Nutrient Supplementation in Certified Organic Commercial Aquaponics

[Michael Brooks]

I co-manage a large USDA Certified Organic Commercial Aquaponics Greenhouse in North Central Indiana. Total volume of  this system is approximately 140K gallons that is divided into a pair of 70K gallon deep water raft cultures. Can anyone share their opinions on where a good starting point might be when supplementing systems of comparable volume? How much Iron would you introduce initially before monitoring any change? Calcium? Potassium? Mg? Is it important to have an extremely slow drip when introducing nutrients into a system of like size? Or can I let the solution in at a higher rate because of the size? Thank You. You can see my system on FB at /green river greenhouse or on our website at www.greenrivergreenhouse.com.

[Vlad Jovanovic]

Hi Michael,

In order for you, or anyone else to answer your questions regarding quantities/weights of particular amendments...we'd need to know some things...

1) Total system water volume. (This value is known, since you stated 140K US Gallons)

2) Your target PPM value for a particular plant essential element (this will largely be determined by the type of plants you grow)

3) The elemental composition of the supplement/item you are adding (atomic weight, divided by molar mass, multiplied by one hundred)

4) The baseline values (BEFORE you start adding supplements) of all those plants essential elements.

About $80 and a laboratory ag/irrigation water analysis should provide you with really good picture of where your system water stands in terms of composition (essential elements...and some other useful values...). For an operation your size, there is no reason not to have your water professionally analyzed FIRST so that someone can help to answer your questions in a meaningful way. You can PM me if you still desire help with the above questions (specific to your system and it's water chemistry)...

Nice looking system btw,,,I read your cover story in ASC magazine...nice work. Glad you were able to successfully modify and mitigate the design flaws that you guys inherited from the previous owners. Glad you folks are trying to make a go of it.

Good luck!

[Michael Brooks]

Thank you Vlad, first for your kind words concerning our efforts to make things work despite a shaky starting point, and then for your answer regarding my initial question. We have since figured everything out - at least to a degree of feeling comfortable - and we did do a lot of the same things you recommended. I will absolutely keep you on my list of contacts. I appreciate your offer to help us. Have a wonderful day, and happy growing!! 
Vlad Jovanovic said:

Hi Michael,

In order for you, or anyone else to answer your questions regarding quantities/weights of particular amendments...we'd need to know some things...

1) Total system water volume. (This value is known, since you stated 140K US Gallons)

2) Your target PPM value for a particular plant essential element (this will largely be determined by the type of plants you grow)

3) The elemental composition of the supplement/item you are adding (atomic weight, divided by molar mass, multiplied by one hundred)

4) The baseline values (BEFORE you start adding supplements) of all those plants essential elements.

About $80 and a laboratory ag/irrigation water analysis should provide you with really good picture of where your system water stands in terms of composition (essential elements...and some other useful values...). For an operation your size, there is no reason not to have your water professionally analyzed FIRST so that someone can help to answer your questions in a meaningful way. You can PM me if you still desire help with the above questions (specific to your system and it's water chemistry)...

Nice looking system btw,,,I read your cover story in ASC magazine...nice work. Glad you were able to successfully modify and mitigate the design flaws that you guys inherited from the previous owners. Glad you folks are trying to make a go of it.

Good luck!

[Scott Roberts]

If you want to keep that organic certification you will have to have water tests performed any time that you want to add micronutrients. 

Technically, NOP requires there to be a deficiency before you supplement, but I've been told that a letter from a crop advisor stating that the plants you are growing require X.XX ppm iron, X.XX ppm boron, etc to perform will suffice.

But, before you do anything - update your organic system plan! Talking to your organic certifier is the easiest way to make sure things go smoothly.