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Keith Merchant Katie Collins Info 1001 10 July 2013 Aquaponics Gardening I used to hate tomatoes with a passion. I hated them because they were hard as a rock and tasted like cardboard. I had the same distaste for strawberries. They are both bright red and look delicious but when you bit into them you find nothing but disappointment. I used to live in a small town with a small grocery store and if they didn’t have what you wanted, you were out of luck. Once I moved out of there to the city, I discovered a little thing called a farmer’s market. I discovered the concept of eating fruits and vegetable when they are in season. When I picked up a fresh vine ripened tomato for the first time and it felt soft, heavy, and warm. The first taste was an epiphany. It was as sweet as a red delicious apple with soft supple flesh. Then I found out that strawberries, when eaten at peak ripeness, are an indescribable pleasure. Unfortunately this is a fleeting experience in this modern society. Often the most reliable way to experience the highest quality fruits and vegetables is to grow them yourself. But the pace and structure of our lives makes it nearly impossible for the average person to find the time, space, and resources to grow their own food. There is a way though. This miracle of food production I will discuss can be scaled to nearly any dimension to fit in a sunroom, a balcony, or in a back yard. Aquaponics is the answer. Sylvia Bernstein describes Aquaponics in Aquaponics Gardening as “…the cultivation of fish and plants together in a constructed, recirculating ecosystem utilizing natural
Merchant 2 bacterial cycles to convert fish waste to plant nutrients.”(Bernstein 1) I will further define Aquaponics, describe the major advantages, and talk about what can be produced. What is Aquaponics farming? The simplest definition is that it is the combination of hydroponics and aquaculture. “Hydroponics is a method of cultivating plants without soil, using only water and chemical nutrients” (Bernstein 3). Whereas aquaculture is, “the cultivation of aquatic animals and plants, especially fish, shellfish, and seaweed, in a natural of controlled marine of fresh water environment” (Bernstein 5). The way an Aquaponics system is physically constructed (see figure 1) is that water from a fish tank is fed into a container which is filled with gravel or some other soil-less growing medium that physically supports the plants and where nitrifying bacteria convert the fish waste into useable nutrients for the plants. The plants remove the nutrients thereby purifying the water, which is drained back into the fish tank (Hallam). The first component we will focus on is the plants. We all know that plants need two things sun and water. We take for granted that we will be growing the plant in some sort of media, usually soil. Soil provides the plant with the third thing that it needs in abundance, nutrients. What nutrients to the plants need? Eliot Coleman breaks necessary plant nutrients into two categories, macronutrients and micronutrients based on the quantity needed. He lists macronutrients as nitrogen first and foremost, then phosphorous, potassium, iron, calcium, and magnesium. He lists micronutrients as zinc, copper, cobalt, boron, and molybdenum (Coleman 95). In a hydroponic system you would add manufactured nutrient solutions to the water in carefully measured amounts to achieve this nutrient balance. The downside to this is that the
Merchant 3 chemicals are expensive and production is non-sustainable. Also the nutrient solution needs to be periodically discarded, which could negatively impact the environment. In an aquaculture (raising fish in an enclosed system), the fish waste must be removed and the water must be periodically discarded. As we will see, in an aquaponic system, typically the only thing you add once the system is mature would be food for the fish. And since the fish waste is converted the nutrients for the plants, there is no need to discard the water or filter out waste(Hallam). Adding the micronutrients to the system is fairly easy. The same product is recommended by both Bernstein and Hallam, as well as Coleman in the case of conventional farming. Seaweed extract is a natural substance comprised of liquefied seaweed and contains hundreds of micronutrients and chemical compounds, some versions even contain chelated iron (Hallam). The macronutrients are added to the system in the forms of calcium carbonate, magnesium carbonate, potassium carbonate, phosphoric acid, and fish waste. The first four, as their name suggests, are in a pure chemical form. They are used primarily as pH adjusters, and used only when needed to adjust pH, provide an appropriate amount of that nutrient (Bernstein 126). The last additive, fish waste, is where the magic happens. It is the source of nitrogen, which is the nutrient the plants need in the highest proportion. Fish excrete ammonia, a compound containing nitrogen, in liquid and solid form. Once a mature Aquaponics system is up and running, two types of bacteria inhabit the growing media, nitrosomonas and nitrospira. As Bernstein explains: “Nitrosomonas bacteria creates nitrites as a byproduct of their consumption of ammonia. Those nitrites, which are still toxic to the fish and a poor source of nitrogen for the plants, attract the second type of nitrifying bacteria: nitrospira. Nitrospira consume nitrites and give off nitrates. Nitrates are largely harmless to your fish and an excellent source of nitrogen for the plants.� (Bernstein 175)
