Review

Intensification for redesigned and sustainable agricultural systems

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Science  23 Nov 2018:
Vol. 362, Issue 6417, eaav0294
DOI: 10.1126/science.aav0294

The future of farming

In the mid-20th century, food production from agriculture sharply increased worldwide; however, this was achieved through heavy use of agrochemicals. Extensive collateral damage from excessive use of pesticides, herbicides, and fertilizers has occurred to the wider environment. This has led to biodiversity loss, pesticide resistance and the emergence of new pests, pollution and decline of freshwater supplies, and soil degradation and erosion, as well as direct harm to health. In a Review, Pretty examines the alternative approaches that can achieve sustainable intensification of farming systems by integrating pest management with agroecological systems to minimize costs, maximize yields, restore ecosystem services, and ensure environmental enhancement.

Science, this issue p. eaav0294

Structured Abstract

BACKGROUND

The mid-20th century brought agricultural transformation and the “Green Revolution.” New crop varieties and livestock breeds—combined with increased use of inorganic fertilizers, manufactured pesticides, and machinery—led to sharp increases in food production from agriculture worldwide. Yet this period of agricultural intensification was accompanied by considerable harm to the environment. This imposed costs on economies and made agricultural systems less efficient by degrading ecosystem goods and services. The desire for agriculture to produce more food without environmental harm, and even to make positive contributions to natural and social capital, has been reflected in many calls for more sustainable agriculture. Sustainable intensification (SI) comprises agricultural processes or systems in which production is maintained or increased while progressing toward substantial enhancement of environmental outcomes. It incorporates these principles without the cultivation of more land and loss of unfarmed habitats and with increases in system performance that incur no net environmental cost.

SI seeks to develop synergies between agricultural and landscape-wide system components and is now a priority for the Sustainable Development Goals of the United Nations. The concept is open; emphasizes outcomes rather than means; can be applied to any size of enterprise; and does not predetermine technologies, production type, or design components. SI can thus be distinguished from earlier manifestations of intensification because of the explicit emphasis on a wider set of environmental as well as socially progressive outcomes. Central to SI is an acceptance that there will be no perfect end point. No designed system is expected to succeed forever, and no single package of practices is able to fit the dynamics of every ecosystem.

Three nonlinear stages in transition toward sustainability have been proposed to occur: efficiency, substitution, and redesign. Although both efficiency and substitution are important, they are not sufficient for maximizing coproduction of favorable agricultural and beneficial environmental outcomes without redesign. Whereas efficiency and substitution tend to be additive and incremental within current production systems, redesign should be the most transformative. Redesign presents social and institutional as well as agricultural challenges.

It is now clear that SI is spreading to increasing numbers of farmers and is being practiced on a growing area of farmland. By 2018, it was estimated from these initiatives that across some 100 countries, 163 million farms had crossed an important substitution-redesign threshold by using SI methods in at least one farm enterprise, and over an area approaching 453 million ha of agricultural land. This is equivalent to 29% of all farms worldwide and 9% of agricultural land.

OUTLOOK

Pest management exemplifies the need for continuing active intervention for SI; the job is never done. Ecological and economic conditions will change, and agroecosystems will have to be adaptable in order to deliver a range of ecosystem services, including food production but also water and soil conservation, soil carbon storage, nutrient recycling, and pest control. Cooperation—or at least individual actions that collectively result in additive or synergistic benefits—is needed for SI to have a transformative impact across landscapes. Farmers will have to be given the confidence to innovate in a flexible way as conditions change. Every example of successful redesign for SI at scale has involved the prior building of social capital. Widespread adoption of IPM needs new knowledge economies for agriculture. Technologies and practices are growing, but new knowledge needs to be collectively created and deployed and needs to give equal emphasis to ecological and technological innovations. The concept and practice embodied in the SI model of agriculture will be a process of adaptation, driven by a wide range of actors cooperating in new agricultural knowledge economies.

