I've seen the same around larger towns my way, but in my instance, I dare say that ground is not farmed as it has been purchased by developers as a buffer or merely the remainder of a larger parcel of land they needed to buy to complete their project. Also depending on regulations might be dumping excess materials from footings of buildings as well as bulk dirt from dressing or cleaning up a building site.
From time to time some people do try to utilise ground that is right beside their own property even if it's just becomes a larger garden ... from what I see of it, a lot of the time it doesn't work out.
Unless you can buy this land cheap or rent it at a fixed rate long term five years minimum, ten is better, I think you'd be wasting your time. The #1 problem people who might do this on the hand shake of the land owner / company director(s) would run into is realisation. Realisation occurs when your efforts prove there is or look like money to be made, and attitudes shifts to where the land owner would like a bigger cut or simply insist it was only for a year or two and you should leave.
If you can secure the land via a rent agreement, then they next challenge is matching a crop with the climate ... then with the soil quality.