Merchant 4 You can now see how this loop is closed and works in harmony. You feed the fish, the fish feed the bacteria, the bacteria feed the plants, and the plants clean the water (Figure 2). The last component that is important is composting red worms. Murray Hallam calls worms “The Aquaponics secret ingredient.” He goes on to say “…they break down and digest the solid waste[solid fish waste and uneaten fish food] and dead root matter that plants slough off, but in return they give us one of nature’s perfect Fertilizers.” (Hallam). Bernstein also promotes the use of worms saying “The waste from worms is called worm castings or vermicompost, and when steeped in water becomes and incredibly potent fertilizer called vermicompost tea or worm tea” (Bernstein 179). So now that we have established what Aquaponics is, we can ask the question; what are the advantages? First we will start out with the fact that you are producing your own food. Nothing beats that. You can pick your fruits and vegetables only when they are perfectly ripe and harvest your fish minutes before they end up on the dinner plate. The freshness factor impresses friend, is intrinsically rewarding, and some might say it increased the nutritional value by eating food that has fully matured. Another reason to choose Aquaponics is that it is necessarily organic. Murray Hallam warns that most pesticides and other chemicals that are commonly used in agriculture to control insects and disease can kill or seriously harm the living components of your system; the fish and bacteria. This does not mean that your system is susceptible to attack. Eliot Coleman as merely an indicator that your plants are not as healthy as they should be and that providing all of the necessary conditions for your plants to grow as well as they can will create plants that are “inherently insusceptible to pests” (Coleman 173). He goes
Merchant 5 on to say that plants only experience pest and disease problems when the plant is “stressed by inadequate growing conditions” (Coleman 173). Murray Hallam agrees and states that as long as you place your system where it can get adequate light, that plant will have all of the water, nutrients, oxygen, and carbon dioxide that it needs to grow as healthy as it possibly can (Hallam). The next major advantage is that there are no weeds involved. Some people are put off of the idea of gardening altogether because of the prospect of tending the beds regularly to keep the weeds from overtaking your crops. As Bernstein says “There are no weeds. I repeat: you will never need to pull weeds from your Aquaponics grow beds” (Bernstein 29). Weed seeds are present in soil. Since there is no soil in an Aquaponics grow bed there will be no weeds. Accessibility is another factor that draws people to grow food in an Aquaponics system rather than soil. Many people have disabilities or mobility restrictions that prevent them from gardening in the traditional way. Bending, digging, reaching, and lifting are just some of the physical requirements for traditional gardening that are a limiting factor for many people. Once the basic design limitations are understood, the only thing that limits the size and layout of an Aquaponics system is your imagination and the space you have to use. Bernstein describes it as “Waist-high, so there is no bending or digging involved – This is actually one of my favorite characteristics of Aquaponics. You can set your grow beds at whatever height suits you, and your back. This is a terrific benefit to anyone who is in a wheelchair or who is otherwise physically challenged. Aquaponic systems can easily be made wheelchair-compatible” (Bernstein 29). The last question is “What can I grow in an Aquaponics system?” The general answer is: freshwater fish and nearly any plant. Nelson and Pade Inc., on their website, state;
Merchant 6 “The fish and plants you select for your Aquaponics system should have similar needs as far as temperature and pH. There will always be some compromise to the needs of the fish and plants but, the closer they match, the more success you will have. As a general rule, warm, fresh water, fish and leafy crops such as lettuce and herbs will do the best. In a system heavily stocked with fish, you may have luck with fruiting plants such as tomatoes and peppers.” When choosing your plants, a quick Google search or a knowledgeable garden center employee will tell you what a plant’s preferred pH range and you can decide for yourself whether it would be appropriate. Bernstein explains that choosing where to set the pH is a compromise between the four living inhabitants of the system – fish, plants, bacteria, and worms – which works out to between 6.8 and 7.0 (Bernstein 125). So if you wanted to grow blueberries, you are out of luck, because they require a pH between 5.5 and 6.5. This is bad for the bacteria because 6.5 is below their optimal range and all activity is inhibited if the ph drops to 6.0 or lower (Bernstein 178). By far the most popular fish is tilapia. Bernstein lists the advantages specific to tilapia in that they are “easy to grow, like warm water, does not have high oxygen requirements, reaches harvest size …in 9-12 months and tastes delicious” (Bernstein 137). Murray Hallam also points out that tilapia tolerate high stocking density so you can grow out more fish in a smaller tank size that many other types of fish. Nelson and Pade Inc. list other food fish such as catfish, barramundi, perch etc. and also suggest that ornamental fish such as goldfish or koi would be appropriate as well. This has been a brief overview of Aquaponics concerning what the major components are, what are the major advantages, and what food product can result from an Aquaponics
Merchant 7 garden. There are volumes of literature and large communities where one can draw information on this topic from the home hobbyist who wants fresh herbs in the winter, to the large scale commercial farmer who wants an organic product with very little environmental impact. This only scratches the surface. Once the core concepts of Aquaponics are understood, the applications of this farming technique are endless.