Abstract

Redesign of agricultural systems is essential to deliver optimum outcomes as ecological and economic conditions change. The combination of agricultural processes in which production is maintained or increased, while environmental outcomes are enhanced, is currently known as sustainable intensification (SI). SI aims to avoid the cultivation of more land, and thus avoid the loss of unfarmed habitats, but also aims to increase overall system performance without net environmental cost. For example, large changes are now beginning to occur to maximize biodiversity by means of integrated pest management, pasture and forage management, the incorporation of trees into agriculture, and irrigation management, and with small and patch systems. SI is central to the Sustainable Development Goals of the United Nations and to wider efforts to improve global food and nutritional security.

The mid-20th century brought agricultural transformation and the “Green Revolution.” New crop varieties and livestock breeds—combined with increased use of inorganic fertilizers, manufactured pesticides (1), and machinery as well as better water control and increased field size—led to sharp increases in food production from agriculture worldwide. As a result, aggregate world food production more than tripled during the past 50 years (2). The intensity of production on agricultural lands has also risen (3). The area under irrigation has doubled, and consumption of nitrogen (N) fertilizers increased sevenfold. At the same time, food production per person has grown, despite considerable population growth (Fig. 1). For each person today, there is 50% more food compared with each person in 1961 (2).

Yet this period of agricultural intensification was accompanied by considerable harm to the environment (46). This imposed costs on economies and made agricultural systems less efficient by degrading ecosystem goods and services, including through pollution of groundwater and losses of beneficial insects. Concern about these negative effects shifted ideas about how agricultural systems could be more effective at both food production and reductions in harm to the environment. The desire for agriculture to produce more food without environmental harm, and even to make positive contributions to natural and social capital, has been reflected in many calls for more sustainable agriculture. These have variously been evoked as a doubly green revolution (7), alternative agriculture (8, 9), evergreen agriculture (10), agroecological intensification (11), save and grow (12, 13), diversified agroecosystems (14), and sustainable intensification (SI) (1517).

SI comprises agricultural processes or systems in which production is maintained or increased while progressing toward substantial enhancement of environmental outcomes. It incorporates these principles without the cultivation of more land and loss of unfarmed habitats and with increases in system performance that incur no net environmental cost (1820). However, some controversy surrounds the SI term (21). Does the term imply no more than business as usual? Is it a vehicle to smuggle into agriculture potentially harmful technologies? Will it lead to losses of productivity as environmental goods are prioritized? At the same time, concepts of land-sparing and land-sharing have brought into sharp focus the need to improve the intensification of agricultural resources without expanding into nonagricultural and usually highly biodiverse habitats (22). SI seeks to make better use of natural and human resources (such as land, water, biodiversity, and knowledge) and technologies.

In many farmed landscapes, the need for effective SI is urgent. Environmental degradation is reducing the asset base of existing agricultural lands (6, 23), expansion of urban and road infrastructure has removed agricultural land [in the current countries of the European Union, agricultural area fell by 31 Mha over 50 years; in the United States and Canada, 0.5 Mha are lost annually (24, 25)], and climate change and extreme weather events create new stresses that test the resilience of agricultural systems. SI seeks to develop synergies between agricultural and landscape-wide system components and is now a priority for the Sustainable Development Goals of the United Nations (26). The concept is open; emphasizes outcomes rather than means; can be applied to any size of enterprise; and does not predetermine technologies, production type, or design components. It can thus be distinguished from earlier manifestations of intensification because of the explicit emphasis on a wider set of environmental as well as socially progressive outcomes. Central to SI is an acceptance that there will be no perfect end point. No designed system is expected to succeed forever, and no single package of practices is able to fit the dynamics of every ecosystem (27).

Redesign framework for SI

Three nonlinear stages in transitions toward sustainability have been proposed to occur: efficiency, substitution, and redesign. Although both efficiency and substitution are important, they are not sufficient for maximizing coproduction of favorable agricultural and beneficial environmental outcomes without redesign (28, 29).

Efficiency aims to make better use of on-farm and imported resources within existing farm configurations. Many agricultural systems are wasteful, permitting natural capital degradation within the farm or the escape of agrochemical inputs across system boundaries, which causes external costs on-farm and beyond. Post-harvest losses reduce food availability, and tackling them contributes directly to efficiency gains and amplifies the benefits of yield increases generated by other means. On-farm efficiency gains can arise from targeting and rationalizing inputs of fertilizer, pesticide, and water to focus impact, reduce use, and cause less damage to natural capital and human health. Precision farming requires sensors, detailed soil mapping, drone mapping, scouting for pests, weather and satellite data, information technology, robotics, improved diagnostics, and delivery systems to ensure that targeted inputs (such as pesticide, fertilizer, and water) are applied at an appropriate rate and time to the right place only when needed (11, 25, 30). Automatic control and satellite navigation of agricultural vehicles and machinery can enhance energy efficiency and limit soil compaction.

