Terraced Agriculture: A Step in the Right Direction?

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Shawn Harquail
Remnants of the Moray Agricultural Terraces, designed by the Inca beside Machu Picchu. The site descends to a depth of approximately 150 meters, with a highly effective drainage system at the bottom.

Our current system of industrial agriculture is destructive and has a variety of negative impacts on both the environment and human health. Conventional, large-scale monocropping relies heavily on inputs from cheap labor and fossil fuels in the form of food transportation, cultivation, and fertilization. It produces outputs such as pollution, massive amounts of waste, land degradation, and little in the way of healthy, diversified crops. The problems of this system have become common knowledge to most and plenty of scientific assessments have contributed to our society’s knowledge of the impacts of our dominant agriculture system, including its large ecological footprint and its ecological degradation and overexploitation of renewable and nonrenewable resources.1

Unsurprisingly, people are today looking to new ways of producing food for our growing population while keeping our natural environment healthy. In many instances, older, traditional models can provide guidance and insight. In the U.S., there has been a grassroots, bottom–up push to establish food systems that are an integral part of our landscapes and ecosystems. Our current system often faces trade-offs between agricultural production and biodiversity and other ecosystem services. The challenge lies in increasing provisioning services, such as food production, by 70 percent for 2050 according to the Food and Agriculture Organization of the United Nations (FAO) for a rapidly increasing population while simultaneously conserving or enhancing biodiversity and the other types of ecosystem services within agricultural systems.2 By looking to examples of food systems throughout history and all around the globe, we can develop agricultural strategies that can conserve biological integrity while providing for human needs.

One tried-and-true method of low-impact food production is terraced agriculture. This has taken many forms over the course of agriculture’s long history and continues to be a prominent method for food cultivation. Some of the better-known forms of terraced agriculture come from South America, where people such as the Inca successfully developed and practiced it for centuries. In fact, despite the lack of human upkeep for almost 500 years, the evidence of precolonial Incan terraced agriculture can still be seen today throughout Peru.3 Built on contour, these terraces were constructed with a top layer of nutrient rich soil over denser clay soils for water retention, all on top of piles of stones to ultimately provide drainage. This method enabled the Inca to expand cultivatable land in Peru’s extremely mountainous terrain.3 Raised terraces were used in the Mayan civilization, too, particularly in riverine environments, the lowlands, and other areas susceptible to seasonal flooding. Like their Incan neighbors, Mayan land alteration also stemmed from the need to alter the hydrological cycle in order to increase production.4

Many farmers in Central America still look to these simple yet sophisticated methods of land alteration in their food production systems. Such methods can greatly increase soil nutrients and moisture levels and are designed to improve biological, climatic, or edaphic conditions for crop plants.5 Certainly, there are potential problems with planting on slopes, including sheet wash and erosion caused by rainfall and gravity. However, placing terraced mounds on contour alleviates this problem by diverting water and slowing runoff. These mounds are then planted with a variety of crops, as well as small shrubs and fruit trees for stabilization. Farmers in this region have also found that keeping the forest intact helps mitigate erosion,5 an idea that works in tandem with increasingly important and influential moves toward producing food in ways that facilitate ecological health and integrity in countries that have for too long relied on high-input industrial agriculture.

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Bethan Phillips
Terraced rice fields in Yuanyang, in the Yunnan Province of Southern China. The Hani have used this method of agriculture for centuries in this region.

Similar to Central and South America, many of the mountainous regions of Asia also have an extensive history of terraced agricultural systems. The Hani of Yunnan Province in Southern China, for example, have for centuries incorporated terraced food production within the forested ecosystem of the Ailao Mountains. They practiced a form of agriculture that relied on working symbiotically within the forest ecology, reflecting the importance of forests as a provider of environmental services. This system where forest and farm are directly related and transformed by each other stems from their local, indigenous knowledge of the forest.6The Hani understand the importance of keeping the forest intact to allow for the ecosystem to continue to provide a water source. Forests have the ability to collect and purify water, and without leaving enough vegetation intact in agriculture systems, biologically rich soil will run off into streams and rivers through erosion. The Hani process of cultivation combines both artificial and natural nutrient accumulation and cycling. By leaving forest processes intact, decaying plant and animal materials help enrich the soil. Such hydrological alterations ensure that nutrients are captured within the terraces rather than running off into rivers and lakes.6 Other farms in this region have also recently adopted an integrated farming approach. One such example is in Java, Indonesia, where upland areas play an important role in the conservation of water resources and the maintenance of a stable ecosystem.7 Animal husbandry and vegetable growing are integrated in a steep, artificially terraced environment where gravity, gradient, and water flow help disperse nutrients throughout the food system.

