Understanding Agroecosystems: Examples and Outlook

Agroecology is an applied science and a practice that uses ecological concepts and principles to achieve more harmonious, synergistic interactions between people and the environment in landscapes known as agroecosystems. Agroecology is also a social movement that evolved as people sought more just, sustainable approaches to agriculture, nutrition, and food security in the face of environmental change and degradation. 

Agroecology as a Practice

Agroecology existed in practice and philosophy long before the term emerged in the late 1920s. Indigenous societies practicing agriculture millennia ago were keenly aware of their food growing practices as part of—and dependent on—natural systems and developed sophisticated techniques for managing agriculture sustainably, methods that endure today.  

Agroecology as a discipline in western science came about in part as a response to industrial agriculture, which in the latter 19th and early 20th century began to replace small producers. With the advent of the mid-20th century Green Revolution, industrial agriculture spread from wealthy western countries to developing nations. The industrial food system involves the use of genetically-modified, high-yield crop varieties, chemical fertilizers and pesticides, and specialized machinery tending vast fields of single crops. These tools allowed for mass production serving a global market but led to environmental degradation and inequality.

The emergence of the modern environmental movement in the 1960s created momentum for practices utilizing traditional and alternative farming methods to foster resilient, diverse agricultural landscapes rather than the monocultures typical of industrial practices. Efforts focused on conserving natural resources, protecting ecosystems by improving soil health, nurturing biodiversity, and exploring how nature could provide beneficial services like non-chemical pest management. 

In the 1970s and 80s, agroecology became more overtly political. A grassroots movement in Latin America began calling for structural changes that would shift power away from large agribusiness interests and toward rural communities and smallholder peasant farmers, who did not benefit equally from agricultural subsidies and were frequently exploited in the industrial food system.

The 1990s brought global attention to the problems of climate change and biodiversity with the United Nations Rio Earth Summit and greater awareness of agroecology as an alternative to what was increasingly recognized as an unsustainable mainstream agricultural system. The emergence of the international peasant movement La Via Campesina in 1993, as well as other groups that centered on social justice and food sovereignty in agroecology, sought transformative actions that empowered people producing and consuming food, not corporations.

Since the turn of the 21st century, the study of agroecology has continued to broaden in scope to incorporate the ecological, economic, and social dimensions of the entire food system. As a movement, it encompasses food justice, food sovereignty, biodiversity, and human health. It maintains a strong focus on how agriculture and food systems can become more resilient in the face of climate change and how to mitigate it without compromising rural communities and food system workers. 

Agroecology is increasingly posed as a necessary alternative to a dominant agricultural system associated with air, water, and soil pollution, soil degradation, pesticides, antibiotic resistance, greenhouse gas emissions, and a food supply increasingly vulnerable to climate change, pathogens, and other threats to food security.

Types and Examples of Agroecosystems

In agroecology, an agroecosystem refers to the relationships and interactions between soils, climates, plants, animals, other organisms, and humans in a physical space. As such, an agroecosystem does not solely pertain to agricultural activities but rather incorporates surrounding ecosystems that are part of such interactions, such as meadows, forest areas, and wetlands.

Agroecology uses a variety of techniques to support productive and sustainable agroecosystem functioning. These include organic farming; building soil health through interventions like crop rotation, no-till agriculture, and composting; growing multiple crops together in ways that provide mutual benefit; protecting wildlife; and exploiting synergistic interactions between crops, soil, water, trees, and wildlife. The emphasis is on supporting the health of the entire system—including the people who work the land and the communities whose wellbeing and economic stability depend on agriculture. 

Here are some examples of agroecosystems.

Polyculture Systems

Polyculture, also known as intercropping, is a stark contrast to monoculture employed in most industrial farming, in which farmers cultivate acre after acre of the same plant. Polyculture intersperses different crops that complement each other and produce mutual benefits.

