Oasis Gardens
An Experimental Wetland Vegetable Production System
Kalu Yala Institute Spring 2017
Steohen Langford Brook Taylor Lacy Kent-Webber
Special thanks to everyone who lended some much needed help collecting and moving materials, especially the Ag crew. Never have I had the pleasure of working with a more hard-working, smart, creative, hilarious, and dirty bunch of people. We came together as strangers from all over the world and left as family. We may be a ridiculous family, but still a family, and while we might now be a world apart, we are far from done with what we started. I’ll get up at sunrise to bust out some ditches out before breakfast with you any time.
Kalu Yala Farm The Kalu Yala Institure farm is a 2.1 acre agroforestry system that supplements the diet of the community with a variety of perennial fruits and vegetables, but it is only a minimal source of the food consumed at Kalu Yala. The farm itself is only 3-4 years old, and as it previously served as a cattle ranch and was subjected to slash-and-burn practices, the primary practices of the Institute farm revolve around regenerative techniques. In addition, as Kalu Yala is located in the tropics, there is also the factor of managing water flow in both the rainy season and dry season and also determining best practices for scaling the system out to a full farm to table capacity.
Overview The intention of this project was to take an overgrown and dilapidated pond on the Kalu Yala Farm and revitalize it by constructing a raised garden bed, inspired by a traditional Aztec agricultural technique known as Chinampas, or “floating gardens.” The idea is that, with a constant water source and a good cycle of nutrients from the plants and fish throughout both the garden bed and the pond, this wetland system will be both self-sustaining and highly productive with consistent yields. In addition, by creating an area on the farm that invites the community into the farm to relax and appreciate their surrounding environment, the Oasis Gardens acts not just as a viable model for how to actually scale out capacity for a full farm to table experience, but also as a source of cultural evolution in that it inspires community members to form an appreciation for where their a comes from. In a way, it is an art that feeds.
Chinampas
Kalu Yala Farm (left)
Chinampas were first used throughout Mesoamerica prior to the rise of the Aztecs. As the Aztecs began to rise, their population grew to great numbers, and such a large population meant that more food needed to be grown in order to sustain them. Therefore, the Aztecs began using a series of chinampas in order to increase food production. These ‘floating gardens’ were created in shallow lakebeds and were roughly 30m x 2.5m rectangular structures. The structures were fenced in by wattle (rods interlaced with twigs/ branches) and were then filled with mud and decaying vegetation to provide a healthy soil for the plants.
In order to eliminate the risk of drowning the plants, the beds were raised above water level, which ensures a constant water source to the roots, creating a nutrient rich and highly productive soil and a vegetable production system that requires little to no maintenance. Crops that were traditionally grown included maize, beans, squash, amaranth, tomatoes, chili peppers, and flowers. Trees were also sometimes added in corners to help secure the structure. Furthermore, it was not the lack of success that destroyed the chinampas system. As raised, well-watered beds, chinampas had very high crop
Traditional chinampas system (above)
yields with up to 7 harvests per year. However, when the Spanish invaded the Aztecs, many of the dams and sluice gates regulating the water flow were destroyed and the chinampas were deconstructed, intended to never rise again. That said, this practice could theoretically be a viable model of sustainable agriculture.
MultiDimensional Design As in good permaculture design, the chinampa plot revolves around turning waste into a resource. It stacks functions to maximize yields and minimize work in a
small-scale, intensive system. With such a design, it is not only a self watering system, which is created by wicking in from the sides as moisture is brought to the surface and then evaporated, but it is also highly productive, and mostly self-sustaining. Hypothetically, the garden bed will never have to be watered once the roots have extended down to the environment where soluble nutrients stay suspended and available. With such a complex biodiversity in both the garden plot and the pond, there is a great cycle of nutrients allowing all forms of life within the system to thrive and grow. By understanding the functions of each component, placing each plant and structure in a place that maximizes its use as a resource, the chinampa system is able to maximize
productivity and minimize waste. Even the fish (Tilapia) are able to take advantage of the organisms attracted to the plants, which become a source of food for the fish, increasing the efficiency of the selfmaintaining system. Moreover, the Oasis Gardens can be said to go beyond the principles of permaculture as it also embodies the practices guided by regenerative agriculture. It appears to have both successfully revitalized the pond and created a healthy layer of topsoil. This, as part of the greater irrigation system of the Kalu Yala Farm, will now allow for a cycle of nutrients that, in time, will help further develop the Kalu Yala Farm. The garden is not only able to prolong the run-off, utilizing as much water, nutrients, and energy as possible before losing them, but it also serves as a catalyst for the expansion process of the farm by initiating a water and soil catchment system.
