Hey don't get me wrong ,It works and most farms are using it here but we farm several thousand acres owned and custom and straight lines are never an issue and overlap is not a problem because i tramline ,My problem is justifying the cost ,I am not alone ?...And we get free soil tests done on every 10 acre square block of every field every year (From local fert supplier) if requested ,It takes 24 hours to do the whole farm and find find no need to increase or reduce fert that often ,We achieve the same yeilds as my good friends next door who farm 10'000 acres on a high tech round the clock system ,I know this is fact because they are good friends and we spend a lot of beer time in the winter ,The only reason they use it is they can minimise machinery ,10'000 acres,2 combines ,3 tractors and 2 trucks and they have a SP sprayer ,And they run most of their work in the dark ,I have a hardi 1000 gal pull type and there is 5 of them ond 2 of us ,Is cost not an issue any more ..