EXPLORACIÓN DE DEFICIENCIAS DE AZUFRE EN ENTRE RÍOS.

MELCHIORI, RJM; CAVIGLIA, OP; FACCENDINI N.

Rosario, Argentina

Congreso; VII Congreso Nacional de Maíz; 2005

Sulfur deficiencies have been determined in some areas of the pampas region. Long intensive land use, soil degradation, and lower organic matter are generally indicative of sites with probable response to S fertilization. Sulfate is not a good indicator of a responsive site, and explorative experimental nets are a tool to identify sites with sulfur deficiencies. The objective of this work was to explore sulfur deficiencies in maize within the more intensive agriculture zone of Entre Rios Province, Argentina . Twenty on-farm experiments were carried out in two growing seasons (2003-2004 and 2004-2005) in the western region of Entre Rios. Treatments included a control, and sidedress dribbling of N 100 kg ha-1, and N 100 kg ha-1 + S 15 kg ha-1. N source was UAN (N 32%) and S source was ammonium tiosulfate (N 12 %, S 24%). Experimental design was a complete randomized block arrangement. Grain yield ranged from 3.6 to 14.4 t. ha-1. A generalized N effect was (p<0.05) detected, whereas only 4 of 20 experiments show significant sulfur responses (p<0.05). Sulfur yield response was not associated to soil sulfate or organic matter content. Sulfur response appears unpredictable according to soil variables studied, however positive yield increase by S effect in 55% of sites need to be elucidated.