Agroecology: principles and transitions
Agroecology as science, practice and movement: FAO's 10 elements, Gliessman's five levels of transition, push-pull, Andhra Pradesh and the evidence.
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Agroecology has moved from a niche academic field to the centre of global food policy debates. FAO hosts international symposia on it. The UN Committee on World Food Security's expert panel (HLPE) reviewed it in 2019. India launched a National Mission on Natural Farming in 2024. Andhra Pradesh's community-managed natural farming programme now involves around a million farmers. Critics, meanwhile, point to yield risks and to Sri Lanka's disastrous overnight fertiliser ban in 2021.
Agroecology means three overlapping things:
- a science: applying ecology to the design and management of farming systems;
- a set of practices that use ecological processes, such as diversity, recycling and biological pest control, in place of external inputs;
- a social movement for farmer knowledge, food sovereignty and fairer food systems.
Principles
FAO's 10 elements of agroecology (2018) are:
- Diversity: of crops, varieties, livestock, trees and soil life.
- Co-creation and sharing of knowledge: combining farmer and scientific knowledge, as in farmer field schools.
- Synergies: designing interactions such as crop–livestock integration, legumes fixing nitrogen for cereals, and trees giving shade and fodder.
- Efficiency: producing more with fewer external resources.
- Recycling: closing nutrient and biomass loops through manure, compost and residues.
- Resilience: buffering against drought, pests and price shocks.
- Human and social values: dignity, equity and inclusion, especially for women and youth.
- Culture and food traditions: healthy, diverse, culturally appropriate diets.
- Responsible governance: secure land and resource rights, and participatory policy.
- Circular and solidarity economy: local markets and fair relationships between producers and consumers.
The HLPE (2019) consolidated these into 13 principles, covering recycling, input reduction, soil health, animal health, biodiversity, synergy and economic diversification, along with social principles.
Levels of transition
Stephen Gliessman describes five levels of transition:
- Increase efficiency of conventional practices, for example through soil-test-based fertiliser use, precise spraying and IPM thresholds.
- Substitute conventional inputs with alternatives, such as biofertilisers, biopesticides and compost.
- Redesign the agroecosystem so that ecological processes do the work: rotations, intercropping, agroforestry, cover crops and integrated crop–livestock systems.
- Reconnect growers and eaters through local markets, community-supported agriculture and fair prices.
- Rebuild the global food system on equity, participation and sustainability.
Levels 1 and 2 are incremental. Many "sustainable" programmes stop there, and pure input substitution can keep the same pest and nutrient problems while swapping chemicals for biologicals. Agroecology's distinctive claim is that redesign (level 3) and beyond deliver more lasting benefits.
Examples
Push–pull in East African maize
Scientists at ICIPE in Kenya developed push–pull. Maize is intercropped with Desmodium, a legume, and bordered by Napier or Brachiaria grass. Desmodium gives off odours that repel ("push") stem borer moths, and it suppresses the parasitic weed Striga. The border grass attracts ("pulls") the moths to lay eggs on it, where few larvae survive. Desmodium also fixes nitrogen and provides fodder. On-farm studies have reported substantial maize yield gains on infested fields, often more than 50%, plus fodder for dairy cows. Push–pull has since been adapted for fall armyworm, and has been adopted by hundreds of thousands of farmers in East Africa.
Other well-known examples include:
- the rice–fish–duck systems of Asia, and System of Rice Intensification practices;
- zero budget or natural farming in India, using on-farm preparations such as jeevamrit and beejamrit, mulching and diverse crops, and Andhra Pradesh's APCNF with pre-monsoon dry sowing and year-round cover;
- the milpa polycultures of maize, beans and squash in Latin America;
- agroforestry and silvopasture systems across the tropics.
What does the evidence say?
- Yields: results vary widely. Meta-analyses comparing diversified and organic systems with conventional ones generally find lower average yields in organic systems, often around 10–25% lower, with large variation. The gap narrows with diversification, rotations and good management. Some redesigned systems, such as push–pull or diversified rice systems, can raise yields where pests, weeds or degraded soils limit production.
- Costs and income: lower input costs often raise net income even if yields fall slightly, especially for smallholders, but extra labour can be a burden.
