Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2008
Publication Date: 7/20/2008
Citation: Sripada, R., Schmidt, J.P. 2008. Variability in observed and sensor based estimated optimum N rates in corn. In: Proceedings of the 9th International Conference on Precision Agriculture, July 20-23, 2008, Denver, Colorado. CDROM Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Recent research showed that active sensors such as Crop Circle can be used to estimate in-season N requirements in corn. The objective of this research was to identify the sources of variability in the observed and estimated economic optimum N rates (EONR) using Crop Circle. Field experiments were conducted at five sites during 2007 growing season using randomized complete block design with different N rates applied at V6 as the treatment factor. Field sites covered different cropping rotations and landscape position so as to generate a range of variability on optimum N rates. Corn canopy reflectance was measured using Crop Circle prior to N application at V6. Soil and plant biomass, tissue and N uptake data were obtained at planting, V6, VT and physiological maturity. Initial analysis of the data indicates a significant grain yield response to N applied at V6. The measured corn biophysical parameters at V6, VT and physiological maturity will be used to explain the potential variability in the observed and predicted EONR.