There seems to be no moral issue with this. The least they can do, if they are in prison, is do some work. The only problems i can see with this is keeping them in the field, or tampering with the food. Maybe somehow this will lead to prison colonies, where prisons can be self sufficient, but i dont agree with that, because that could lead to security issues and integration problems. Maybe if we let minor offenders/ non-violent criminals be able to work, but the harsh guys, like rapists and murderers... i dont know if they can be let out into such an open area. Another problem that comes up is land usage. how much land does it take to grow enough food to support a supermax prison? probably a lot. It may end up costing us more than we think it will save us.