New Blog – Sustainable Intensification: Efficiency, Substitution and Redesign

Jules Pretty, author and academic whose work focuses on sustainable agriculture and the relations between people and the land. This blog is based on his Sustainable Intensification – Concepts, Prospects and Redesign presentation at SIRN first Annual Event in November 2016 and poses us questions on redesigning agricultural systems.  

Despite great recent progress, we know that total food production will need to grow again before world population stabilises. The desire for agriculture to produce more food without environmental harm, even positive contributions to natural and social capital, has been reflected in calls for a wide range of different types of more sustainable agriculture: for a doubly green revolution, alternative agriculture , an evergreen revolution, agroecological intensification, green food systems, greener revolutions, agriculture durable, and evergreen agriculture. All centre on the proposition that agricultural and uncultivated systems should no longer be conceived of as separate entities. In light of the need for agriculture to contribute directly to the resolution of other global social-ecological challenges, there have also been calls for nutrition-sensitive, climate-smart and low-carbon agriculture. This is a great deal to ask. Can agricultural systems across the world respond positively?

Compatibility of the terms “sustainable” and “intensification” was hinted at in the 1980s, and then first used together in a paper examining the status and potential of African agriculture in 1997. Until this point, “intensification” had become synonymous for a type of agriculture characterised as causing harm whilst producing food. At the same time, “sustainable” was often seen as a term to be applied to all that could be good about agriculture. The combination of the terms is an attempt to indicate that desirable ends (more food, better environment) could be achieved by a variety of means. The term was further popularised by a number of key reports from the Royal Society, UK Foresight and now the UN FAO: Reaping the Benefits, The Future of Food and Farming, and Save and Grow.

Sustainable intensification (SI) is defined as a process or system where yields are increased without adverse environmental impact and without the cultivation of more land. The concept is thus relatively open, in that it does not articulate or privilege any particular vision of agricultural production. It emphasises ends rather than means, and does not predetermine technologies, species mix, or particular design components. Sustainable Intensification can be distinguished from earlier conceptions of intensification because of an explicit emphasis on a wider set of environmental and health outcomes than solely productivity enhancement.

In 1985, Stuart Hill of McGill and earlier the radical Hawkesbury College in Sydney, developed a concept of change in agricultural systems that helps plot both steps towards new and more effective systems, and set the scale for ambition. Hill observed “there is something seriously wrong with a society that requires one to argue for sustainability,” and suggested there were three critical stages:

1. Efficiency
2. Substitution
3. Redesign

I find these extremely helpful in understanding what we might have achieved on a path towards sustainability in agricultural and food systems.

Step 1: Efficiency

This focuses on making best use of resources within existing system configurations. This would include targeting inputs of fertilizer and pesticide to reduce use and cause less pollution and damage to natural capital and human health. Precision agriculture is another example, using GPS, robotics and drones to reduce both financial costs and environmental externalities. Machine design can reduce the use of fossil fuels. In these ways, the unnecessary use of external inputs is avoided.

These can be argued to be brilliant basics: they should be done by all diligent farmers, but will probably not be much noticed when undertaken. They also do not result in system change.

Step 2: Substitution

This focuses on the use of new technologies and practices to replace existing ones that may be less effective on both productivity and sustainability grounds. The development of new crop varieties and livestock breeds is one example of substitution replacing less efficient system components with new ones. Beetle banks substitute for insecticides; releases of biological control agents can also substitute for inputs. Hydroponics is an extreme example of substitution, where water-based architectural systems replace the use of soils. No- and zero-till systems substitute new forms of direct seeding and weed management for inversion tillage. Substitution implies an increasing intensification of resources, making better use of existing resources (e.g., land, water, biodiversity) and technologies.

Substitution approaches can result in compellingly different systems on a considerable path towards sustainability.

