Agroforestry is the intentional integration of trees and shrubs into agricultural systems to create environmental, economic and social benefits. This can be done on a small or broadscale basis.
The roots of agroforestry go deep; it’s one of the oldest ways of growing food in the world. There are 2000 year old date-palm food forests in the Sahara, and forests hundreds of years old that feed villages and tribes all over the world. We still have much to learn from how indigenous people have grown food regeneratively for thousands of years.
One of the most sustainable agricultural methods in the world is the “milpa”, used by the Maya in Central America, and other people. This short video explains how it works. This is something that can be adapted to many areas, and has been by indigenous people all over the world. This particular approach is most useful in the tropics because of the rapid growth of perennial species like bananas.
As a subject agroforestry has been in use and studied for decades and is practiced worldwide. One of the main differences between agroforestry and permaculture is that agroforestry doesn’t have to be regenerative. There are many agroforestry systems that have two or three crops in them and continue to need outside inputs of fertilizer, weeding and other supports. It is mainly used commercially, though many of the techniques and discoveries within it can be translated to smaller food forests. More people in this movement are starting to study indigenous approaches which tend to be more regenerative than methods that come from a tradition of huge monocrop, straight row fields.
Agroforestry is one of the many tools that permaculture designers can use when growing food. The discovery process and amount of hard research done by agroforestry practitioners on soil building and yield can be of great value to permaculturists making decisions about which plants to use in various systems and their specific needs.
Adding any trees or other perennial plants to a system tends to make it more regenerative even if not fully regenerative.
The subject is focused on plants, though economics and community considerations usually become a part of a workable system. There are ways that we, as permaculturists, can maximize the benefits of agroforestry. One of these is by integrating the entire permaculture flower into agroforestry projects.
Benefits of agroforestry:
- Increase and maintain fertility and soil health over the long term through leaf drop or chop and drop.
- Reverse soil degradation. In annual systems, at least 20% tree coverage is needed.
- Increase the ability of the system to maintain closed nutrient cycles (especially true for food forests, must be properly designed).
- Increase ecosystem health and biodiversity, offering habitat and other ecosystem protection and services.
- Reduce erosion of healthy soil, and flooding - roots absorb much more water than annual fields
- Capture and retain moisture in dry times - roots efficiently access water, organic matter holds it.
- Regulate temperature (moderate microclimates) and prevent wind damage.
- Absorb toxicity, blackwater sewage, etc, safely. Remediate or check salinization.
- Regulate pH (through rich organic matter of forest floor).
- Reduced pests and diseases with a mixed system vs monocrop (habitat for pest predators, etc).
- Sequester carbon (one of the top ways to do so in the world).
- Increase economic resilience (through diversifying crops and markets, use of marginal land, and increasing self sufficiency).
- Provide resources for home use (firewood, building materials, food, medicine, fodder, etc).
- Utilize marginal land/edges (edges of fields, driveways, around buildings, riparian areas).
- Increase crop yield over the long term (from layering polycrops and mature fruit and nut tree yields).
- Nitrogen fixing trees used as “chop and drop” greatly enhance fertility of soils for annual crops and fruit or nut crops.
Products from agroforestry
- Timber for housing and furniture.
- Firewood and charcoal.
- Fodder for livestock.
- Livestock enclosures.
- Green manure.
- Food for local consumption or sale e.g. macadamia nuts, mangoes, nectarines, apples.
- Decorative and medicinal products e.g. Prunus africana can be used to treat prostate cancer erosion control.
- Eco sanitation (using manures, including humanure, in agriculture, keeping it out of waterways and ecosystems).
Types of agroforestry
There are many ways to incorporate trees into western monocrop agricultural systems and thus transition them to regenerative models. These are some of the major approaches currently being used..
Alley cropping - Annual or short term perennial crops are planted between rows of trees. The trees create fertility, wind protection, water catchment, pollination and other benefits. A common alley crop combination is nitrogen fixing trees and maize/corn. Tree selection and proper timing of pruning is important to success and balance of nutrient needs. In some versions, the tree species are the most important harvest, and annuals are grown until the trees start producing.
Corn or other crops can be grown between trees while they grow up. This is a good system to use with slow growing nut trees like chestnuts, for instance. The farm can make an income while trees are maturing.
Maize and leucaena (nitrogen fixing tree) alley cropping system. The tree is chopped and dropped to feed the corn. Corn can be rotated with beans and other crops to further feed the soil.
Permaculture version - more diversity in trees and crops, some crops in alley can be perennial. Crops can include pollinators, subsistence food, medicine, multiple cash crops. Soil stays healthier, the system is more resilient.
Buffers - Trees used as windbreaks, protection for riparian areas, flood control, contour erosion protection, filtration of pollution, shading of pond or structures, apiculture (pollinators), visual barrier. Buffers can include edible and other useful tree species and be very viable economically. The Natural Resources Conservation Service, part of the USDA, pays farmers and ranchers to buffer their rivers and add windbreaks and advises them to plant trees that can produce crops if possible.
