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\"Describes how Africa's farmers can be helped not only to feed themselves and their families but also to gain income by producing food and other crops and livestock products for sale to Africa's growing urban and export markets\"-- Provided by publisher.

Climate change will be the greatest threat to humanity and global ecosystems in the coming years, and there is a pressing need to understand and communicate the impacts of warming, across the perspectives of the natural and social sciences. Hoegh-Guldberg et al. review the climate change–impact literature, expanding on the recent report of the Intergovernmental Panel on Climate Change. They provide evidence of the impacts of warming at 1°, 1.5°, and 2°C—and higher—for the physical system, ecosystems, agriculture, and human livelihoods. The benefits of limiting climate change to no more than 1.5°C above preindustrial levels would outweigh the costs. Science , this issue p. eaaw6974 Increased concentrations of atmospheric greenhouse gases have led to a global mean surface temperature 1.0°C higher than during the pre-industrial period. We expand on the recent IPCC Special Report on global warming of 1.5°C and review the additional risks associated with higher levels of warming, each having major implications for multiple geographies, climates, and ecosystems. Limiting warming to 1.5°C rather than 2.0°C would be required to maintain substantial proportions of ecosystems and would have clear benefits for human health and economies. These conclusions are relevant for people everywhere, particularly in low- and middle-income countries, where the escalation of climate-related risks may prevent the achievement of the United Nations Sustainable Development Goals.

There is an ongoing debate on what constitutes sustainable intensification of agriculture (SIA). In this paper, we propose that a paradigm for sustainable intensification can be defined and translated into an operational framework for agricultural development. We argue that this paradigm must now be defined—at all scales—in the context of rapidly rising global environmental changes in the Anthropocene, while focusing on eradicating poverty and hunger and contributing to human wellbeing. The criteria and approach we propose, for a paradigm shift towards sustainable intensification of agriculture, integrates the dual and interdependent goals of using sustainable practices to meet rising human needs while contributing to resilience and sustainability of landscapes, the biosphere, and the Earth system. Both of these, in turn, are required to sustain the future viability of agriculture. This paradigm shift aims at repositioning world agriculture from its current role as the world's single largest driver of global environmental change, to becoming a key contributor of a global transition to a sustainable world within a safe operating space on Earth.

Background Phosphorus (P) is a limiting nutrient in many agroecosystems and costly fertilizer inputs can cause negative environmental impacts. Cover crops constitute a promising management option for sustainable intensification of agriculture. However, their interactions with the soil microbial community, which is a key driver of P cycling, and their effects on the following crop, have not yet been systematically assessed. Scope We conducted a meta-analysis of published field studies on cover crops and P cycling, focusing on plant-microbe interactions. Conclusions We describe several distinct, simultaneous mechanisms of P benefits for the main crop. Decomposition dynamics, governed by P concentration, are critical for the transfer of P from cover crop residues to the main crop. Cover crops may enhance the soil microbial community by providing a legacy of increased mycorrhizal abundance, microbial biomass P, and phosphatase activity. Cover crops are generally most effective in systems low in available P, and may access ‘unavailable’ P pools. However, their effects on P availability are difficult to detect by standard soil P tests, except for increases after the use of Lupinus sp. Agricultural management (i.e. cover crop species selection, tillage, fertilization) can improve cover crop effects. In summary, cover cropping has the potential to tighten nutrient cycling in agricultural systems under different conditions, increasing crop P nutrition and yield.

