What is in this article?:
• In some years irrigation has little impact on yield and in some years, at the Georgia facility, it actually decreased yields slightly.
• In the Southeast, irrigation timing and application curves go back to when Florunner was the overwhelming choice of variety.
10 years of research
“Based on 10 years of research, we knew the water curves used by many peanut growers in the Southeast were outdated. So, some colleagues and I set about to update these guidelines to help growers make more profitable use of irrigation,” Faircloth explains.
The new guidelines are quite different from the old ones. First, water amounts are depressed during most times in the growing season. The new USDA guidelines call for more water during the first couple of weeks, then an extended lower use rate during the next eight weeks of the crop.
“When the crop gets into pod development and pod fill, we step up water and stay about the same as the old guidelines at the end of the season. Overall, our water usage guide calls for less water over the course of the peanut growing season,” Faircloth says.
Some work in west Texas led to a further refinement of the irrigation scheduling guidelines that is totally new and different from the past theories about water usage for crops.
Faircloth calls the new approach prime acclimation. Basically, it is the intentional use of drought stress to improve plant water use efficiency. He says the way flu vaccines work is similar to the concept. When a person gets a flu shot, they get a small dose of the flu virus, so their body is acclimated to the flu and better able to handle a naturally occurring case of the flu, he explains.
“We started looking at production in west Texas, where they often produce 6,000-7,000 pounds of peanuts per acre. Growers frequently complain about running out of irrigation water or having restricted water usage during the season. Yet, they seem to produce these high yields with what most would consider less than optimum water usage,” the USDA researcher says.
Faircloth showed the South Carolina peanut growers an aerial infrared photograph of a 120-acre west Texas pivot with peanuts growing under the irrigation system. The grower has 24 hours a week for peanuts to be under good water conditions and for 3-4 days part of the field is okay on water.
However, in half the field, peanuts are under moderate to severe drought stress. Then the drought stressed areas get irrigation water and areas of the field that had been in a good water situation and okay water situation go to moderate to severe water stress as the pivot moves away from these areas of the field.