Band vs. Broadcast Fertilizing?

A few months ago I bought an old 2 row planter, to plant sunflowers, milo, corn, etc in the field. I had been broadcasting the fertilizer and seed, then disking it all up in the previous years, but I had quite a bit of pigweed that came up.

This year I am going to apply a preplant herbicide to control the pigweed, and plant the sunflowers in 30" rows.

The row planter is missing the fertilizer boxes, but it has the mounting brackets, sprockets and other hardware.

I did a little research, and band fertilization is good when soil is relatively cooler. Since the roots are growing slower the nutrients are right there. I have to plant some time in April in order for the plants to be ready by Sept 1. When I planted in early May, the sunflowers were still green and not mature when dove season started. The average high temp near the end of April is 71 degs, the average low is 47.

Questions:

Will band fertilization be that much of significant benefit for a dove field as opposed to broadcast fertilization?

Any ideas on how to fabricate something to apply the fertilizer in bands? I thought about a couple of short piece of 4" or 6" pvc mounted on the frame with a small funnel on one end of each, and then running 2 plastic tubes from the funnels to where the furrows are. basically something that would look and function like a gigantic hourglass that's been cut at the narrow portion and has the plastic tube where it's been cut in half. Bagged 12-12-12 is in little round uniform pellets, and I'm thinking that it would flow easily through the funnel. Fertilizer from the co-op is in larger pellets and they often have clumps or clusters of the pellets. Potash looks like rock salt, it's rectangular shaped. I don't think anything from the co-op would work very well because it would clog up the gravity feed.

Any other tips or advice you can give me would be appreciated.

I have a 15 gallon spot sprayer tank with an electric pump, but it pumps at 1 gallon/minute which is probably too much. I could maybe use two nozzles to spray the liquid into the two furrows, and then have another nozzle or discharge tube back into the 15 gallon tank. Part of the fert that is pumped gets applied in the band, and the rest goes back into the tank. That would solve the 1 gallon/minute problem. Does this sound feasible?

I wanted some liquid N this past spring, some can fill containers, some sell 5 gal pails, some don't want to bother as their pumping just too fast. I found the best source was a farmer on a rainy day, most have a graviety system that can fill small containers.

Thanks for the advice Hugh.