6-8-3 is pretty weak as far as fertilizers go. If a person really did need to add much N, P, or K, it would take a lot to get the job done.

I farm with a product that may be similar. Nutri-pack if I recall correctly. It does have some low levels of N, P, and K, but it isn't so much a fertilizer. It has some micronutrients in it and also an innoculant of sorts that helps promote mycchoriza formation and growth on plant roots.