Effect of nitrogen fertilization on production and chemical composition of a native pasture

Abstract

The work had the objective to evaluate the response of a native pasture of Rio Grande do Sul to nitrogen rates (0, 50, 100, 150 e 200 kg ha^-1 N), split into four application after cuts taken at 42 days intervals among September 2003 and March 2004. The dry matter (DM) production ranged from 858 kg ha^-1 (November) to 1267 kg ha^-1 DM (March), which corresponded to 20.42 and 30.16 kg ha^-1.d^-1 DM, respectively. The total forage yield increased linearly with N rate (y= 13.38x + 2692.7) resulting in 5420 kg ha^-1 MS with 200 kg ha^-1 N rate. The cutting horizon density, defined by the relationship between the DM produced and the canopy height, ranged from 47.3 (0 kg ha^-1 N) to 76.6 kg MS ha^-1 cm^-1 (200 kg ha^-1 N). The chemical composition was not affected by N. The crude protein, acid detergent fiber and neutral detergent fiber concentration were 8%, 44% and 70% respectively.