AquacultureGeneral

Can a Tableful of Food be Produced Economically in an Urban Environment?

The reality has always been that it takes land to grow crops…no matter the type of crop. People need certain nutrients (protein, carbohydrate, roughage, and others) to thrive and all come from crops that are presently grown on arable land. The problem is that as the population increases, the amount of land available for crop production decreases. But, more people also mean the need to produce more food. It is a circular problem and it requires a solution.

Since land is needed to grow crops, it has been difficult to produce what is needed in urban areas. According to United Nations estimates 66% of the world’s population will live in urban areas by 2050. These people will need a means of producing some of their own food because more arable land will be used for housing.

Aquaponics is among the possible solutions to this problem.

What is Aquaponics?

The term is the portmanteau of “aquaculture” and “hydroponics”. Fish snails and various types of crustaceans have been farmed and harvested for many years. A farmer builds a small pond, introduces the animals and induces growth with proper nutrition. The ponds are naturally aerated and waste is disposed of via runoff. Hydroponics is a means of using water as a growth medium for plants rather than soil. When the two are combined, the waste products of the fish become plant food (with a little help from naturally occurring bacteria) and the plants serve to help aerate and filter water that is recirculated to the fish.

How Does Aquaponics Help?

Millions of acres are required to supply the growing food needs of the world. Presently, arable land can easily feed the global population, but that will likely not be true as it approaches a projected 10 billion by 2040. Agriculture has advanced to the point that it takes only an acre of land to feed one person for a year, so right now there is plenty of land per person (about 1.15 acres per person on Earth). This average will only get worse since the number of people continues to grow and arable land continues to decrease.

This means that either the population has to stop growing or some means of increasing food production have to be found. With closed system aquaponics, an individual can use an urban rooftop, backyard Koi pond or even a basement to grow food. More importantly, it is a project that doesn’t require a lot of money or time to maintain.

What are the Basics of an Aquaponics System?

An aquaponics system can be set up in as small an area as you have, but you have to consider all of the elements of the system. The different types of material you can use will be discussed, but first let’s talk, in general, about what you will need. Basically, all you need is a place to keep the fish and a place to grow your food. Sounds simple right? Just hold on a minute though. Fish produce waste (the reason these types of systems are feasible) but that waste is toxic to the fish if there is too much gathers. The fish waste is used as food for your plants (that is after natural bacteria have turned it into plant-usable nitrates), but you have to keep the fish healthy by filtering out the ammonia waste and you have to keep the tank aerated enough so that they can thrive.

Many different varieties of greens and other vegetables/roughage can be grown in an aquaponics system but understand that the design of the system will dictate what you can grow. In a system from which you wish to grow simple salad greens and some tomatoes, you won’t need more than the fish can provide. For the home or hobby grower who is just wanting some fresh produce and an occasional fish, you can think small. But larger systems may require more thought. This article deals with the requirements for a small hobby aquaponics setup.

You will need:

• an environment in which to house the fish (a small outdoor pond, a large plastic container, or a fish tank),
• A tub, pots or other container to hold the plants,
• Plastic tubing that will be run from the fish tank to the grow beds,
• A small pump to get the water into the hydroponic growing environment,
• Fish,
• Plants.

This is very simplified because when you start, you will only want a few moving parts. An aquaponics system can get as complicated as you want, but there is no need to start out that way.

When first embarking an aquaponics project, start small. There is always time to increase the number of fish used or the number of plants grown, but to be successful you must make sure that your initial setup will survive. It is best to start with just a few fish (you can by more when your system is cycling efficiently) than to have the amount of ammonia and waste kill your first try.

Your first two decisions are do you want ornamental or food fish, and what type of plants do you want to produce. Perch are an easy food fish to grow (little maintenance, very hardy and taste great) or you can start with koi and/or gold fish. As far as plants go, it is important to realize that it may take a month for the natural bacteria to grow and make the fish waste palatable for your plants. Therefore, choose some greens (different types of lettuce) to start with. Fruit plants such as tomatoes and peppers take more nutrients and may not produce the way you want until the cycle is more established.

