, a lot of technical processes concerning the conversion of biomass into energy exist in practice. Since all of them have different emission factors the derivation of realistic reduction capacities is a nontrivial problem. This work restricts the problem by combining existing biomass with those technologies which provide largest benefit concerning the reduction of GHG emissions. Thereby it is possible to evaluate the maximum contribution of GHG reductions from biomass usage in agriculture in Germany, which aggregates up to 50,341 Gg CO2-equivalent. This means that 78.3% of the emissions from the source group agriculture in 2004 could be compensated if biomass was used within those technologies which produce the largest benefit. In this regards the subsidy of energy crops in biogas plants based on the Erneuerbare Energien Gesetz (renewable energy law) in Germany should be reviewed because there they do not produce the largest benefit. Energy crops should be applied to replace solid fuels instead. Since in practice several biogas plants are already using energy crops as input material without having an option for alternatives, the question raises how this fact can be improved for the future regarding climate protection.Therefore the third part of this monograph analyses the possible emission reductions of different technologies for converting biogas into energy. Objects of investigation are existing technologies like block heat and power plants or direct gas feeding into public gas distribution system as well as future technologies like the application of biogas in different types of fuel cells. Although direct gas feeding has a better ratio concerning the conversion of primary to secondary energy the GHG reduction capacity is much less compared to technologies of cogeneration. The reason for this is that the production of electricity has much more effect on GHG emissions than the production of heat. This is to be seen when comparing the emission factors of certain reference systems used in this part like condensing boilers running with natural gas (253 gCO2/kWhheat), gas steam power plants (432 gCO2/kWhel) and the average emissions factor of German power production (653 gCO2/kWhel). The more electricity is produced by a conversion technology based on biogas, the higher is its GHG reduction capacity. Direct gas feeding is not the most efficient way of using biogas in matters of climate protection considering that only 13% of the natural gas in Germany is used for electric purposes and considering that replacing natural gas by biogas means that the part of fossil fuels with lowest emissions is replaced. Direct gas feeding is not even then the most efficient way of using biogas if there is a consumer at the other end of the public gas distribution system who theoretically uses the injected biogas for running cogeneration systems. The conditioning of biogas in order to feed public distribution combined with additional heat source for running the fermenter of the biogas plant is worse for efficiency. Considering ecological standpoints local heat and power production next to the fermenter is the most efficient way of using biogas in matters of climate protection. This can only be improved by using more efficient systems like fuel cells instead of existing block heat and power plants.

To achieve the goal of "carbon peak and neutrality," the strict requirements for greenhouse gas (GHG) emissions control in the agricultural sector were recommended in relevant plans for Beijing during the 14th Five-Year Plan period. Through collecting agricultural activity data and calculating and screening the emission factors, the amount and emission characteristics of agricultural GHG emissions in Beijing in 2020 were estimated and set as the baseline condition. On this basis, the GHG emissions in 2025 with optimized measurements implemented, which were selected in combination with the natural conditions and planting-breeding mode of Beijing, were set as the reduction condition. The emission reduction potential and its distribution during the 14th Five-Year Plan Period were predicted simultaneously. Meanwhile, the reduction effects on the GHG emissions of optimized measurements were evaluated. In addition, relevant policy recommendations on GHG reduction were proposed accordingly. The results revealed that the total agricultural GHG emissions in Beijing were estimated to be 456000 t (CO2-eq) in 2020, primarily from sources of animal intestinal fermentation and manure management, with contribution rates of 50.7% and 26.7%, respectively. Spatially, it was mainly distributed in districts with large livestock and poultry breeding scales, such as Shunyi District, Miyun District, and Yanqing District, etc. It was predicted that in 2025, the total agricultural GHG emissions would be 349000 t (CO2-eq), and the emission reduction potential in the 14th Five-Year Plan period would be 107000 t (CO2-eq). Animal intestinal fermentation would be the emission source with the largest reduction potential (60000 tons, CO2-eq), followed by the emission source of animal manure management (37000 tons, CO2-eq). Adjusting fodder composition and optimizing manure management were analyzed to be the most effective optimized measurements for agricultural GHG emission reduction. Moreover, the emission reduction potential of CH4 would be greater than that of N2O. The emission reduction potential would be mainly distributed in Miyun District, Shunyi District, Yanqing District, Fangshan District, Tongzhou District, and other suburbs with large livestock and poultry breeding scales, accounting for more than 10% of the total emission reduction potential for each. These regions with large emission reduction potential should be prioritized and then the assessments should be extended to the whole city. The measurements were recommended as follows:① the research and promotion of technologies such as fodder optimization and the efficient treatment of manure should be strengthened, ② the scope of the combination of planting and breeding model should be expanded to promote the development of circular agriculture, and ③ relevant standards, guidelines, and specifications for green and low-carbon agriculture should be formulated, and the regulatory and policy system for synergy reduction of agricultural pollution and GHG should be developed.

