• Energy Research

Abstract Sustainably feeding the growing population in China attracts attention globally. Despite practices success, producing enough food to simultaneously address resource and pollution problems has been infeasible. To assess how to achieve this goal in 2035, we created a pathway that synergistic combining improved managements and cropland redistribution based on 11.1 million farmer surveys and 4,272 georeferenced field observations. Here, we firstly selected the practices of top 10% performers in crop yield and nitrogen (N) efficiency as crop-specific attainable improved managements at the county level. The optimized crop distribution within improved managements was then performed to minimize inputs (N and phosphorus fertilizer, irrigation water) or environmental impacts (reactive N [Nr] loss and greenhouse gas [GHG] emissions). We identified that combing improved managements and cropland redistribution could produce enough food demands in 2035, with 24% more production compared to 2012. It also reduced the inputs and environmental impacts in a range of 19%-35%, mainly sourced from the central and eastern coastal areas by improved productivity and diminished cropland of fruit and vegetables. These findings highlight the necessity for a synergistic combination of measures to sustainably feed the growing population and establish a more realistic and effective policy.

AbstractChina 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. Meeting China's milk demand in a business as usual scenario will increase global dairy‐related (China and the leading milk exporting regions) greenhouse gas (GHG) emissions by 35% (from 565 to 764 Tg CO2eq) and land use for dairy feed production by 32% (from 84 to 111 million ha) compared to 2010, while reactive nitrogen losses from the dairy sector will increase by 48% (from 3.6 to 5.4 Tg nitrogen). Producing all additional milk in China with current technology will greatly increase animal feed import; from 1.9 to 8.5 Tg for concentrates and from 1.0 to 6.2 Tg for forage (alfalfa). In addition, it will increase domestic dairy related GHG emissions by 2.2 times compared to 2010 levels. Importing the extra milk will transfer the environmental burden from China to milk exporting countries; current dairy exporting countries may be unable to produce all additional milk due to physical limitations or environmental preferences/legislation. For example, the farmland area for cattle‐feed production in New Zealand would have to increase by more than 57% (1.3 million ha) and that in Europe by more than 39% (15 million ha), while GHG emissions and nitrogen losses would increase roughly proportionally with the increase of farmland in both regions. We propose that a more sustainable dairy future will rely on high milk demanding regions (such as China) improving their domestic milk and feed production efficiencies up to the level of leading milk producing countries. This will decrease the global dairy related GHG emissions and land use by 12% (90 Tg CO2eq reduction) and 30% (34 million ha land reduction) compared to the business as usual scenario, respectively. However, this still represents an increase in total GHG emissions of 19% whereas land use will decrease by 8% when compared with 2010 levels, respectively.

AbstractReactive nitrogen (N) is a requisite nutrient for agricultural production, but results in greenhouse gas and air and water pollution. The environmental and economic impacts of N fertilizer use in China are particularly relevant, as China consumes the largest amount of N fertilizer in the world to meet its soaring food demand. Here, we use an agro-economic land system model (MAgPIE) in combination with a difference-in-differences econometric model to provide a forward-looking assessment of China’s fertilizer policies in terms of removing fertilizer manufacturing subsidies and implementing measures to improve agricultural nutrient management efficiency. Our model results indicate that enhancing soil N uptake efficiency and manure recycled to soil alongside fertilizer subsidy removal can largely reduce N fertilizer use and N losses and abate N pollution in the short and long term, while food security remains largely unaffected. Enhancing soil N uptake efficiency appears to be decisive to achieving China’s national strategic target of zero growth in N fertilizer use. This study also finds that improving agricultural nutrient management efficiency contributes to higher land productivity and less cropland expansion, with substantial benefits for the environment and food security.

