Geotropism isn’t a term that’s tossed out in everyday conversation, and you can be forgiven if it sends you to the dictionary.
But Hamilton, Miss., peanut producer Don Self (see On the Selfs' Mississippi farm, it's wall-to-wall peanuts this year ) knows it all too well — it caused him to replant 379 acres of this year’s peanut crop.
“Basically,” he explains, “geotropism refers to the natural gravitational effect on plant growth — roots grow down into the soil, shoots grow up toward the surface. It’s something we take for granted, right?”
So, it goes without saying that he was more than a little astounded when he went out in early June to check on peanuts that he and his father, Dennis, and son-in-law, Hank Harrington, had planted earlier in May.
“It was a strange sight,” Don says. “There were a few peanuts that had broken through the soil, as you’d normally expect, but the stand was extremely spotty, and in places roots were poking up out of the soil. We dug some, and the peanut cotyledon — the shoot part of the plant that should’ve been growing upward — was growing downward into the soil, as if headed for China, while the root part was growing upward.”
It was when his consultant, Mitt Wardlaw, described the situation to University of Georgia peanut specialist John Beasley, that they heard the word ‘geotropism.’
“I laughed when he said that.” said Wardlaw, “ I thought Dr. Beasley was joking, throwing a big word at me. But he didn’t laugh back, so I knew he was serious.”
As they talked it through, the pieces of the puzzle fell into place.
“When we planted in May,” Don says, “the weather was hot. Then, we had a cold spell the first day of June; the ambient temperature was 58 degrees, one of the coolest on record for that date. But the soil temperature at peanut seed depth was still 70 degrees. The germinating peanuts were confused — the roots grew upward toward the surface, while the cotyledon/shoot part grew downward where the soil was warmer.
“We had only 1.8 to 2.2 plants per foot of row that were growing normally. We couldn’t hope to make a crop with that plant density. Dr. Beasley said the plants growing downward would eventually turn back upward, but we had no clue what kind of impact that kind of development would have on eventual yield.
“With GPS, we moved over six inches from the original planting and replanted 3.57 seed per row foot. At mid-July, the older vines had covered the young replants and it was hard to visually tell the difference in the plants. Dr. Beasley says with adequate weather the two plantings should be within 10 days of each other by harvest. We won’t know for sure until we dig.”
Crop insurance paid most of the cost of the replanting, Don says.
“Over the years, I haven’t been a fan of crop insurance, and have said many times it isn’t worth a flip for most of the losses we incur. I had to eat crow this time, but [he laughs] I’ve done that before — and I’ve got lots of recipes for crow.”