How Do Plants Get Nutrients in Aquaponics.
// Murray Hallam's Practical Aquaponics
The primary source of plant nutrient in an Aquaponics system is the fish food. The beautiful thing is that the fish food is a one source of nutrient for the plants and the fish, a very important principle in working towards sustainability.|
Two uses from the same resource.
It is therefore important to choose a good quality fish food to feed your fish. There is no magic happening in the body of the fish whereby it can mysteriously produce a full range of plant nutrient from a poor input for it's own needs. It is basic logic that a good quality, balanced fish food pellet will serve the overall Aquaponics system very well.
However, there are three elements that do not come into the Aquaponics easily from the fish food input.
1 Potassium, 2 Calcium, 3 Iron.
Happily, we can supply the Potassium and Calcium to the system when adjusting the system pH upwards. As you would know, the natural state of affairs in a well found Aquaponics system is that the pH is always slowly drifting downwards, so there is a need to adjust the system pH upwards periodically as required.
Iron is added in the form of Iron chelates as required when the plants exhibit some iron deficiency or on a regular basis , say once every three months.
A good way to provide all the micro nutrients the plants require is to make sure you are running your system with the incorporation of some media beds. Media beds provide a wonderful environment for the development of what I like to term, a "Nutrient Bank". Over time we find that there is a build up of fine solids in the media beds, we find that worms take up residence, or we add them. The worms do what worms do to all organic material. They move about in the media bed and process the solids collected there. The solids are reduced in volume by up to 80% by this process and locked up nutrients are released.
Additionally, and very importantly we make good use of our own home-grown compost teas. Every Aquaponics gardener should become a master composter. The compost tea so produced provides a myriad of plant nutrients for the system. Compost tea has other important uses in our Aquaponic garden…..but that is the subject of another post.