Investing in mini-livestock production for food security and carbon neutrality in China.

Future food farming technology faces challenges that must integrate the core goal of keeping the global temperature increase within 1.5 °C without reducing food security and nutrition. Here, we show that boosting the production of insects and earthworms based on food waste and livestock manure to provide food and feed in China will greatly contribute to meeting the country's food security and carbon neutrality pledges. By substituting domestic products with mini-livestock (defined as earthworms and insects produced for food or feed) protein and utilizing the recovered land for bioenergy production plus carbon capture and storage, China's agricultural sector could become carbon-neutral and reduce feed protein imports to near zero. This structural change may lead to reducing greenhouse gas emissions by 2,350 Tg CO2eq per year globally when both domestic and imported products are substituted. Overall, the success of mini-livestock protein production in achieving carbon neutrality and food security for China and its major trading partners depends on how the substitution strategies will be implemented and how the recovered agricultural land will be managed, e.g., free use for afforestation and bioenergy or by restricting this land to food crop use. Using China as an example, this study also demonstrates the potential of mini-livestock for decreasing the environmental burden of food production in general.

Thermal imprint of wide-angle viewing bi-stable cholesteric liquid crystal displays.

A thermal-imprint addressable and electrically erasable bi-stable cholesteric liquid crystal (CLC) display with a wide viewing angle is demonstrated. The proposed device with a multi-domain planar state is realized by filling a negative CLC in a vertical-alignment cell. The thermal-imprint method is introduced to restore the CLC from a reflective state (multi-domain planar state) to a translucent state (focal-conic state) to display images, and an electric field is used to erase the device back to totally reflective mode. This CLC display is bi-stable and does not require a complex driving circuit. Together with the features of a large viewing angle and less color shift, this device shows great potential for update-on-demand applications.

Urban nitrogen budgets: Evaluating and comparing the path of nitrogen through cities for improved management.

Reactive nitrogen (Nr) released to the environment is a cause of multiple environmental threats. While Nr flows are often only analyzed in an agricultural context, consumption and emission takes place in the urban environment, and opportunities for Nr recycling and effective policy implementation for mitigation often appear in cities. Since little information is available on the bigger picture of Nr flows through the urban environment, these opportunities often remain unexploited. Here we developed a framework to model Nr pathways through urban and surrounding areas, which we applied to four test areas (Beijing and Shijiazhuang (China), Vienna (Austria), and Zielona Góra (Poland)). Using indicators such as recycling rates and Nr surplus, we estimated environmental risks and recycling potentials based on Nr flows and their entry and exit points. Our findings show marked differences between the core and surrounding areas of each city, with the former being a site of Nr consumption with largest flows associated with households, and the latter a site of (agricultural) production with largest flows associated with industry (fertilizers) and urban plants. As a result, Nr transgresses the core areas in a rather linear manner with only 0-5 % being re-used, with inputs from Nr contained in food and fuels and outputs most commonly as non-reactive N2 emissions to the atmosphere from wastewater treatment and combustion processes. While the peri-urban areas show a higher Nr recycling rate (6-14 %), Nr accumulation and emissions from cultivated land pose significant environmental challenges, indicating the need for mitigation measures. We found potential to increase nitrogen use efficiency through improved Nr management on cultivated areas and to increase Nr recycling using urine and sewage sludge as synthetic fertilizer substitutes. Hence our framework for urban nitrogen budgets not only allows for consistent budgeting but helps identify common patterns, potentially harmful flows and Nr recycling potential.

Relocate 10 billion livestock to reduce harmful nitrogen pollution exposure for 90% of China's population.

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. Relocating 5 billion animals by 2050 according to crop-livestock integration criteria could reduce nitrogen emissions by two-thirds and halve the number of people exposed to high ammonia emissions. Relocating 10 billion animals away from southern and eastern China could reduce ammonia exposure for 90% of China's population. Spatial planning can therefore serve as a powerful policy instrument to tackle nitrogen pollution and exposure of humans to ammonia.

Strategies to reduce ammonia emissions from livestock and their cost-benefit analysis: A case study of Sheyang county.

Ammonia (NH3) emissions, the majority of which arise from livestock production, are linked to high concentration of PM2.5 and lower air quality in China. NH3 mitigation options were well studied at the small-scale (laboratory or pilot), however, they lack of a large-scale test in China. This study fills this crucial gap by evaluating the cost-benefit of pioneering NH3 mitigation projects carried out for a whole county - Sheyang, Jiangsu province, China. Measures were implemented in 2019 following two distinct strategies, improved manure treatment for industrial livestock farms, and collection and central treatment for traditional livestock farms. Emission reductions of 16% were achieved in a short time. While this is remarkable, it falls short of expectations from small-scale studies. If measures were fully implemented according to purpose and meet expectations from the small scale, higher emission reductions of 42% would be possible. The cost benefit analysis presented in this study demonstrated advantages of central manure treatment over in-farm facilities. With improved implementation of mitigation strategies in industrial livestock farms, traditional livestock farms may play an increasing role in total NH3 emissions, which means such farms either need to be included in future NH3 mitigation policies or gradually replaced by industrial livestock farms. The study found an agricultural NH3 reduction technology route suitable for China's national conditions (such as the "Sheyang Model").

Food and feed trade has greatly impacted global land and nitrogen use efficiencies over 1961-2017.

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. However, crop trade decreased global cropland productivity when productivity is expressed on an energy (per calorie) basis. Agricultural trade has generally moved towards optimality, that is, has increased global land and nitrogen use efficiencies during 1961-2017, but remains at a relatively low level. Overall, mixed impacts of trade on resource use indicate the need to rethink trade patterns and improve their optimality.

A spatial total nitrogen budget for Great Britain.

Understanding nutrient budgets makes it possible to predict where and by how much nutrients are accumulating in the environment. Previous studies have considered this problem for nitrogen (N) but have limited themselves to reactive N species (i.e. excluding N2) or have considered total N (including N2) but have been limited to regional or national scales. In this study the spatially-distributed total nitrogen (N) budget of Great Britain (GB) was estimated at a 1 km2 grid scale. The inputs of N considered were: biological N fixation; atmospheric deposition; food and feed transfer; and inorganic synthetic fertilizer. The outputs of N considered were: atmospheric emission; terrestrial denitrification; fluvial loss from the soil; gaseous emissions from sewage treatment plants; direct sewage flux loss; and groundwater loss. All pathways were considered over a number of years. This study constructed a spatially-differentiated total N budget for GB, which not only includes all major N pathways but also distributes the N budget to various land uses with a 1 km2 spatial resolution. The results showed that both sink and source areas exist across GB, although the majority of 1 km2 grid squares were identified as sources. Based on a mass balance model calculated for 2015, total N exhibited a net flux of a source of -1045 (±244) ktonnes N/year. The spatial N budget across GB ranged from -21 (±3) tonnes N/year to 34 (±5) tonnes N/year, where 66% of grid squares were source areas and 34% were sink areas. Urban and arable land use were predominantly source areas: 97% of total urban land use and 98.5% of total arable land use. 65% of grassland was a sink area. The total amount of N released to the environment by human activity in 2015 was -16.65 kg N/ca/yr.