By Paul Kassel
Does the recent increase in nitrogen (N) cost and the increase in corn grain price warrant a change in nitrogen rates in 2021? The following discussion gives an overview of the current N cost and corn price situation
New crop corn for delivery during the fall of 2021 was $4.05 per bushel locally on January 10, 2021. And the price of a ton of anhydrous ammonia was $415 per ton the fall of 2020.
Fast forward to April of 2021 and new crop corn for delivery in the fall of 2020 is $4.60 per bushel and anhydrous ammonia is $690 per ton.
A quick look at the Corn Nitrogen Rate Calculator can give us some answers.
spring 2021 fall 2020
Nitrogen price ($/lb) 0.42 0.25
NH3 cost ($/ton 690 415
Corn price, ($/bu) 4.60 4.05
MRTN rate (lb N/acre) 143 153
Net return to N at MRTN rate ($/acre) 252.60 240.07
NH3 cost at MRTN rate ($/acre) 60.06 38.25
This info shows a 66% increase in the cost of N from last fall to this spring. Corn grain price has increased about 13% since January.Source : iastate.edu
So, should the N rate be adjusted as a result of a greater increase in the cost of N as compared to the smaller increase in the value of corn grain? This info - based on the Corn Nitrogen Rate Calculator would suggest a 10 lb/a reduction in N rate. Obviously, the increased value of corn grain did not make up for the increased cost of ammonia.
Many agronomists and farmers would argue the practicality of an N rate reduction by 10 lb/acre. However, this info does show the importance of N fertilizer. So even though N costs have increased over $21/acre since last fall in this example - the net return to N fertilizer is only reduced by about $12/acre as a result of the 66% increase in anhydrous ammonia cost.
This scenario was calculated with anhydrous ammonia, a corn soybean rotation and in the main part of Iowa. The Corn Nitrogen Rate Calculator would allow you to evaluate other rotations, other N sources and other geographies.