Substitution focuses on the replacement of technologies and practices. The development of new crop varieties and livestock breeds deploys substitution to replace less efficient system components with alternatives, such as plant varieties that are better at converting nutrients to biomass, that tolerate drought and/or increases in salinity, and with resistance to specific pests and diseases. Other forms of substitution include the release of biological control agents to substitute for agrochemical inputs, the use of RNA-based gene-silencing pesticides, replacement of the use of soil in hydroponics, and no-tillage systems that use new forms of direct seeding and weed management to replace inversion ploughing.

The third stage is fundamental for SI to achieve sustainability at scale. The redesign of agroecosystems is essential to harness ecological processes such as predation, parasitism, allelopathy, herbivory, N fixation, pollination, trophic dependencies, and others (31, 32). A prime aim is to modulate greenhouse gas emissions; provide clean water; maximize carbon sequestration; promote biodiversity; and disperse and ameliorate the effects of pests, pathogens, and weeds. Whereas efficiency and substitution tend to be additive and incremental within current production systems, redesign should be the most transformative.

Redesign presents social and institutional as well as agricultural challenges (3134). Unintended consequences must also be identified and mitigated as part of the redesign process.

SI impacts on productivity

The two key questions to ask of an SI system is first whether it actually generates more food, fiber, and other valued products while simultaneously improving natural capital, and second, can this be done without harming key renewable capital assets? Farmers who adopt various SI approaches can increase food outputs by multiplicative or by additive means (35). Multiplicative approaches improve yields per hectare by combining use of new and improved varieties with changes to agronomic-agroecological management. Additive methods require diversification of farms into a range of new crops, livestock, or fish that add to the existing staples or vegetables already being cultivated. Additive components range from use of fish ponds or concrete tanks; raised beds and vegetable cultivation; rehabilitation of degraded land; fodder grasses and shrubs for livestock (which can increase milk productivity); new crops or trees brought into rotations with staple crops such as clovers, soybean, and indigenous trees; to the adoption of short-maturing varieties (such as sweet potato and cassava) that permit the cultivation of two crops per year instead of one.

An early large-scale assessment of SI was commissioned by the U.S. National Research Council (NRC) (8). Partly driven by increased costs of fertilizer and pesticide inputs, plus growing scarcity of natural resources (such as groundwater for irrigation), and continued soil erosion, farmers had been adopting new approaches in a wide variety of farm systems. The NRC noted that “alternative agriculture” was not a single system of farming practices but rather used a mix of crop rotations, integrated pest management (IPM), soil- and water-conserving tillage, animal production systems that emphasized disease prevention without antibiotics, and genetic improvement of crops to resist pests and disease and to use nutrients more efficiently. Well-monitored alternative farming systems nearly always used less synthetic pesticide, fertilizer, and antibiotics per unit of production than comparable conventional farms. They also required more information and management skills of farmers per unit of production. The NRC (9) conducted follow-up studies on 10 of the original farms. These included integrated crop-livestock enterprises, fruit and vegetable farms, a beef cattle ranch, and one rice farm. After 22 years, there were four common features of these farms: (i) accumulation and maintenance of a natural resource base and maximization of internal resources; (ii) environmental sustainability and closed nutrient cycles; (iii) careful soil management, the use of crop rotations and cover crops, and for livestock, management practices that did not use hormones or antibiotics; and (iv) taking advantage where possible of direct sales markets (via farmers markets and/or internet sales), with some sold at a premium with labeled traits and products (such as organic, naturally raised livestock).