BackgroundAgricultural systems are amended ecosystems with a variety of properties. Modern agroecosystems have tended towards high through-flow systems, with energy supplied by fossil fuels directed out of the system (either deliberately for harvests or accidentally through side effects). In the coming decades, resource constraints over water, soil, biodiversity and land will affect agricultural systems. Sustainable agroecosystems are those tending to have a positive impact on natural, social and human capital, while unsustainable systems feed back to deplete these assets, leaving fewer for the future. Sustainable intensification (SI) is defined as a process or system where agricultural yields are increased without adverse environmental impact and without the conversion of additional non-agricultural land. The concept does not articulate or privilege any particular vision or method of agricultural production. Rather, it emphasizes ends rather than means, and does not pre-determine technologies, species mix or particular design components. The combination of the terms ‘sustainable’ and ‘intensification’ is an attempt to indicate that desirable outcomes around both more food and improved environmental goods and services could be achieved by a variety of means. Nonetheless, it remains controversial to some.Scope and ConclusionsThis review analyses recent evidence of the impacts of SI in both developing and industrialized countries, and demonstrates that both yield and natural capital dividends can occur. The review begins with analysis of the emergence of combined agricultural–environmental systems, the environmental and social outcomes of recent agricultural revolutions, and analyses the challenges for food production this century as populations grow and consumption patterns change. Emergent criticisms are highlighted, and the positive impacts of SI on food outputs and renewable capital assets detailed. It concludes with observations on policies and incentives necessary for the wider adoption of SI, and indicates how SI could both promote transitions towards greener economies as well as benefit from progress in other sectors.

The projected human population of nine billion by 2050 has led to ever growing discussion of the need for increasing agricultural output to meet estimated food demands, while mitigating environmental costs. Many stakeholders in agricultural circles are calling for the intensification of agriculture to meet these demands. However, it is neither clear nor readily agreed upon what is meant by intensification. Here, we compare the three major uses, ‘ecological intensification’, ‘sustainable intensification’ and ‘agroecological intensification’, by analysing their various definitions, principles and practices, and also their historical appearance and evolution. We used data from the scientific literature, the grey literature, the websites of international organizations and the Scopus and FAOLEX databases. Our major findings are: (1) sustainable intensification is the most frequently used term so far. (2) The three concepts ecological intensification, sustainable intensification and agroecological intensification overlap in terms of definitions, principles and practices, thus creating some confusion in their meanings, interpretations and implications. Nevertheless, some differences exist. (3) Sustainable intensification is more widely used and represents in many cases a rather generalised category, into which most current farming practices can be put so long as sustainability is in some way addressed. However, despite its wider use, it remains imprecisely defined. (4) Ecological and agroecological intensification do introduce some major nuances and, in general, more explicitly stated definitions. For instance, ecological intensification emphasizes the understanding and intensification of biological and ecological processes and functions in agroecosystem. (5) The notion of agroecological intensification accentuates the system approach and integrates more cultural and social perspectives in its concept. (6) Even if some boundaries can be seen, confusion is still predominant in the use of these terms. These blurred boundaries currently contribute to the use of these terms for justifying many different kinds of practices and interventions. We suggest that greater precision in defining the terms and the respective practices proposed would indicate more clearly what authors or institutions are aiming at with the proposed intensification. In this sense, we provide new definitions for all three intensification concepts based on the earlier ones.

Dairy production systems have rapidly intensified over the past several decades. Dairy farms in many world regions are larger and concentrated in fewer hands. Higher productivity can increase overall economic gains but also incurs site-specific social and environmental costs. In this paper, we review the drivers and impacts of dairy intensification. We identify in the literature four prominent concerns about dairy intensification: the environment, animal welfare, socioeconomic well-being, and human health. We then critically assess three frameworks—sustainable intensification, multifunctionality, and agroecology—which promise win–win solutions to these concerns. We call for research and policy approaches that can better account for synergies and trade-offs among the multiple dimensions of dairy impacts. Specifically, we suggest the need to (1) consider dairy system transitions within broader processes of social-environmental change and (2) investigate how certain framings and metrics may lead to uneven social-environmental outcomes. Such work can help visualize transformations towards more equitable, ethical, and sustainable food systems.

