"Talk to a farmer about his square 160 acre field and we want to put a circle in it, [he says,] 'What are we going to do about the corners?' Well, we can't do anything about the corners. That was in the beginning. Today we can certainly solve that problem because we have the means of putting an attachment on the end of a typical system. It will swing out and retract as the system goes around so that the corners are covered. Well, the problem with that is that arm that swings out and all the equipment that goes with it is quite expensive. So, farmers don't generally buy those unless they are growing valuable crops. And some crops like potatoes, as an example, where you're talking somewhere between $2- and $3,000 per acre. Then, it makes sense to put on a corner system. And so, it depends on, really, the value of the crop that is being grown as to whether it's economically practical to put in a corner system…
     "We use a buried wire that sends a signal, so to speak, to the drive unit on the end and it tells it when to go in and when to go out. So, that's how that's done today. We've tried other means, but the buried wire is the one that's been used in most corner systems."

Robert Daugherty – Making Circles Square


Other Excerpts from Robert Daugherty’s Interview:

Omaha Stockyards
The Impact of Pivots
Early Days of Valmont
Pivots Go Worldwide
Installing First Systems
Making Pivot Systems Work
Valmont's Patent Expires