On Thu, 28 Nov 2002 08:25:06 -0600, Dean Hoffman
wrote:

It's because of center pivot irrigation systems. The irrigation system
rotates around a fixed point. The water and power supply for the system
attaches at that point. There are thousands of these sprinklers in farming
areas. The circles you're seeing are probably 1/2 to 1 mile across. Most
irrigation systems are set up to irrigate a quarter section. That size would
make a 1/2 mile circle. Crops ore planted in a straight line just as in
conventional farming. The perfect circle effect you see is just the watered
area. The crops aren't usually planted that way.
Irrigation is pretty common in states generally west of a line running from
the west border of Minnesota south to the Gulf of Mexico. The farther west
one is the drier the climate. The Front (eastern) Slope of the Rocky
Mountains is dry because the mountains block the rainfall.
Eastern Nebraska gets about 26" of precipitation a year. That's enough to
raise crops if the rains come at the right time. Crops usually stay green
all summer even if they don't produce much. You probably wouldn't notice
the irrigation systems from the air but they're here. Nebraska had about
6.9 million acres of irrigated cropland in 1997. Just under 63% of that
was irrigated with pivots. There's more pivot irrigation now as farmers
quit using less efficient methods.

Thanks for the reply Dean, that explains everything she asked me!

Cheers,


Aido