I think it may depend on the crop and the insurance company.  Around here there has never been a question about whether you use fertilizer or even a herbicide program for wheat, milo, oats or barley.  Currently they have no idea if you fertilize heavy, light or not at all.  They may ask next year, but with past history and no new requirements from the government for their subsidized premium, I think it will be more of a insurance company, location, and crop decision than a blanket approach to all.

I've noticed when I submit a claim they ask a lot of questions about cropping practice, but the answers never have stopped them from paying.  Hate to think they are going to get that nosey.  Next they may ask for plant populations just to be sure you are trying to grow a good crop.