Buffering this river keeps it healthy, helps keep the aquifer recharged, helps control flooding, provides a wildlife corridor, and can provide an income source via the outer band of trees/bushes if desired. Now just think if the rest of the farm used permaculture!
There are many ways to create a riparian buffer depending on the site's needs. This is pretty common. The pollinator buffer provides pollination and habitat, and soaks up fertilizer before it can pollute the waterways. This could include perennial crops. Zone 2 slows water flows in both directions, mitigating flooding. Zone 1 trees shade waterways, hold soil, provide habitat, and absorb excess water.
Mixed crops home garden - this method is used worldwide by many indigenous groups over centuries. A small (1 hectare or less) garden is kept for personal use and includes annuals and perennials often mixed together. Sometimes, there is an annual garden that is lined with perennials. Chickens and goats may eat from the system and bring their manure to it. When balanced, this system can maintain fertility for many years. This is the kitchen garden fully integrated with perennial systems.
Multi-story crops - Also called a “food forest”, often replicate a forest system with many layers and a wide range of diversity. Emphasis is on perennials. When there is a high diversity and plants are placed randomly, this approach is most useful in subsistence farming on small plots to feed families or villages. This is sometimes semi-wild. In larger systems, a main tree crop may be planted (Coconut, coffee, cacao) and a number of other symbiotic or supporting crops grown with the main crop.
Our tropical food forest is indistinguishable from a wild jungle yet packed with food and medicine. This is what many indigenous “farms” looked like in jungles around the world (and still do).
Shade grown coffee mixed with timber trees, bananas sweet potatoes and other food crops
Polyculture or polycrop - There are several ways in which this can be done - adding species over time, mixing long and short season crops, using nurse crops. Increases fertility, reduces water needs and other input needs, and improves soil. Similar to multi-story crop except that the system can support annuals such as castor bean, ginger, etc, Usually planted in rows.
In our orchard, one of our polycultures includes lemongrass, rosemary, mulberries, sage, aloe, and nitrogen fixing trees.
One of the most successful polycrop systems, by Marsha Hanzi in the drylands of Bahia, Brazil. This is one of her new projects. In her original project, the main crop is castor bean. Support crops (also commercially viable and food sources for farmers) included opuntia cactus, citrus, nitrogen fixing trees, soy, corn, herbs and others. Her fields produced 3-8X the yield of nearby castor bean farmers with no extra fertilizer or water inputs. Farmers could feed their families in years when castor beans failed or weren’t profitable because of market fluctuations.
Polycrop Compatibility
Roots do not compete (tap rooted plants with a surface feeder, for instance).
Plants do not compete for sunlight, nutrients or water.
Plants may support each other (nitro fixing, creating something for vines to climb on, shade).
Plants can be accessed and harvested in spite of proximity.
Plants cover a range of economic or use niches for maximum resiliency (in case of crop failure of one or more of them).
Silvopasture - Trees and animals are placed together - trees can provide fodder, shade, and other yields (wood, fruit), and animals provide manure and keep grass low. A productive and regenerative use of land when holistic or paddock grazing techniques are used.
Taungya - Plantation crop is planted, and cared for by local farmers who are allowed to grow their own crops between the rows of trees until they are shaded out by the trees. This is used in many countries and in many variations. A regenerative version would include ways in which the farmer can become more economically resilient and continue to improve his lot and his opportunity over the long term through this relationship.
Carbon Farming is the use of trees and tree crops to enhance carbon capture of farm land. Agroforestry and perennial crops are two approaches that store the most carbon. Mix of animals and trees are most carbon efficient when regenerative grazing techniques such as paddock grazing are used, and trees are used as timber after maturity, thereby capturing carbon in buildings. This is a new science and there is a lot to learn about which methods are most effective, and where, but shows a lot of promise in producing resilient food sources that address multiple problems. (The Carbon Farming Solution, Eric Toensmeier)
Syntropic agriculture is a relative newcomer. It is similar to a food forest approach, but amplifies the results by creating aggressive layering and chop and drop care to the system. There have not been a lot of studies of this approach yet but the ones that have been done show very positive results. With everything we know, it makes sense that this type of focus would be successful.
We’re using this approach on the orchard part of our farm, chopping enterlobium, lemongrass and pasture weeds into a system that started with a swale on contour filled with logs and wood chips, and though we’re still in the baby stages, thus far our yields have been great and water needs have been minimal.
Aggressive layering in a syntropic system is achieved by understanding which plants can thrive in various levels of light.
Principles of syntropic agriculture:
Prune to stimulate growth (plant densely, prune aggressively).
Cover the soil (at least 6” of biomass, produced through pruning).
Plant intelligent consortiums (compatible plants at different stages of succession).
