Alfalfa U speaker Curt Woolfolk went back to the basics during his session on fertilizers Feb. 21 at the event in Dodge City, Kansas, sponsored by Alforex Seeds, John Deere and High Plains Journal.
“Whenever you talk about soil fertility, you kind of need to start off with basics of crop nutrients,” he said. Woolfolk is the senior agronomist for Western North America for The Mosaic Company.
There are 118 elements on the periodic table, and Woolfolk said only about 14 percent of those are relative to crop and plant nutrition. There are only 17 essential elements agronomists and growers need to be concerned about.
“It doesn’t matter if it’s the wife’s house plant or alfalfa under a pivot, we have 17 essential elements,” Woolfolk said. “And the carbon, hydrogen and oxygen.”
In terms of carbohydrates and cellulose, agronomists and producers don’t think about these nearly as much or spend time managing them, unless there’s a problem and something needs addressed.
“We may never manage the carbon, hydrogen and oxygen, but for all practical purposes, we have six macronutrients and eight micronutrients,” Woolfolk said.
As part of Woolfolk’s job on the agronomy side of Mosaic, his goal and objective at new product development is to bring new fertilizer products to farmers. For example, dry granular fertilizer products use primary macronutrients for the six macronutrients as a carrier for micronutrients, he said.
“Typically when we talk about macronutrients, we’re talking about pounds per acre,” Woolfolk said. “When we talk about micronutrients, we don’t call them micronutrients because they’re less important. All these are essential to crop production. We call them micronutrients because we needed a much lesser amount, ounces per acre, rather than pounds per acre.”
Woolfolk is constantly looking for ways to take phosphorus and put zinc or sulfur with it.
“How can we build a granular fertilizer that combines a bunch of nutrients?” he said.
Digging a little deeper, he posed the question, “What do you feel like is limiting your alfalfa production?”
The elephant in the room,obviously, is water and irrigation, he said. What about soil pH?
“The point of the conversation here today is balanced crop nutrition,” he said. “We understand Mother Nature drives our production in western Kansas.”
Once past the obvious, how is the crop nutrition plan tweaked to best fit the alfalfa?
“So aside from pointing out 17 essential elements, we need to address another obvious number—soil pH. What pH is optimal for alfalfa?” Woolfolk said.
Geographies vary wildly when it comes to the optimum level, and many books and guides say 6 to 7 pH is prime. There’s a wide variety of levels according to Woolfolk.
“For a lot of us that doesn’t work,” he said. “We have 7 at my farm. We have a lot of calcium carbonate in our soil, almost higher pHs. And we can still have these in production.”
Woolfolk said alfalfa producers need to understand soil pH and what it does with certain nutrients. As pH rises, calcium gets higher too and consequently ties up more phosphorus, which leaves less available to the alfalfa as the soil gets more acidic.
“Remember less than 7 is acid. Greater than 7 is more alkaline,” Woolfolk said. “Less than 7, we start running into more iron issues. And if you’ve ever grown soybeans or for another crop, you understand that iron chlorosis can be the issue for something like soybeans.”
There is a little bit of wiggle room on alfalfa, but maybe not as much for other crops. However, the farmers with soil pH levels at 8 or higher have fewer tools available to them.
“How will we adjust our pH from 8 now to 7 or 7.5? Good luck. It’s not going to happen in my lifetime,” Woolfolk said.
Some people say to apply “tons and tons” of elemental sulfur to the soil and it will reduce it, but it’s only temporary.
“You’re not going to change the overall soil pH,” he said. “It’s like adding a dropper of colorant into a big ocean. You’re making a minuscule difference in the grand scheme of things.”
If the soil is acidic there’s more that can be done by adding lime to the soil.
“Right now, ideally, alfalfa likes that 6.5,” Woolfolk said. “But 6.1, I’ve seen a lot of phenomenal production at 6 to 6.1 pH. That’s not super problematic.”
Once the soil is headed in the right direction, alfalfa production can be increased.
Kylene Scott can be reached at 620-227-1804 or email@example.com.