Publications by authors named "Gerard Velthof"

Agricultural practices are causing a variety of environmental impacts such as emissions of ammonia (NH) and greenhouse gases (GHG), and leaching and runoff of nutrients to groundwater and surface water. Measures need to be taken to achieve environmental targets set in European agreements and directives, such as the Birds and Habitats Directives, Nitrates Directive, Water Framework Directive and Fit for 55 package. To explore solutions for these issues an integral approach is needed, in which synergies between measures are included and pollution swapping is avoided.

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Nearly half of global pork production and consumption occurs in China, but the transition towards intensification is associated with worsening environmental impacts. Here we explore scenarios for implementing structural and technological changes across the pork supply chain to improve environmental sustainability and meet future demand. Following the middle-of-the-road socio-economic pathway (SSP2), we estimate that the environmental footprint from the pork supply chain will increase by ~50% from 2017 to 2050.

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The Water Framework Directive (WFD) aims to protect and improve water quality across Europe through an integrative and multi-level water governance approach. The goal is to ensure that water quality in Europe meets good ecological status by 2027. Whilst the WFD has been hailed as a cornerstone for governance innovation in water management, most EU member states (MS) still struggle to achieve good ecological status of their waters.

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Livestock production in China is increasingly located near urban areas, exposing human populations to nitrogen pollution via air and water. Here we analyse livestock and human population data across 2,300 Chinese counties to project the impact of alternative livestock distributions on nitrogen emissions. In 2012 almost half of China's livestock production occurred in peri-urban regions, exposing 60% of the Chinese population to ammonia emissions exceeding UN guidelines.

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The rapid specialization of livestock production in China has contributed to spatially decoupled crop and livestock production, leading to various environmental pollution issues. Some regional agro-environmental policies have recently promoted the coupling of specialized crop and livestock farms through cooperation. However, the environmental and economic performances of such cooperation remain unclear.

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International trade of agricultural products has complicated and far-reaching impacts on land and nitrogen use efficiencies. We analysed the productivity of cropland and livestock and associated use of feed and fertilizer efficiency for over 240 countries, and estimated these countries' cumulative contributions to imports and exports of 190 agricultural products for the period 1961-2017. Crop trade has increased global land and partial fertilizer nitrogen productivities in terms of protein production, which equalled savings of 2,270 Mha cropland and 480 Tg synthetic fertilizer nitrogen over the analysed period.

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Manure application to land and deposition of urine and dung by grazing animals are major sources of ammonia (NH ) and nitrous oxide (N O) emissions. Using data on NH and N O emissions following land-applied manures and excreta deposited during grazing, emission factors (EFs) disaggregated by climate zone were developed, and the effects of mitigation strategies were evaluated. The NH data represent emissions from cattle and swine manures in temperate wet climates, and the N O data include cattle, sheep, and swine manure emissions in temperate wet/dry and tropical wet/dry climates.

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Nitrous oxide (N O), ammonia (NH ), and methane (CH ) emissions from the manure management chain of livestock production systems are important contributors to greenhouse gases (GHGs) and NH emitted by human activities. Several studies have evaluated manure-related emissions and associated key variables at regional, national, or continental scales. However, there have been few studies focusing on the drivers of these emissions using a global dataset.

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China's fertilization practices contribute greatly to the global biogeochemical nitrogen (N) and phosphorus (P) flows, which have exceeded the safe-operating space. Here, we quantified the potentials of improved nutrient management in the food chain and spatial planning of livestock farms on nutrient use efficiency and losses in China, using a nutrient flow model and detailed information on >2300 counties. Annual fertilizer use could be reduced by 26 Tg N and 6.

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Manure acidification is recommended to minimize ammonia (NH) emission at storage. However, the potential for acidification to mitigate NH emission from storage and the impact of manure acidification (pH range 5-8) on composting have been poorly studied. The effects of manure acidification at storage on the subsequent composting process, nutrient balance, gaseous emissions and product quality were assessed through an analysis of literature data and an experiment under controlled conditions.

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Recycling of livestock manure to agricultural land may reduce the use of synthetic fertilizer and thereby enhance the sustainability of food production. However, the effects of substitution of fertilizer by manure on crop yield, nitrogen use efficiency (NUE), and emissions of ammonia (NH ), nitrous oxide (N O) and methane (CH ) as function of soil and manure properties, experimental duration and application strategies have not been quantified systematically and convincingly yet. Here, we present a meta-analysis of these effects using results of 143 published studies in China.

