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Battle for the Belt: Season 2 Episode 12- Nitrogen Recommendations for Corn

Episode 12 of Battle for the Belt is now available: https://www.youtube.com/watch?v=Y2kzyppty88

In Episode 12, we discuss nitrogen management in corn with Dr. Manbir Rakkar, the Ohio State Soil Fertility and Nutrient Management Specialist.

What is the optimal rate for sidedress nitrogen application in Ohio?

The optimal rate is the amount of nitrogen that will give us the maximum net profit. Nitrogen is a major essential nutrient but the relationship between corn yield and nitrogen input is not always linear. When we add nitrogen, the very first units of nitrogen are what gives the largest yield increase. The yield response of corn to nitrogen application generally will plateau and decline after a certain point. Another factor to consider is the cost of nitrogen and the price of corn.

There is a tool that considers all these factors, yield response, cost of nitrogen, and corn price, called the Maximum Return to Nitrogen or MRTN. You can find the tool at https://www.cornnratecalc.org/. To use this tool, enter your location, the crop rotation (corn after corn or corn after soybean), the source of N (UAN, anhydrous ammonia, urea, etc), the nitrogen product price, and the corn price per bushel. The tool will then calculate the recommended N rate for your specific situation. The tool is informed by intensive research conducted across Ohio and several other corn belt states and is continually updated.

Figure 1. The first step in the MRTN calculator. Selecting an example for the average Ohio farmer using UAN as a sidedress application source and current fertilizer and crop prices.

Figure 2. The output of the MRTN tool including recommended rates in table and graph format.

Figure 2. The output of the MRTN tool including recommended rates in table and graph format.

At what stage should we sidedress corn?

The recommended stage of sidedress application in corn is the V4/V5 stage. Corn only uptakes about a pound of nitrogen from planting to V4. After V4 through tasseling the corn dramatically increases (Figure 3). The target for sidedress application is to apply nutrients with crop needs.

Figure 3. Nitrogen partitioning and uptake of corn throughout the season. From “How a corn plant develops” Iowa State Univserity.

I missed my sidedress application timing, what do I do?

Even if the weather did not permit a sidedress application at the V4/V5 stage, this application is necessary for yield, and crop uptake is at a high from the V4 to tasseling. So, any time that you have the ability to get into the field to make the application that will be agronomically and economically practical.

How do we identify a nitrogen deficiency?

Nitrogen deficiencies are characterized by chlorosis of the leaf in a V shape beginning at the tip of the leaf and moving down the midrib toward the leaf base (Figure 4). Nitrogen is mobile in the plant so this deficiency will be seen in the lower leaves because the plant will use the older leaves to supply new leaves with nitrogen.

Figure 4. Nitrogen deficiency in corn.

What are more resources for fertility recommendations in Ohio?

For more information and Ohio fertility recommendations including phosphorus, potassium, lime, and micronutrient recommendations for our main crops consult The Tri-State Fertility Guide. A physical copy of the book can be purchased or a free pdf can be downloaded.

Another option is the Ohio Agronomy Guide which has cultural management practice recommendations for corn, soybean, wheat, and alfalfa.

What’s happening in the field?

In the field this week, the ultra-early planted (3/25) soybeans at the Western location began to show pods and the second planting date (4/16) was at full flowering (R2). Both planting dates have had early flower dates and will be interesting to follow the rest of the season. For both crops, there is no sign of disease.

At the Northwest location, planting date three was put in the ground on June 10th. This area of Ohio has progressed in planting in the last week.

At the Wooster location, there has not been significant disease pressure in either crop but a presence of Septoria brown spot in soybean and anthracnose in the corn. Neither of these diseases should affect yield.

A summary of weekly conditions for all three sites and completed planting dates is presented in Table 2.

Table 1. Planting conditions for planting date three at the Northwest Agricultural Research Station.

Location

Planting date

2-inch soil temperature
 (at planting)

Air Temperature

(at planting)

Northwest,

Wood County

June 10, 2024

72°F

70°F

 

 

Table 2. Weekly weather conditions for each updated planting date at the Western Agriculture Research Station, Northwest Agriculture Research Station, and Wooster Campus, with day of planting, soil, air temperature averages, and Growing Degree Days (GDDs) from June 10 to June 16. Information from CFAES Weather System (https://weather.cfaes.osu.edu/).

Location

Precipitation

(Inches)

(June 10- June 16)

2-inch soil temperature
 (June 10-

June 16)

Air Temperature

(June 10- June 16)

Planting date

GDDs

(Cumulative)

 

Soybean

Stage

 

Corn

Stage

Western,

Clark County

 

0.0

Max: 78°F

Mean: 70°F
Minimum: 62°F

Max: 90°F

Mean: 69°F

Minimum: 47°F

March 25th

April 16th

May 6th

May 24th

1097

988

752

446

R2

R2

V4

VC

V9

V8

V6

V3

Northwest,

Wood County

 

 

0.02

 

Max: 87°F

Mean: 71°F
Minimum: 56°F

 

Max: 92°F

Mean: 71°F

Minimum: 48°F

 

May 16th

May 23rd

June 10th

638

473

144

 

V1

VC

 

V5

V2

 

Wooster, Wayne County

 

 

0.01

Max: 76°F

Mean: 69°F
Minimum: 63°F

Max: 87°F

Mean: 65°F
Minimum: 44°F

 

April 22nd

May 3rd

May 21st

June 4th

 

776

670

434

216

 

 

V4

V2

VC

VE

 

V7

V6

V4

VE

 

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.