When USDA Researcher Wilson Faircloth began his recent presentation to the annual South Carolina peanut meeting talking about cutting back on irrigation water to improve yields, he got mostly blank stares.

By the time he finished his presentation there wasn’t enough time to answer all the questions about selected water stress on peanuts, called ‘prime acclimation’ by Faircloth.

Faircloth is a Research Agronomist at the USDA National Peanut Lab in Dawson, Ga. In 10 years of research at the USDA research facility near Albany, Ga., Faircloth says irrigation does increase yield — over a 10-year average.

However, in some years irrigation has little impact on yield and in some years, at the Georgia facility, it actually decreased yields slightly. In 2005, he says, a series of tropical storms produced an excess in rainfall and irrigated fields actually produced lower yields.

When peanut plants are stressed from lack of water, especially at key times in the growing season, yields can suffer dramatically. Again, over the 10-year test period in southwest Georgia, irrigation frequently improved yield by 1,000-1,500 pounds per acre.

The bottom line, Faircloth says, is that water is the limiting factor in crop production in the Southeast. He says the irrigation application rates and timing for peanuts and most other crops grown in the Southeast are out-dated.

In the Southeast, irrigation timing and application curves go back to when Florunner was the overwhelming choice of variety. As he and colleagues set out to update irrigation timing and amount guidelines they made some interesting observations about peanuts and moisture requirements.

“When peanut growers don’t have irrigation they are at the mercy of timely rainfall to get a high yield. With 100 percent irrigation, the same is true,” Faircloth says. Running an irrigation system costs money and if it doesn’t produce increased yield, then it costs more money, he adds.

“Fully irrigating peanuts, as we have been doing, according to our best available irrigation scheduling tool, is not our best economic choice. It became clear to us, that we need more precise timing and application rates to make irrigation really pay off year in and year out for peanut growers, he notes.

Most peanut growers grow other crops, especially cotton. Faircloth says the same principle of 100 percent irrigation not paying off applies to cotton as well as peanuts.