Try to use one that is more plant friendly than sodium chloride, like calcium chloride or epsom salts. Both of these are essentially fertilizers so kill two birds with one stone.
For something more long lasting (than salt, in rain) and common than diatomacious earth, you can use ground egg shells. This too, eventually fertilizer after enough acid rain dissolves it, but don't count on it being your primary calcium fertilizer (compared to burying it) because the decomp rate is so slow.
An old school thing to do is bury to soil surface, a tuna can full of beer. They'll crawl in and drown.