While there is still plenty of theoretical outcomes, farmers are most interested in practical impacts that sensing technology can provide. Dr. Ray Asebedo explains how agronomists working with no-tillers and strip-tillers can leverage collected sensor data to refine fertilizer prescriptions through what he calls the “agronomist nitrogen recommendation algorithm.”
“An agronomist uses this data, along with observations from scouting, to come up with a N recommendation,” Asebedo says. “But input from the farmer will be just as critical a factor in the process. Some of the agronomist’s first questions should be about yield, including, ‘What’s the average from year to year?’ and ‘What’s the current yield goal, and why?’ Final grain yield is the end result of all the interactions observed between crop, soil and weather.”
Then the agronomist will make a visual determination of N stress in crops. They will consider soil type, soil textural changes and soil test analysis data, if available throughout the field, along with weather.
But crop physiology is another factor to weigh, Asebedo says, because different growth stages are linked with specific yield determining factors. “For instance, with corn at V6 to V12 stage, I'm going to be very attentive to making sure that my corn crop is not nitrogen stressed during that period. Why is that? Because ear size determination takes place,” he says.
Then it’s time to decide whether the sensing data warrants additional N application. “For example, say we come in at V14 stage for corn and it's been clearly stressed, and was stressed through V10, through V12,” Asebedo says. “Odds are pretty good that we have suffered permanent yield loss, and shouldn't be applying high rates of an additional 150 pounds of N because it's never going to improve our yield. I'd be better off pulling that nitrogen recommendation back and only apply N rates again for what we can actually truly obtain for yield."