Life Begets Life
Aquaponic nitrogen cycle (above)
Cultural Revolution Homo Sapiens began our estrangement from nature around 10,000 B.C. when hunter-gatherer societies transitioned to ones of agriculture and settlement. Since then, as populations have grown exponentially in numbers and in technologies, agricultural practices, too, have advanced. At the same time, concentrations of people in urban areas have skyrocketed, resulting in a drastic general disassociation with the food production process and even nature as a whole. Current food systems also contribute to multiple practices that are detrimental to our natural environment. However, their remains an affinity for nature built into man’s DNA, the key is just to figure out how to foster that affinity and make it meaningful. Therefore, by creating a space on the farm within eyesight of a path with heavy community foot traffic, the Oasis Gardens invites in both individuals and groups, whether for relaxation or recreation, while also helping them form an attachment
and appreciation for the system that feeds them. They are able to learn about the system, watching their food grow, seeing the process, the trials and tribulations. They become more educated and informed and are able to make more conscientious decisions. Then, by also serving as the beginning of an expansion of the farm, the visitors will also get to witness the development of a full farm-to-table system whereby all food and nutrients are produced within one big closed-loop system, just as within the Oasis Gardens. This is an attempt to localize peoples food systems, which is key in a sustainable community. The connection to food must go beyond the farm to table method and create an emotional and mindful connection to the food consumed. It then goes from an experiment in a dilapidated pond to a catalyst for the sustainable development of the entire community.
Construction To say that the construction of the first Kalu Yala Chinampa was labor intensive would be an understatement. Before even beginning to ideate on designs for the structure, we first needed to clear out the pond so that we could really know how much space we were dealing with. To our surprise, it was going to be a much larger project than we expected. However, after clearing out all the grass and weeds that had overtaken the area, we were then able to begin envisioning what this “floating garden” would look like. We played with ideas like dendritic patterns, narrow paths, crenelated shapes, and eventually decided on a wider bed as this design would allow for the highest number of plants able to take advantage of this great nutrient cycling system. We also decided to use bags of sand to form the walls of the chinampa, and to repurpose used air-mattresses as liners for the bottom of the pond and the walls of sandbags. From there, the next steps consisted of preparation and then physical construction. We began planting seeds we knew to be water-loving plants in pods in the greenhouse, filling poly sandbags with sand from a beach on the Rio Pacora,
and cutting air-mattress no longer functioning down the seam. It was then time to line the bottom of the pond with a few mattresses to ensure water remains in the pond, transport the bags of sand to the pond area, and stack the bags in the pond to ensure maximum stability and resiliency for both rainy and dry seasons. As we are unfortunately unaware of the water level variability between seasons, it was decided that it would also be best to dig a large irrigation ditch on the other side of the pond that will allow water to flow out whenever when the levels increase to a level that would flood the garden plot. Once both walls were constructed,
Initial state of “ish” pond before beginning designs for chinampa plot (above)
shade cloth was also applied on top of the liner for aesthetics purposes, as reaching plants, such as Wandering Jew, can grow across them and give a natural appearance to the wall, as well as contributing to the biodiversity of the wetland system. In addition, branches of balo were propagated in a similar manner along the bank of the entire pond in order for the roots to grow and help serve as a retaining wall.
