Effects of sources and rates of nitrogen on forage production and quality of coastcrossgrass

[摘要] Forage production and quality of coastcross grown on a dark red latosol (Hapludox) were evaluated in 1998-1999 and 1999-2000, from November to April, in São Carlos, São Paulo state, Brazil, under a tropical altitude climate. The experimental design was a randomized block design, in a split-plot arrangement, with four replications. In the main plots were allocated ten treatments, organized in a 2 ´ 5-factorial scheme (two nitrogen sources: urea and ammonium nitrate, and five N levels: 0, 25, 50, 100, and 200 kg N/ha/cutting, in five consecutive cuttings – repeated measures). Data were analyzed by MIXED procedure of SAS, using a repeated measure model. Nitrogen fertilization increased DM yield, CP concentration, in vitro DM digestibility, and nitrate concentration, and reduced DM and NDF concentrations in the forage. In the first year, N doses associated with 80% of the maximum forage yield were 88 and 78 kg/ha, corresponding to average dry matter yields of 2,769 and 3,202 kg N/ha/cutting, respectively, for urea and ammonium nitrate. In the second year, N doses which produced 80% of the maximum forage yield were 91and 116 kg/ha, respectively, for urea and ammonium nitrate, corresponding to average DM yields of 2,312 and 3,073 kg ha/cutting, respectively.

[学科分类] 兽医学

[关键词] ammonium nitrate;crude protein;nutritive value;tropical grass;urea    Introdução Embora as gramíneas forrageiras tropicais não possuam qualidade nutricional comparável à de gramíneas de clima temperado;seu elevado potencial de produção de MS pode resultar em alta produtividade animal