Applying fertilizer in late November or December is ideal for smooth bromegrass fields, as long as the ground is not frozen or saturated, said Dave Mengel, K-State Research and Extension soil fertility specialist.
Late-fall fertilizer applications will generally lead to earlier spring greenup and greater forage production than spring fertilizer applications. As nitrogen fertilizer prices have risen while hay prices have remained relatively flat during the past year, producers may want to reevaluate the rates of nitrogen used for bromegrass hay production, Mengel said.
"Traditional recommendations for hay production have been to apply 40 pounds of nitrogen per ton of expected hay yield, or about 80 to 160 pounds of nitrogen per acre to unfrozen ground, according to the field´s productive capability," he said.
With nitrogen fertilizer costs having increased, and hay prices remaining fairly constant, many farmers are questioning how much, if any, nitrogen fertilizer should be applied to bromegrass this winter or next spring. To answer this question, Mengel said he evaluated the results of more than 100 experiments conducted in Kansas since 1975 on the response of bromegrass to both spring and fall-applied nitrogen fertilizer.
Using a price of $0.80 per pound of actual nitrogen and $60 per ton as the value of hay, the soil specialist calculated the appropriate nitrogen rate this fall to maximize returns would be between 60 and 70 pounds of nitrogen per acre -- not the 120 pounds of nitrogen normally recommended for 3-ton hay production.
"While yields will be lower, the economics of using reduced nitrogen rates are much more attractive. But keep in mind that nitrogen prices are volatile right now, and if they drop significantly, nitrogen rates should increase accordingly," Mengel said.
One issue these calculations don't consider is hay quality, he added. Protein levels will drop at the lower nitrogen fertilizer rates.
"So where producers are relying on high-quality hay as their primary protein source, they may want to push nitrogen rates a little higher, or be prepared to add supplemental protein to rations," he said.
If the bromegrass pasture will be grazed instead of hayed, the adjusted recommendations also call for about 60 to 70 pounds of nitrogen per acre, he added.
For phosphorus or potassium recommendations, a soil test is needed. Smooth bromegrass will respond to phosphorus in combination with nitrogen when soil test phosphorus levels are below 15 to 20 parts per million.
More information is available at county and district K-State Research and Extension offices and in the K-State Extension publication C402, "Smooth Brome Production and Utilization," on the Web at: http://www.oznet.ksu.edu/library/crpsl2/c402.pdf.