See more from this Session: S4/S8 Graduate Student Oral Competition-Tools and Techniques for Assessing Crop Nitrogen Needs
Monday, October 17, 2011: 4:00 PM
Henry Gonzalez Convention Center, Room 214B
Estimating corn N status during the growing season with active optical reflectance sensors can improve N management efficiency by estimating the effects of early season management practices and environmental conditions on N availability. Utilization of crop sensor-based N management will increase if crop sensing can be performed early in the growing season as N applications can be made with traditional sidedress equipment. A field experiment was conducted to determine the earliest growth stage that N stress occurs and can be detected with sensors. High N reference areas (251 kg N/ha) were established with different methods – [pre-planting banded anhydrous ammonia (Pre-AA), pre-planting broadcast then incorporated urea ammonium nitrate (Pre-UAN), and post planting banded UAN (Post-UAN)] to evaluate their performance to detect N stress compared to a starter-only control (27 kg N/ha). Total aboveground biomass was collected ten times throughout the growing season beginning at V4 and continuing through R6 for dry matter (DM) and N concentration measurements. Crop reflectance was collected with the Greenseeker RT200 and Crop Circle ACS-210 at V4, V7, V8 and V10. All high N methods other than Post-UAN had no effects on plant DM, N content, or crop reflectance at V4 compared to the starter-only control. At V7, Pre-AA reduced DM and N content compared to all other treatments. Whereas DM, N content, and crop reflectance for Pre-UAN and Post-UAN were no different than the starter-only control. At V8, all high N reference methods increased N content equally (avg. 42%) and crop reflectance compared to the starter-only control. At V10, all high N methods increased DM and N content equally compared to the low N control, 22% and 67% respectively while differences in crop reflectance values were also evident. After V7, all high N reference treatments were effective in distinguishing N stress compared to the starter-only control as each sensor detected N stress.
See more from this Division: S08 Nutrient Management & Soil & Plant AnalysisSee more from this Session: S4/S8 Graduate Student Oral Competition-Tools and Techniques for Assessing Crop Nitrogen Needs