Secondary and micronutrient application effects on corn fertilized for different yield goals under highly weathered soil conditions

Abstract

Highly weathered soils have low native fertility; thus, optimum nutrient management is critical, especially for a high-input crop such as corn (Zea mays). Field studies were established in Plains and Tifton, GA, to assess secondary nutrient (SN; Mg, Ca, and S) and micronutrient (MN; B, Zn, Mn, Fe, Cu, and Mo) application effects on corn fertilized with primary nutrients (PN; N, P, and K) to achieve 12.5 Mg ha−1 (low) and 25.1 Mg ha−1 (high) yields. Both Plains and Tifton have Ultisol soil. However, the Tifton soil has a 30-cm top sandy layer, and the Plains soil has no top sandy layer. Differences in corn nutrient concentrations were observed at the V5–V7 stage but not in biomass accumulation. The 12.5 Mg ha−1 target grain yield from applying the low PN was exceeded at both locations (by 19.0%–26.6% in Plains and 6.3%–19.7% in Tifton), irrespective of the SN or MN application. However, the 25.1 Mg ha−1 target grain yield from applying the high PN rate was not achieved, with yields of 16.9–17.7 Mg ha−1 in Plains and 15.7–17.1 Mg ha−1 in Tifton obtained. The SN and/or MN application increased corn yield (by 2.3%–13.6%) across all conditions, but the differences were statistically significant under just the low PN rate in Tifton. Overall, the results showed that SN and MN could be yield-limiting factors of corn in the Ultisol soils tested in the study, and also 12.5 Mg ha−1 corn yield can be achieved with lower PN rates than currently recommended.