A climate-dependent global model of ammonia emissions from chicken farming

Ammonia (NH3) has significant impacts on the environment, which can influence climate and air quality and cause acidification and eutrophication in terrestrial and aquatic ecosystems. Agricultural activities are the main sources of NH3 emissions globally. Emissions of NH3 from chicken farming are highly dependent on climate, affecting their environmental footprint and impact. In order to investigate the effects of meteorological factors and to quantify how climate change affects these emissions, a process-based model, AMmonia–CLIMate–Poultry (AMCLIM–Poultry), has been developed to simulate and predict temporal variations in NH3 emissions from poultry excretion, here focusing on chicken farms and manure spreading. The model simulates the decomposition of uric acid to form total ammoniacal nitrogen, which then partitions into gaseous NH3 that is released to the atmosphere at an hourly to daily resolution. Ammonia emissions are simulated by calculating nitrogen and moisture budgets within poultry excretion, including a dependence on environmental variables. By applying the model with global data for livestock, agricultural practice and meteorology, we calculate NH3 emissions from chicken farming on a global scale (0.5∘ resolution). Based on 2010 data, the AMCLIM–Poultry model estimates NH3 emissions from global chicken farming of 5.5 ± 1.2 Tg N yr−1, about 13 % of the agriculture-derived NH3 emissions. Taking account of partial control of the ambient environment for housed chicken (layers and broilers), the fraction of excreted nitrogen emitted as NH3 is found to be up to 3 times larger in humid tropical locations than in cold or dry locations. For spreading of manure to land, rain becomes a critical driver affecting emissions in addition to temperature, with the emission fraction being up to 5 times larger in the semi-dry tropics than in cold, wet climates. The results highlight the importance of incorporating climate effects into global NH3 emissions inventories for agricultural sources. The model shows increased emissions under warm and wet conditions, indicating that climate change will tend to increase NH3 emissions over the coming century

Future global pig production systems according to the Shared Socioeconomic Pathways

peer-reviewedGlobal pork production has increased fourfold over the last 50 years and is expected to continue growing during the next three decades. This may have considerable implications for feed use, land requirements, and nitrogen emissions. To analyze the development of the pig production sector at the scale of world regions, we developed the IMAGE-Pig model to describe changes in feed demand, feed conversion ratios (FCRs), nitrogen use efficiency (NUE) and nitrogen excretion for backyard, intermediate and intensive systems during the past few decades as a basis to explore future scenarios. For each region and production system, total production, productive characteristics and dietary compositions were defined for the 1970–2005 period. The results show that due to the growing pork production total feed demand has increased by a factor of two (from 229 to 471Tg DM). This is despite the improvement of FCRs during the 1970–2005 period, which has reduced the feed use per kg of product. The increase of nitrogen use efficiency was slower than the improvement of FCRs due to increasing protein content in the feed rations. As a result, total N excretion increased by more than a factor of two in the 1970–2005 period (from 4.6 to 11.1 Tg N/year). For the period up to 2050, the Shared Socio-economic Pathways (SSPs) provide information on levels of human consumption, technical development and environmental awareness. The sustainability of pig production systems for the coming decades will be based not only on the expected efficiency improvements at the level of animal breeds, but also on four additional pillars: (i) use of alternative feed sources not competing with human food, (ii) reduction of the crude protein content in rations, (iii) the proper use of slurries as fertilizers through coupling of crop and livestock production and (iv) moderation of the human pork consumption

Environmental footprint family to address local to planetary sustainability and deliver on the SDGs

peer-reviewedThe number of publications on environmental footprint indicators has been growing rapidly, but with limited efforts to integrate different footprints into a coherent framework. Such integration is important for comprehensive understanding of environmental issues, policy formulation and assessment of trade-offs between different environmental concerns. Here, we systematize published footprint studies and define a family of footprints that can be used for the assessment of environmental sustainability. We identify overlaps between different footprints and analyse how they relate to the nine planetary boundaries and visualize the crucial information they provide for local and planetary sustainability. In addition, we assess how the footprint family delivers on measuring progress towards Sustainable Development Goals (SDGs), considering its ability to quantify environmental pressures along the supply chain and relating them to the water-energy-food-ecosystem (WEFE) nexus and ecosystem services. We argue that the footprint family is a flexible framework where particular members can be included or excluded according to the context or area of concern. Our paper is based upon a recent workshop bringing together global leading experts on existing environmental footprint indicators