Substantial progress toward SI has also been made in developing countries over the past two decades. One study analyzed 286 projects in 57 countries, and a later one assessed 40 projects in 20 African countries (36, 37). In both, several million farmers on tens of megahectares had adopted practices that had led to yield increases of 79% (study 1) and 113% (study 2). The time scale for these improvements varied from 3 to 10 years. A further analysis of 85 IPM projects from 24 countries in Asia and Africa implemented over a 25-year period (1990 to 2014) further illustrated the potential for productivity improvement and substantial reductions in pesticide costs (38). Overall, mean yields increased by 41%, and pesticide use declined to 31% of prior use (Fig. 2). Compared with the benchmark preproject point, 30% of the crop combinations resulted in a transition to zero pesticide use.

Although pesticide reductions with IPM should be expected, explanations for yield increases induced by IPM are more complex. IPM may, for example, reduce the incidence of severe-loss years, although yield increases in a normal year may not be evident, but mean production does increase across years. Many IPM projects involve interventions focused on more than just pest management. For example, they may involve a substantial component of farmer training [for example, through farmer field schools (FFS)], in which case, farmers’ capabilities at innovating in several areas of their agroecosystems may also have increased, such as in soil and water management (39). Farmer training through FFS has resulted in greater and continuing innovation, with positive outcomes for both productivity and environmental services (34, 39).

Global extent of SI redesign

It is now clear that SI is spreading to increasing numbers of farmers and is being practiced on a growing area of farmland. A recent global assessment screened 400 SI projects, programs, and initiatives worldwide (20). The intention was to assess where agricultural innovation had scaled to have potentially positive landscape-scale outcomes on ecosystem services (Table 1).

Table 1 Redesign for SI.

Subtypes of SI, farm numbers, and hectares (at 2018). Some subtypes span several types (for example, “organic agriculture” also appears in elements of 4 and 7). [Source (20)]

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There are some 570 million farms worldwide, 84% of which are landholdings of less than 2 ha (40). These small farms make up only 12% of total agricultural area. Of all farms, 74% are in Asia (of which 35% are in China and 24% are in India), 9% in sub-Saharan Africa, 7% in Central Europe and Central Asia, 3% in Latin America and the Caribbean, and 3% in Middle East and North Africa. Only 4% of farms are in industrialized countries. To be effective, SI will have to encompass larger numbers of farms in less developed countries and larger farms of smaller numbers in industrialized countries.

In the analysis summarized in Table 1, 47 of the SI initiatives exceeded the 104 scale for either hectares or farm numbers, of which 17 exceeded the 105 threshold and 14 exceeded 106 (21). Many SI initiatives worldwide show promise but remain limited in scale. By 2018, it was estimated from these initiatives that in some 100 countries, 163 million farms had crossed an important substitution-redesign threshold using SI methods in at least one farm enterprise, and on an area approaching 453 million ha of agricultural land (not counting the SI initiatives in home and urban gardens and on field boundaries). This is equivalent to 29% of all farms worldwide and 9% of agricultural land (total worldwide crop and pasture land is 4.9 × 109 hectares).

Such a global assessment might imply that numbers of farms and hectares are fixed. Flux may arise from farmer choice and agency but equally from the actions of vested interests, agricultural input companies, consolidation of small farms into larger operations, changes in agricultural policy or shifts in market demand, and discrepancies between on-paper claims and what farmers have implemented. Efficiency-substitution adoption was not included in this assessment. For example, European Union regulations require all farms to use IPM, but this has not yet led to major redesign of agricultural practices that substantially benefit ecosystem services (25, 30).

