Remote Sensing for Nitrogen Management in Corn

Final Report for FNE03-454

Project Type: Farmer
Funds awarded in 2003: $6,298.00
Projected End Date: 12/31/2003
Region: Northeast
State: Connecticut
Project Leader:
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Project Information

Summary:

Note to readers, attached is the complete final report for FNE03-454

The purpose of this project was to use aerial photos and lower than typical nitrogen rates in strips in corn fields to show that insurance applications of nitrogen are not needed. We completed one experiment with four rates of nitrogen in strips. Aerial photos of the field were taken on September 12 and the photos showed that 0 pounds of nitrogen was insufficient for maximum yield, but that there was no difference in color for the 30, 60 and 90 pound nitrogen rates. The yield results showed that 60 pounds of nitrogen was sufficient for maximum yield in this field. The aerial photos were not sensitive enough in this field and for these conditions to separate yields for the 30 and 60 pound rates. More work is needed before aerial photos can be recommended for improving nitrogen management in corn.

Introduction:

2. Goals
I propose to use remote sensing of cornfields using an airplane to determine the correct nitrogen fertilizer rate for corn. We will apply nitrogen fertilizer at three different rates in strips across the field. The rates will be lower and higher than the recommended rate, and lower than the rates that most farmers apply. Color photographs of the cornfields will allow us to see nitrogen deficient corn, that is, pale green or yellow corn. If the corn is deficient in nitrogen, we will apply liquid nitrogen with drop tubes using a high-axle tractor to correct the deficiency. If we are successful, farmers will be able to safely eliminate insurance nitrogen applications because the color photographs will provide assurance that the corn has sufficient nitrogen, and if the photographs show deficiency, I can apply extra N with my high-axle tractor.

3. Farm profile
I farm 150 acres. I have a greenhouse operation, retail vegetable business and 40 beef cattle. I also have a custom fertilizer application and pesticide spraying business. We grow 40 acres of sweet corn, 25 acres of field corn, and 10 acres of vegetables and pumpkins, with the remainder as hay.

4. Participants
Tom Morris from the University of Connecticut Department of Plant Science was my technical advisor. He helped set up the on-farm strip trial and helped measure the yields in the strips and in the small nitrogen response plots in the same field as the strips. The Norman Brother’s Farm in Thompson, CT was our cooperator who provided the field for the strip trial and provided the equipment for planting and harvesting the trials.

5. Project activities
We established a strip trial in a corn field on the Norman Brother’s farm. The field had not received a manure application for at least 15 years. Continuous corn silage had been grown on the field for the past 20 to 25 years. The strip trial consisted of three nitrogen treatments of 30, 60 and 90 pounds of nitrogen per acre replicated two times, and one strip of 0 pounds of nitrogen. The farmer did not want to replicate the 0 pound nitrogen per acre for fear of losing too much yield and money. Each strip was 16 rows wide. The fertilizer was urea applied by me in one of my fertilizer trucks at the time of sidedressing when the plants were 3 to 5 inches tall.

An application rate of 140 pounds nitrogen per acre was applied to the remainder of the field. This is the rate of nitrogen that the farmer normally applies to this field.

I took pictures of the field on September 12 from my airplane using standard 35-mm color film. The pictures were taken from an elevation of about 1200 feet.

The strips were harvested on October 8 by chopping the center 8 rows of the 16-row plots. We harvested the entire plant and measured the weight of the corn biomass on each strip by weighing the silage wagon on portable scales before and after each strip harvest. Moisture samples were collected from each strip. The yields were adjusted for moisture and reported on a 30% dry matter basis.

Small research plots for nitrogen response were included at the end of the field by Tom Morris. The plots were 15 feet wide (6 rows) by 30 feet long. The rates of nitrogen were 0 and 200 pounds of nitrogen per acre as a preplant application and 0, 50, 100 and 200 pounds nitrogen per acre at the time of sidedressing, with 3 replications. Yields were measured by harvesting the entire plants from a 15-foot section of the center two rows of each plot.

6. Results
The yields for the strip trials showed that the application of 60 pounds of nitrogen per acre was sufficient to attain maximum yield in this field. There was a significant yield increase of 28% for the 60 pound nitrogen treatment compared with the 0 nitrogen treatment. The 30 pound N rate per acre increased the yield by 17% compared with the 0 nitrogen treatment, but the 90 pound per acre treatment had a statistically similar yield as the 60 pound treatment.

The yields in the small plots were similar to the yields in the strip trial. The 0 treatment plots yields 16.6 ton per acre and there was a significant increase in yield for the 50 pound nitrogen rate, which yielded 23.8 tons per acre, but no additional increase in yield for the 100 and 200 pound nitrogen rates.

The pictures taken from the airplane did not show the deficiency of nitrogen in the 30 pound strip, but the 0 N strip could be easily identified. The 60 and 90 pound per acre nitrogen strips had the same green color as the main part of the field that was fertilized with 140 pounds of nitrogen. The aerial photo was useful to show the extreme deficiencies of nitrogen, but did not seem to have the capability to show small differences color that resulted in significant yield increases. The reason may be that we measured silage yields and this technology of using aerial photos to find nitrogen deficient areas in corn fields has only been used on grain corn fields in Iowa. More research would be required before aerial photos could be used to distinguish nitrogen deficient silage corn.

7. Conditions
No unusual conditions occurred that would have affected our results.

8. Economics
We are uncertain if the use of aerial photos would be profitable for farmers to use on silage cornfields. This experiment clearly showed that corn can yield at maximum with much less nitrogen than commonly applied.

9. Assessment
More strip trials with silage corn would need to be completed before we could recommend the use of aerial photos to adjust nitrogen rates.

10. Adoption
We are not planning to use aerial photos to adjust nitrogen rates for silage corn. There is project in the Delmarva area to more fully evaluate the use of aerial photos to improve nitrogen management in corn. Tom Morris is working with the Iowa Soybean Association and Environmental Defense on the project.

11. Outreach
Tom Morris presented the results of this experiment at two workshops. One workshop was the New England CCA conference in 2004 in Portsmouth, NH, and the other workshop was the Northeast Soil Testing Group annual meeting in Newark, DE in 2004.

12. Report summary
The purpose of this project was to use aerial photos and lower than typical nitrogen rates in strips in corn fields to show that insurance applications of nitrogen are not needed. We completed one experiment with four rates of nitrogen in strips. Aerial photos of the field were taken on September 12 and the photos showed that 0 pounds of nitrogen was insufficient for maximum yield, but that there was no difference in color for the 30, 60 and 90 pound nitrogen rates. The yield results showed that 60 pounds of nitrogen was sufficient for maximum yield in this field. The aerial photos were not sensitive enough in this field and for these conditions to separate yields for the 30 and 60 pound rates. More work is needed before aerial photos can be recommended for improving nitrogen management in corn.

Cooperators

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  • Tom Morris

Research

Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.