Alberta Grains wanted a tool to help growers understand the possible economic returns of various nitrogen (N) fertilizers and crop prices. This N Rate Calculator, developed by Rigas Karamanos, Ph.D., P.Ag., FCSA, for spring wheat and feed barley, can be used to evaluate different net return per acre scenarios which compare different N sources and costs, various crop prices and soil test N levels (nitrate-N in lb/ac to 24").
For more resources, see links below:
Use the tool to select and change fertilizer source, cost, crop price, N fertilizer rate and soil test N. The calculator determines the N fertilizer amount with the maximum net returns.
Fertilizer Type and %N: The N source is entered by the user, stating the fertilizer type and the %N i.e. urea = 46-0-0 = 46% N, i.e. ammonium sulfate = 21-0-0-24 = 21% N. i.e. anhydrous ammonia = 82-0-0 = 82%.
Soil test N (0-24"): Soil test nitrate-N in the 0-24" sampling depth from your soil test report. This is entered by the user.
Input the increments in which you wish to view calculator results.
Planned nitrogen applciation (lb N/ac): The rate of N fertilizer recommended on your soil test report from a soil test lab (which may or may not be based on economics) or the decided plan based on soil tests and yield expectation of the grower.
Note: To recalculate results adjust the values in the inputs above, and then click "Calculate".
| Expected CWRS Wheat Price | ||||||||
|---|---|---|---|---|---|---|---|---|
| N Rate | Yield Increase from 0 lb. N* |
Net Return ($/ac.)** | ||||||
| CWRS Wheat:N Price Ratio | ||||||||
| (lb./acre) | (bu./au.) | |||||||
Planned N Rate
Expected price to receive for each bushel of grain ($/bushel)
*Calculations are based on the premise that an "ideal" fertilization program results in 30 lb N/acre residual N in 0-24" depth Current N rate from your soil test report or common practice.
**Net Return = (Expected CWRS Wheat Price *Yield Increase) - (Cost/Unit of N*N Rate)
Net return in green represents maximum for the CWRS Wheat: N Price Ratio range in this table.
Net return in yellow represents CWRS Wheat: N Price Ratio range within $1.00 of maximum in this table.
Equals the yield increase expected with applied N fertilizer above the yield achieved from soil test N only (as inputted by user).
For example, if the soil test showed 30 lbs of nitrate-N/acre, then "Yield Increase from 0 lbs N" would indicate the yield increase achieved from additional N fertilizer applications beyond what would be achieved with zero N fertilizer application.
The crop price per bushel divided by the cost of N ($/lb). This ratio represents the lbs of N that can be purchased with one bushel of crop. Crop price and fertilizer cost may change but the most economic rate of N (MERN) remains constant as long as the Crop:N Price ratio is unchanged. As the Price ratio increases, so does the N rate.
The net return to N fertilizer from the yield increase achieved with that N fertilizer rate above the unfertilized yield.
Net Return = (crop price x yield increase) – (N price x N rate)