Cost of pest management by pesticides

Pathogens, weeds, and invertebrates cause substantial crop losses worldwide. Although the reporting of pesticide use and market data are patchy, the use of synthetic pesticides in agriculture has grown steadily to 3.5 billion kg of active ingredient (AI) per year (38). The value of the global market is now US$45 billion per year, with herbicides accounting for 42%, insecticides 27%, fungicides 22%, and disinfectants and other agrochemicals 9% of sales. China, the United States, and Argentina account for 70% of world pesticide use in agriculture (2.44 billion kg of AI annually) (38), and six countries each consume between 50 million and 100 million kg (Brazil, Canada, France, Italy, Japan, Thailand). In the past 20 years, pesticide consumption has grown fourfold in China, eightfold in Argentina, threefold in Brazil , fivefold in Bangladesh, and fourfold in Thailand. Pesticides are intended to be hazardous to life, and there will be risks associated with their use; their full costs illustrate the often hidden harm of nonsustainable deployment. The value of pesticides lies in their ability to kill unwanted organisms, but their toxicity can also cause unintended harm on and beyond the farm (external costs). The collateral effects of pesticide use show features commonly found across the agricultural sector. The costs of unintended harm are often neglected, in part because they may occur after a time lag and may damage groups whose interests are not well-represented. Furthermore, it is not always clear where harmful compounds in the environment may have come from. In studies of pesticide externalities in China, Germany, Thailand, the United Kingdom, and the United States, costs have been calculated to range from$4 to 19 (€3 to 15) per kg of AI (4145). These costs put annual pesticide externalities worldwide in the range of $10 billion to$60 billion (for use of 3.5 billion kg and for a market size of $45 billion). Additional private costs are borne by farmers themselves and tend not to be included in calculations of damage, such as the costs of personal ill-health resulting from exposure to pesticides (46) or from increased pest, weed, or fungal resistance. Worldwide, weed species have evolved resistance to every herbicide class, and more than 550 arthropod species have gained resistance to at least one insecticide (47). New research has also shown that residues of some classes of pesticide (such as neonicotinoid insecticides) are more ubiquitous than previously assumed, suggesting that external costs may be underestimated: 97% of neonicotinoids brought back in pollen by bees in arable landscapes originates from nearby wildflowers rather than from crops themselves (48). At the same time, it has been found that the total flying insect biomass in central Europe has declined by 75% over a 27-year period (22). The ecosystem services provided by wild insects have been estimated at$57 billion annually in the United States (49). Such private and external costs reveal that some forms of agriculture are less effective and efficient than might appear from productivity data alone, indicating the need for new metrics and system design (50).

Redesign for SI-integrated pest management and ecosystem services

Redesign is critical as ecological, economic, social, and political conditions change across whole landscapes. The rapidly changing nature of pest, disease, and weed threats illustrates the continuing challenge to respond with agility. New pests and diseases can suddenly emerge because of resistance to pesticides, which can then lead to secondary pest outbreaks owing to pesticide overuse. Climate change has facilitated invasions of pests and pathogens, the accidental long-distance transfer of organisms, as well as long-distance trade (for example, of bees, pets, and plants). For example, wheat blast fungus (Magnaporthe oryzae) has recently emerged as a crop pathogen in Bangladesh (2016), and the Fall Army Worm (Spodoptera frugiperda) is spreading across sub-Saharan Africa (2017). The papaya mealybug (Paracoccus marginatus) is native to Mexico but spread to the Caribbean in 1994; then to the Pacific islands by 2002; and then to Indonesia, India, and Sri Lanka by 2008; and is currently found in West Africa. Although the mealybug’s preferred host is papaya, it has now adapted to mulberry, cassava, tomato, and eggplant (51). Each geographic spread, each shift of host, requires redesign of local agricultural systems and rapid responses from research and extension services. Such new pests and diseases may also affect crop pollinators, as illustrated by host shifts and the anthropogenic spread of bee parasites (such as Varroa mites) and pathogens (such as Nosema ceranae) (5).

A further example is the cassava pink mealybug, which was first reported in the greater Mekong region of Thailand in 2008 and caused an immediate 27% drop in cassava production (52). An IPM program was developed with multiple tactics, involving ploughing and drying soil, soaking stalk cuttings in insecticide, burning of infested plants, banning transport of infested plant materials, and the release of Anagyrus lopezi parasitoids. In 2010–2011, 6 million pairs of Anagyrus were released in Thailand, which brought the pest completely under control and enabled a lasting recovery of fresh root yields. This further underlies how important ecologically based tactics are to the SI of agriculture.

Old pests can return. The brown planthopper (BPH) has been called the “ghost of green revolutions past” (53). It was the primary threat to rice in the 1960s yet has resurfaced as a major pest threat in the 2000s owing to resistance to insecticides coupled with the heavy use of N fertilizers. BPH outbreaks are often triggered by overuse of insecticides, which reinforces farmers’ fears of insect pests, provoking in them the wish to apply more. In China, between 6 and 9 Mha were infested with BPH in 2005–2007, up from 2 Mha in the 1990s (51). Farmers in China apply on average 180 kg N/ha to rice as fertilizer, and N-enriched plants are known to enhance size, performance, and abundance of herbivorous pests.

