I have a small pasture with chickens and goats in it. I’d like to spray it for broadleaf weeds. I know there are some sprays that are grazable (Grazon maybe?) but we use the manure in our garden and flowerbeds. I’m concerned that we don’t kill good plants and vegetables with “digested residues” captured in the manure. Is there a spray that would break down eventually and allow us to use the manure?