Nitrogen Sensors Revisited

Bob Bottens made a presentation last week on being more effective with fertility in No-Till Corn.  His presentation was the most disappointing one I attended.  The quality of the presentation was fine, the disappointment was in his findings.  You may recall that I reported on research out of the University of Missouri by Peter Scharf.  Dr. Scharf had very positive results with GreenSeeker technology.  Bottens also researched the GreenSeeker and found some disappointing quirks.  He found that the amount of nitrogen metered out depended on which direction he was traveling in the field. He shared his monitor data to show what was happening.  Because the GreenSeeker measures the light reflected off the leaf, the amount of green reflected depends on which direction the light is coming from.  Good photographers know this.  He found the same at night depending on what lighting he was using.  He did not talk about how often or when he calibrated.  Scharf did tell us that frequent calibration is needed.

Scharf's results were very positive.  It could be that the good results outweigh the shortcomings.  I expect that Trimble is working on the GreenSeeker to correct this issues, and I expect that they can be overcome.  It is just something to keep in mind if you are using the technology.  Botten's information also emphasized the need for frequent calibration.