Variable Rate Fertilizer Applications: Signs of Progress?

Available research suggests that most corn fields have a wide range of optimal N rates. Coming up with a system to correctly predict where to put more and where to put less has been surprisingly difficult. To date, crop color (which can be measured a variety of ways) has been the most accurate way to predict the best N rate. My opinion is that crop sensors provide the best tool for putting the right N rate in the right place. Sensors can be mounted on a fertilizer applicator for in-season applications. When they see a dark green crop, a low N rate is applied; when the crop is light green, a high rate is applied. In Missouri, sensor-based management has increased yield by 2 bushels and decreased N rate by 14 pounds over 55 demonstration fields, and is eligible for EQIP funding. I will also touch briefly on how I think variable-rate P and K can be profitable, and why past approaches have not been very successful.

Speakers