These are my costs, in bulk of course:
Southern Excelence: 20 lbs, phosphorus = 46, so 920 units of P at a cost of $18, so $1.96 per 100 units of P
Trophy Maker: 25 lbs, P = 62, so 1550 units of P at a cost of $20, so $1.29 per 100 units of P
Liquid: 12 lbs, P = 37, so 444 units of P at a cost of $1.50, so $0.34 per 100 units of P
I thought that cost per unit of phosphorus would be the most useful, as that is the limiting factor we are trying to increase.
All of these costs would be about double for retail sales of these products.
These costs don't include time or equipment. Liquid requires the most time, first to obtain the product, break it down into 5 gallon containers, then apply it, which can take a while. It also requires the most equipment.
It seems to me that SE has the advantage of time during application over water soluble powders, but you still have to pick up and dispose of the bucket. It's probably a wash either way, just which one is best for your particular application.
For me, the water soluble powder is looking fairly competive with liquid when the elements of time and equipment are considered.