We hypothesize that biological diversification across ecological, spatial, and temporal scales maintains and regenerates the ecosystem services that provide critical inputs—such as maintenance of soil quality, nitrogen fixation, pollination, and pest control—to agriculture. Agrobiodiversity is sustained by diversified farming practices and it also supplies multiple ecosystem services to agriculture, thus reducing environmental externalities and the need for off-farm inputs. We reviewed the literature that compares biologically diversified farming systems with conventional farming systems, and we examined 12 ecosystem services: biodiversity; soil quality; nutrient management; water-holding capacity; control of weeds, diseases, and pests; pollination services; carbon sequestration; energy efficiency and reduction of warming potential; resistance and resilience to climate change; and crop productivity. We found that compared with conventional farming systems, diversified farming systems support substantially greater biodiversity, soil quality, carbon sequestration, and water-holding capacity in surface soils, energy-use efficiency, and resistance and resilience to climate change. Relative to conventional monocultures, diversified farming systems also enhance control of weeds, diseases, and arthropod pests and they increase pollination services; however, available evidence suggests that these practices may often be insufficient to control pests and diseases or provide sufficient pollination. Significantly less public funding has been applied to agroecological research and the improvement of diversified farming systems than to conventional systems. Despite this lack of support, diversified farming systems have only somewhat reduced mean crop productivity relative to conventional farming systems, but they produce far fewer environmental and social harms. We recommend that more research and crop breeding be conducted to improve diversified farming systems and reduce yield gaps when they occur. Because single diversified farming system practices, such as crop rotation, influence multiple ecosystem services, such research should be holistic and integrated across many components of the farming system. Detailed agroecological research especially is needed to develop crop- and region-specific approaches to control of weeds, diseases, and pests.

Over half of the European landscape is under agricultural management and has been for millennia. Many species and ecosystems of conservation concern in Europe depend on agricultural management and are showing ongoing declines. Agri-environment schemes (AES) are designed partly to address this. They are a major source of nature conservation funding within the European Union (EU) and the highest conservation expenditure in Europe. We reviewed the structure of current AES across Europe. Since a 2003 review questioned the overall effectiveness of AES for biodiversity, there has been a plethora of case studies and meta-analyses examining their effectiveness. Most syntheses demonstrate general increases in farmland biodiversity in response to AES, with the size of the effect depending on the structure and management of the surrounding landscape. This is important in the light of successive EU enlargement and ongoing reforms of AES. We examined the change in effect size over time by merging the data sets of 3 recent meta-analyses and found that schemes implemented after revision of the EU's agri-environmental programs in 2007 were not more effective than schemes implemented before revision. Furthermore, schemes aimed at areas out of production (such as field margins and hedgerows) are more effective at enhancing species richness than those aimed at productive areas (such as arable crops or grasslands). Outstanding research questions include whether AES enhance ecosystem services, whether they are more effective in agriculturally marginal areas than in intensively farmed areas, whether they are more or less cost-effective for farmland biodiversity than protected areas, and how much their effectiveness is influenced by farmer training and advice? The general lesson from the European experience is that AES can be effective for conserving wildlife on farmland, but they are expensive and need to be carefully designed and targeted.

Major declines in insect biomass and diversity, reviewed here, have become obvious and well documented since the end of World War II. Here, we conclude that the spread and intensification of agriculture during the past half century is directly related to these losses. In addition, many areas, including tropical mountains, are suffering serious losses because of climate change as well. Crops currently occupy about 11% of the world’s land surface, with active grazing taking place over an additional 30%. The industrialization of agriculture during the second half of the 20th century involved farming on greatly expanded scales, monoculturing, the application of increasing amounts of pesticides and fertilizers, and the elimination of interspersed hedgerows and other wildlife habitat fragments, all practices that are destructive to insect and other biodiversity in and near the fields. Some of the insects that we are destroying, including pollinators and predators of crop pests, are directly beneficial to the crops. In the tropics generally, natural vegetation is being destroyed rapidly and often replaced with export crops such as oil palm and soybeans. To mitigate the effects of the Sixth Mass Extinction event that we have caused and are experiencing now, the following will be necessary: a stable (and almost certainly lower) human population, sustainable levels of consumption, and social justice that empowers the less wealthy people and nations of the world, where the vast majority of us live, will be necessary.