I think it would depend on a number of factors such as the lcoation, whether it is good land or not and whether the local farmer really needs it. I'd ask around to see what other farmers in the area are paying.
Try Daft... i just did a search for commercial lettings in Ireland and agricultural land and these came up.
well as far as i know and im from the country if its good land you could get anything from €140 up to €200 per acre for the year the better the land the more money you can look for. a friend of mine is getting €184 an acre for prime grazing land i hope this has been a help to you