By Brad Haire
University of Georgia

A University of Georgia study has looked at the watering habits
of farmers in drought and rainy conditions for the past five
years. And the study shows they can vary widely.

Scientists working on the Agricultural Water Potential Use and
Management Program in Georgia gathered data monthly from about
800 irrigated fields in Georgia.

They gathered daily, automated data from about 180 of these
fields in the Dougherty Plain. That’s where much of Georgia’s
irrigation takes place, said Jim Hook, a professor with the UGA
College of Agricultural and Environmental Sciences.

The initial study began in 1999 and will end next month. But the
Georgia Environmental Protection Division has asked that it
continue another year. EPD funded the study with $250,000 in
each of the five years.

“We can compare data taken during four years of drought
conditions (from 1999 to 2002) in the state and one year of good
rainfall (in 2003),” said Hook, who worked on the study.

Less?

Data from the study shows that most Georgia farmers don’t apply
as much water as previously figured during drought.

They aren’t using water to go for the highest possible yields
for many crops, either, said Kerry Harrison, a UGA Extension
Service irrigation expert who also worked on the study.

In the mid-1990s, the Natural Resources Conservation Service
figured Georgia farmers would need to apply 18 acre-inches of
water in a dry growing season to give a crop optimal yields.
(One acre-inch of water is about 27,000 gallons, or the amount
in a typical swimming pool.)

But that’s not what Georgia farmers do, according to the
study.

The 2002 growing season was a severe drought in Georgia. The
corn farmers monitored that year in southwest Georgia applied,
on average, 13 inches of water to their crop.

Farmers in coastal Georgia applied 7 inches that year. About 20
percent of those studied applied 5 inches or less, 45 percent
applied 5 to 11 inches and 35 percent applied more than 11
inches.

“How much water farmers apply can’t be tied to one number,”
Harrison said. “These are averages. The study tells us that
irrigation management styles can vary widely for the same
crop.”

The 2003 growing season wasn’t a drought year. Corn farmers that
year applied, on average, about half the water they did in
2002.

“In the real world, farmers weigh the cost of applying water to
how much return they get from increasing yields,” Harrison said.
It costs about $4 to apply 1 acre-inch of water.

Study says

The study also shows:

• Over the five-year study, 30 percent of the monitored sites
  had vegetables grown on them.




• Farmers apply about the same amount of water to vegetable
  crops like sweet corn, tomatoes and peppers as they do to row
  crops like peanuts and cotton. But they often have two vegetable
  crops in one year.




• The average age of a Georgia irrigation system is 13 years.
  But 80 percent of systems in the study have had newer, more
  efficient water nozzles put on them.




• Farmers applied irrigation most often on Thursday. They
  irrigated the least on Sunday.