Zinc Limits Corn Yield In Argentina.

The Argentine Pampas are typically not considered to be zinc (Zn) deficient and as a consequence producers do not typically apply Zn fertilizer. However, Zn deficiency symptoms on maize have recently been detected. The objective of this study was to evaluate the response of maize to Zn fertilization and determine the optimal application rate of this micronutrient. Eightteen trials were conducted in different locations in the Pampas during the 2009/10, 2010/2011 and 2011/12 growing seasons. Treatments were: NP, NPS, and four rates of Zn (0.5, 1, 1.5 and 2 kg Zn ha-1). The sources used were monoammonium phosphate (MAP 11-52-0), MES10 (12-40-0-10S) and MESZ (12-40-0-10S-1Zn). Nutrients rates of N, P and S were 180 kg N ha-1 (soil N + fertilizer N), 35 kg P ha-1 and 20 kg S ha-1. These treatments were banded at planting. Statistically significant responses were observed in twelve of the fourteen sites. There was no negative response to the application of Zn in any site. On average across 18 sites, the optimal rate was 1.5 kg Zn ha-1, resulting in a 7.6% response (765 kg ha-1) compared to the NP treatment and 4.7% (487 kg ha-1) compared to the NPS treatment, with statistically significant differences between treatments (p <0.1). The loss of maize yield due to Zn deficiency indicates that this nutrient should be incorporated into maize production systems in the Argentina Pampas.