To avoid chemical carryover on to organic crops and promote natural foods, establish zones of organic farming. Larger the better.
Designate geographic areas to transition to organic farming. (Possibly in areas with established Amish communities to start).
As area farmers retire, or sell property, require new property owner in the zones to use organic farm practices.
Subsidized Farm Transion
During transition, allow Hemp, or other suitable crop, to be planted to extract farm chemical residue from the soil for ground reclamation purposes. (Hemp used for non edible products, Rope, etc.)
Once residual chemicals have been adequately removed build the soil complex through a period of fallow years, using suitable crops.
Follow with 4 - 7 years of subsidized organic farming.