Grass height and soil cover under nitrogen fertilization, irrigation and grazing during the seasons of the year/Altura de capins e cobertura do solo sob adubacao nitrogenada, irrigacao e pastejo nas estacoes do ano

• Published in: Acta scientiarum. Agronomy 2010-01, Vol.32 (1), p.21
• Main Authors: de Alencar, Carlos Augusto Brasileiro, Coser, Antonio Carlos, Ma, de Oliveira, Rubens Alves, da Cunha, Fernando Franca, Figueiredo, Jose Luis Aguiar
• Format: Article
• Language: Spanish
• ISSN: 1679-9275
• DOI: 10.4025/actasciagron.v32i1.319

This study aimed to evaluate the soil cover and plant height of six irrigated grasses under different levels of nitrogen fertilization over the seasons of the year. The experiment was carried out in a split-plot design, with a 4 x 6 factorial scheme (nitrogen and grasses) in the sub-plots and the seasons (autumn/winter and spring/summer), in randomized blocks, with four repetitions. The nitrogen doses were 100, 300, 500 and 700 kg [ha.sup.-1] [year.sup.-1] and the grasses were: Xaraes, Mombaca, Tanzania, Pioneiro, Marandu and Estrela. The height was measured from the soil to the extremities of the leaves, and the soil cover was visually estimated by three observers. Effects of the grasses, nitrogen and seasons of the year were observed on the two evaluated characteristics. The Estrela and Tanzania grasses provided the largest and smallest soil cover, respectively. Pioneiro and Marandu presented the highest and lowest height, respectively. The highest temperatures in the spring/summer season caused higher plant height, but they did not affect soil cover. The increase in nitrogen dosages had little influence on the appraised characteristics in the autumn/winter season: there was a reduction in soil cover and increase in the height of Xaraes. In the spring/summer season, there were reductions in soil cover for Pioneiro and in the height of Pioneiro and Estrela. Key words: Brachiaria brizantha, Panicum maximum, Pennisetum purpureum, Cynodon nlemfuensis, soil conservation. Objetivou-se avaliar a altura de planta e a cobertura do solo de seis capins irrigados manejados por pastejo sob efeito de diferentes adubacoes nitrogenadas e estacoes do ano. O experimento foi conduzido em esquema de parcelas subdivididas, tendo nas parcelas um esquema fatorial 4 x 6 (doses de nitrogenio e forrageiras) e nas subparcelas as estacoes do ano (outono/inverno e primavera/verao) no delineamento em blocos casualizados, com quatro repeticoes. As doses nitrogenadas foram de 100, 300, 500 e 700 kg [ha.sup.-1] [ano.sup.-1], e as forrageiras foram: Xaraes, Mombaca, Tanzania, Pioneiro, Marandu e Estrela. A altura foi medida desde o solo ate as extremidades das folhas e a cobertura estimada visualmente por tres observadores. Observou-se efeito dos capins, adubacao nitrogenada e estacoes do ano nas caracteristicas avaliadas. Os capins Estrela e Tanzania proporcionaram maior e menor cobertura, respectivamente. Os capins Pioneiro e Marandu apresentaram maior e menor altura, respectivamente.