Essential Elements

Inoculants, calcium and boron are the primary needs,
but don’t forget a proper soil pH.

By Amanda Huber

Peanuts may not need the amount of applied fertilization as required by many other row crops, but there are fertility issues to keep in mind. “When we think of peanuts, we think of needing an inoculant, plus calcium and boron,” says Glen Harris, University of Georgia Soil Extension specialist. “Soil testing is really the key.”

Because peanuts are a legume, the addition of an inoculant provides the nitrogen-fixing bacteria needed to supply the crop with that essential element. That leaves Phosphorus (P) and Potassium (K) from the big three.

“Peanuts are very good scavengers of P and K,” Harris says. “Put your money into maintaining the fertilization of other crops, and the P and K needed for peanut will be taken care of.”

Provide The Calcium
Calcium is an element that can be applied at two different times, but is essential to prevent pops and pod rot.

“The best way to know if you need calcium or not is to take a soil sample at cracking time,” Harris says. “Sometimes you provide calcium in the pegging zone and it doesn’t rain, and you still end up with pops or pod rot. But, you’ve still got to start out doing the best job you can providing calcium to the pegging zone.”
Harris says producers can apply gypsum or land plaster at bloom time or use the liming method at planting.
“Notice the timing,” Harris says. “The calcium in gypsum is very soluble, so you can use it at bloom time. But, if you are going to use the liming method, you have to put it on at planting because the calcium in lime is not as soluble.

“At planting, the lime is left on the surface and rain or irrigation moves it into the soil,” he says. “Liming really kills two birds with one stone: it provides the crop with calcium and also helps raise your soil pH.”

More Calcium For Large-Seeded Runners
Harris says for years the recommendation has been that Virginias and seed peanuts automatically got a calcium application. But now, there is a new category of varieties that are being called large-seeded runners.

“These large-seeded runners could benefit from a calcium application somewhere between what is recommended for normal runners and for Virginias,” he says. “For runners, the rate is usually somewhere around 160 to 200 pounds calcium per acre, which is about 1,000 pounds of most materials. For Virginias and seed peanuts, more like 2,000 pounds of material is needed to provide the needed calcium. So the large-seeded runners would be somewhere in between.”

Is Soil pH Right For Peanuts?
Boron is needed to prevent “hollow heart.” Boron deficiency is more likely on deep sands with higher pH. A soil test below .5 pounds per acre indicates a potential need for foliar boron.

Harris points out that soil pH is a critical factor and is important for nitrogen-fixation.

“A soil pH below 5.5 will get you into some problems and below 5.0, peanuts will die,” he says.

“Remember that N fertilizers are acidifying, so you have to keep in mind what happens to the field before you put peanuts on it.”