My OH and I bought an acre of field a few years ago and part of that is now my raised bed veg area. Raised beds as the soil is heavy and silty and the top soi is very shallow due to farming cultivation depth, then a hard "pan" where the cultivation depth ends (Google this for a proper explanation), then very compacted sub-soil that drains badly. It depends on what your soil is like, but I'd dig a hole and see how much top soil you have and if there is any compaction there beneath from tractor wheels etc, then you can plan what to do. Potatoes break up the soil great as do leeks, though you will find that wireworms abound on farmed grass fields.