A friend of mine who’s getting into home brewing has noted the following:
Yeast Nutriment is “food grade” ammonium nitrate. Miracle-Gro is (among other things) ammonium nitrate. He’s sure that the two are essentially the same on the supposition that anything that would hurt plants would also hurt us, and that the only difference is that YN has a “food grade” label (and a large markup) slapped onto it at the production plant.
Can someone run down what it is that makes Miracle-Gro not “food grade” and thus why it can’t be used in home brewing?