To set up the system, all you have to do is set up the fish space is use clean water, make sure it is properly oxygenated and buy a food you are happy with. There are many varieties of fish food depending on the type of fish and how many you are starting with. Make sure that the aquaculture environment is sufficient for the number of fish you have. Better to have too few than many.

After you have made the fish happy, start growing some plants. For hydroponically grown plants, all you need is a tub filled with small rock and a tray of your favorite varieties. The tub should be filled to the level of the rocks with water that will be filtered by the rock and the plants then returned to the fish tank. Remove the plants from their receptacles and with the dirt or compost attached move the rocks aside creating a hole and place the plants in the rock. Again, start small. The bacteria that break down the fish waste into usable nitrites will grow naturally, but it will take about a month for it to reach capacity.

When both receptacles are ready, use the associated hoses and pumps to attach the environments. One end will pump the fish tank water to the plants and a hose on the other side will take the filtered water back to the fish. If you want, the hose going back to the fish tank can be attached to the bottom of the plant receptacle and gravity fed into the fish tank.

Building a Better System

Above is an example of a simple system that can be used by even the most amateur farmer to grow both fish and plants. However, there are improvements that will help you grow better plants (especially the fruit plants) and more fish.

After your initial system is running efficiently, you may want to add more fish. In general, this step is only for those who want to grow the fish for food, but more ornamental fish can be added also. The problem with adding more fish is that you have to have a better means of removing the waste so that you can keep the added fish in the same amount of space. Of course you could just add a larger or more tanks to your existing system, but for the small operation, let’s just stick to the single fish tank.

You will need to either construct or buy a filter system through which the fish tank water can be recycled. The plants may not want all of the waste extra fish supply, and for the water to be sound for more fish the ammonia and waste have to be removed. Of course the effluent from the filter can be saved and used as fertilizer later on also. Just run the hose from the fish tank to the plant receptacle through a filter, or filter some of the fish tank water through a filter and then return it directly to the fish tank after it is cleansed.

The natural fertilizer produced by the fish may not be rich enough to grow the abundant produce you may want, but there is a way to improve and expand the nutrients the plants receive. Some farmers use coir as a medium for their plants (a much better filter than rocks) and then plant the plants in nutrient rich compost rather than dirt. This combination adds to the mineral levels the plants receive and allows them to produce more and larger fruit.

Besides improving the filtration and grow mediums, you can add tanks in series to produce more fish and plants, or you can use a small pond. If a pond is used, make sure that it is lined since soil can upset the balance you are trying to create.

Commercial Applications

Most people who use the aquaponics systems mentioned above will only be interested in this application as a hobby. However, there is the possibility of some commercial profit. Many growers turn to aquaponics as a means to preserve the environment. Up to 90% less water is used (since it is continuously recycled—the only loss being from a small amount of evaporation) and few or no chemicals need to be used to set up an efficient system. Thus, it makes since to assist the slow food movement by selling excess produce and fish to local markets.

Some small hobbyists have increased their systems to include as many as a thousand fish and a large amount of produce. Of course, the fish take time to grow as do the plants, but when harvest time comes it may be possible to share or reap a small profit. If this interests you, check with small local markets and restaurants to see if they would buy your extra produce and fish. The added funds may allow you to pay for your aquaponics system.

Conclusion

The world is changing and new technologies and means of growing food are necessary. Although aquaponics is not a new system, it is one that urban growers are just starting to utilize. It may not always be easy to get the fresh produce and protein from the local market that has previously been so available. By supplementing your diet with homegrown, urban food stuffs you are going to be a part of the solution.

An aquaponics system is really no more difficult to design and set up than the average fish tank, but is so much more rewarding. With just a few simple items (and at a very low cost) you can have a year round produce and protein source. You could also take that pretty little koi pond of the back patio and turn it into a simple means to grow your favorite vegetables. It can be a fun way to grow food for the family and show children the importance of thinking outside the box. With the current depletion of crop land worldwide, you will also help increase the amount of growing space that can be used.

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