Farming used to be a good match for inmates who were on the farms, but in today's society we could use plumbers, welders, mechanics, chefs, warehouse operators and the like more than ex-con farmers. The system was useful but its time has passed or so says Craig Jones, executive director of the John Howard Society of Canada; certainly no antagonist to prisoners. http://www.cbc.ca/news/canada/ottawa/story/2009/02/25/prison-farms.html
I think training in a skilled trade of any sort outweighs the farm system of yesteryear.
P.S. My dad and uncle learned good skills in prison when they were very young, but the job skills have to match what employers are going to be looking for.
There is another system that Corcan has that produces office furniture which works pretty well that should be expanded, so that prisoners can work in all phases of the system; receivers, unloaders, cutters, etc. etc. all the way to the shipper of the finished product and many of the office staff. These would be skills and positions which can be transferred directly to a job.
I am a firm believer that prisoners should either be in the classroom, on the shop floor, or doing hard manual labour no laying around and wasting time watching tv or relaxing.