IPM consists of a toolbox of interventions that combine the use of targeted compounds with agronomic and biological techniques to control different classes of crop pests. Complementary and alternative modes of pest control that exploit specificities in pest ecologies have been gaining increasing attention. The use of on- and off-farm biodiversity is key in IPM because biodiverse agroecosystems experience less pest damage and have more natural pest enemies than those of nonbiodiverse ones (27, 54). At the same time, both social and human capital are important for successful outcomes (33). IPM is knowledge-intensive. For successful IPM, farmers need to monitor pests and natural enemies, understand thresholds for decisions, and be competent in the deployment of a range of different methods.

IPM approaches span the efficiency-substitution-redesign (ESR) framework (Table 2). These range from targeted use of pesticide compounds to habitat and agroecological design. In only rare cases—such as the aerial release of the parasitic wasp Epidinocarsis lopezi to control cassava mealybug in West and Central Africa (55)—can IPM be implemented without farmer engagement. Recent years have seen a substantial increase in understanding how to increase farmers’ knowledge so that they are able to husband crops and livestock while reducing or eliminating pesticides.

Table 2 ESR options for integrated pest management and SI.

[Source: adapted from (38)]

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Social capital matters greatly. IPM strategies have now transitioned from individual field-based practice to coordinated, community-scale decision-making covering wider landscapes. Although this improves the effectiveness of pest control, it presents a considerable obstacle to wider adoption by presenting a collective-action dilemma: How can farmers as individual businesses be persuaded to work together for personal as well as wider landscape benefits (33)? FFS, which were started in the 1980s (56, 57), are among the most important mechanisms for the development and spread of IPM. FFS are not an extension method; they increase knowledge of agroecology, problem-solving skills, group building, and political strength. They can be particularly effective where there are simple messages (for example, do not use insecticides in the first 40 days of rice cultivation because herbivore-damaged plants recover with no yield loss) (58). FFS have been used in 90 countries (34, 59, 60), with 19 million farmer graduates, and now some 20,000 FFS graduates are now running FFS for other farmers.

One of the most effective IPM-redesign systems is the “push-pull” system (in which pests and beneficial insects are pushed and pulled into and away from valued crops), which is yielding notable successes in monocropped cereal systems (16). This method has been deployed with great effect against Striga weed and stemborer infestations in maize, millet, and sorghum (61, 62) and involves the use of interplanted “decoy” crops. Across Kenya, Uganda, Tanzania, and Ethiopia, push-pull systems are used on about 130,000 small farms. Interplanting of the leguminous forage crop Desmodium suppresses Striga and repels stemborer moths while attracting their natural enemies; planting Napier grass as a border crop attracts stemborer moths out of the crop. The interplanted fodder crop not only fixes N but has also provided an additional resource that has enabled farmers to diversify into dairy and poultry production, which in turn provides animal manure for application on fields. As a result, yields of maize and sorghum have increased substantially, with an up to threefold increase over control plots. Better quality of fodder for dairy animals has increased milk yields by at least 2 liters daily and ultimately gives considerably higher economic returns to the farmer than does monocropping.

This kind of redesign has been deployed in many agroecosystems, resulting in increased rotational diversity, use of wildflowers for pollinators and other beneficial insects, and deployment of conservation headlands and trap crops (63, 64), often with large reductions in input use without yield compromise (65). In tropical systems, fish, crab, and duck reintroduced into rice systems reduce pest and weed incidence, often eliminate the need for pesticides, and increase gross productivity through the provision of animal protein outputs (66).

Toward collective action and landscape-scale change

Pest management exemplifies the need for continuing active intervention for SI; the job is never done. Ecological and economic conditions will change, and appropriate responses will be needed. Agroecosystems will have to be adaptable consistently to deliver a range of ecosystem services, including food production, but also water and soil conservation, soil carbon storage, nutrient recycling, and pest control.

