Large scale implementation of sensor based technology using the GreenSeeker(TM)

itrogen (N) fertilizer needs vary from year to year and field to field. Small grain producers are continuously looking for new techniques to improve their fertilizer use efficiency. Using the GreenSeeker(TM) Sensor and nitrogen (N) reference strips, crop response to N can be measured and yield potential can be predicted. This is done using the Sensor Based Nitrogen Rate Calculator (SBNRC), which uses Normalized Difference Vegetative Index (NDVI) readings taken from the reference strip and the farmer practice. Also, commercially available is the variable rate technology (VRT) that uses multiple GreenSeeker(TM) sensors mounted on a boom. This study was designed to evaluate the use of optical sensors for N rate determination in producer's fields. This study was important to do on a large scale rather than the traditional small plot research in an effort to show producers how precision agriculture works and how it can benefit them. Comparing the no topdress and what the producer typically applies topdress on winter wheat with the SBNRC recommended rate and the VRT rate was evaluated in this study. Also evaluated was the economics of using the SBNRC and the VRT technology and comparing it with the typical farmer practice (FP) and no topdress. In 2009 the SBNRC recommended 11 kg ha-1 less N than the farmer practice and had an 8 kg ha -1 increase in grain yield. The SBNRC had a gross return of...