Tuesday, November 14, 2006 - 9:45 AM
191-7
Ramp Calibration Strip Technology for Determining Mid-Season N Rates in Wheat and Corn.
No consistent methodology is currently available for making mid-season fertilizer N recommendations in wheat and corn. While the use of soil testing, yield goals, economic optimums, chlorophyll meters, and yield prediction using sensors have shown promise, all are limited regionally. The objective of this paper is to demonstrate a new applied procedure for applying preplant N strips used for determining a midseason N rate based on plant response to preplant N fertilization. The new ramp calibration strip (RCS) applicator applies 16 different N rates (10 to 20 foot intervals), over 160 to 320 feet (actual rates and distances can be adjusted depending on the crop). Because the RCS is superimposed on the farmer preplant N practice, producers can simply examine plant responsiveness over the range of rates to determine the optimum topdress N rate. Whether determined visually or with a handheld sensor, the point where visual growth differences no longer exist is the topdress N Rate. Recording distance is required as you walk the RCS since distance is associated with a predetermined N rate within the ramp. This approach assumes that we can catch up or achieve maximum yields from mid-season N applications, and assuming that yield potentials were not severely restricted by early season N stress. In corn, the ramp interpolated rate could be short, because you don't know whether or not this rate will run out later in the season. Assuming we can project the preplant non-N limiting rate, the ramp interpolated rate is an effective method to determine how much topdress N should be applied to the rest of the field to achieve the same visible response in growth that has been shown to be highly correlated with final grain yield.
Recorded presentation