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Developing sustainable food systems is essential, especially for emerging economies, where food systems are changing rapidly and affect the environment and natural resources. We explored possible future pathways for a sustainable food system in China, using multiple environmental indicators linked to eight of the Sustainable Development Goals (SDGs). Forecasts for 2030 in a business as usual scenario (BAU) indicate increases in animal food consumption as well as increased shortages of the land available and the water needed to produce the required food in China.

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China's livestock industry has experienced a vast transition during the last three decades, with profound effects on domestic and global food provision, resource use, nitrogen and phosphorus losses, and greenhouse gas (GHG) emissions. We provide a comprehensive analysis of the driving forces around this transition and its national and global consequences. The number of livestock units (LUs) tripled in China in less than 30 years, mainly through the growth of landless industrial livestock production systems and the increase in monogastric livestock (from 62 to 74% of total LUs).

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China has an ever-increasing thirst for milk, with a predicted 3.2-fold increase in demand by 2050 compared to the production level in 2010. What are the environmental implications of meeting this demand, and what is the preferred pathway? We addressed these questions by using a nexus approach, to examine the interdependencies of increasing milk consumption in China by 2050 and its global impacts, under different scenarios of domestic milk production and importation.

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Animal manure contributes considerably to ammonia (NH) and greenhouse gas (GHG) emissions in Europe. Various treatment technologies have been implemented to reduce emissions and to facilitate its use as fertilizer, but a systematic analysis of these technologies has not yet been carried out. This study presents an integrated assessment of manure treatment effects on NH, nitrous oxide (NO) and methane (CH) emissions from manure management chains in all countries of EU-27 in 2010 using the MITERRA-Europe model.

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The largest livestock production and greatest fertilizer use in the world occurs in China. However, quantification of the nutrient flows through the manure management chain and their interactions with management-related measures is lacking. Herein, we present a detailed analysis of the nutrient flows and losses in the "feed intake-excretion-housing-storage-treatment-application" manure chain, while considering differences among livestock production systems.

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Livestock manures are major sources of nutrients, used for the fertilisation of cropland and grassland. Accurate estimates of the amounts of nutrients in livestock manures are required for nutrient management planning, but also for estimating nitrogen (N) budgets and emissions to the environment. Here we report on N excretion factors for a range of animal categories in policy reports by member states of the European Union (EU).

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Livestock manure contributes considerably to global emissions of ammonia (NH3 ) and greenhouse gases (GHG), especially methane (CH4 ) and nitrous oxide (N2 O). Various measures have been developed to mitigate these emissions, but most of these focus on one specific gas and/or emission source. Here, we present a meta-analysis and integrated assessment of the effects of mitigation measures on NH3 , CH4 and (direct and indirect) N2 O emissions from the whole manure management chain.

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The nitrogen (N) and phosphorus (P) costs of food production have increased greatly in China during the last 30 years, leading to eutrophication of surface waters, nitrate leaching to groundwater, and greenhouse gas emissions. Here, we present the results of scenario analyses in which possible changes in food production-consumption in China for the year 2030 were explored. Changes in food chain structure, improvements in technology and management, and combinations of these on food supply and environmental quality were analyzed with the NUFER model.

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Nitrous oxide (N(2)O) direct soil emissions from agriculture are often estimated using the default IPCC emission factor (EF) of 1%. However, a large variation in EFs exists due to differences in environment, crops and management. We developed an approach to determine N(2)O EFs that depend on N-input sources and environmental factors.

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Manipulation of the diets of pigs may alter the composition of the manure and thereby the environmental and agricultural qualities of the manure. Laboratory studies were performed to quantify the effect of manipulation of pig diets on the chemical composition of the derived manure (slurry), the potential emission of methane (CH4) and ammonia (NH3) during anaerobic storage of the manure, and the potential nitrous oxide (N2O) and carbon dioxide (CO2) emission after application of the manure to soil. The diets differed in contents of crude protein and salt (CaSO4), and the type and contents of nonstarch polysaccharides (NSP).

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Autotrophic ammonia-oxidizing bacteria produce nitrous oxide (N(2)O) as a by-product of nitrification or as an intermediate of nitrifier denitrification. In soil incubations, acetylene (C(2)H(2)) and large partial pressures of oxygen (O(2)) are used to distinguish between these sources. C(2)H(2) inhibits ammonia oxidation and should therefore inhibit N(2)O production by both nitrification and nitrifier denitrification.

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