Produtividade de matéria seca e composição mineral do capim-tifton 85 sob diferentes doses de nitrogênio e idades de rebrotação

Abstract

The dry matter production and mineral content of Tifton 85 bermudagrass (Cynodon nlemfüensis x Cynodon dactylon) on nitrogen rates (0, 100, 200, 300 and 400 kg/ha) and regrowth ages (28, 42 and 56 days) were evaluated. The experimental design was completely randomized with a split plot feature. The main plots referred to N-rates whereas subplots were regrowth ages. The forage yield ranged from 5.75 to 20.46, from 8.13 to 22.85 and from 10.52 and 25.23 t/ha of DM, in response to rates of 0 to 400 kg N/ha, in plants harvested at 28, 42 and 56 days of regrowth, respectively, with a response efficiency of 36.8 kg DM/kg N. The P contents decreased with N rates and plant age increased ranged from 0.27 to 0.16%. The K contents decreased as plant age increased; the maximum K content of 1.25, 1.11, and 0.96% were recorded for plant harvest with 28, 42 and 56 days of regrowth, respectively, fertilized with 55 kg N/ha/cutting. The average Ca content was 0.48%. The Mg content increased as N rates increased and decreased as plant age increased, with values between 0.24 and 0.45%.