Agricultural by-products for feed

Global consumption of animal-sourced foods must decrease if more sustainable food systems are to be achieved. Yet, projections suggest that the demand for livestock products will continue to grow over the next half-century. Strategies to curb the demand for crop-based feed are therefore key to reduce environmental impacts and free up land and water resources for agricultural production for human consumption. The replacement of some substitutable feed crops with available agricultural by-products, such as cereal bran, sugar beet pulp, molasses, distiller’s grains and citrus pulp, is one of these strategies. Replacing 11–16% of energy-rich feed crops (that is, cereals and cassava) with agricultural by-products is estimated to save approximately 15–27 Mha of land, as well as 3–19 km3 and 74–137 km3 of blue and green water, respectively.

See Govoni et al.

Dietary substitutions

The contribution of our dietary patterns to the health of the planet and to our own is considerable. In the United States, among different types of food, mixed dishes (for example, pizza and burgers) and protein foods (including meat) contribute the most to the dietary carbon footprint. At the same time, Americans’ average dietary patterns are associated with high mortality rates following the development of non-communicable diseases. Major dietary changes are needed but can be difficult to implement when eating habits have been part of the daily routine of some populations for many years. Simple dietary substitutions (for example, replacing beef with poultry) are a realistic way to have a positive impact on the environment and on dietary quality. Small substitutions across all four food groups that together make up 85% of US dietary carbon emissions — namely, mixed dishes, dairy, proteins and beverages — could reduce the US dietary carbon footprint by more than a third.

See Grummon et al.

Integrated aquaculture–agriculture

Aquatic and terrestrial foods produced on the same plot of land can enhance production diversity, land productivity and nutrient cycling on farm. In Bangladesh, a wide variety of integrated aquaculture–agriculture approaches are practised. The species and combinations of aquatic and terrestrial foods produced influence economic and nutrient productivity, and the mix of aquatic foods and vegetables included in integrated farming systems could be key to optimizing economic productivity and nutritional adequacy. Comparing the economic and nutrient productivity per hectare for 12 distinct integrated aquaculture–agriculture combinations allows for an intuitive measure of nutrient sensitivity that can be used by researchers and policymakers and mobilized by development practitioners and food producers.

See Ignowski et al.

Phosphorus and food trade

The expansion of international agricultural trade in the past decades has influenced the flow of phosphorus around the world through the movement of phosphorus embedded in products as well as differences in phosphorus use efficiencies between countries. From 1961–2019, trade has increased global partial factor productivity of phosphorus for crop and livestock production. Yet, phosphorus loss and waste might increase due to suboptimal import–export patterns and limited recycling. Evaluating both intermediate and end uses of phosphorus (including feed, food, seed, processing, losses, human and animal intake, application to farmland and so on) is essential to get a full picture of the spatiotemporal distribution of phosphorus and to identify phosphorus saving strategies.

See Bai et al.

Wildfires and agriculture

Wildfires occur naturally and have an important role for many ecosystems around the world but constitute a potentially disruptive force on agricultural systems. Climate change has led to an increase in wildfire season length, frequency and burnt area. In the United States, the land area burned by wildfires has steadily increased over the past 40 years. Three main pathways of impact exist — direct, downwind and downstream — through which wildfires influence agricultural products, resources (for example, including soil, water, air and photosynthetically active radiation) and agricultural workers. The complexity of wildfire–agriculture interactions requires collaborative, systems-oriented research to inform mitigation and adaptation measures.

See Kabeshita et al.

Supply chain chokepoints

Food systems around the world are increasingly interconnected through price transmission mechanisms, policies, physical trade flows and other factors. While this integration helps secure food availability in the event of disruptions to food-producing regions, it also means that supply shocks in one place may rapidly affect food availability and accessibility in others. Agri-food supply chains in the USA are critical for ensuring the stability of both domestic and global food systems. Complex network statistics reveal 14 logistics hubs in the USA that contribute to the efficient movement of goods and determine the structural resilience of food supply chains.

