Application of minimum tillage, mechanical cut, and herbicide in the establishment of Panicum maximum cv. Mombaza

The experiment was undertaken in a native grassland with predominance of Bahia grass (Paspalum notatum) and wire grass (Sporobolus indicus) in more than 85 % of the area on calcic ferrallitic soil. A split plot design was used with four replicates. The principal plots were in correspondence with the plant cuts and the application of herbicides, and the subplots, with the activities of tillage plus harrowing, harrowing plus furrowing and harrowing alone. In the first sampling, the number of tufts/m(2) and the pasture height were similar when cutting or applying herbicide before the soil tillage. Nevertheless, the number of tillers/plants was higher (P <0.05) when applying herbicide and the number of tufts/m2 was lower (P <0.05) when sowing in furrows. In the first sampling, the highest yield was obtained when cutting and applying harrow plus tillage (2.86 t/ha of DM). There were no differences as to the application of herbicide with tillage plus harrow (2.15 t/ha of DM). In the second, after fertilizing with 75 kg/ha of N, there was significant interaction (P < 0.05) between the type of tillage and the level of preparation of the soil for the grassland height, which was higher. (P <0.05) when applying herbicide and harrow (207.75 cm), not differing from the application of herbicide with the activity of tillage plus harrow (200.5 cm). The latter did not differ from the cut with tillage plus harrow (191.0 cm). In the second sampling, there was significant (P < 0.01) interaction for the yield. The best (P < 0.001) forage productions were obtained when applying herbicide combined with the activities of tillage plus harrow or harrow alone, before the sowing of Guinea grass (Mombaza). The total yield was similar to the second sampling. Biomass productions of 21.34 and 22.05 t/ha of DM were attained by applying herbicides combined with the activities of tillage plus harrow or harrow alone, respectively. These results differed (P <0.001) from those of the rest of the treatments. In the second sampling, the percentage of Guinea grass ranged from 96.2 to 98.5 %, regardless the cultural activities applied to facilitate the establishment. The lowest costs per ton of DM were obtained when applying herbicide and sowing after harrow or after tillage plus harrow. It is concluded that the best results, from the technical and economical point of view, were obtained when applying herbicide (glyfosfate a rate of 5 L/ha), followed by the harrow or the tillage plus harrow, before the sowing