They have moved locations due to the change in food conditions. Another factor that may have driven them away is the actual process of the farmer plowing the field (with the loud machines and comotion and stuff like that). You still may have a chance in that same field, but if you think that they are still coming to the border line of the property where the other farmers wheat is, then I would go and sit up that direction and see if you can get one to cross over to your side and then let him have it! Turkeys are weird though...they might acutally like the plowed up field and once they feel comfortable with the land again, they will return.