Pond with air-mattress liners (left); Constructed chinampa plot waiting to be planted (below)
Soil Building
Biochar, Leaf Cutter Ant Waste, & Compost
With the construction of the walls completed, it was time to begin building up the layers of the garden bed. The base layer consisted of mostly large rocks and clay. Once this was brought up to about 3 inches below the surface of the water, clay and rocks were substituted for organic material in a sheet mulching technique by layering both green and brown mulch, with the goal being to build up a healthy layer of top-soil. With the primary components of the mulch being straw and water-lettuce, soil pockets were then used to transplant the seeds that had been planted several weeks prior and had been filled with a mixture of compost, leaf cutter ant litter, and biochar. Biochar, a soil additive that helps to reduce Co2 emissions into the atmosphere, resists degradation and sequesters the carbon in soils for thousands of years. The biochar used in this chinampas system was created by putting organic matter inside a Top Lit Up Draft (TLUD) biochar processor. This system consists of a steel 55 gallon drum with small air holes in the bottom and a partially opened lid. The processor creates the conditions for pyrolysis of wood into biochar by smothering a short, intense, top lit
fire with the cover. The biomass is slowly charred, taking roughly 2 to 6 hours to complete, depending on the organic matter that was used. The charcoal produced can then be used in soils that are depleted as it improves water quality and quality of the soil by improving retention of nutrients as well as agrochemical utilization. This ensures that more nutrients will stay in the soil helping reduce risk of pollution. The leaf cutter ant litter was also used in the soil mixture as it is assumed, and can be seen, to have high soil nutrients with an active bacteria and fungi population. This adds richness to the soil and adds to the productivity of the soil and chinampa plot. Compost holds the same characteristics, which makes this soil an ideal mixture for successful vegetation within this experiment.
Biochar after being processed (right)
Vegetation
Chinampa plot after being planted (right)
All of the vegetation planted in the garden bed is edible, and, with the exception of Malabar Spinach, all are annuals. Malabar Spinach is a perennial green that can be found in tropical climates. It is a productive leafy green vine that can be continuously harvested and thrives in moist lowlands. The reason for choosing annuals for the chinampa system are because they tend to thrive in rich soil and love constant irrigation. These annuals included: bush beans, cucumbers, beets, eggplant, tomatoes, watercress, bibb lettuce and swiss chard.
and stable when beside them. The addition of beets to the garden bed was fully experimental and was an attempt to see if a root vegetable could thrive in a chinampa system. The success of a beet grown in the garden would fuel the production of root vegetation such as carrots and onions.
Certain companion planting techniques were applied in the placement of the vegetation in the garden bed, such as the row of bush beans down the center of the bed, as lettuce, beets and cucumbers are known to be more productive
Then, tomatoes and eggplants are hypothesized to be the most successful in the garden bed because they both enjoy rich soil and deep, well-watered roots. They also enjoy being watered from below up as opposed to overhead watering, this actually stunts the growth of these annuals.
A salad mixture was also thought into the design, in that when harvesting the chard, bibb lettuce, Malabar spinach and watercress together, it makes for a delicious lunch or dinner.
A row of large golden sunflowers was planted throughout the center of the bed to improve the aesthetic of the Oasis Gardens. In the water there are water lettuce plants and red mangroves. This vegetation is to ensure shade for the tilapia in the pond, create an ecosystem for the frogs, can be harvested for mulch and cleans the water.
Costs As the majority of materials for this project consisted of natural materials such as rock, dirt, sand, straw, compost, ant litter, and biochar, the cost to construct the Oasis Gardens was minimal. In actuality, the monetary cost of constructing the Chinampa plot was about $24.00, which consisted entirely of the poly sandbags that were used to form the structure of the bed walls. As the rubber air mattresses and shade cloth that were used as liners no longer held air or functioned as originally intended, by using them in the chinampa, we are able to keep them from being discarded in a landfill and are repurposing them for a more meaningful and beneficial purpose. In regards to environmental costs, if the manufacturing of synthetic rubber materials emits 1,780 tons of Carbon Dioxide (CO2) per $1 million spent, and 1 mattress costs $20, then the manufacturing of 1 synthetic rubber air mattress emits about .0356 tons of CO2 equivalent. With 17 air mattresses used in the construction of the chinampas plot, that means the estimated emissions resulting from synthetic rubber manufacturing is .6052 tons of CO2 equivalent. For poly sandbags, if 736 tons of
CO2 equivalent are emitted per $1 million spent, and one sandbag costs about $0.30, the emissions of one bag is estimated to be around .0002214 tons of CO2 equivalent, which when calculated by the 80 bags used, comes out to be around .017712 tons of CO2 equivalent. *Estimates include emissions of Carbon (CO2), Methane (CH4), Nitrous Oxide (NO2), and Hydrofloric Carbons (HFC).