La Chine nourrit 19,1 % de la population mondiale avec 8,6 % des terres arables. Nous proposons ici une approche intégrée combinant la redistribution des cultures et une meilleure gestion pour répondre à la demande alimentaire de la Chine en 2030. Nous avons simulé la demande alimentaire, estimé la production agricole nationale grâce à la productivité des 10 % de producteurs les plus performants de chaque comté et optimisé la répartition spatiale de 11 groupes de types de cultures entre les comtés à l'aide des données des principaux producteurs. L'intégration de la redistribution des cultures et d'une meilleure gestion a augmenté la production agricole et peut répondre à la demande alimentaire en 2030, tandis que les intrants agricoles (engrais azotés et phosphatés et eau d'irrigation) et les impacts environnementaux (perte d'azote réactif et émissions de gaz à effet de serre) ont été réduits. Bien qu'il existe des obstacles socio-économiques et culturels importants à la mise en œuvre d'une telle redistribution, ces résultats suggèrent que des mesures intégrées peuvent assurer la sécurité alimentaire et réduire les impacts environnementaux négatifs. Des politiques spécifiques aux comtés et un soutien consultatif seront nécessaires pour tenir les promesses de combiner les stratégies d'optimisation. Une base de données provenant d'une enquête auprès des agriculteurs, d'articles publiés et d'annuaires statistiques a été développée pour cartographier les rendements spécifiques aux cultures et aux comtés, les intrants agricoles, les pertes d'azote réactif et les émissions de gaz à effet de serre en Chine. On estime que les distributions optimisées des cultures combinées à une meilleure gestion améliorent la productivité des cultures et diminuent les intrants agricoles et les coûts environnementaux. China alimenta al 19,1% de la población mundial con el 8,6% de la tierra cultivable. Aquí proponemos un enfoque integrado que combina la redistribución de cultivos y una mejor gestión para satisfacer la demanda de alimentos de China en 2030. Simulamos la demanda de alimentos, estimamos la producción nacional de cultivos a través de la productividad del 10% superior de los productores en cada condado y optimizamos la distribución espacial de 11 grupos de tipos de cultivos entre condados utilizando los datos de los principales productores. La integración de la redistribución de cultivos y la mejora de la gestión aumentaron la producción de cultivos y pueden satisfacer la demanda de alimentos en 2030, mientras que se redujeron los insumos agrícolas (fertilizantes de N y P y agua de riego) y los impactos ambientales (pérdida reactiva de N y emisiones de gases de efecto invernadero). Aunque existen importantes barreras socioeconómicas y culturales para implementar dicha redistribución, estos resultados sugieren que las medidas integradas pueden lograr la seguridad alimentaria y disminuir los impactos ambientales negativos. Se necesitarán políticas específicas del condado y apoyo de asesoramiento para lograr las promesas de combinar estrategias de optimización. Se desarrolló una base de datos a partir de una encuesta de agricultores, artículos publicados y anuarios estadísticos para mapear los rendimientos específicos de los cultivos y los condados, los insumos agrícolas, las pérdidas reactivas de N y las emisiones de gases de efecto invernadero en China. Se estima que las distribuciones optimizadas de cultivos combinadas con una mejor gestión mejoran la productividad de los cultivos y disminuyen los insumos agrícolas y los costos ambientales. China feeds 19.1% of the world's population with 8.6% of the arable land. Here we propose an integrated approach combining crop redistribution and improved management to meet China's food demand in 2030. We simulated the food demand, estimated the national crop production through the productivity of the top 10% of producers in each county, and optimized the spatial distribution of 11 groups of crop types among counties using the data of the top producers. Integrating crop redistribution and improved management increased crop production and can meet the food demand in 2030, while the agricultural inputs (N and P fertilizers and irrigation water) and environmental impacts (reactive N loss and greenhouse gas emissions) were reduced. Although there are significant socio-economic and cultural barriers to implementing such redistribution, these results suggest that integrated measures can achieve food security and decrease negative environmental impacts. County-specific policies and advisory support will be needed to achieve the promises of combining optimization strategies. A database from a survey of farmers, published articles and statistical yearbooks was developed to map crop- and county-specific yields, farm inputs, reactive N losses and greenhouse gas emissions in China. Optimized crop distributions combined with improved management are estimated to improve crop productivity and decrease farm inputs and environmental costs. تغذي الصين 19.1 ٪ من سكان العالم بـ 8.6 ٪ من الأراضي الصالحة للزراعة. نقترح هنا نهجًا متكاملًا يجمع بين إعادة توزيع المحاصيل وتحسين الإدارة لتلبية الطلب الصيني على الغذاء في عام 2030. قمنا بمحاكاة الطلب على الغذاء، وتقدير إنتاج المحاصيل الوطنية من خلال إنتاجية أعلى 10 ٪ من المنتجين في كل مقاطعة، وتحسين التوزيع المكاني لـ 11 مجموعة من أنواع المحاصيل بين المقاطعات باستخدام بيانات كبار المنتجين. أدى دمج إعادة توزيع المحاصيل وتحسين الإدارة إلى زيادة إنتاج المحاصيل ويمكن أن يلبي الطلب على الغذاء في عام 2030، في حين تم تقليل المدخلات الزراعية (الأسمدة النيتروجينية ومياه الري) والآثار البيئية (فقدان النيتروجين التفاعلي وانبعاثات غازات الدفيئة). على الرغم من وجود حواجز اجتماعية واقتصادية وثقافية كبيرة أمام تنفيذ إعادة التوزيع هذه، إلا أن هذه النتائج تشير إلى أن التدابير المتكاملة يمكن أن تحقق الأمن الغذائي وتقلل من الآثار البيئية السلبية. ستكون هناك حاجة إلى سياسات خاصة بالمقاطعة ودعم استشاري لتحقيق وعود الجمع بين استراتيجيات التحسين. تم تطوير قاعدة بيانات من دراسة استقصائية للمزارعين والمقالات المنشورة والحوليات الإحصائية لرسم خرائط للمحاصيل والمحاصيل الخاصة بالمقاطعة والمدخلات الزراعية وخسائر النيتروجين التفاعلية وانبعاثات غازات الدفيئة في الصين. من المقدر أن تؤدي التوزيعات المثلى للمحاصيل جنبًا إلى جنب مع الإدارة المحسنة إلى تحسين إنتاجية المحاصيل وتقليل المدخلات الزراعية والتكاليف البيئية.

