What is in this article?:
• With foliar feeding, you either love it or hate it.
• Petiole testing is the best way to tell whether you need to foliar-feed cotton.
• A valuable feature of petiole testing programs is that weekly sampling tracks nutrient level trends and allows the detection of deficiencies or excesses up to two weeks in advance.
There aren’t many controversial subjects in the area of cotton fertilization, but foliar feeding comes close.
“With foliar feeding, you either love it or hate it,” says Glen Harris, University of Georgia Extension soil scientist. “People who love it say you don’t need to feed cotton through the soil, you can do it all through the leaf. And others say don’t bother feeding through the leaf because it doesn’t work.”
Harris discussed foliar feeding and petiole testing during the recent Beltwide Cotton Conferences in Atlanta.
“I don’t fall into either of those camps,” he says. “I fall in the middle. I think it has a place, but it doesn’t work all the time. I don’t think foliar feeding works all the time, and you can’t rely on it totally. It won’t work everywhere in every state — our soils are different in Georgia.”
Petiole testing, says Harris, is the best way to tell whether you need to foliar-feed cotton.
“The University of Georgia petiole testing program is a very complex one. We adopted it from Arkansas, and it’s a 10-week program. You buy a kit for $50, and it handles one field. You get 10 envelopes, and you start a week before bloom. You take samples from the field, fill out a card describing moisture conditions and other things, and they analyze it and come back with a recommendation. It’s very complex but very fine-tuned in predicting especially nitrogen and potash deficiencies and helping you to correct them,” he says.
In 1996, when Georgia producers grew 1.5 million acres of cotton, 800 petiole kits were sold, notes Harris. “That probably covered about 80,000 acres of that 1.5 million. That’s not a huge amount but probably significant in helping some people to foliar feed. Last year, eight kits were sold by the University of Georgia. So obviously, the petiole testing program as it currently stands is not being used.”