Nitrogen Challenges and Opportunities for Agricultural and Environmental Science in India

In the last six decades, the consumption of reactive nitrogen (Nr) in the form of fertilizer in India has been growing rapidly, whilst the nitrogen use efficiency (NUE) of cropping systems has been decreasing. These trends have led to increasing environmental losses of Nr, threatening the quality of air, soils, and fresh waters, and thereby endangering climate-stability, ecosystems, and human-health. Since it has been suggested that the fertilizer consumption of India may double by 2050, there is an urgent need for scientific research to support better nitrogen management in Indian agriculture. In order to share knowledge and to develop a joint vision, experts from the UK and India came together for a conference and workshop on “Challenges and Opportunities for Agricultural Nitrogen Science in India.” The meeting concluded with three core messages: (1) Soil stewardship is essential and legumes need to be planted in rotation with cereals to increase nitrogen fixation in areas of limited Nr availability. Synthetic symbioses and plastidic nitrogen fixation are possibly disruptive technologies, but their potential and implications must be considered. (2) Genetic diversity of crops and new technologies need to be shared and exploited to reduce N losses and support productive, sustainable agriculture livelihoods. Móring et al. Nitrogen Challenges and Opportunities (3) The use of leaf color sensing shows great potential to reduce nitrogen fertilizer use (by 10–15%). This, together with the usage of urease inhibitors in neem-coated urea, and better management of manure, urine, and crop residues, could result in a 20–25% improvement in NUE of India by 2030

The value of manure - Manure as co-product in life cycle assessment

Research ArticleLivestock production is important for food security, nutrition, and landscape maintenance, but it is associated with several environmental impacts. To assess the risk and benefits arising from livestock production, transparent and robust indicators are required, such as those offered by life cycle assessment. A central question in such approaches is how environmental burden is allocated to livestock products and to manure that is re-used for agricultural production. To incentivize sustainable use of manure, it should be considered as a co-product as long as it is not disposed of, or wasted, or applied in excess of crop nutrient needs, in which case it should be treated as a waste. This paper proposes a theoretical approach to define nutrient requirements based on nutrient response curves to economic and physical optima and a pragmatic approach based on crop nutrient yield adjusted for nutrient losses to atmosphere and water. Allocation of environmental burden to manure and other livestock products is then based on the nutrient value from manure for crop production using the price of fertilizer nutrients. We illustrate and discuss the proposed method with two case studiesinfo:eu-repo/semantics/publishedVersio

Nutrient challenges in global livestock supply chains : an assessment of nitrogen use and flows