Livestock are by far the greatest contributor to Australian agricultural greenhouse gas (GHG) emissions and are projected to account for 72% of total agricultural emissions by 2020. This necessitates the development of GHG mitigation strategies from the livestock sector. Currently there are many research streams investigating the efficacy of GHG mitigation technologies, though most are at the individual animal level. Here we examine the effect of a promising animal-scale intervention - increasing ewe fecundity - on GHG emissions at the whole farm scale. This approach accounts for seasonal climatic influences on farm productivity and the dynamic interactions between variables. The study used a biophysical model and was based on real data from a property in south-eastern Australia that currently runs a self-replacing prime lamb enterprise. The breeding flock was a composite cross-bred genotype segregating for the FecB gene (after the 'fecundity Booroola' trait observed in Australian Merinos), with typical lambing rates of 150-200% lambs per ewe. Lambs were born in mid-winter (July) and were weaned and sold at 18 weeks of age at the beginning of summer (December). Livestock continuously grazed pastures of phalaris, cocksfoot and subterranean clover and were supplied with barley grain as supplementary feed in seasons when pasture biomass availability was low. Biophysical variables including pasture phenology and flock dynamics were simulated on a daily time-step using the model GrassGro with historical weather data from 1970 to 2012. Whole farm GHG emissions were computed with GrassGro outputs and methodology from the Australian National Greenhouse Accounts Inventory (DCCEE, 2012). Increasing ewe fecundity from 1.0 lamb per ewe at birth (equivalent to scanning rates at pregnancy of 80% of ewes with single lambs, 17% with twins and 3% empty) to 1.5 (scanning rates of 20% ewes with singles, 51% with twins, 26% with triplets and 3% empty as observed at the property) reduced mean emissions intensity from 9.3 to 7.3 t CO2-equivalents/t animal product and GHG emissions per animal sold by 32%. Increasing fecundity reduced average lamb sale liveweight from 42 to 40 kg, but this was offset by an increase in annual sheep sales from 8 to 12 head/ha and an increase in average annual meat production from 410 to 540 kg liveweight/ha. A key benefit associated with increasing sheep fecundity is the ability to increase enterprise productivity whilst remaining environmentally sustainable. For the same long-term average annual stocking rate as an enterprise running genotypes with lower fecundity, it was shown that genotypes with high fecundity such as those on the property could either increase meat and wool productivity from 449 to 571 kg/ha (clean fleece weight plus liveweight at sale) with little change in net GHG emissions, or reduce net GHG emissions from 4.1 to 3.2 t CO2-equivalents/ha for similar average annual farm productivity. In either case, GHG emissions intensity was reduced by about 2.1 t CO2-equivalents/t animal product. From a methodological perspective, this study revealed that differences in computing the relative effect of increased fecundity on total farm production, GHG emissions or emissions intensity either within or across years were relatively small. For example, the mean difference in emissions intensity of an enterprise obtaining 1.5 lambs per ewe relative to an enterprise obtaining 1.0 lamb per ewe computed within years was -25%, whereas the relative difference in mean emissions intensity across years was -27%. Such findings justify the traditional approach of previous GHG mitigation studies which compare differences (e.g. abatement potential) between values averaged across multiple-year simulation runs, as opposed to the method of computing the differences between intervention strategies within years then comparing the average difference.

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

<p>Agricultural greenhouse gas (GHG) emissions in Africa contribute 15 % to the global total agricultural emissions, which is in the same range as agricultural emissions from Europe. The majority of these agricultural GHG emissions is attributed to livestock farming (up to 80 % at national scale), of which 10-25 % originate from livestock manure. At the same time, livestock production is essential for the livelihoods of millions of people in Sub-Saharan Africa (SSA), where 45-80 % of livestock production occurs in smallholder systems. With the growing population in SSA, the demand for livestock products is expected to increase, and – without low-emission manure management – a rise in manure-borne GHG emissions will occur. However, reliable <em>in situ</em> measurements from SSA are scarce, leading to substantial uncertainties in agricultural GHG budgets and making assessments of potential mitigation options difficult.</p><p>Here we present results from two cattle manure incubation experiments in Kenya, using manure from Boran (<em>Bos indicus</em>) cattle, a breed common in East Africa that were fed with typical feeds used in SSA smallholder farms. Manure was collected and piled in heaps (solid storage), the most common form of manure storage in Kenyan smallholder systems, and CH<sub>4</sub> and N<sub>2</sub>O emissions were measured over 140 days. In the first trial, cattle were fed a diet that either met their maintenance-energy requirements (i.e. animals received enough food to support their metabolism), or a diet at sub-maintenance energy levels to simulate common conditions in smallholder farming systems, particularly during the dry seasons. Cumulative manure N<sub>2</sub>O emissions from the sub-maintenance diet (i.e. the “hungry” cows) were lower than from cattle fed at maintenance energy levels. These lower N<sub>2</sub>O emission likely resulted from lower N concentration and a wider C:N ratio in the manure than in the “better fed” animals. Furthermore, the urine-N:faecal-N ratio in the “hungry” cows decreased, indicating a shift from urine-N (mostly inorganic N) to faecal-N (mostly organic N), which further backs the lower observed N<sub>2</sub>O emissions. Both N<sub>2</sub>O as well as CH<sub>4</sub> emissions from manure were lower than the IPCC default emission factors for solid storage in tropical regions across all diets tested.</p><p>In the second trial, Boran cattle were fed with three different tropical forage grasses common in Kenya: Napier (<em>Pennisetum purpureum</em>), Rhodes (<em>Gloris gayana</em>), and Brachiaria (<em>Brachiaria brizantha</em>). Manure from the Rhodes grass diet had the lowest N concentration and also the lowest cumulative CH<sub>4</sub> emissions, while N<sub>2</sub>O emissions did not differ between diets. Similar to the sub-maintenance feeding trial, total CH<sub>4</sub> and N<sub>2</sub>O emissions were lower than the IPCC default factors. Taken together, these results are an important step towards reducing the uncertainties in GHG emissions from agriculture in SSA. Furthermore, if African nations use IPCC default values for their national GHG reporting on livestock, emissions are likely to be overestimated, highlighting the importance and benefits of localized data from Africa.</p>

Toward carbon mitigation resiliency in the agriculture sector: An integrated LCA-GHG protocol-IPCC guidelines framework for biofertilizer application in paddy field.