The effects of nitrogen and potassium fertilization on elephantgrass - Napier cv. were evaluated. An incomplete N x K factorial arrangement was studied in randomized block design with three replications with seven N levels (20, 50, 100, 200, 300, 350 and 380 kg/ha) and seven K levels (16, 40, 80, 160, 240, 280 and 304 kg/ha). The fourteen N and K combinations were obtained according to the Box Berard Matrix, increased 3, with an extra point. The elephantgrass - Napier cv. mass production increased 86% in response to N and K fertilizers. The leaf/stem ratio and Mg2+ content negatively decreased as K levels increased. The P and Ca2+ contents decreased as N levels increased , while the crude protein content quadraticly increased by the N and K fertilization. Potassium content increased with K fertilizer but decreased as N fertilizer doses increased. The critical K level was 1.85 dag/kg herbage dry matter.
critical level; crude protein; dry matter; mineral