Expansion of the greenhouse and nursery using only materials at hand: Bamboo, Balo trees, shade cloth, and a few staples (above)
Key Findings If there is anything of significance to be learned from this process, it would be to plan for resiliency, think creatively, and persevere. When building a structure in a wetland area, all factors had to be considered. How much will the water level vary? What materials do we have to work with? How well will the water drain? How stable can we make the walls? How can we ensure water flow? How can we minimize anaerobic bacterial growth? This was certainly not all discussed prior to beginning the design and construction process, but by getting in the water (literally), and getting a close-up look at the problem and understanding it, it was possible to make adjustments and problem solve for each situation as
it arose Sometimes ideas worked well the first try, other times, it took a couple of attempts. In the end, a system was built with as much resiliency as could be anticipated and incorporated. Another useful finding is that Tilapia are great for cleaning a pond system. After finishing the chinampa plot, bacterial ridden water began wicking through the side of the wall, creating an oil-like stream across the surface of the pond. With the addition of the large amount of mosquito larvae, concerns began to grow about the viability of this project. However, within 24 hours after adding 15 small Tilapia to the OG pond, the water was completely clear, not even murky from the clay, and the mosquito larvae were gone.
Next Steps The immediate next steps will be to see how well the plants grow. However, assuming they do grow well, there is an opportunity for an additional Chinampa plot in the OG pond, but as previously mentioned, there is also the opportunity for continuing the expansion of the irrigation system behind the Oasis Gardens. Once the system is expanded, the model of this chinampa inspired system could be applied in a significantly larger scale and even leading to the full production of all
food consumed at Kalu Yala on the Kalu Yala Farm. Another opportunity for the future of this project would be to conduct a full cost-benefit analysis, in both monetary and environmental terms. In monetary terms, once the value of a single harvest can be estimated, we can easily compare this against the costs and determine the net savings. In environmental terms, if we can estimate the carbon sequestered along with all activity
performed within the garden bed itself and compare this against the environmental costs of manufacturing used materials and the carbon released from disturbing the dirt, the net environmental impact can also be added to the cost-benefit analysis.
Resources Since the Spanish conquered the Aztecs, Chinamaps went largely unused. Therefore, apart from what brief history exists, there does not appear to be much information on the actual implementation and productivity of these agricultural techniques. While there have been some other organizations who have published their ideas for Chinampas, it seems to be mostly theory. That being said, it is fortunate that the director of the Agriculture Program, Jon Trimarco, had previously experimented with a chinampa inspired system on his own and had some key insights into how to best design the system. In addition, environmental costs for manufactured components were estimated using data collected by Clare Bassi, Sustainability Coordinator, in conjunction with data available online with EIOLCA.net.
Team photo op before final presentations at Kalu Yala for Spring 2017 semester (above)
Exhibit A
Plant List Red Zebra Tomatoes: Flavorful and sweet, and great for eating fresh, roasting or making sauces, Red Zebra tomatoes have a high antioxidant content and lycopene concentration, which accounts for the red color and has been found in studies to prevent certain types of cancer. They are rich in vitamin C as well as offering a good amount of vitamins A and B, also a good source of calcium and iron. Red Zebra Tomatoes, as the name might suggest, are characterized by a bold red color and bright orange/yellow stripes, as well as producing large crops of up to 3-inch fruits.
Beefsteak Tomatoes: Beefsteak tomatoes, named for their size as well as meaty texture, are rich in vitamins A and C with high amounts of fiber, and similar to other tomatoes, are found to help prevent certain types of cancers. Beefsteak tomatoes are mostly pink or red with a small amount of seed compartments and do well in sunny, well draining soil.
Beets: A goldmine of nutrients, beets are loaded with essential nutrients such as vitamin B, iron, manganese, copper, magnesium, and potassium. In addition, as they are also rich in nitrates, which relax and dilate the blood vessels, beets promote increased circulation, potentially lowering blood pressure and increasing brain function. They can also lower the risk of heart disease, increase physical endurance, reduce the accumulation of fat in the liver, battle certain forms of chronic illness, and are chalk full of fiber, improving digestion.
