1. Real-Time Corn Assessment for Variable Rate Nitrogen Management Newell R. Kitchen, Kenneth A. Sudduth USDA-ARS, Columbia, MO Peter Scharf, Harlan Palm, and Kent Shannon Univ. of MO, Columbia, MO Newell R. Kitchen, Kenneth A. Sudduth USDA-ARS, Columbia, MO Peter Scharf, Harlan Palm, and Kent Shannon Univ. of MO, Columbia, MO

3. Nitrogen Rate Yield Economic Optimal N Rate (EONR)

4. Nitrogen Rate Yield Economic Optimal N Rate (EONR)

5. Oran00 Rep1 Block6 0 4 8 12 16 0100200300 N rate (kg ha -1 ) Yield (Mg ha -1 ) N opt Oran00 Rep3 Block26 0 4 8 12 16 0 100200 300 N rate (kg ha -1 ) Yield (Mg ha -1 ) N opt Economic Optimum Nitrogen Rate

8. 2004 Field Testing of Variable Rate N Applicator Using Active Light Sensors

9. Seven Field Research Sites

10. Active Light Sensors Two types of active-light sensors –“green” GreenSeeker by NTech – Crop Circle by Holland Scientific Two types of active-light sensors –“green” GreenSeeker by NTech – Crop Circle by Holland Scientific

19. EONR prediction is not easily accomplished, and is more of a challenge in rainfed environments. If one could reliably predict yield, this factor alone does not do a good job of predicting EONR. In 2004 and averaged over all sites, we achieved ~$5/acre more profit when using the sensors when compared to the farmer’s single blanket rate. (average of 30 lbs/acre less N). Data needs to be collected to test current and yet-to-be developed algorithms.

20. Research supported in part by the USDA- NRI, IFAFS, and CIG Grant Programs. Assistance also given by OSU, NTech, and Holland Scientific Instruments.