The global livestock sector is rapidly transforming. Over the past few decades, many livestock systems over the world have evolved from local, small-scale mixed crop-livestock systems to global and demand-driven supply chains, in which feed and animal production stages are often disconnected. These changes, driven by economic opportunities, have altered the way livestock production impacts global nitrogen and phosphorus flows and emissions. These emissions take place in several stages of the supply chains, namely feed production, animal production and processing of animal products and threaten water, soil and air quality, but also climate, biodiversity and human health. Achieving better nutrient management is thus an important aspect of improving environmental performance in the livestock sector. Improving the efficiency of nutrient use has been identified as the main strategy to reduce environmental pressures while achieving global food security and sustainability. To reduce nutrient losses in livestock supply chains, there is a need for methods and indicators that determine these losses or the other way around, determine the nutrient use efficiency (NUE). Most studies that evaluate NUE focus on animal, farm or regional level. For global livestock supply chains, however, that run across national and continental boundaries, such approaches over-look nutrient losses associated with off-farm activities, such as the production of feed. Some studies assess nutrient losses and NUE at a chain level, but they do not consider the entire supply chain and do not consider the effect of nutrient recycling and stock changes on NUE, or do not identify hotspots of nutrient loss along the chain that are required to support targeted nutrient improvement pathways towards sustainable nutrient use. The two objectives of this thesis, therefore, were to develop a framework of indicators to assess nutrient flows and emissions along global livestock supply chains, while identifying data, which can be improved to enhance the accuracy of the results, and to assess the impacts of the global livestock supply chains on the nitrogen flows, while exploring the improvement options. Evaluating nutrient use and flows in livestock supply chains requires a framework and data to estimate flows, emissions and relevant indicators from each production stage. To develop such a framework, Chapter 2 first reviewed existing studies on nutrient use in the livestock sector. The review showed that four methods were used previously to analyse nutrient use in the livestock sector, namely a nutrient balance, nutrient use efficiency, material flow analysis and life cycle assessment. Among these methods, nutrient use efficiency appeared a suitable approach to benchmark nutrient management at the animal level, and to some extent at the farm level. The analysis showed that integrating the life cycle approach into NUE, therefore, could allow for the computation of supply chain level NUE, which was proposed as a valuable indicator of nutrient management sustainability. To this end, in Chapter 3, a comprehensive framework of indicators, based on the life-cycle approach, was developed to assess the efficiency of nitrogen and phosphorus use. The framework represents nutrient flows in the typical livestock supply chain from the cradle-to-primary-processing-gate, including crop/pasture production, animal production and primary processing stage as well as the transportation of feed materials, live animals or animal products. It encompassed three indicators, including the life-cycle nutrient use efficiency (life-cycle-NUE), life-cycle net nutrient balance (life-cycle-NNB) and nutrient hotspot index (NHI). The framework was tested for a case study of mixed dairy supply chains in Europe. The proposed indicators were found to be suitable to describe different aspects of nitrogen and phosphorus dynamics and, therefore, were all needed. This framework of indicators developed requires detailed data such as nutrient inputs into soils, herd parameters, climate, emission factors, and manure management, to estimate nutrient flows and three nutrient use indicators. These data are highly variable at the global scale, resulting in large uncertainties due to the differences in geographical representation, time boundaries, farming technology and completeness. In Chapter 4, a method was proposed to identify the important inputs parameters that contribute significantly to the variance of the results. This method, which relies on a global sensitivity analysis is tested for the cases studies of mixed cattle dairy systems in the Netherlands and Rwanda, using the Global Environmental Assessment Model (GLEAM) dataset. The results showed that uncertainties of a few important input parameters, such as manure deposited on grasslands, applied manure and synthetic fertilizer, milk production and emission factors, could explain most of the variance of N use indicators. We subsequently fixed non-important and substituted important parameters in GLEAM with new field survey data, which substantially improved the results of N use indicators. This method can be applied to any environmental modelling using global datasets to improve their relevance by prioritizing important parameters for additional data collection. In Chapter 5, the