How Much Nitrogen Does Your Corn Need?

Sally Krueger

Mar 06, 2023

Corn plants use large quantities of nitrogen (N) to grow and yield. Determining the optimal nitrogen (N) application rate is crucial for maximizing crop yield and profitability. However, choosing the optimal nitrogen application is challenging, as it depends on factors such as soil type, weather, and crop rotation. 

Currently, seven land grant Universities in the Midwest use the Maximum Return To Nitrogen (MRTN) to recommend N. This method refers to the N rate that maximizes profit per acre, rather than simply maximizing yield. By using this approach, farmers can better control nitrogen costs while maximizing profitability. For example, with current N and corn prices, the MRTN rate for central Illinois is approximately 168 lb/ac.

Each Growth Stage Requires Different Nitrogen Amounts

Corn will accumulate 65% of the total nitrogen needs by the time flowering begins. In the seedling stage of corn growth through V5 (5 leaf), corn plants have taken in approximately 10% of total nitrogen needed. It may be the most important 10% used because ear size, as well as both rows around and row length, are developing then. A shortage of nitrogen at V5 can cause reduced ear size formation and lessen yield potential, which cannot be reversed as the plant continues to grow.

During the rapid growth stage, or V6 (6 leaf) to V18 (18 leaf), corn will absorb up to 8 pounds of nitrogen per acre per day. If environmental conditions are right, corn plants can grow more than 4 inches per day. A nitrogen shortage at this stage of corn development can result in a significant and permanent yield loss. Look for yellowing corn leaves and any aborted kernels on the ear tips as symptoms of a nitrogen deficiency.

Benefits of Nitrogen for Corn

Nitrogen plays a major role for corn production because it is a major component of amino acids which are the building blocks of proteins. Nitrogen will help corn reach its genetic yield potential.

[READ: Get More Out of Your N Applications Using a Nitrogen Stabilizer]

How Much Nitrogen Is Too Much Nitrogen?

Nitrogen is one of the most expensive nutrients applied in corn production. That is typically due to the quantity of N that corn requires. It makes sense not to over-apply from an efficiency standpoint, but over-applying nitrogen can have a negative effect on yield, too.

Stalk rot diseases flourish in high nitrogen environments and can cause premature plant death and stalk lodging, which makes machine harvest difficult and can cause some grain loss.

Get Nitrogen Credits Where You Can

It is important to determine the appropriate nitrogen rate based on sound agronomic practices and not to exceed the recommended rate. Going beyond this rate may not result in a significant yield increase and can be wasteful and harmful to the environment.

Once we calculate the N rate we want to apply, it is important to deduct any nitrogen applied as a starter fertilizer and any nitrogen used as a herbicide carrier or irrigation.

[READ: How Can the Maximum Return to Nitrogen Calculator Increase Your Profit Potential?]

Applying Just Enough Nitrogen

Split applications of nitrogen prevents nitrogen losses from leaching and other volatilization issues, and they are more efficient than applying the total amount of nitrogen required as preplant. This time of year, sidedressing nitrogen will soon be completed. However, if you’re injecting nitrogen through a pivot, now is the time to apply so you can reduce your chances of not being able to do so later due to rain.

All in all, it is best to have all of your nitrogen applied to corn before R1 (or silk emergence) because nitrogen applied after that stage is not as efficient and generally has little, if any, impact on your final yield.

Copyright © 2014 - 2023 Farmer's Business Network, Inc. All rights Reserved. The sprout logo, “Farmers Business Network”, “FBN”, “FBN Direct” are trademarks, registered trademarks or service marks of Farmer's Business Network, Inc.

FBN Direct products and services and other products distributed by FBN Direct are offered by FBN Inputs, LLC and are available only in states where FBN Inputs, LLC is licensed and where those products are registered for sale or use, if applicable. If applicable, please check with your local extension service to ensure registration status. Nothing contained on this page, including the prices listed should be construed as an offer for sale, or a sale of products. All products and prices are subject to change at any time and without notice. Terms and conditions apply.

ALWAYS READ AND FOLLOW LABEL DIRECTIONS. It is a violation of federal and state law to use any pesticide product other than in accordance with its label. The distribution, sale and use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. We do not guarantee the accuracy of any information provided on this page or which is provided by us in any form. It is your responsibility to confirm prior to purchase and use that a product is labeled for your specific purposes, including, but not limited to, your target crop or pest and its compatibility with other products in a tank mix and that the usage of a product is otherwise consistent with federal, state and local laws. We reserve the right to restrict sales on a geographic basis in our sole discretion. You must have a valid applicator license to use restricted use pesticides. Please consult your state department of agriculture for complete rules and regulations on the use of restricted use pesticides, as some products require specific record-keeping requirements.

All product recommendations and other information provided is for informational purposes only. It is not intended to be a substitute for consulting the product label or for specific agronomic, business, or professional advice. Where specific advice is necessary or appropriate, consult with a qualified advisor. Neither Farmer's Business Network Inc. nor any of its affiliates makes any representations or warranties, express or implied, as to the accuracy or completeness of the statements or any information contained in the material and any liability therefore is expressly disclaimed.

Sally Krueger

Mar 06, 2023