Nitrogen Uptake in Corn
Nitrogen (N) is the most commonly applied nutrient and one of the costliest inputs in corn production. N application averages 18% and 13% of the variable costs in a corn-corn and corn-soybean rotation, respectively. The cost-to-benefit ratio usually exceeds that of other fertilizer inputs, but growers have many options to improve N use efficiency to maximize its value. These include minimizing N losses and applying optimal rates at ideal times that coincide with peak uptake by the crop. Timing of N uptake and sources of N utilization by corn include:
- N for grain development originates from both remobilized N from vegetative tissues and continued N uptake from the soil. Therefore, ensuring a season-long N supply is critical for maximizing yield.
- By flowering (R1), corn has taken up approximately 63% of its N requirement for the season. The rest is taken up during the grain-fill period (R1 to R6).
- With high yields, ~140 to 210 lbs N/acre is needed to support grain development. Approximately 38% of this demand is remobilized from vegetative tissue; the rest is supplied from continued uptake after flowering.
- In high-yield environments, post-flowering N uptake can range from 85 to 130 lbs N/acre.
N applied closer to maximum crop use is less likely to be lost and more likely to be taken up by the crop and potentially available to support kernel set at flowering and late-season grain development. Click here to read our Product Technology Update on Nitrogen Uptake in Corn for more information.