Well, here is my 0.02c (CDN) worth on the subject of DIY micronutrient
fertilizers: Fe 1.0, B 0.98, Mn 0.10, Zn 0.09, Mo 0.08, Cu 0.004 and Co
0.004. These values are are all compared to Fe which is added as an EDTA
chelate twice a week at 0.45 uM. Currently I mix up the stock solution so
that I need 0.5 ml per liter. I am experimenting with a 5x solution where
I would only need 0.1 ml per liter ... it gets tiresome mixing
micronutrients every few months. Unfortunately, this gets close to the
solubility of EDTA (0.1 M) so Im having some trouble dissolving the EDTA.
This mix was originally designed to grow duckweeds in the lab. Using it
(and other optimal conditions) Lemna trisulca would routinely double its
biomass every 2 days and at times every 1.5 days.
The chemicals for this type of mix are cheap. I estimate it costs
about 12 dollars to produce 4 L of a 5X micronutrient mix (1 ml per 10
liters twice a week). For my setup, this would last about 15 months.