Evaluation of Sensor-based Variable Rate Nitrogen Fertilization for Winter Wheat Production

Abstract

Field trials of variable rate nitrogen fertilization with a　tractor-mounted optical real-time sensor were conducted in eight fields over 6 years for winter wheat. The algorithm determining the nitrogen application rate was based on the following procedure. First, a standard application rate was set to an average sensor value in a field measured by pre-sensing. Sensor readings were then translated into nitorogen uptake differences from an average point and converted to an application rate in real-time application. The experimental results showed that the average yield with variable rate application increased by 4.0% compared with uniform application, and that this effect was well-defined in panicle formation-stage fertilization. Protein content was more equalized in flag-leaf stage application. Furthermore, nitrogen harvest index with variable rate application was higher than that with uniform application. Therefore, variable rate application is an effective approach for winter wheat production.