Large Scale Implementation of Sensor Based Technology.

Nitrogen (N) needs for plants vary from year to year and field by field. Small grain producers are continuously looking for new techniques to improve the efficiency of the N fertilizer applied. One such method utilizes sensors and reference strips to measure crop response to N and predict yield potential. This study evaluated the use of optical sensors for N rate determination at in producer's fields. Eleven sites were established in producer's fields. Each trial consisted of four N treatments. Treatments were arranged in a RCDB with three replications at each site. Each plot measured 18.3 m by 122.0 m. The treatments were applied at Feekes 5. The first treatment consisted of 0 kg N ha top-dress with producer applied pre-plant. The second treatment (FR) was a uniform rate chosen by the producer prior to sensing, typically the rate of the rest of the field. The third treatment (SBNRC) was the Sensor Based Nitrogen Rate Calculator uniform rate. The SBNRC rate is determined by comparing the NDVI readings from the GreenSeeker™ handheld sensor of the N-rich Strip and the farmer practice (farmer's pre-plant N rate). Those reading are used to predict yield potential from both and back calculate N rate from expected removal. For the fourth treatment (VRT) a sensor based variable rate applicator was used. This applicator is commercially available. Six sensors are attached to the boom. While traveling across the field the applicator collects readings and prescribes a rate to apply in which a new rate is prescribed every second. At seven of the eleven sites the SBRNC application rate was lower than the FR average N rate of 44 kg N ha and 44 Kg N ha, respectively. The VRT rate was lower that both the SBNRC and FR treatments at 8.4 kg N ha.