Can I apply ProGibb through solid stream nozzles?

No. These nozzles are designed to apply liquid fertilizers that are primarily taken up through the plants root system. ProGibb is absorbed by the leaf material of the plant and therefore needs to be applied evenly over the pasture surface. Solid stream nozzles will give a very patch response to ProGibb. Any boom spray suitable for herbicide applications will be suitable for ProGibb.