News Release
April  1, 2008

UW extension bulletin, spreadsheet help manage hay meadow fertilizer costs

Producers are probably looking at another year of record fertilizer prices, and even the fertilizer salesmen are a bit surprised at the levels, said a University of Wyoming Cooperative Extension Service (UW CES) educator.

Prices could be 30 to 40 percent above last year’s records, said Eric Peterson, who serves Lincoln, Sublette, Sweetwater, Teton and Uinta counties.

A bulletin describing pasture responses to fertilizer and a spreadsheet for producers to use is available online through the UW CES.

The reason for the increase is the dramatic rise in natural gas prices.  “Natural gas is an important input into the cost of fertilizer, and, while high natural gas prices are good for the state’s coffers, their impact on fertilizer prices provide ranchers a dilemma to consider,” said Peterson. “Will it make sense to fertilize hay meadows?”

High hay prices might justify using high-priced fertilizer.

 “In the realm of the plant kingdom, nitrogen is almost always your first nutrient restriction on productivity.  You will nearly always see an improvement in productivity when supplemental nitrogen is provided,” he said.

For native, improved, and grass-alfalfa mix forages, the normal responses to fertilizer, determined through a number of trials, are summarized in a UW CES publication titled, “Fertilizing Wyoming Hay Meadows: How Much Fertilizer Can You Afford?” available for download at http://agecon.uwyo.edu/agecon/whatwedo/publications/B828r.pdf. A spreadsheet performing the math of those economic analyses is available for download at http://fp1.centurytel.net/sublette/anr.html.

The law of diminishing returns will dictate when fertilizing is no longer profitable, Peterson said. When inputs are added, returns should increase until a point is reached when the inputs cancel out any returns.

“It is at that point the addition of resources ceases to be economically rational,” said Peterson. “The trick is in knowing the point at which you are no longer getting a satisfactory return on the investment.”

Plant agronomists pay close attention to a plant’s response to the addition of nutrient resources.  When a nutrient shortage limits the productivity of a plant, addition of that nutrient will generate a response.  Keep adding that nutrient, and the plant will continue to respond until something else begins limiting the plant’s ability to produce, said Peterson.

“As you approach the productive limits imposed by other limiting factors, the response generated by the nutrient you add will begin to level off,” he said, “so that the rate of return on your investment gradually decreases to nil.”

Agronomists determine and describe, in mathematical terms, this response.  “Team the agronomist’s findings with an economist’s calculations for marginal rate of return, and you can determine whether fertilizing will be profitable,” noted Peterson.

The UW CES spreadsheet accepts cost of fertilizer, value of hay, and the added cost of harvesting the additional production resulting from the fertilizer input. 

“When you run some numbers through the spreadsheet,” he said, “you’ll see that, although fertilizer is very expensive, the value of the additional hay you get from that input offsets the cost, making the decision to fertilize hay meadows a rational decision at reasonable application rates.”

John Hewlett, UW CES farm management specialist, has devised a series of similar worksheets employing fertilizer response projections for more than a dozen Wyoming crops.  Producers can run their own numbers by visiting the Farm Management Online Software Web site at http://agecon.uwyo.edu/farmmgt/software/.

“There are a great many variables that will enter into the productivity of a field,” said Peterson. “Some we can control or manage, and some we cannot.  One variable we can manage is soil fertility.  Soils are quite variable in their potential to generate or retain plant nutrients.  Soil testing is so inexpensive it is irrational to make fertilizer decisions, particularly decisions at the edge of the breakeven, without a fertilizer recommendation.  Don’t go without a soil analysis and report from UW.  Your county extension office can help you in taking samples or interpreting a soil analysis report.”

Online extension office information is at http://ces.uwyo.edu/Counties.asp. Soil testing information is at http://uwadmnweb.uwyo.edu/renewableresources/soil/soil_lab.htm.

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Contact: Steven L. Miller, Senior Editor
Phone: (307) 766-6342
E-mail: slmiller@uwyo.edu
Archived News Site http://uwadmnweb.uwyo.edu/UWAG/news.asp

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