A well-known example is the “three sisters” cultivated by many Indigenous cultures of the Americas: corn, beans, and squash. The beans fertilize the soil and the tall corn stalks support the beanstalks as they grow. The squash provides ground cover that helps ward off pests. Variations on these traditional crop groupings can be found all over the world. 

Permaculture Systems

Similar to polyculture, permaculture systems create synergies between different elements of the landscape that imitate natural systems. But the scope of permaculture is broader. Permaculture applies holistic techniques to support healthy ecosystem functioning, both on croplands and in surrounding ecosystems and communities impacted by food production. Permaculture systems may integrate everything from hydrology, soil science, forestry, livestock, to renewable energy generation, waste management, sustainable building design, sustainable markets, and community development.

Rice agroecosystems, for example, are a type of man-made wetlands with the potential to support a multitude of birds, fish, insects, reptiles, amphibians, mammals, and aquatic plants. Industrial rice systems can be very polluting, but in traditional rice systems and modern adaptations, more sustainable practices reduce the greenhouse gas emissions, nitrous oxide, and water pollution associated with chemical fertilizers and pesticides. In addition, the rice functions as a nitrogen sink and reduces ammonia concentrations in the water.

One especially notable type of traditional rice system incorporates fish aquaculture as well, which has mutually beneficial effects. Fish feed off the insects attracted to the rice, and the water is shaded and cooled by the plants’ leaves. Fish also provide fertilizer for the rice. Studies that have compared these traditional rice-fish polyculture systems to conventional Green Revolution rice monoculture found that the synergies between rice and fish dramatically reduced the need for chemicals while maintaining high yields.

Agroforestry

Agroforestry is a term that encompasses a variety of methods of growing trees, crops, and animals together for mutual benefit, including climate mitigation. There are three main categories of agroforestry: silvopastoral systems, agrisilvicultural systems, and agrosilvopastoral systems. 

Agrisilvicultural systems pair crops and trees. For example, many coffee growers in Indonesia, Central and South America, and Ethiopia cultivate shaded coffee, which is grown under a diverse canopy of trees such as fruit, timber, or legumes. Studies have shown a number of biodiversity benefits, including support of bird and insect diversity, helping to control erosion, reducing or eliminating the need for chemical fertilizers and pesticides, sequestering carbon, and improving pollination. Some research indicates that farmers also enjoy higher profits for shade-grown coffee.

A silvopastoral system is a type of agroforestry that combines livestock with a mixed landscape of trees, shrubs, and grasses. These can include timber plantations with grazing areas, fruit, nut, and legume trees, and pastures bordered by rows of trees that can serve as windbreaks or other purposes. Farmers typically rotate grazing between pastures to allow plants and trees time to recuperate. 

A study of silvopastoral systems in Latin America, where it has been extensively practiced, showed that dairy and meat production increased, animal welfare improved, and biodiversity of birds and insects thrived in these arrangements. Other research has found that silvopastoral systems support climate mitigation.

Finally, combining all three elements—crops, forests, and pasture—is an agrosilvopastoral system, which provides similar benefits. 

The Future of Agroecology

In 2015, a gathering of small-scale food producers and consumers from around the world took place in Nyéléni, Mali to discuss the importance of agroecology to food sovereignty and to plot its future path. The attendees at the landmark Nyéléni forum included peasant farmers, Indigenous peoples, rural workers, pastoralists, fishers, and urban people working toward a common understanding of agroecology and ways to prevent it from being co-opted by corporate agribusiness.

Friends of the Earth recently addressed this growing threat of co-optation in a 2020 report entitled “Junk Agroecology,” critiquing corporate agribusiness and large environmental NGOs that collaborate with them for “greening” some of their practices without committing to environmental justice. Instead, the report charges, many are redefining agroecology on their own terms to bolster their image and profits without actually making substantive changes.

As the world grapples with the challenge of feeding a predicted 9.2 billion people by mid-century, it faces an urgent decision about whether to undertake the massive structural changes agroecology proponents say is necessary to create a truly sustainable food system.