Response to Zinc in Maize Crops in the Argentinian Pampas

Grain crops of the Pampas region of Argentina, mainly maize, have shown Zn deficiencies. However, research on Zn responses in maize is scarce. The objectives of this research project are to: 1) quantify maize response to Zn in the Pampas region, 2) determine the optimum Zn rate for maize, and 3) validate local Zn analyses and critical levels. Fourteen field experiments were carried out in the 2009-10 and 2010-11 seasons at different locations of the Pampas regions, including: Alejo Ledesma, Chaján, Adelia María, Guatimozin, and Rio Cuarto in Cordoba; San Justo, M. Teresa, Rafaela and Oliveros in Santa Fe; and 9 de Julio, Balcarce, Lincoln, and Gral. Villegas in Buenos Aires. Treatments include NP, NPS, and NPS with different Zn rates (0, 0.5, 1, 1.5, and 2 kg Zn/ha). Fertilizer sources were MAP+ urea (NP treatment), MES10^TM (12-40-0-10S; NPS treatment) and MESZ^TM (12-40-0-10S-1Zn; NPS plus Zn treatments). N, P and S rates were of 80 kg N, 35 kg P and 20 kg S.

Visual deficiency symptoms were observed in most locations. Results from the 2 seasons of experimentation showed significant grain yield responses in eight of the fourteen sites. Average grain yields for the fourteen experiments were 11,051, 11,283, 11,342, 11,535, and 11,568 kg/ha for the 0, 0.5, 1, 1.5, and 2 kg Zn/ha rates, respectively. Optimum Zn rates varied between 0.5 and 1.5 kg Zn/ha, depending on the location. New experiments will be established at different locations in the 2011-12 growing season. Argentina-29