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Works Cited Aquaponics: The first 12 Months. Dir. Frank Gapinksi. 2010. DVD. EcoFilms Australia, 2008. Aquaponics secrets. Dir. Frank Gapinksi. 2008. DVD. Ecofilms Australia, 2008. DIY Aquaponics. Dir. Frank Gapinksi. 2011. DVD. EcoFilms Australia, 2008. Bernstein, Sylvia. Aquaponics Gardening. Canada. New Society Publishers. 2011. Print. Coleman, Eliot. The New Organic Grower. White River Junction, Vermont. Chealsea Green Publishing Company. 1995. Print. Coleman, Eliot. The Winter Harvest Handbook. White River Junction, Vermont. Chealsea Green Publishing Company. 2009. Print. Woy, Joann. Accessible Gardening. Mechanicsburg, Pennsylvania. Stackpole Books. 1997. eBook. Nelson and Pade. “Recommended plants and fish in Aquaponics.� Aquaponics.com. n.p. n.d. Web. 7 July 2013. http://aquaponics.com/page/recommended-plants-and-fish-inaquaponics
Merchant 9 Aquaponics: The first 12 Months. Dir. Frank Gapinksi. 2010. DVD. EcoFilms Australia, 2008.
The star of this DVD, Murray Hallam, is an expert in Aquaponics and describes the setup, maintenance, and evolution of an Aquaponics system over the course of one year.
Aquaponics secrets. Dir. Frank Gapinksi. 2008. DVD. Ecofilms Australia, 2008. Murray Hallam Describes in detail the biological components of an Aquaponics system and how they integrate with one another to create an organic and sustainable food production system. DIY Aquaponics. Dir. Frank Gapinksi. 2011. DVD. EcoFilms Australia, 2008. Murray Hallam gives a step-by-step tutorial on how to construct an organic and sustainable food production system with inexpensive and recycled components. Bernstein, Sylvia. Aquaponics Gardening. Canada. New Society Publishers. 2011. Print. Sylvia Bernstein describes, in-detail the history, theory, and practical application of Aquaponics as a food production method. She delves into the chemistry, biology, and mechanics that one must know to create their own Aquaponics setup on whatever scale they choose. Coleman, Eliot. The New Organic Grower. White River Junction, Vermont. Chealsea Green Publishing Company. 1995. Print. Coleman describes the principles of organic agriculture and how to produce food with no herbicides, pesticides, or manufactured fertilizers. He delves into the science of plant biology and how to provide the proper conditions for a highly productive vegetable farm to thrive with as little off-farm inputs as possible.
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Coleman, Eliot. The Winter Harvest Handbook. White River Junction, Vermont. Chealsea Green Publishing Company. 2009. Print. Coleman describes how to overcome the challenges that cold weather presents to vegetable production through the use of unheated greenhouses. Woy, Joann. Accessible Gardening. Mechanicsburg, Pennsylvania. Stackpole Books. 1997. eBook. Woy describes the challenges faced by those with disabilities when it comes to gardening. She details design techniques that provide accessibility to people of all abilities.
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Plant height in cm Plant Hydroponic Aquaponic Basil 30 Rosemary 31 Cucumber 138 Tomato 110
35 35 156 114
Source: Bernstein 157
180 156
160 138
140 120
110
114
100
Plant he ight in cm Hydroponic Plant he ight in cm Aquaponic
80 60 40
30
35
31
35
20 0 Basil
Rose ma ry
Cucum be r
Tom ato