This is not a new regulation, has been in effect for at least several years. The DNR regulations (booklet or online) provide a definition for who is eligible, for what type of land (definition of "agricultural unit"). Basically, the land has to be used for agricultural purposes, and the landowner's tag can only be obtained by the operator of the "agricultural unit". The Iowa Code generally defines a farm as being 10 acres or more, and also contains a definition of agricultural commodities. The enforcement is probably going to depend on the feelings of your local DNR officer (and perhaps your demeaner). Some might feel that if hunting on the 10 acres of closely manicured lawn surrounding your house trips your trigger, more power to you. Others might be more rigid, in which case you might want to research the Code a bit (also available on line, although not quite as thrilling as looking through the Victoria Secrets catalog) before discussing with your friendly officer in an effort to pursuade him to adopt your point of view, and ask him to seek a second opinion from his superior if you're unsuccessful. Much cheaper to do that in advance, than later in court. Especially if it turns out that your interpretation was incorrect. (Phew, that'll probably occupy a whole page by itself).
[This message has been edited by GDCooper (edited 12-20-2001).]