AbstractNitrous oxide (N2O) is a potent greenhouse gas and causes stratospheric ozone depletion. While the emissions of N2O from soil are widely recognized, recent research has shown that terrestrial plants may also emit N2O from their leaves under controlled laboratory conditions. However, it is unclear whether foliar N2O emissions are universal across varying plant taxa, what the global significance of foliar N2O emissions is, and how the foliage produces N2O in situ. Here we investigated the abilities of 25 common plant taxa, including trees, shrubs and herbs, to emit N2O under in situ conditions. Using 15N isotopic labeling, we demonstrated that the foliage‐emitted N2O was predominantly derived from nitrate. Moreover, by selectively injecting biocide in conjunction with the isolating and back‐inoculating of endophytes, we demonstrated that the foliar N2O emissions were driven by endophytic bacteria. The seasonal N2O emission rates ranged from 3.2 to 9.2 ng N2O–N g−1 dried foliage h−1. Extrapolating these emission rates to global foliar biomass and plant N uptake, we estimated global foliar N2O emission to be 1.21 and 1.01 Tg N2O–N year−1, respectively. These estimates account for 6%–7% of the current global annual N2O emission of 17 Tg N2O–N year−1, indicating that in situ foliar N2O emission is a universal process for terrestrial plants and contributes significantly to the global N2O inventory. This finding highlights the importance of measuring foliar N2O emissions in future studies to enable the accurate assigning of mechanisms and the development of effective mitigation.

Satisfying China’s food demand without harming the environment is one of the greatest sustainability challenges for the coming decades. Here we provide a comprehensive forward-looking assessment of the environmental impacts of China’s growing demand on the country itself and on its trading partners. We find that the increasing food demand, especially for livestock products (~16%–30% across all scenarios), would domestically require ~3–12 Mha of additional pasture between 2020 and 2050, resulting in ~−2% to +16% growth in agricultural greenhouse gas (GHG) emissions. The projected ~15%–24% reliance on agricultural imports in 2050 would result in ~90–175 Mha of agricultural land area and ~88–226 MtCO2-equivalent yr−1of GHG emissions virtually imported to China, which account for ~26%–46% and ~13%–32% of China’s global environmental impacts, respectively. The distribution of the environmental impacts between China and the rest of the world would substantially depend on development of trade openness. Thus, to limit the negative environmental impacts of its growing food consumption, besides domestic policies, China needs to also take responsibility in the development of sustainable international trade.

AbstractFast socio‐economic development in agriculture and urbanization resulted in increasing nutrient export by rivers, causing coastal eutrophication in China. In addition, climate change may affect hydrology, and as a result, nutrient flows from land to sea. This study aims at a better understanding of how future socio‐economic and climatic changes may affect coastal eutrophication in China. We modeled river export of total dissolved nitrogen (TDN) and phosphorus (TDP) in 2050 for six scenarios combining socio‐economic pathways (SSPs) and Representative Concentration Pathways (RCPs). We used the newly developed MARINA 2.0 (Model to Assess River Inputs of Nutrients to seAs) model. We found that global change can make coastal eutrophication control in China more difficult. In 2050 coastal waters may be considerably more polluted or considerably cleaner than today depending on the SSP‐RCP scenarios. By 2050, river export of TDN and TDP is 52% and 56% higher than in 2012, respectively, in SSP3‐RCP8.5 (assuming large challenges for sustainable socio‐economic development, and severe climate change). In contrast, river export of nutrients could be 56% (TDN) and 85% (TDP) lower in 2050 than in 2012 in SSP1‐RCP2.6 (assuming sustainable socio‐economic development, and low climate change). Climate change alone may increase river export of nutrients considerably through hydrology: We calculate 24% higher river export of TDN and 16% higher TDP for the SSP2 scenario assuming severe climate change compared to the same scenario with low climate change (SSP2‐RCP8.5 vs. SSP2‐RCP2.6). Policies and relevant technologies combining improved nutrient management and climate mitigation may help to improve water quality in rivers and coastal waters of China.