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dc.contributor.advisorScharf, Peter C. (Peter Clifton), 1959-eng
dc.contributor.authorOliveira, Luciane Farias deeng
dc.date.issued2008eng
dc.date.submitted2008 Falleng
dc.descriptionThe entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.eng
dc.descriptionTitle from PDF of title page (University of Missouri--Columbia, viewed on October 2, 2009).eng
dc.descriptionThesis advisor: Dr. Peter C. Scharf.eng
dc.descriptionM.S. University of Missouri--Columbia 2008.eng
dc.description.abstractNitrogen (N) is an essential nutrient for cotton production; consequently there is a tendency to over-apply nitrogen. High N causes excessive vegetative growth and delayed crop maturity, which result in increased cost in pesticides, growth regulator, and defoliant. Currently, the most common methods for obtaining information about the nitrogen needs of cotton are labor-intensive and time-consuming limiting their use. Reflectance sensors offer the potential to diagnose N needs immediately in a spatially intensive manner. The objective of this study was to develop on-the-go sidedress N rate recommendations based on sensor readings and quantify variability during the day for both passive and active sensors mounted above cotton plants. Reflectance was measured with three sensors (Crop Circle, GreenSeeker, and Cropscan) at three growth stages (early square, mid square and early bloom) and at three heights above the cotton canopy (25, 50, and 100 cm) in 2006 and 2007. Results indicated that all three sensors have potential for accurate prediction of optimal N rate. Prediction accuracy was low at the first square stage but acceptable at mid square or early flower. These results suggest that variable-rate N applications to cotton based on real-time reflectance sensor readings are feasible for the mid-square to first flower growth stages. Variability in reflectance values during the day was relatively large for all three sensors. Mid-day was the time with the least error introduced into N rates by drift in sensor readings.eng
dc.description.bibrefIncludes bibliographical referenceseng
dc.identifier.merlinb71544045eng
dc.identifier.oclc444710231eng
dc.identifier.urihttps://doi.org/10.32469/10355/5775eng
dc.identifier.urihttps://hdl.handle.net/10355/5775
dc.languageEnglisheng
dc.publisherUniversity of Missouri--Columbiaeng
dc.relation.ispartofcommunityUniversity of Missouri--Columbia. Graduate School. Theses and Dissertationseng
dc.rightsOpenAccess.eng
dc.rights.licenseThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.
dc.subject.lcshCrops -- Effect of nitrogen oneng
dc.subject.lcshCottoneng
dc.subject.lcshReflectanceeng
dc.titleReflectance sensors to predict mid-season nitrogen need of cottoneng
dc.typeThesiseng
thesis.degree.disciplinePlant, insect and microbial sciences (MU)eng
thesis.degree.grantorUniversity of Missouri--Columbiaeng
thesis.degree.levelMasterseng
thesis.degree.nameM.S.eng


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