Are You Mining Your P and K?

January 19, 2010 06:00 PM

Pam Smith, Farm Journal Seeds & Production Editor
High prices for Phosphorus (P) and potassium (K) discouraged producers from applications over the past two years. Bring on a big yielding crop. Are you now wondering if you've drawn levels down too low?
University of Nebraska soil scientist Gary Hergert says 2010 fertilizer picture is shaping up as a good year to consider building P and K levels. "Prices for phosphorus are currently running under $330 per ton f.o.b. at many Corn Belt locations. Prices of 18-46-0 and 11-52-0 in western Nebraska are priced in the $400 per ton to $480 per ton range,” says Hergert.
World prices did increase about $50 to $70 per metric ton during late December 2009, Hergert notes, but these prices won't be reflected at dealers unless you are buying right now.  "Many producers have booked part or all of their fertilizer already and there have been some great deals ($375-$380/T for 18-46-0),” he says. "Prices now will be probably be in the $415 to $440 range.  You will pay a premium for liquid as it is running about $0.07 to $0.10 cents per pound of phosphorus higher than dry.  Some farmers are wrapping up purchases and may see somewhat higher prices, but still, prices are significantly lower than a year ago.”
Hergert says national fertilizer statistics indicates farmers bought less N, but quite a bit less P and really decreased K in 2009. "The Canadian K manufacturers saw that dropping P prices didn't stimulate sales early in 2009 and as a result, they were slow to cut prices of K,” he notes. "Eventually that decision held down potash sales significantly and prices have since dropped to $400/MT or less.” 
Farmers know they need nitrogen year in and out, but figure they can draw on P and K reserves for awhile since they do not change rapidly. They also know inattention to optimum fertilization is not a sustainable practice in the long run.
How much you apply depends on where your soil test levels are. Fall soil testing got put on the back burner when harvest was delayed for many growers, but it's still possible to soil test this spring. "If producers have yearly samples and they skipped or decreased P or K application during 2009, it might be reflected in soil tests,” Hergert says. "I say ‘might' as those levels decrease slowly.
"Also, the growers must have yearly samples of a given field to be able to compare. If levels are low, they should follow university guidelines for their state, while keeping an eye on overall budgets and crop prices.”

You can email Pam Smith at

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