Hi!
So- pesticides and other bad things of industrial agriculture - definitely a consideration and you will be playing land doctor. What are they growing around you? How are they applying these things? Aerial?
Tractor? Hand?
If it's by tractor or some other land application, a think hedge
should work. You will want to choose things that can stand accidental overspray and leaching etc. etc. and won't cause your neighbors to hate you. For organic certification in the US some sort of buffer like this is required. Same for some of the other certifications. Some people will use this for animal grazing for their own personal use.
If it's airplane spray....I don't know.
Many of the chemicals that will obviously inhibit plant growth will be done being affective in like 12 months or less from their application, but if the place was tilled, chem feritilized, and pesticided regularly, the soil quality will probably be pretty bad. Think cover crops of green manure might be your friend the first year. If you are looking for rapid production for animal fodder and relatively cheap seed, you may be able to/want to seed and harvest alfalfa for 3-5 years because alfalfa is a deep rooted
perennial nitrogen fixer that, once established, doesn't require much in the way of weeding. By the time that is done with it's life, your home front will be ready and your soil will have drastically improved.
Anyway, there's a lot of variety of ideas on how to get the land fit once degraded - alfalfa being just one in the heartland easily accessed. But in short-yes buffers are used for this purpose.