Not sure about nvz or how long 6acre will last for at the moment looks like I need more cattle out in it to get over it for ploughing in the spring put another 6in yesterday after tb testing so got23 out now will make this do till the new year and se how things are going as for costing of the crop no how much it cost to grow it but not planning on comparing it to housed cattle just done it as have a shortage of shed space so needed to do something.