Acumulación de materia seca, absorción de Nitrógeno, Fosforo y Potasio por el maíz en diferentes condiciones de manejo de la Fertilización Nitrogenada

the pattern of dry matter (dm) accumulation and n, p, and k uptake by maize, zea mays l., could be used in determining the amount and optimal stages of fertilizer application to improve nutrient efficiency. in this experiment it was evaluated the parameters mentioned above by 1) maize hybrid in a mollisol soil of maracay where between 0 to 180 kg n ha-1 was applied, and 2) in a ultisol and in a mollisol soil of el pao (cojedes) and turén (portuguesa) where 120 kg n ha-1 was applied whole at the sowing time, or split between sowing time and dressing at 15, 25, or 35 days after sowing. it was found that dm production had a similar pattern in the three places: between 47% and 58% of the dm was accumulated during the first 60 days, and between 88 and 100% 90 days after sowing. however between 56 and 88% of n, and between 84 and 100% of k were taken up at the 60 days after sowing, with maximum uptake rate between 1.6-3.1 and 2.1-3.9 kg ha-1 d-1 of n and k at the 45-60 and 30-45 days periods respectively. there was a linear relationship between dm production and p uptake (r2 = 0.95-0.99), although p uptake changed between 16.5 (turén) and 42 kg ha-1 (el pao). the maximum p uptake rate changed from 0.30 kg ha-1 d-1 at 60-90 days period (turén), and 1.2 kg ha-1 d-1 at 75-90 days period (el pao). the amount of nutrient uptake followed the order k>n>p.