framework of indicators was applied to assess N use, flows and emissions, in the global pork supply chains and to evaluate the effects of feeding swill to pigs as a strategy to integrate better livestock in a circular bio-economy. Results showed that N emissions into the environment amount to around 14.7 Tg N y-1. More than half of these emissions take place in the backyard system, although this system contributed only 27% to total pork production. Industrial systems emitted 23% of total N emissions but contributed more than half of the global pork production (56%). Intermediate systems contributed around 19% to both pork production and N emissions. We found that most of N emissions are in the form of NO3- and organic N lost to surface and groundwater, with large implications for aquatic eutrophication. Backyard and intermediate systems, with relatively high connectivity between animal and crop production were more efficient than industrial systems. These results showed that the efficiency of N use and the magnitude of N losses per unit of area depend chiefly on the region (agro-ecological and economic context), on the origin of feed, and on manure management systems. The results also showed that the substitution of swill for grains and soybeans could improve N use indicators and abate N emissions. Applied on a global scale to industrial systems, this strategy was estimated to save 31 Mt of soybeans and 20 Mt of grains on dry matter basis, equivalent to 16 M ha of land use. Implementing swill feeding, however, would require innovative policies to guide the collection, treatment, and usage of swill, and ensure safety and traceability. In Chapter 6, the global nitrogen use and flows were evaluated for livestock supply chains using the spatially explicit Global Livestock Environmental Assessment Model and its database. The results showed that, globally, livestock supply chains are responsible for around one-third of human-induced N emissions of which 63% take place in 2 regions (i.e. South Asia and East and Southeast Asia), and 61% at the feed production stage. These emissions are in the form of NO3- (28 Tg N y-1), NH3 (26 Tg N y-1), NOx (8 Tg N y-1) and N2O (2 Tg N y-1). The magnitude and concentration of N losses imply that there is both urgent need to reduce these emissions and the opportunity to design targeted mitigation interventions. The wide range of values calculated for N use indicators further indicates that good practices are available and already implemented in parts of the value chains. Mitigation options proposed include improvement of feed fertilization, and manure management through the adoption of innovative technology and best practices. These improvement pathways can be effective because N emissions are concentrated in few regions, supply chains and steps along the chain and the wide variability of N use indicators offers opportunity to design mitigation interventions. The adoption of good practices would likely require additional investments, knowledge transfer and additional solutions to improve simultaneously the socio-economic conditions of farmers worldwide. The design and implementation of interventions should consider potential trade-offs and synergies with other sustainability dimensions, such as climate change, resource scarcity and food security. In Chapter 7, the development of the framework of indicators, modelling challenges and data quality were discussed. The discussion revealed that the three indicators proposed in this framework: Life-cycle-NUEN, Life-cycle-NNBN and NHIN provide a comprehensive analysis of nutrient use, flows and emissions in global livestock supply chains. The discussion revealed that livestock supply chains play a role in the net transfer of soil fertility from grassland to cropland and in shifting N embodied in feed between countries, which may be lost through unregulated disposals of manure. The chapter discussed the potential improvement options but emphasised the need to consider rebound effect related to the improvement of NUE, which may result in a consumption surge. The chapter discussed nutrients challenges in connection to the overall sustainability of the livestock sector, which uses of a large number of natural resources such as land, freshwater, often with low efficiency and contributes to global human-induced greenhouse emissions. Because the livestock supply chains are embedded in the economy and culture of societies. They contribute to rural development, human diets, trade balances, risk management and other relevant development outcomes, while building resilience and adaptation to climate change. Livestock can also negatively affect these outcomes, e.g. contributing to public health issues (diets, zoonoses, Anti-microbial resistance), and offering poor conditions to livestock producers and animals themselves. Addressing N challenges will require the consideration of potential trade-offs and synergies with these wider sustainability dimensions (e.g. poverty eradication, nutrition, human health) and it will also need to be done in conjunction with other interventions that address the growth of the livestock sector. The chapter ends up by calling for a global initiative with a strong representation of livestock sector scientists and stakeholders to tackle the N pollution.</p

