Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: August 13, 2007
Publication Date: October 4, 2007
Citation: Bausch, W.C. 2007. Reference strip location for in-season nitrogen management. American Society of Agronomy 2007 Annual International Meeting, New Orleans, LA, November 4-8.2007 Technical Abstract: Reference strips (areas that have more than adequate nitrogen applied) have been used to normalize SPAD chlorophyll as well as canopy reflectance measurements to determine nitrogen (N) sufficiency of field areas to assess the need for additional N during vegetative growth periods. Fields that have highly variable soils may require reference strips in several areas to minimize over- or under-applying N to the field. This paper will address four scenarios for locating and utilizing reference strips. These are: (1) based on the “best” crop condition that may exist in the field, (2) based on an average value from the reference strip regardless of soil texture differences, (3) based on soil map units, and (4) based on apparent electrical conductivity (EC) as a surrogate for soil texture. Two commercial center pivot-irrigated corn fields with considerable soil variability were used to evaluate reference strip location. Reference strips that included all major soil differences gave the best indication that in-season N was actually applied were needed by the crop. Using an EC map as a surrogate for soil texture provides the information required to locate and use reference strips.