See Karakoc et al. and MacDonald

Wild foods

The definition of ‘wild foods’ remains contested, but there is no doubt that the availability of wild food species from forests and common lands is declining due to agricultural expansion, environmental degradation, urbanization and climate change. In many places, people’s access to wild foods is also impaired by institutional factors, such as insecure land tenure. Wild fruits, leaves, mushrooms, roots, animals, nuts, and so on are culturally important and represent key sources of nutrient and dietary diversity — especially for forest communities and the poor. Research demonstrating causal linkages between dietary diversity and wild foods in India reveals that, thanks to wild foods, women are more likely to consume dark green leafy vegetables during the lean season.

See Zavaleta Cheek et al. News & Views by Sunderland and Research Briefing

Cocoa plantations and deforestation

Cocoa is grown by an estimated two million farmers in West Africa, most of whom are smallholders living below the poverty line. Ghana and Ivory Coast, the two largest producers in the region and around the world, have seen cocoa expansion contribute to forest loss in biodiversity hotspots over the past years — together with mining, selective logging and the cultivation of other crops. Yet, the exact location and extent of cocoa plantations in these two countries remain unknown, hindering land use monitoring and planning. New satellite-based high-resolution maps generated through a deep learning framework reveal that official reports have underestimated the total planted area and that cocoa cultivation is linked to deforestation in protected areas.

See Kalischek et al.

Food price volatility

Recent increases in food prices have resulted from several factors, including adverse impacts on supply, increasing global demand and financial speculation. An additional threat to food security is posed by short-term price fluctuations, which generate investment uncertainty and pose serious risks to producers and consumers. The need to address price anomalies has been recognized in the 2030 Agenda for Sustainable Development. Price volatility’s detrimental effects are most pronounced in the developing world, where people have limited options to hedge against price uncertainty. Many countries respond to price hikes by adopting export restrictions and importing liberalization measures, but the announcement of trade policy changes can aggravate global price volatility even further — especially under low stock levels

See Brander et al. and Ivanic

Integrated biochar solutions

Climate change mitigation targets set by the Paris Agreement will not be met unless carbon dioxide removal is attained. Biochar, a carbon-rich material produced by heating biomass in an oxygen-poor environment, could mitigate up to 6.6 gigatonnes of CO2 equivalent per year by 2050 at moderate cost and low risk of reversibility. If produced using crop residues, urban green waste, manure and other sources of biomass, biochar would help nutrient cycling and improve soil fertility when applied to agricultural fields. In China, the production of rice, wheat and corn releases 666.5 teragrams of CO2 equivalent per year, representing approximately 5% of national emissions; integrated solutions that combine biomass pyrolysis and electricity generation systems with commonly applied methane and nitrogen mitigation measures could reduce staple crops’ life-cycle greenhouse gas emissions to −37.9 teragrams of CO2 equivalent per year.

See Xia et al.

Tropical small-scale octopus fisheries

Small-scale fisheries represent one-quarter of the global fishing sector and are particularly important in the tropics, where they provide socioeconomic benefits and essential micronutrients. Tropical small-scale octopus fishery catches account for almost half of all octopus caught in the tropics, with 88,000 tonnes of catch and processed octopus worth US$2.3 billion. Octopus consumption contributes copper, iron, selenium and vitamin B12 to regional diets. Small-scale catch methods, such as pots and traps, have minimal bycatch and improved sustainability compared with catch methods that target overexploited finfish stocks. Tropical small-scale octopus fisheries benefit from octopuses’ fast growth rates and adaptability to warming oceans, offering an environmentally sustainable option to expand future small-scale fishing activities in the tropics.

See Willer et al.

Structural and farm-level innovation for sustainable pork in China

Pork supply in China is expected to increase between 2017 and 2050, as population and pork consumption per capita increases. Almost 90% of pork will be produced by medium and large farms, and this intensification will increase the cropland use per kilogram of pork and the footprints of carbon, nitrogen and phosphorous. The contribution of pork and the environmental impact from small farms will decrease over time. Structural interventions can address negative impacts of this transition, including through relocation of production across regions, international trade and demand-side adjustments. Farm-level technical measures to reduce the environmental impact of pork production include the use of feed additives, low-protein feeding, anaerobic digestion and improved manure management. Scenarios of structural adjustment and farm-level technical measures are modelled to support sustainability of the pork supply chain in China to 2050.

See Tong et al.