It is now pretty common understanding that "living cover"--making sure that something is always growing and taking up nitrogen on our farm land--will be a big part of the solution to our ongoing ag-related water pollution problem. "Cover crops"--planting something either after the corn/soybean harvest or essentially between the rows--is an old tool that needs to make a major comeback. Happily, research at the U and other places is breaking down whatever technical barriers might exist and even showing how farmers can earn additional profits from certain cover crop choices.
We know, of course, that there will be resistance to change no matter what, but the opportunity for farmers and researchers to work on this together is a reason to be optimistic. Here is an MPR report on that.
That is not to say that, without public policy drivers, the problems will solve themselves. Living cover needs to be a standard that farmers need to comply with to qualify for federal farm bill assistance, it already is a requirement for state certification for water quality, and it ultimately needs to be an enforceable water quality standard for all agricultural producers.