Nitrogen pollution policy beyond the farm

Nitrogen is a crucial input to food production and yet its oversupply in many parts of the world contributes to a number of environmental problems. Most policies dedicated to reducing agricultural nitrogen pollution focus on changing farmer behaviour. However, farm-level policies are challenging to implement and farmers are just one of several actors in the agri-food chain. The activities of other actors — from fertilizer manufacturers to wastewater treatment companies — can also impact nitrogen losses at the farm level and beyond. Consequently, policymakers have a broader range of policy options than traditionally thought to address nitrogen pollution from field to fork. Inspired by the concept of full-chain nitrogen use efficiency, this Perspective introduces the major actors common in agri-food chains from a nitrogen standpoint, identifies nitrogen policies that could be targeted towards them and proposes several new criteria to guide ex-ante analysis of the feasibility and design of different policy interventions. Sustainably feeding ten billion people by 2050 will require fundamental changes in the global food system — a broad portfolio of policy options and a framework for how to select them is essential

Nitrogen flows in global pork supply chains and potential improvement from feeding swill to pigs

The global pork sector contributes to food security and supports livelihoods for millions of households but also causes nitrogen (N) pollution. Here we assess N flows, losses, and N use indicators for global pork supply chains, from “cradle-to-primary-processing-gate” and for three production systems: the backyard, intermediate and industrial systems. Subsequently, we evaluate the effects of feeding swill to industrial pigs on N flows and land use. To produce 3.5 Tg N of pork globally, 14.7 Tg N are lost into the environment, of which 68% is lost to watercourses in the form of nitrates and organic N and the reminder emitted to the atmosphere as N-gas (e.g., NH 3 , NOx and N2O). We found that the efficiency of N use, hotspot and magnitude of N losses per unit of area depend chiefly on the region (agro-ecological and economic context), origin of feed, and manure management systems. Swill feeding increases N use efficiency and reduces N losses at the feed production stage. It achieves a saving of 31 Mt of soybeans and 20 Mt of grains on dry matter basis, equivalent to 16 M ha of land used. Its adoption would require innovative policies to preserve food safety and public health. Future research may explore the feasibility and requirements to adopt swill feeding at a country level and may investigate potential impacts on other sustainability objectives. </p

Nitrogen emissions along global livestock supply chains

Global livestock supply chains have significantly altered nitrogen (N) flows over past years, thereby threatening environmentaland human health. Here, we provide a disaggregated assessment of the livestock sector’s impacts on global N flows and emissions, including international trade. The results show that the sector currently emits 65 Tg N yr−1, equivalent to one-third of current human-induced N emissions and sufficient to meet the planetary boundary for N. Of that amount, 66% is allocated to Asiaand 68% is associated with feed production. Most emissions originate from locally produced animal-sourced food, althoughN emissions embedded in international trade are significant for some importing countries. Given the magnitude of its impactsand its central role in both domestic and international N challenges, the livestock sector urgently requires a global initiative totackle N pollution while supporting food security

Invited review: Current enteric methane mitigation options

peer-reviewedRuminant livestock are an important source of anthropogenic methane (CH4). Decreasing the emissions of enteric CH4 from ruminant production is strategic to limit the global temperature increase to 1.5°C by 2050. Research in the area of enteric CH4 mitigation has grown exponentially in the last 2 decades, with various strategies for enteric CH4 abatement being investigated: production intensification, dietary manipulation (including supplementation and processing of concentrates and lipids, and management of forage and pastures), rumen manipulation (supplementation of ionophores, 3-nitrooxypropanol, macroalgae, alternative electron acceptors, and phytochemicals), and selection of low-CH4-producing animals. Other enteric CH4 mitigation strategies are at earlier stages of research but rapidly developing. Herein, we discuss and analyze the current status of available enteric CH4 mitigation strategies with an emphasis on opportunities and barriers to their implementation in confined and partial grazing production systems, and in extensive and fully grazing production systems. For each enteric CH4 mitigation strategy, we discuss its effectiveness to decrease total CH4 emissions and emissions on a per animal product basis, safety issues, impacts on the emissions of other greenhouse gases, as well as other economic, regulatory, and societal aspects that are key to implementation. Most research has been conducted with confined animals, and considerably more research is needed to develop, adapt, and evaluate antimethanogenic strategies for grazing systems. In general, few options are currently available for extensive production systems without feed supplementation. Continuous research and development are needed to develop enteric CH4 mitigation strategies that are locally applicable. Information is needed to calculate carbon footprints of interventions on a regional basis to evaluate the impact of mitigation strategies on net greenhouse gas emissions. Economically affordable enteric CH4 mitigation solutions are urgently needed. Successful implementation of safe and effective antimethanogenic strategies will also require delivery mechanisms and adequate technical support for producers, as well as consumer involvement and acceptance. The most appropriate metrics should be used in quantifying the overall climate outcomes associated with mitigation of enteric CH4 emissions. A holistic approach is required, and buy-in is needed at all levels of the supply chain