Glenn Lyford wrote in
rec.crafts.metalworking on Fri, 12 Nov 2010 08:03:46 -0800 (PST):

A lot of commercial farming is also done using a GPS, such as when
using a sprayer or broadcast spreader on a non-row crop where you want
to minimize gaps and overlaps (and thus over- or untreated spots)
without the reference points you get when dealing with produce grown
in rows.

In addition, the combines keep a map of the yeld when harvesting, and
then you can use that map to adjust your fertilizer. Saves from over
or under fertilizing any one area.
--

Dan H.
northshore MA.