Demonstration Of Innovative Technology For
Optimizing Nitrogen Application
Harlan Palm
Research Assistant Professor
Peter Scharf
Associate Professor
Larry Mueller
Research Specialist
Kent Shannon
Extension Associate |
Ken Sudduth
Adjunct Associate Professor
Newell Kitchen
Adjunct Associate Professor
Scott Drummond
Science Program/Analyst II
Matt Volkmann
Senior Research Specialist |
Excess nitrogen application on corn fields results in increased potential for nitrogen loss to
ground or surface waters, while reducing the amount of nitrogen applied creates a risk of
diminished productivity and lower yields. The purpose of this project is to demonstrate and
stimulate the adoption of innovative crop canopy reflectance sensor technology for optimizing
nitrogen application on corn.
The overall approach of the project is to use active crop canopy sensors to assess crop reflectance
differences that are used to vary nitrogen fertilizer application. The reflectance from a nonnitrogen-
limiting reference strip standardizes the reflectance from the application area.
To accomplish this task, a Spray Coupe was equipped with two sets of active light sensors,
"green" GreenSeeker by NTech and Crop Circle by Holland Scientific. To apply the nitrogen
the Spray Coupe was setup to apply UAN fertilizer to 6-rows of corn using drop nozzles with
orifices sized to output 1x, 2x, and 4x. This nozzle combination allows for a range of nitrogen
rates from 0-210 lbs-N/acre.
Below is a flow chart outlining the process of sensor-based nitrogen application:
Results from the 2004 demonstration sites are as follows:
Conventional Rate (CR) Compared to Sensor-Based Variable Rate (VR):
Amount of Nitrogen Applied
| Site | Nitrogen Rate in lbs/acre - CR | Nitrogen Rate in lbs/acre - VR | Nitrogen Saved in lbs/acre | EONR - Economic Optimum Nitrogen Rate in lbs/acre | Savings |
| B | 150 | 145 | 5 | 157 | $1.50 |
| C | 150 | 175 | -25 | 198 | -$7.50 |
| D | 180 | 122 | 58 | 179 | $17.40 |
| H | 150 | 95 | 55 | 167 | $16.50 |
| P | 180 | 90 | 90 | 77 | $27.00 |
| S | 150 | 99 | 51 | 158 | $15.30 |
| W | 120 | 154 | -34 | 150 | -$10.20 |
Price used for N was $0.30/lb
Conventional Rate (CR) Compared to Sensor-Based Variable Rate (VR): Yield
| Site | Yield in bu/acre – CR | Yield in bu/acre - VR | Yield Difference in bu/acre | Yield Difference in $/acre | Overall Savings in $/acre |
| B | 196 | 188 | -8 | -$16.00 | -$14.50 |
| C | 117 | 124 | 7 | $14.00 | $6.50 |
| D | 215 | 199 | -16 | -$32.00 | -$14.60 |
| H | 207 | 190 | -17 | -$34.00 | -$17.50 |
| P | 221 | 224 | 3 | $6.00 | $33.00 |
| S | 174 | 167 | -7 | -$14.00 | $1.30 |
| W | 179 | 196 | 17 | $34.00 | $23.80 |
Average Overall Savings - $2.57
Price used for corn was $2.00/bu
Research supported in part by the USDA- NRI, EPA, NRCS-CIG, and IFAFS Grant Programs.
Assistance was also given by N-Tech, and Holland Scientific Instruments.
2005 Field Day Report