Swiss Chard: Swiss Chard is one of the most nutritious veggies around, ranking second only to spinach. Its nutrient rich leaves can be green or reddish in color, with stalks that can typically be white, yellow, or red. The leaves can be harvested while young and tender or after they have reached maturity when larger and with tougher stems. As they are a highly productive plant, harvesting becomes a continuous process, but are loaded with vitamins A, K, and C, with raw chard also containing significant levels of vitamin E, magnesium, manganese, iron, and potassium.
Red Mangroves: Broad-leaved trees that have aboveground prop roots, which help to transport air to the waterlogged roots underground. Red mangroves have thick and grey-brown colored bark, slender leaves with a darker green on the top than the bottom, produces pale, pink flowers, and cab reach a height of up to 80 feet in ideal conditions, although typically resides at the 20 foot marker.
Bibb Lettuce: Bibb lettuce matures earl as small and compact rosettes with large ruffled outer layer leaves, which surround a soft, folded, and blanched heart. Although smaller than other similar lettuce species, Bibb lettuce has an almost identical appearance, texture, and shape. They have a soft and buttery texture with a slightly sweet flavor and are low in sodium, are a good source of vitamin A, and has small amounts of iron and calcium.
Sunflowers: Sunflowers are a tall annual or perennial plant that can grow to heights of 120 inches or more. They typically bear one wide, terminal capitula, with bright yellow ray florets at the outside and yellow disc florets inside. While during growth, sunflowers tend to tilt to face the sun throughout the day, once they begin to bloom this heliotropism comes to a stop. As a mature plant, they generally face east.
Thai Basil: A tropical perennial, Thai Basil can be grown from seeds or cuttings, requiring fertile, well-draining soil and 6-8 hours of full sunlight per day. Sturdy and compact, this plant can grow up to 1 ½ feet and has shiny green, slightly serrated and narrow leaves with a sweet anise-like scent and hints of licorice, along with a slight spiciness.
Oregeno: A tropical perennial herb, oregano has exhibits spade-shaped, olive green leaves with purple flowers and prefers hot, relatively dry climate. However, it can also do well as an annual in other environments. With a name that means “mountain joy�, Oregeno is a good source of calcium, fiber, iron, manganese, and vitamin K. It is a flowering plant in the mint family.
Bush Beans: Bush beans are a versatile food that can be used either as a green vegetable or a protein source. It is an annual plant, and very easy to grow, simply needing full sun and well drained soil, but with consistent moisture. Bush beans are characterized by green foliage and white flowers, and are an excellent companion plant for broccoli, cabbage, collards, radishes, eggplant, potatoes, tomatoes, cucumbers, and summer squash.
Malibar Spinach: A tropical perennial, able to be grown as an annual in other climates, Malibar Spinach is a highly productive leafy green vine that can be continuously harvested and thrives in moist lowlands. These thick, semi-succulent heart shaped leaves, with a mild flavor and mucilaginous texture, are fast growing, have a soft-stemmed vine, and reach up to 33 feet in length. They prefer full sunlight in hot and humid climates and are rich in vitamins A and C, as well as iron and calcium.
Watercress: A rapidly growing aquatic, or semi-aquatic, perennial characterized by hollow stems and pinnate, feather-like leaves and the production of clusters of small, white and green flowers. They are rich in vitamin K, A, C, B6, riboflavin, calcium, manganese, and folate, while low calorie, with low amounts of carbohydrates, proteins, fats, and dietary fiber.
Eggplant: A delicate, tropical perennial, this fruit, or berry, is typically valued for its deep and shiny purple color, and its unique taste and texture. Like other members of the nightshade family, Eggplant grows from vines and can grow up to 5 feet in height. It has a spiny stem, a white to purple flower, five lobed corolla, and yellow stamens. Although there are several different cultivars with slightly different tastes and textures, all at least exhibit a bitter, spongy texture and are an excellent source of fiber, copper, potassium, folate, as well as vitamins B1, B6, and B3.
Wandering Jew: Prized for its white, green, and silver stripes and purple color in the leaves, Tradescantia Zebrina, more commonly referred to as the wandering jew plant, gets its name for its ease of propagation and ease of care. With some bright light and moist soil, this plant, with its trailing vines flowing from the stem, can grow quite well and produce small blooms with 3 petals, which can be violet or white.
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