How to Grow Fruit Trees or Blueberries in Aquaponics
– by Colle and Phyllis Davis
Growing fruit trees with aquaponics requires having patience, being willing to follow instructions and being flexible in your choice of trees, fish and output. The main difference in using aquaponics to grow ‘fruit’ trees is that the equation shifts from extremely high value real estate (areas in gravel beds is valuable space when placed inside of a climatically adapted structure) to seasonal, outdoor controlled growing. Here are the main parameters that need to be addressed when considering raising fruit trees with aquaponics.
- Pollination. Bees do not do well at all inside buildings. Hand pollination is VERY expensive
- Which fruit(s) should you raise?
- What market is being addressed and can the fruit compete with regular ‘dirt farming’ methods currently used for growing fruit?
- What is to be done with the fish waste water when the trees are dormant?
- What training will the personnel need to have in order to make the aquaponics-fruit-growing-installation most productive?
All of these issues have to be addressed before looking at the land to be used for the orchard/vineyard for the fruit. For the moment we’ll assume that the go-ahead has been made to install an aquaponics orchard to raise apricots, a high value crop which does not ship well and is in demand in the local markets. Fruit that travel well (apples, oranges, lemons, and limes) and that can be stored for long periods are not good candidates for aquaponics because the installation costs are too high to compete with current growing methods. The other fruit this method covers well is blueberries, so you may substitute blueberries for apricots in the information below.
The first step for installing an orchard is to dig trenches on the contour across the slope of the designated orchard area. These trenches need to be 18 to 24 inches (45cm to 60cm) deep and the same wide with a 4 to 6 inch berm build up on each side to prevent ground water from entering the trench at any time. Then an impermeable membrane is placed covering the entire berm trench berm area to insure that no water either leaves or enters the trench. (Blueberries only need half the trench size.)
At one end of the top trench, install an automatic trip valve in a sump area and have it drain into the trench below so the water is flowing back across the slope in the next trench down the slope. This arrangement will mean the water travels from one end of the trench to the other, drops to the next level and traverses the slope in the opposite direction for each trench. The slope must be great enough for the trench to fill nearly full each time and then to drain out completely. The ideal slope is 1:6 up to 1:8, less or more slope requires some consulting time to design a functioning system.
Before filling the lined trenches with gravel, fill them with water first to observe that each automatic trip valve is working correctly and that each trench drains completely.
The next step is placing the gravel that has been to be washed and screened to remove sand, mud and debris into the trenches up to two inches below the top of the berm. The gravel needs to be level in all directions. Fill each trench insuring the pipe surrounding the automatic trip valve has no gravel inside of it.
Finally make sure the last trench drains completely into the fish tank/pond. Now it is the time to plant the trees (bushes) and install the fish into their new home. The choice of fish is much broader than it is with indoor aquaponics. Local fish can be used very successfully. Feed the fish what they will eat in 15 to 30 second once or twice a day after they are two to three inches long.
When the fruiting season is over, reduce the water flow through the system to twice a week and after the leaves drop only run the water once or twice a month to insure the trees have some water. In the spring, begin the water flow before the first thaw and before the leaves start to swell.
Now, here is a quick and dirty method. Cut several 55-gallon plastic drums in half, install a drain line with a shut off valve in the bottom so you can control the water level, fill with gravel, plant your favorite fruit trees and water with fish waste water a couple times a week during growing season and once or twice a month when they are dormant. AQUAPONIC FRUIT GROWING: DONE.
For commercial installations of orchard aquaponics please contact Portable Farms Ltd for more information and quotes on your specific requirements.