Uneven Spread of Dry N in Production Corn Fields.

Urea use is increasing nationally and globally. The machines used to spread this fertilizer are dominantly spinners that throw the fertilizer from a spinning plate. The physics of creating even spread from this type of applicator is complex, but vital to efficient N use and crop production. Six trials catching dry N applications in corn fields were carried out in 2016. Uneven spread was observed in all six fields. Uneven patterns were not high rates in the middle due to dusty fertilizer as we had expected. Several different kinds of uneven spread patterns were seen: high on the left, high on the ends, and up-and-down. Breakage of granules due to spreader vane impact was seen. Uneven spread affected corn yield in both fields where dry N was applied preplant as the total N program. Average yield loss due to uneven spread was 1 Mg/ha in one field and 0.3 Mg/ha in the other. It seems likely that spreader adjustments would solve the pattern problems that we saw in these fields. Uneven spread did not affect corn yield in the fields where it was applied in-season; this would be expected since rate was much lower and the difference between the lowest and highest rates was small.