He's a very big contractor with all the gear!Its popular here. Theory about a subsoiling = big taproot = more yield. I'm a sceptic as never really seen any convincing trials that it is superior but if you have previously had wheat in and ploughed it then there may be no soil structure so it needs "lifting" as some like to call it.
At the end of the day though that's probably a contractor outfit so the farmer may only be paying £25 or so per acre for it