Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2004
Publication Date: 11/1/2004
Citation: Shanahan, J.F., Inamasu, R., Schepers, J.S., Francis, D.D., Schlemmer, M.R., Caldwell, B. 2004. Description of a high-clearance applicator for making variable rate n applications to corn using active sensor readings. Agronomy Abstracts #4299. Interpretive Summary:
Technical Abstract: A major factor contributing to low nitrogen (N) use efficiency and environmental contamination for traditional corn N management schemes is routine application of large and uniform doses of N to spatially variable landscapes, before when the crop can effectively utilize N. Our long-term research goal is to develop practical N application systems using remote sensing as a means to assess crop N status and apply N where needed at times when the crop can most efficiently utilize N. Preliminary testing of a robust active sensor system has shown considerable promise for rapid and accurate assessment of canopy N status under a variety of environmental and crop conditions. For research purposes, we have assembled a prototype high-clearance applicator capable of delivering in-season variable rates of liquid N fertilizer based on crop need. Major applicator components include active sensors, nozzles with electronic solenoid valves, and a variable rate controller. Key components of the variable rate system include an industrial controller, DGPS, and portable computer (PC) running commercial control software with a graphical user interface. A serial hub connected to a USB interface is used to connect sensors, DGPS receiver, PC and variable rate controller. Our system is able to use real time sensor data, prescription map data, or both as input to the controller. The system response time is accurate enough to sense and apply fertilize with a spatial resolution of two meters.