I think using the dirt that's already there and building the structure with some kind of machine would be cheaper than having someone mounting them on a steel r

I think using the dirt that's already there and building the structure with some kind of machine would be cheaper than having someone mounting them on a steel rack. See for instance large potato fields [0]. The point is instead of putting them on flat ground, make the ground have a better shape first. [0] http://www.thompsonpotatofarm.com/common-tater/banking-the-potato-farm-way http://www.thompsonpotatofarm.com/common-tater/banking-the-p...