Over the past few decades, a small but increasingly influential group of farmers and scientists in North America and Western Europe have advocated a form of agriculture called permaculture. Bill Mollison, thought to be the father of permaculture, coined this term in the 1970s and defined the movement as the conscious design and maintenance of cultivated ecosystems that have harmonious integration of landscape and people. Permaculture is a philosophy and an approach to land use which works with natural rhythms and patterns specific to place, weaving together elements of microclimate, annual and perennial plants, animals, water and soil management, and human needs into intricately connected and productive communities.8 Although this form of ecological agriculture is far from new—as the Hani example demonstrates—it is new and different compared to the environmentally degrading conventional model that dominates agriculture in much of the world.

A key element of permaculture is the construction of earthworks. Earthen mounds, known as berms or Hugel mounds, help create microclimates and stimulate plant growth. Ben Falk, a renowned permaculture farmer from Vermont, has documented the success of his plants through the creation of these mounds. “We have noticed that all plants respond positively to being on a mound,” Falk notes, “and the increase in growth and health seems to vary from moderate to extreme. Often, we’ve seen plants respond with twice the growth rate.”9 Falk also discusses the added benefits of working on contour and building mounds. Not only does this increase available acreage by adding surface area, but biological activity and soil health are most heavily concentrated in the upper layers of the soil. Mounding, therefore, also increases the availability of productive, healthy soils.9

Methods such as terracing and permaculture, in both their traditional and modern forms, can benefit humans without having devastating effects on the environment. Such models seem particularly promising in places like New England, where large-scale industrial agriculture is largely absent and progressive attitudes toward land use are strong. Jon Turner has been using permaculture earthworks, terraced on contour within a forested ecosystem, on his farm in Bristol, Vermont. Located in the foothills of the Green Mountains, Turner’s Wild Roots Farm is adapted to the steep terrain and operates as a productive farm benefiting the local community and environment. Turner understands the importance of maintaining a healthy ecosystem and enhancing opportunities for biodiversity while also providing for his community in Bristol. He firmly believes that terraced forest farming should become more widespread throughout New England’s hilly landscapes. He also stresses the added benefit of starting in fresh soil that is free of pesticides and other harmful chemicals, a strategy that has the added benefit of allowing lowland soils to regenerate.10

Another added benefit of implementing this method of agriculture in areas such as New England is that it promotes adaptation and resilience to climate change. Since a great deal of farmland is located in floodplains along rivers in mountain valleys, the probability of climate change-intensified storms causing flooding and inundated fields, as seen with Hurricane Irene in 2011, is increasing. Moving agriculture out of floodplains would make for a more resilient food system in the face of climate change, thereby safeguarding farms from extreme floods.

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Rachel M. Fry
Participants construct a berm in a permaculture design class.

Despite the benefits of ecologically designed terraced agriculture for the future of the New England food system, there are some inherent problems with this model, and it is not a fix-all solution. It probably only makes sense on a fairly small scale, as it is unlikely that New Englanders will want to convert too much of their forest into terraced agricultural land. It would therefore be best suited to communities within already developed areas. Another problem could be convincing farmers wedded to industrial agriculture to alter their current methods. However, by looking to examples of successes throughout history, as well as current models like Wild Roots, it is likely that an increasing number of farmers will see the ecological advantages and economic benefits of added surface area and reduced inputs like fertilizers and fuels. Although it cannot be the sole solution to our current agricultural system, terraced-forest farming utilizing ecological design could begin to improve our food system, facilitating at least one step in the right direction towards a method of food production that will enhance the lives of humans and the environment.