Management Zone Based Variable Rate Nitrogen Management for Corn in Semi-Arid Western Nebraska.

Variable rate nitrogen management based on productivity level management zones has shown the potential to decrease nitrogen application rates while maintaining corn yields. This combination can lead to greater nitrogen use efficiency and decreased potential for nitrogen loss through leaching. However, little work has been in the semi-arid region of western Nebraska where soils can be highly variable. Therefore, a study was conducted at the University of Nebraska-Lincoln West Central Research and Extension Center Water Resources Lab to determine the viability of crop canopy sensor based variable rate nitrogen management on highly variable soils. This study was conducted from 2014-2016 and included 2 methods of management zone delineation (landscape position and apparent electrical conductivity). In each year crop canopy sensor readings were collected at the V12 growth stage within each management zone and nitrogen was variably applied based on sensor determined rates. Overall, the field this study was conducted on presents large challenges in determining management zones and N recommendations due to the extreme soil variability that exists. However, even with this being the case, the sensor based approach recommended lower amounts of N as compared to uniform application methods in every year of this study. In years 2014 and 2015 the higher uniform N applications did yield higher than the sensor based approach, but the yield increase with these treatments would not have offset additional expense of the added N making the sensor based approach more economical while reducing potential N leaching from over application. In 2016 the sensor based approach recommended far less N without negatively affecting yields.