Aquaponics

I have been wanting to do a blog about this  topic since Natalie and I decided we needed to blog. You see in a previous life I worked as a fish facility manager. Once a week there was a farmers market downstairs and outside of our building. I never connected those dots.

When we moved to Iowa I came across a group Coalition to support Iowa Farmers. This group was actively providing educational resources and support for aquaculture in Iowa. They even hosted a conference in 2016 and another in 2017 on the topic. The conference was very informative and the networking was pretty good as well.

I also started paying attention to Practical Farmers of Iowa and looking at the regulatory picture for farms in general, livestock farms, vegetable farms, and organic farms. In a previous blog I mentioned going to events sponsored by these organizations. However there is no organization in Iowa that combines aquaculture and vegetable production. There are a couple of farms that do it.

So why combine them? As I see it you have the ability to produce ( with appropriate planning) enough high quality, organic, nutrient dense and healthy food on a smaller scale and with less environmental impact then traditional row farming. How?

The excrement from the fish becomes the fertilizer for the plants. The plants provide filtration and nutrient removal for the fish.  The end result is a cyclical relationship that poses unique challenges but also uses less resources then growing conventionally.

What do I mean when I say less resources? There are tanks and fish food and water and space. When compared to conventional farming aquaponics uses 85 to 90% less water than growing in ground. The reason is filtration and re circulation. The water from the fish is used to hydrate and to convey nutrients to plants which use very little water when you consider how much water is lost in conventional irrigation. Drip irrigation is more water efficient then overhead or flooding but still less efficient than aquaponics.  You do not need fertilizer as fish waste is converted to fertilizer by microbial action (fish waste is high in ammonia), which is converted to nitrites and then nitrates which are taken up by plants. The ammonia and nitrites are not fish safe so removing them is essential to growing fish. It is an example of one groups waste being another groups raw materials.

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The nature of aquaponics allows you to grow things closer as nutrient competition is removed from the equation and if designed appropriately light and ventilation is adequately addressed. You can grow more plants in a square foot of space than you can in the ground conventionally. Tanks are a cost but are more of a fixed expense than a recurring one. If they become recurring you need to really think about why your fish tanks are being abused so much. Water is an issue as it has to be of appropriate composition and temperature for both fish and plants.

Now that you have plants growing and you have your fish. As you harvest plants you can also cycle your fish and have a more healthy protein source. Tilapia is common but any fish can work as long as it is fresh water and it will grow at a temp appropriate for the plants you want to grow. I have heard people growing colder weather plants with cooler water fish successfully.

We will be constructing a small pilot aquaponics system in the future so stay tuned for that. This blog post is really just a primer for that post.

 

Doug

 

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