I'm sure other market gardeners have had soluble fertilizer get hard in the bags with time, making it very difficult to handle - especially if stored without climate control. Last year, we got Scott's 20-10-20 at a real good price and bought extra. We have 400#, in 25# bags, left over from 2010 and it's hard as ROCK - impossible to handle.
When it hardens a little, you can simply drop the bag on concrete, of course, and it breaks-up enough to measure-out and weigh. But this is way beyond that stage! It doesn't effect the fertilizer, though - thank goodness! (It's EXPENSIVE - and I'm the guy that bought extra
)
So here's how we solved the problem. We put the bag in a metal wash tub and cut the bag off, leaving a solid brick-hard block. Then we broke it into pieces with a hammer, and kept beating on it with the blunt end of a 2X4 until it approached it's original granular form (small chunks, like 1/2", are okay). Then we measured it into zip-lock bags in the sizes we use. If it gets hard in the small bags, no problem.
It dawned on me that the bags will be so convenient - no weighing, just dump it in the sprayer or injector - that we may always re-package it like that in the future, which will be easy when it's fresh.
I hope someone finds this uselful.
Jack