Submitted to: European Conference on Precision Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/25/2015
Publication Date: 7/12/2015
Citation: Sudduth, K.A., Drummond, S.T., Kitchen, N.R. Operational characteristics of commercial crop canopy sensors for nitrogen application in maize. In: Precision Agriculture '15 - Proceedings 10th European Conference on Precision Agriculture, 12-16 July 2015. pp. 51-58. Wageningen Academic Publishers, Wageningen, Netherlands. 2015.
Technical Abstract: Crop canopy reflectance sensing can be used to assess in-season nitrogen (N) health for automatic control of N fertilization, and several systems are commercially available. Because data comparing the performance of the different sensor designs is lacking, the objective of this research was to evaluate and compare commercial canopy reflectance sensors for N fertilization in maize. Two units of each of four commercial sensors were mounted to a high-clearance applicator for field data collection on plots where a range of N rates was applied. Data from nadir-looking sensors were highly correlated, but were less strongly related to data from an oblique-looking sensor. Data from the oblique sensor were more strongly related to SPAD chlorophyll readings, while the nadir sensors were more affected by crop height variations. Little variation was seen with any sensor across multiple data collection runs in a single day. As the nadir-looking sensors see a mixed scene of soil and plant, readings varied with soil darkness, and could translate to significant N application rate error. Differences among commercial sensors need to be considered and understood by developers and users of sensor-controlled N application equipment systems.