It's a major undertaking to switch from conventional to organic farming. Much more labor intensive, can take a few years for pesticide residues to dissipate, not even possible in some location due to neighbors. Not something most farmers are in a position to do, at least for their entire acreage.
Pioneer and some other company I can't think of right now seem to be the main seed companies around here, not Monsanto. And central Kansas is definitely farming country.