155-13 Crop Sensors As in-Season Nitrogen Management Tool for Winter Wheat in Wisconsin.
Poster Number 1402
Field experiments were conducted at two and three farms, in 2014 and 2015, respectively, where crop canopy reflectance measurements, using the Holland Scientific Crop Circle ACS-430 (Holland Scientific, Inc., Lincoln, NE), were collected from May (approximately GS 25) to mid-June (GS 40). Whole plant samples were collected at GS 30 in 2014. In 2015, whole plant samples were collected at GU, GS 30, and GS 40 and soil samples 0 to 30 cm were collected at GU. All plant samples were analyzed for total N and all soil samples were analyzed for NO3-N and NH4-N. In 2014, both normalized difference vegetation index (NDVI) and normalized difference red-edge index (NDRE) at GS 30 were significantly positively correlated with GS 30 N uptake. A quadratic-plateau regression model had the best fit for yield, NDVI, or NDRE response to N rate at both locations.