If it were me, I would hold on to the chemical fertilizers and use them sparingly on my regular crops when they seem deficient in something, or if it's a bad year, or as a quick fix on a patch of infertile soil while waiting for organic methods to build fertility. It's not ideal, but small amounts once in a great while shouldn't disrupt the soil ecology to the point it can't rebound and I wouldn't use
enough for runoff to be a concern. For me personally, I feel like "waste not, want not," and fertilizer (not pesticides) is only toxic with repeated application and in the quantities the industrial farms use. Plants don't know the difference between nitrogen derived from petrochemicals or the cleanest, sweetest
pee of vestal virgins.
It's not a
sustainable long-term strategy for food production, but the material already exists in your possession, so might as well use it responsibly to get a direct yield rather than laundering it through non-edibles.