What Does $500 Nitrogen Mean For Spring Wheat?

Nitrogen prices for 2006 are forecast at over $500 per tonne of urea. Hard red spring wheat prices for the 2006 crop have been hovering around $180 per tonne ($162 ^a plus $18 protein premium). Recommended nitrogen rates need to be re-evaluated based on higher N prices.

Two, 3 year projects looking at “Nitrogen Rates On Hard Red Spring Wheat”, were recently completed in eastern Ontario. This projects evaluated the efficient use of nitrogen in spring wheat production by assessing the yield, grain protein and economics at various nitrogen rates. One project also looked at the timing of nitrogen application. The Most Economical Return for Nitrogen (MERN) was calculated for each site. The MERN is the rate where applying more nitrogen will not produce enough additional yield to pay for the additional nitrogen applied.

Kevin Ferguson of Osgood, John Nanne of Pakenham, Cliff Pringle of Napanee, and several other farm co-operators put in plots with actual nitrogen rates of 0, 60, 90 and 120 pounds per acre (lbs/ac). At the Ferguson site, the project varied the N application timing and the N rates applied, as well as split applications of 30, 60, 90 lbs/ac at planting, followed by 30 lbs/ac applied at the “tillers formed stage” of the wheat (Zadok’s 22). Urea was used at most of the sites. Graph 1 shows the yield response to the four nitrogen rates applied at planting at the Ferguson Farms site in 2005.

 Graph 1 - 2005 GHG Nitorgen Rates on HRS Wheat

If N is $0.90/kg ($0.41/lb) MERN = 92 kg/ha (83 lbs/ac)
If N is $1.15/kg ($0.52/lb) MERN = 70kg/ha (64 lbs/ac)

Link to data table equivalent description of chart

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Reduction of 20 lbs/ac N

Over the three years and site the data from the project showed the MERN is about 90 lbs/ac at a traditional urea price of $420 per tonne. However, with the higher nitrogen prices forecasted for this spring, the MERN is 70 lbs/ac when urea is at $500 per tonne. This is a reduction of 20 lbs/ac of nitrogen.

No Improvement from Splitting Applications

The project showed that only a slight reduction in nitrogen required resulted when applying some of the urea at “tillers formed stage” of the wheat (Zadok’s 22) versus applying all the urea at planting. Split applications of urea did not reduce the MERN.

Consider N Credits for Previous Manure & Legumes

Fields with a history of manure or legumes crops have lower MERN values and nitrogen rates should be adjusted. While not perfect a soil nitrogen sample taken at planting to a depth of 12 inches, can aid in determining the nitrogen rate to be applied. At John Nanne’s site, the field has a history of manure and alfalfa in previous crop rotations. For this field, Graph 2 shows a MERN of 53 lbs/ac. The soil nitrogen sample was taken at planting and indicated that there was 55 lbs/ac. of nitrogen available in the soil to the wheat crop. Using the plant uptake value of 120 lbs/ac of nitrogen (2.1 lbs of N per bu of grain), then adjusting the rate by the soil nitrogen sample would have recommended (120-55)= 65 lbs/ac. This would give a saving of (90-65=25lbs N @ $0.52/lb) $13.00 per acre in nitrogen costs.

Graph 2 - Nitrogen Rates on Hard Red Spring Wheat

Link to data table equivalent description of chart

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Grain Protein

The MERN at all sites was sufficient to maximized the grain protein premium of 12.5%

Funding for these projects was provided by the Green House Gas program and the Ontario Soil & Crop Improvement Association.

Report by FARM MARKET NEWS, Ridgetown College from September to October

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