I need to correct a zinc deficiency on 1,700 acres. The field soil tests indicate Zinc at .41 PPM, and recommends 5-8 pounds/acre of zinc sulfate, to be applied. Zinc sulfate is typically 35% Zinc. That would require 1.75 pounds of actual per acre. That is almost 3,000 pounds of Zinc. I neglected to price bulk zinc sulfate, and will do so today.
Foliar feeding would require less zinc, 1 quart/acre of 9% Zinc, or 0.23 pounds of actual. That requires 425 pounds of pure Zinc for 1,700 acres, if my math is correct.
1 quart of 9% costs $4.50, or $19.56/pound of pure Zinc, for a cost $7,650/ 1,700 acres. The 9 ingots, weighing 55 pounds each, cost $694. Possible $7,000 savings.
I under estimated the effort to convert the solid zinc into a colloidal solution. Today, I am considering purchasing zinc sulfate granular from the Co-op for this seaon's needs, as I need to begin planting in 2 weeks. I can work on the ingots for next season. Still, I'll obtain sulfuric acid today to do a test.