Adjusting Midseason Nitrogen Rate Using a Sensor-Based Optimization Algorithm to Increase Use Efficiency in Corn

ABSTRACT

This study was conducted to formulate an in-season nitrogen (N) fertilization optimization algorithm (NFOA) to estimate midseason N rates that maximize corn (Zea mays L.) growth and minimize fertilizer inputs. Treatments included: a zero kg N ha^?1; three treatments of 134 kg N ha^?1 fixed rate applied in split, preplant, or sidedress; two treatments of 67 kg N ha^?1 fixed rate preplant or sidedress applied; three NFOA-based midseason N rates (RI-NFOA, RICV-NFOA, flat-RICV-NFOA) with (67 kg N ha^?1) and without preplant N; and two resolutions (0.34 and 2.32 m²) tested for RICV-NFOA only. With the 67 kg N ha^?1 preplant application, midseason RI-NFOA-based N rates resulted in an N use efficiency (NUE) of 65% while the 134 kg N ha^?1 fixed rate split applied had 56% NUE. Using the RICV-NFOA, NUE and net returns to N fertilizer were higher when spatial variability was treated at 2.32 m² resolution.