MOMENTOS DE FERTILIZACIÓN NITROGENADA EN MAÍZ EN EL CENTRO-OESTE DE ENTRE RÍOS

MELCHIORI, RJM; CAVIGLIA, OP; BIANCHINI A

Rosario, Argentina

Congreso; VII Congreso Nacional de Maíz; 2005

Plant nitrogen (N) status in maize as estimated by reflectance sensors is more accurate at delayed stages. However, the effects of late fertilization on yield have been rarely reported. The objective of this study was to evaluate the effects of timing and rate at planting of N fertilization on maize yield and its components. Two experiments were carried out during 2003/4 and 2004/5 growing seasons at Paraná, Argentina (31º50´ S). Experiments included combinations of N rates applied at planting (0, 70, 140 y 210 kg N/ha) and timing of late fertilization (LF) (70 kg N/ha at V8, V10, V12 and V14 and a control not late-fertilized). Yield and its numerical components were recorded on an area of 10 m2 per plot. Treatments were laid out in a complete randomized block design in a factorial arrangement. Yield was affected by N at sowing (p<0.0001) and by LF (p<0.002). LF outyielded controls irrespective of timing, when no N was supplied at planting, in the two growing season. In 2004/5, LF outyielded controls even in treatments that had 210 kg N ha-1 at planting. Yield increase was associated with both kernel number and weight, suggesting that kernel weight play a key role to increase yield in the region of Paraná. Significant yield response to LF in experiments suggests that the application window for N is wider than the classical V6 sidedress.