Concentración crítica de nitrato en el suelo en función del distanciamiento entre hileras de

• PABLO BARBIERI HERNÁN ECHEVERRÍA Y HERNÁN SAINZ ROZAS

Rosario, Santa Fe

Congreso; VIII Congreso Nacional de Maíz; 2005

AIANBA

Soil NO3--N (0-30 cm) at V6 stage (SNV6) is used as nitrogen (N) diagnostic method for N fertilizations at V6. Narrower rows increase N uptake at early stages and reduce soil N concentration at V6. Therefore, the objective of this work was to evaluate the relationship between grain yield and SNV6. An experiment was carried out at INTA Balcarce in 1996/97, 1999/00 and 2000/01 to evaluate row spacing on performance of SNV6. Treatments consisted of a factorial combination of row width (70, 52 and 35 cm) and N rates (0, 90 and 180 kg N ha-1), applied at planting. In both years, N rate increased grain yield (7190, 9714 and 10860 kg ha-1, for 0, 90 y 180 kg N ha-1, respectively). Grain yield responses to narrow rows (52 and 35 cm) decreased as N availability was increased (16, 4 and 0.4%, for 0, 90 and 180 kg N ha-1, respectively) respect to conventional row spacing. Relative yield was highly correlated (r2= 0.67-0.75) with soil NO3--N concentration (0-30 cm) at V6 stage. Soil NO3--N critical concentration for relative yield equal to 0.95 was 18.3 (±1,5), 12.9 (±1,2) and 15.8 (±1,9)mg kg-1, for 70, 52 and 35 cm row spacing, respectively. The results of this study shows that SNV6 was correlated with grain yield, and that soil NO3--N critical concentration was greater for conventional row spacing.    Palabras clave: maíz, nitratos en suelo en seis hojas, distancia entre hileras. Key words: maize, soil nitrate at six leaf stage, row spacing.