- Environment: diversified systems generally improve soil organic matter, biodiversity, and pest and pollinator services, and reduce pesticide and nutrient losses.
- Resilience: diversity and soil cover can buffer against drought and price shocks.
- Evidence gaps: many claims rest on case studies, and long-term, rigorously controlled trials are fewer than for conventional practices. Andhra Pradesh's results are being studied by independent researchers.
Lessons from Sri Lanka
In April 2021, Sri Lanka banned imports of synthetic fertilisers and pesticides almost overnight, aiming to become fully organic. Without time, training, biological inputs or market support, rice yields fell sharply, by around 20–30% in the following season, and tea output dropped. Rising imports, food prices and protests followed. The ban was reversed within months. Agroecologists themselves stress that this was not agroecology, which requires a gradual, farmer-led transition with knowledge, redesign and support. The episode shows the risks of top-down input bans.
In India
- The National Mission on Natural Farming (2024) aims to reach 10 million farmers with training, bio-input resource centres and certification support.
- The Paramparagat Krishi Vikas Yojana supports cluster-based organic farming.
- States such as Andhra Pradesh, Himachal Pradesh and Sikkim (fully organic since 2016) have their own programmes.
- ICAR is evaluating natural farming practices in multi-location trials.
Key points
- Agroecology is a science, a set of practices and a movement that applies ecology to farming and food systems.
- FAO lists 10 elements (diversity, knowledge sharing, synergies, efficiency, recycling, resilience, human and social values, culture, governance, circular economy); HLPE lists 13 principles.
- Gliessman's five levels are efficiency, substitution, redesign, reconnecting producers and consumers, and food system change.
- Push–pull is a model redesign: Desmodium repels stem borers and suppresses Striga, and border grass traps the moths.
- Evidence shows environmental benefits and often lower costs, with variable yield effects that depend on management.
- Sri Lanka's 2021 overnight ban shows the danger of abrupt, unsupported transitions.
What the exams ask
- Define agroecology and list FAO's 10 elements.
- Describe Gliessman's levels of transition.
- Explain push–pull or another agroecological practice.
- Compare agroecology with organic farming and conventional intensification.
- Discuss India's natural farming policies and their evidence.
Described in general terms: the kind of examination, not a past paper. Laisha never reproduces exam questions.
Questions people ask
Is agroecology the same as organic farming?
Not exactly. Organic farming is defined by certification standards, mainly about which inputs are allowed. Agroecology is broader: it focuses on system redesign, ecological processes and social dimensions, and it does not necessarily exclude all synthetic inputs. Many organic farms are agroecological, but an input-substitution organic monoculture is not.
Can agroecology feed the world?
This is debated. Supporters argue that agroecology combined with less food waste, fairer distribution and diet change can meet needs, and that it improves resilience. Sceptics worry that lower yields would require more land and drive deforestation. Most analysts see a role for agroecological redesign alongside improved varieties, efficient inputs and better markets, adapted to each context.
What is the difference between natural farming and organic farming?
Natural farming, as promoted in India, emphasises on-farm preparations from cow dung and urine, mulching, soil cover and minimal purchased inputs, including organic ones. Organic farming allows approved purchased organic fertilisers and pesticides, and relies on certification for market premiums.
Sources
- FAO. The 10 Elements of Agroecology: Guiding the Transition to Sustainable Food and Agricultural Systems. FAO, Rome, 2018.
- HLPE. Agroecological and Other Innovative Approaches for Sustainable Agriculture and Food Systems. Report 14, Committee on World Food Security, Rome, 2019.
- Gliessman, S. R. Agroecology: The Ecology of Sustainable Food Systems, 3rd edition. CRC Press, 2015.
- Khan, Z. R., Midega, C. A. O., Pittchar, J. O., Pickett, J. A. and Bruce, T. J. A. "Push–pull technology: a conservation agriculture approach for integrated management of insect pests, weeds and soil health in Africa." International Journal of Agricultural Sustainability 9, 162–170 (2011).
- Ponisio, L. C. et al. "Diversification practices reduce organic to conventional yield gap." Proceedings of the Royal Society B 282, 20141396 (2015).
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