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While peanut plants can absorb calcium from the soil, “They can’t translocate it down into the developing nuts — that’s why it’s important that the calcium has to be available in the top three inches of the soil," says Glen Harris, University of Georgia Extension fertility specialist.
ADEQUATE CALCIUM in the top three inches of the soil profile is critical for optimum development of peanuts.
If developing peanuts aren’t getting the calcium they need — in the pegging zone, where it really matters — yield and quality can suffer, says Glen Harris.
And an important step in providing that calcium, he said at the annual meeting of the Mississippi Peanut Growers Association, is soil sampling to determine what’s there and how much more may be needed.
Harris, University of Georgia-Tifton Extension professor of crop and soil sciences, notes that while peanut plants can absorb calcium from the soil, “They can’t translocate it down into the developing nuts — that’s why it’s important that the calcium has to be available in the top three inches of the soil.
“We recommend soil sampling to a three-inch depth, close to the plants after they’ve come up, to determine the calcium level and calcium/potassium ratio.”
Why is calcium so important to peanut development? “If there isn’t enough in the pegging zone to be absorbed into the nuts, you’ll get ‘pops’ (no nuts developing in the shell), pod rot, black heart, and poor germination,” Harris says.
Further, “If you’re producing peanuts for seed to plant the next year, calcium is critical for optimum germination of those seed. Research has shown there’s a very strong relationship between seed calcium level and germination. For a bare minimum 85 percent germination, you need 200 parts per million (ppm) to 300 ppm in the peanuts. But for really good germination — seed companies shoot for 95 percent or better — you need 500 ppm to 600 ppm in the seed.”
Harris worked extensively with cotton fertility before shifting more toward peanuts in 2008, when a major switch was under way from small-seeded varieties such as Georgia Green to large-seed varieties such as Georgia 06G.