Aquaponics and Wasabia japonica
Pairing Aquaponics and Wasabia japonica sounds like a perfect match. Right?
After all fish grow in water, and Wasabia japonica grows in water.
Fish produces fertiliser, Wasabia japonica needs fertilizer to grow.
That though is where the similarities end.
This is the science (some people call it an art) of growing fish in one tank and then circulating that tank water through the roots of growing plants in another tank. Just like a swamp works. Easy, eh!
The problem with this simple explanation is that it doesn’t adequately describe what is going on.
Before you even start down this path, you must make a decision.
What is your main crop going to be?
Is it going to be the fish, or is it going to be the plants you are growing?
Main Crop = Fish
If you are going to concentrate on growing fish, with the plants being a catch crop then you need to find a freshwater fish that is in demand that grows fast. Most people use Tilapia or Prawns as the fish of choice.
Now you need to find a plant or plants that will grow in the nutrient rich soup produced by these fish. It doesn’t really matter what the plants are so long as they can use the same temperature water as the fish.
Also bear in mind that as the fish grow the amount of nutrients increase and changes, as does the Ammonia content and the pH. All of these need to be controlled within specified limits to maintain the health and growth of the fish.
The majority of growers prefer to use lettuce; tomatoes, cucumbers, pumpkin, taro or similar plants that grow fast and demand a high level of nutrients.
Main Crop = Plants
If the plants are the prime crop then everything above is reversed.
You need to use a fish that can grow at the temperature that the plants require.
The number of fish determines the nutrient level for the plants. Therefore, this must be carefully monitored if the plant requires specific growing conditions.
If the Main Crop = Wasabi
Now that you have some idea of the balancing act you must perform to get both parts of the Aquaponics operation to work properly we can look at the Wasabia japonica growing operation and Aquaponics.
Wasabia japonica grows in a specific range of low temperature water in the region of 12°C (55°).
Wasabia japonica requires a specific pH range to grow at all (slightly acidic).
Wasabia japonica requires a minimal amount of nutrients.
Wasabia japonica requires clean water with no sediment.
All of the above indicates that you are limited in your freshwater fish choice. One is Trout, and there are a few others such as Goldfish, Koi and Guppies.
The number of fish you can raise in one tank that supplies a Wasabia japonica growing bed has to be controlled to maintain the nutrient level at a point where the rhizome will grow. Too many nutrients will cause the Wasabia japonica to produce very large leaves and hardly any rhizome. If the Wasabia japonica grows too fast there will be no flavour when you grate the rhizome, or active ingredient if you process it.
Removing the sediment from the water must happen before being fed to the Wasabia japonica plants.
Finally, is there a market that will purchase your product at the price you need to at least break even?
Bear in mind that Wasabia japonica takes approximately 60 – 80 weeks to grow to a marketable size, compared to 10 weeks for lettuces, etc.
Of course, you can always set up a completely separate system for growing Wasabia japonica that uses some of the fish tank water. This will require that the water be filtered, pH and EC adjusted, and temperature controlled. Basically, you will need the same equipment and control requirements as if you were going to build a dedicated Wasabia japonica farm. The only saving is in the cost of the fertilizer so long as you control the Ammonia and Nitrate levels (see below).
There is no ‘normal’ pH in an Aquaponic system as such. The pH level will change over time depending on the system and how it is running. The system will not settle on a particular pH and stay there. This is why it is a good idea to test the pH at least once a week.
pH is a measure of the degree of the acidity or the alkalinity of a solution as measured on a scale (the ‘pH scale’) of 0 to 14. Technically it is a measure of the activity of the hydrogen ion (H+). The midpoint of 7.0 on the pH scale represents neutrality. pH 7.0 is called a ‘neutral’ solution and is neither acid nor alkaline. Numbers below 7.0 are known as acid. Numbers greater than 7.0 are known as alkaline.
The pH in an Aquaponic system should be maintained between 6.8 and 7.2.
Nitrification is the process whereby Ammonia in waste-water is oxidized to Nitrite and then to Nitrate by bacterial or chemical reactions. Basically there are Ammonia-oxidizing bacteria (AOB) that convert Ammonia into Nitrite in the presence of oxygen for energy. Then Nitrite-oxidizing bacteria (NOB) convert Nitrite to Nitrate in the presence of oxygen for energy.
While growing Wasabia japonica in an Aquaponics system is certainly feasible, the cost of doing so is likely to be expensive.
The success or failure of such an Aquaponic system hinges on both parts of the equation.
The Wasabia japonica takes a long time to get to a marketable size, and therefore the fish need to be fast growing with a sufficient demand that they are easily sold with a reasonable profit margin.
Furthermore, the cost of fish food, mortality rate (both of the fish and Wasabia japonica) and transport costs to the identified markets must all be factored in before committing yourself to building such an Aquaponics system.
It is the fast growing part of an Aquaponics operation that allows time and resources (money) for the slow-growing part to reach maturity. It is normally the slow-growing part that provides the profit.
Hopefully you found this article interesting and useful. If you would like more information on growing Wasabia japonica, then go to http://wasabigrowers.com/ and sign up for their FREE email Wasabi Growers Homework Course. This will give you more ideas about what you need to concentrate on if you really want to become a Wasabi Grower.