Step 3: Redesign

This final step centres on the design of agro-ecosystems to deliver the optimum amount of ecosystem services to aid food, fibre and oil production whilst ensuring that agricultural production processes improve natural capital. Redesign harnesses agroecological processes such as nutrient cycling, biological nitrogen fixation, allelopathy, predation and parasitism.  The aim is to minimise the impacts of agroecosystem management on externalities such as greenhouse gas emissions, clean water, carbon sequestration, biodiversity, and dispersal of pests, pathogens and weeds. Redesign is a fundamentally social challenge, as there is a need to make productive use of human capital in the form of knowledge and capacity to adapt and innovate and social capital to resolve common landscape-scale or system-wide problems (such as water, pest or soil management).

Redesign is a game changer: it accepts there is no single solution to the productivity and sustainability challenges in agriculture. Systems will need to learn and develop, addressing new opportunities and challenges as they emerge. Thus sustainable intensification is a paradigm for continuous learning, where means will differ temporally and spatially to achieve desired ends.

This suggests the job is never done. Ecological and economic conditions change. This is particularly well illustrated by the challenges for integrated pest management. Pests, diseases and weeds evolve, new pests and diseases emerge (sometimes because of pesticide overuse), and pests and diseases are easily transported or are carried to new locations (often where natural enemies do not exist). New pests that have emerged in the past 3 years include banana leaf roller (Nepal), invasive cassava mealybug (SE Asia), cucumber mosaic virus (Bangladesh), tomato yellow leaf curl virus (West Africa) and cassava mosaic virus and brown streak virus (Uganda).

The papaya mealybug (PM) is a native of Mexico. It spread to the Caribbean in 1994, jumped to Pacific islands by 2002, and was reported in Indonesia, India and Sri Lanka in 2008. In these new locations, there is an absence of natural enemies. Parasitoids were collected in Puerto Rico and released in India and Sri Lanka in 2009–10, producing first year benefits to farmers of the order of $300 million (and preventing spread to northern India). By this time, PM had spread to Thailand and the Philippines, and then was discovered in Ghana. It then rapidly spread 4000 km along the coasts of West and Central Africa. The pest’s preferred host is papaya, but it is highly polyphagous, feeding on 80other species. Parasitoids were released in West Africa in 2013. In SE Asia, it has spread to mulberry, cassava, tomato and eggplant. Each spread, each shift of host, requires new redesigns of agricultural systems.

Redesigned systems tend to i) be multifunctional within landscapes and economies; ii) produce jointly food and other goods for farmers and markets, while contributing to a range of valued public goods; iii) be diverse, synergistic and tailored to social-ecological context; iv) have new configurations of social capital, comprising relations of trust embodied in social organizations, horizontal and vertical partnerships between institutions, and human capital comprising leadership, ingenuity, management skills, and capacity to innovate.

There are many pathways towards agricultural sustainability, and no single configuration of technologies, inputs and ecological management is more likely to be widely applicable than another. Agricultural systems with high levels of social and human assets are able to innovate in the face of uncertainty and farmer-to-farmer learning has been shown to be particularly important in implementing the context-specific, knowledge-intensive and regenerative practices of sustainable intensification.

Two key questions for SIRN are thus: how can the network best contribute to thinking about redesign of temperate and tropical agroecosystems? How can we move from efficiency through substitution to redesign of whole landscapes?

Key references

Hill S. 1985. Redesigning the food system for sustainability. Alternatives 12, 32-36

MacRae R J, Henning J and Hill S B. 1993. Strategies to overcome barriers to the development of sustainable agriculture in Canada: the role of agribusiness. J Agriculture & Environmental Ethics, 6(1), 21-51

Pretty, J and Bharucha, Z P. 2014. Sustainable intensification in agricultural systems. Annals of Botany 205, 1-26

Pretty J and Bharucha Z P. 2015. Integrated pest management for sustainable intensification of agriculture in Asia and Africa. Insects 6, 152-82




16th November 2016