Estimated Nitrogen Release from OM

To our Valued Customers,                                                                 April 27, 2017

          Nitrogen requirements for next year's crop can be met from several sources, such as: residual nitrogen in the soil, fertilizer applied to the soil, manure residues, cover crop residues, organic matter, and other variables like lightning.  Estimated nitrogen release from organic matter can be useful in predicting the amount of nitrogen available for next year’s crop. 

 We have updated our estimated nitrogen release to 11.2 pounds per acre of nitrogen per percent of soil organic matter.

 In the Canola Watch March 17, 2016 edition they state the following:

“Mineralization of soil OM will provide available nitrogen to the crop, but the amount varied widely based on soil type, soil OM levels and moisture. In general, OM can generate 6 to 30 pounds of available nitrogen per acre for each percentage point of OM. Rigas Karamanos, a soil scientist with decades of experience in western Canada, uses 14 lb./ac. per OM% and that of that amount, only 80% is available to the crop that year. Using Karamanos’s number, soil with 5% OM will supply 56 lb./ac. of N through the growing season (5 x 14 x 0.80 = 56). He adds that with more than average moisture, mineralization can increase by up to 25% and in drier conditions, it can be 25% lower”    

Alberta Agriculture and Forestry published a document that was last reviewed/revised on January 20, 2017 stating that the “Potential mineralization rates ranged from 0 to 20 mg N/kg in southern Alberta but rates were over 20 mg N/kg in central and northern Alberta.” These convert to 40 pounds per acre on dryland and higher in areas with more sufficient moisture and better conditions.$department/deptdocs.nsf/all/aesa8891           

Due to the possible 25% reduction in N release estimated by Rigas Karamanos and the differences seen between dryland and irrigated fields from Alberta Ag, we will continue to place a cap on our reported estimated Nitrogen release.  Our ranges will cap at 40 lbs/acre for dryland and 60 lbs/acre for irrigated fields.  Please note that this cap will be 5 lbs/acre lower than we had previously used.

The estimated nitrogen release value is provided for your information and is not included in our fertilizer guidelines, however, you are welcome to use it as you see fit.

If you have any questions, you can contact us for more information.

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