The other question is, what if you do not have the rocks on site? Transportation of tons of material is not free either. Neither is spreading it on field (labo

The other question is, what if you do not have the rocks on site? Transportation of tons of material is not free either. Neither is spreading it on field (labor notwithstanding). That said, if farmers are already putting tons of imported materials, this could be a matter of switching it up. But if it would be better just to not do this, the whole thing just starts to look silly and worth it only locally at best.