Land Minds: Additives, schmadditives

By Dick Hagen
The Land Staff Writer

May 09, 2008 03:13 am

— A special treat in listening to George Rehm — a longtime University of Minnesota Extension agronomist, now retired — is his remarkable candor.
Functioning as a soil and nutrient management specialist, Rehm still speaks at various agricultural events. Without the “political restraints” of being on the U of M payroll, he thrives on “telling it like it is.” Such was the case at a Barrier’s To Profit meeting in Marshall earlier this year.
“Every year at this time there are traveling minstrels who ride across the state extolling the praises of some new product, or new concept that is sure to unlock the potential for higher yields,” Rehm told the crowd. “This year is no exception.”
Reflecting on recent agricultural history, he labeled the 1960s to 1980s as the era when individual products were introduced into the farm market. In the 1990s fertilizer additives got the promotional headlines. From 2000 to the present, he spoke of “specific products for special situations” as the new vogue in “snake oil,” “fufu juice” and “woof-n-poof” products. Rehm definitely uses colorful words.
“For example, regardless the claims of ‘magic product A’, or ‘magic product B’, soil organic matter is still the best soil conditioner,” said Rehm. “Higher yields mean more organic matter. More organic matter means more nitrogen released into the soil. And that means a richer soil. It’s really that simple.”
Citing NaChurs 9-18-9 fertilizer, he said it’s a good product using orthophosphoric acid as the phosphorous source. A basic 10-34-0 uses polyphosphoric acid. “Poly converts to ortho in seven to 10 days so why should there be a difference? There isn’t and the 10-34-0 costs less,” Rehm said.
Naming off several fertilizer additives — including ACA, Awaken, Asset PPS, Amisorb, Remedy and Achieve — he indicated replicated plot work by U of M soil scientists shows no significant difference in crop yield with any of these products. “The University’s recommendation is still five gallons per acre of a 10-34-0 in a banded placement for maximum efficiency.
A newer candidate, Jump Start, may be a product with some value improving phosphorous release in calcareous soils, “but we don’t have enough testing. We’re still up in the air on Jump Start.”
Another fertilizer additive, Avail, is marketed with the concept that when mixed with phosphate fertilizer, Avail adsorbs soil calcium and magnesium thus there is less tie-up of phosphorous. “The chemistry is right. I don’t dismiss this product without more information. But it needs further evaluation.”
Nutrisphere, designed to be applied with either 46-0-0 or 28-0-0, is another “interesting piece of chemistry. The chemistry is in the right direction but it, too, needs more trials,” he said.
“Yes, there are new products out there. The concept behind some is legitimate. For others, there is no justification for the sales claims. The concept that there is an ‘ideal’ ratio among calcium, magnesium and potassium is most disturbing.
“The growing crop is not concerned about a ratio. The amount or concentration of a nutrient in a soil is the most important consideration. In other words, is there enough of a specific nutrient present to meet the requirement of high yields?
“If you are a grower and some adviser tries to tell you that your soil is out of balance, you should look for a different adviser. They often are critical of the Land Grant system. But they have no valid data to support the ratio concept. And there’s a reason they don’t have data — none exists,” Rehm said.
He noted that any crop-soil amendments in the commercial market:
• Must be registered with the Minnesota Department of Agriculture;
• That application must supply data to support the claims on the label; and
• Data must be evaluated before there is approval.
Perhaps a key reason so many of these “would-be” new products don’t get MDA approval is because of the scientist doing the approval for the MDA. Rehm is that scientist.
“If a product gets out that isn’t registered, the sheriff can padlock the warehouse.”
Rehm simply cautioned that as producers head into the 2008 cropping season, they should be careful. Nutrient ratios in the soil are not important. A belief in ratios leads to higher fertilizer costs. “Better to keep the checkbook in the pocket, or give it to the wife for safe keeping,” Rehm chuckled. “You’ve got to expect this stuff today because of the skyrocketing costs of fertilizer.”
He credited the better genetics of today’s corn hybrids for getting by with less nitrogen. “Because of better root systems, and traits that lessen stress conditions, that corn plant today produces more with less. The old thumb rule of 1.2 pounds N per bushel anticipated yield now sits at 0.8 pounds.
“Give today’s farmers credit, too. They know their soils, and their tillage. They know that one way to get more residual release of N from soil organic matter is simply to ‘stir that soil’ with tillage equipment. No-till doesn’t trigger that process, however.
“Last year in the Cannon Falls area a producer did 250 bushel corn with 150 pounds nitrogen on ground that had grown sweet corn the previous year. Yes, this was an irrigated field. And it was a near-perfect season. Plus the sweet corn was harvested early so there was more time for decomposition and mineralization of the residue.
“When it comes to soil fertility, our farmers today are doing more Best Management Practices than ever before,” said Rehm, who got in one more judgment: “Based on what we learned years ago about humic acid, we can forget about that one.”
It’s always a special treat to hear a former college professor tell it like it really is, especially when all of the political shackles are off and no longer tempering his comments.
George Rehm truly is one of those guys who likes to share “the rest of the story.”

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