New larger-seeded peanut varieties — such as GA-06G, FLA-07 and Tifguard — have changed how growers think about calcium requirements.

“A peanut is fairly unique,” says Glen Harris, University of Georgia Extension soil scientist. “Being a legume, it fixes nitrogen, and it’s also a good scavenger of P and K. So really, as far N, P and K fertilizers, there’s not as much emphasis as with calcium. Calcium is needed in peanuts for yield, for avoiding pops, and for germination.”

For the past couple of years, says Harris, Georgia researchers have looked at peanut calcium nutrition and germination.

“The buzz words nationwide in fertilization for all crops are the four R’s — the right rate, the right time, the right place and the right source. With peanuts, we’ve concentrated mostly on the rate side, looking at rates mostly of gypsum. This past year, we started looking not only at sources but also at timing. We’ve talked about putting out lime at planting, gypsum at bloom-time, and exploring questions of how late is too late to put on gypsum, so we have different issues with timing,” he says.

With peanuts, “place” can be critical because you have to have soluble calcium in the pegging zone or the top 3 or 4 inches, says Harris.

“It needs to dissolve in water and get right through the hull to the developing nut. That’s why we’re looking at surface-applying most of these materials,” he says.

If you’re producing a peanut for seed, University of Georgia recommends that a grower put on 1,000 pounds of gypsum, no matter the calcium level in the soil. “If you’re using the lime method, we say use it at planting. And for everything else, we say you can take a pegging zone test. If you have at least 500 pounds of calcium, you don’t need to put gypsum on those peanuts,” says Harris.

Peanut yields definitely can be limited in low-calcium environments, he says. “We looked at Georgia Green as our smaller-seeded peanut and GA-06G as the larger seeded. In a very low-calcium environment, 271 pounds in the pegging zone, we see dramatic yield increases when we put on that gypsum.”