Produção de seis gramíneas forrageiras tropicais submetidas a diferentes lâminas de água e doses de nitrogênio, na região Leste de Minas Gerais / Yield of six tropical grasses under different irrigation depths and nitrogen fertilization in Eastern Minas Gerais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this study was to evaluate the yield of six tropical grasses subjected to different irrigation depths and nitrogen fertilization, in Eastern Minas Gerais. Two experiments were carried out independently, in Eutrophic Cambisol, for two years: Experiment 1- Influence of irrigation depths on yield of six tropical grass; and Experiment 2 - Influence of nitrogen fertilization on yield of six tropical grass. The studied grass species were: Pioneiro (Pennisetum purpureum), Estrela (Cynodon nlemfuensis L.), Tanzânia (Panicum maximum), Mombaça (Panicum maximum), Marandu (Brachiaria brizantha) and Xaraés (Brachiaria brizantha). Experiment 1 received 50, 150 and 300 kg ha-1 year-1 of P2O5, K2O and N respectively as total fertilization, being arranged in a split-split plot, complete randomized design. The applied irrigation depths, using an in-line sprinkler system, were 0, 18, 45, 77, 100 and 120% of the reference water depth. Were appraired: fresh matter (GM) and dry matter (DM) yields, dry matter percentage (% DM), plant height, soil cover, crude protein level (CP), neutral detergent insoluble fiber (NDIF), in vitro true digestibility of dry matter (IVTDDM), soil density, root density (RD) and root effective depth (RED). The experiment 2 was arranged in a split plot, complete randomized design. The nitrogen doses were 100, 300, 500 and 700 kg ha-1 year-1. The used irrigation system was semi-fixed conventional sprinkling. Only the DM yield was evaluated in this experiment. In the two experiments, the animals were used only as a cutting tool. The results showed that: (a) the irrigation depths, during fall/winter, provided increase in DM, FM, and soil cover and reduction in the % of DM, whereas during spring/summer, the irrigation depths had no effect on DM yield, however, they increased DM % and soil cover and reduced FM yield and plant height; (b) the increase in nitrogen fertilization did not increase the DM yield of the studied grasses; (c) irrigation in the fall/winter period was shown efficient in breaking the seasonality of pasture yield; (d) Xaraés showed the largest yields of DM and FM and root density; (e) Estrela provided good soil cover and had the largest DM %. On the other hand, Pioneiro provided low soil cover and gave the smallest DM %; (f) Pioneiro and Xaraés had the highest plant heights and Marandu the lowest; (g) Marandu and Tanzânia showed the largest root effective depths and Xaraés and Mombaça the most superficial root systems; (h) the highest DM and FM yields and the highest plant heights were obtained in the seasons spring/summer; (i) the seasons had no effect on DM%, soil cover and NDF; (j) the seasons fall/winter provided higher levels of crude protein (CP) and in vitro digestibility of DM (IVDDM) for Mombaça and Marandu; (l) grazing reduced the soil basic infiltration rate by 67%.

ASSUNTO(S)

line source sprinkler compactação engenharia de agua e solo fertilization adubação compaction irrigação root system pasture pastagem sistema radicular irrigation line source sprinkler

ACESSO AO ARTIGO

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