These principles are the same as permaculture principles. One thing we appreciate about this method is that it has focused on the most important elements of a permanent permaculture food system and amplified them. Ernst Goetz, the developer of this method, has not studied permaculture that we know of. He, like Mollison and so many others, including numerous indigenous tribes throughout the ages, engaged in thoughtful, protracted observation and design.
Summary
Any of these methods can be combined with any other. A permaculture designer will assess client needs and the land itself and determine which of these is most appropriate, where and when.
Indigenous Hawaiian farming is one of the best examples of people doing this in a regenerative way and is one of the most productive long term agricultural systems in the world.
Islands in Polynesia each developed their own agricultural methods and focused on different foods but there were similarities too. Native Hawaiians integrated some of these methods and developed others, in response to the unique ecologies of Hawaii. They worked closely with the microclimates on their islands to produce abundant food while maintaining fertility.
One recent study indicates that if those methods were used today, the current population on the islands could be sustained locally. It’s an interesting system because it became gradually more sophisticated and thoughtful over time, a succession process of human interaction with natural abundance.
This became one of the most well-designed, productive and regenerative agricultural systems in the world. And we can follow that progress as the islands have been populated for only about 1500 years.
The first approach was shifting agriculture, or uma. This is common among many tribes. They would grow food in one plot and then clear a new one when the fertility of that plot was reduced. After a time, they took more conscious action to ensure the plots regained their fertility sooner, similar to the milpa system of Mayans.
Lo’i agriculture focuses on growing taro, used as a staple like rice in Asia, through a careful crop rotation and often efficient and sophisticated low tech flood irrigation system. Fish and waterfowl helped maintain self-sustaining fertility.
Limahuli gardens. Hawaiians responded to the land they were on. Here, taro fields were terraced and surrounded by food forests that were often planted with useful seven layers and left to grow wild for times of need. This forest, by being placed high, helped protect the health of the watershed.
Elsewhere, earth was formed into rafts in swamps and taro planted on it. Animals and sea life were integrated into the systems. These systems were very abundant with numerous thoughtful beneficial connections.
Forests that protected watersheds were considered sacred and left alone, except for sustainable harvest of wild plants.
Kohala drylands system. Rock walls are built on contour which holds moisture and allows windbreaks to be grown which in turn prevent evaporation. This design helped the area to become productive in drier regions of Hawaii.
These drylands agriculture field systems on slopes are perhaps the most impressive. The people kept mountaintops intact with forests, which ensured that the aquifer and springs would stay intact and continue to flow.
They terraced the middle hillsides and designed sophisticated water catchment systems that would maximize use of the rains, and could also use stream water in times of drought where it existed.
Hawaiians built walls on contour to capture water and nutrients and provide support for windbreaks, which reduced the significant salt spray and evapotranspiration created by strong sea breezes. This, plus chop and drop of grasses, held enough moisture in the system to create a more intensively productive agriculture system than anything developed by their ancestors in Polynesia. This was real, innovative, ecological whole systems design, keeping the entire system thriving and healthy.
The trees surrounding watershed sources are protected, named “realm of the gods.” This ensures that streams don’t dry up, and is a common belief and practice among many indigenous people. Water is wai, wealth is waiwai in Hawaiian.
A high level of cooperation and coordination was needed to create these systems. The cultural and political aspects that allowed these systems to be created and to flourish are an important component. Each watershed had a resource manager called konohiki, trained from childhood to recognize levels of resources and restrict their use to keep the system healthy. They interacted with other managers on the island; there was significant cooperation between them.
Aspects that make regenerative indigenous agriculture examples around the world work over the long term, whether in drylands or moist areas:
- Understanding weather and other patterns of the land.
- Careful, observant and sustainable design and interaction with water in the landscape.
- Consistent and observant soil building and care.
- Creation of or use of microclimates most suitable for each type of plant.
- Use of multiple forms of agroforestry, responding to the needs of the land (wet/dry, fertile/less fertile); this helps create resilience for changes in climate, population, etc.
Any of these methods can be combined with any other. A permaculture designer will assess client needs and the land itself and determine which of these is most appropriate, where and when.
These are the main categories agroforesters use, but there are many other ways of approaching regeneratively managed forests.
One example is a 230,000-acre Menominee Forest in northeastern Wisconsin, which has been sustainably harvested for more than 150 years. “Sustainability, the Menominee believe, means “thinking in terms of whole systems, with all their interconnections, consequences and feedback loops.”
They maintain a large, old and diverse growing stock, prioritizing the removal of low-quality and ailing trees over more vigorous ones and allowing trees to age 200 years or more — so they become what Simard might call grandmothers.
Ecology, not economics, guides the management of the Menominee Forest, but it is still highly profitable. Since 1854, more than 2.3 billion board feet have been harvested — nearly twice the volume of the entire forest — yet there is now more standing timber than when logging began. “To many, our forest may seem pristine and untouched,” the Menominee wrote in one report. “In reality, it is one of the most intensively managed tracts of forest in the Lake States.”