Cooperation, or at least individual actions that collectively result in additive or synergistic benefits, is needed for SI to have a transformative impact across landscapes. Farmers will have to be given the confidence to innovate in a flexible way as conditions change. Every example of successful redesign for SI at scale has involved the prior building of social capital (20). Such initiatives require relations of trust, reciprocity and exchange, common rules, norms and sanctions, and connectedness in groups. As social capital reduces the costs of working together, it facilitates cooperation, which gives people the confidence to invest in collective activities, knowing that others will do so too. Individuals are then less likely to get away with free-rider actions that cause resource degradation.

Widespread adoption of IPM needs new knowledge economies for agriculture (67). Technologies and practices are growing, but new knowledge needs to be collectively created and deployed and needs to give equal emphasis to ecological and technological innovations. Extension systems and FFS must give equal consideration to environmental as well as agronomic skills (34). For example, the Landcare movement in Australia consists of 6,000 groups of farmer-led watershed councils. The agroecosystem research network in the United States, the French network of agroecology farms, and the Farmer Cluster Initiatives in the United Kingdom (68, 69) are all important examples from industrialized countries that are delivering practices to address locally specific problems of erosion, nutrient loss, pathogen escape, and waterlogging. In Cuba, the Campesino-a-Campesino movement has built agroecological methods with knowledge and technologies spread through exchange and cooperatives. As a result, the productivity of 100,000 farmers has increased by 150% over 10 years, and pesticide use has fallen to 15% of former levels (70). In Bangladesh, innovation platforms have driven adoption of direct seeding and use of early-maturing rice (71). In China, Science and Technology Backyard (STB) platforms operate in 21 provinces, covering many cereal, root, and fruit crops (72). STB platforms bring agricultural scientists to live in villages and use field demonstrations and farm schools for the development of innovations. They are successful because they center on in-person communication, sociocultural bonding, and trust developed among farmer groups of 30 to 40 individuals.

In general, policymakers and regulators find it easier to seek to prevent practices or problems, such as the regulation of certain pesticide compounds or the establishment of safe drinking water limits for certain compounds. It has been harder to encourage positive practices. In most contexts, state policies for SI remain poorly developed or counterproductive. In the European Union, farm subsidies have increasingly been shifting toward targeted environmental outcomes rather than payments for production (73), but this seldom guarantees synergistic benefits across whole landscapes. Ethical and sustainable sourcing by food manufacturers, processors, and retailers would help drive up demand, particularly if producers connect directly with consumers (74). There are some regional-scale exemplars of positive policy practice. One example is India’s state of Andhra Pradesh, where the state government has made explicit its support to zero-budget natural farming (a local form of uncertified organic farming that does not require the expenditure of farmer income on inputs), aiming to reach 6 million farmers by 2027 (75). The greening of the Sahel through agroforestry began when national tree ownership regulations were changed to favor local people (18), and in China, where the 2016 No. 1 Central Document emphasizes innovation, coordination, greening, and sharing as key parts of a new strategy for SI (76).

There are arguments from some quarters that we would not need to increase agricultural production if less food was wasted and less energetically inefficient meat was consumed by the affluent. These would help, but there is no magic wand of redistribution. Most if not all farmers need to raise yields while improving environmental services. As the evidence shows, redesign of agroecosystems around SI can achieve both yield increases and resilience. The evidence from farms of redesign and transformations toward SI offers scope for optimism. A full transition from increased efficiency through substitution to redesign will be essential. The concept and practice embodied in the SI model of agriculture will be a process of adaptation, driven by a wide range of actors cooperating in new agricultural knowledge economies.

References and Notes

1. In this paper, the term “pesticide” incorporates all synthesized pest, disease, weed, fungal, and other control compounds. There is also no single accepted terminology for grouping of types of countries. Terms relate to past stages of development (developed, developing, or less developed), state of economy or wealth (such as industrialized or affluent), geographic location (such as global south or north), or membership [Organisation for Economic Cooperation and Development (OECD) or non-OECD]. None are perfect. Here, I have simply used “industrialized” and “less-developed” and acknowledge the shortcomings.
Acknowledgments: Competing interests: The author declares that there are no conflicts of interest regarding this research, nor funding or remuneration from consultancies or industrial links. There are no external funding sources for this paper nor paid consultancies for industry. J.P. is chair of the Kansas State University Sustainable Intensification Innovation Lab, funded by the United States Agency for International Development (USAID).
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