Abstract

SILVA-ACUNA, Ramón et al. Physical and chemistry properties changes of a well drained savanna soil, with three tillage systems, in a degraded pasture of Brachiaria humidicola. Zootecnia Trop. [online]. 2005, vol.23, n.4, pp.373-392. ISSN 0798-7269.

During three years, on a sandy loam soil, at Monagas savannas, it was evaluated the effect of tillage in the recovery of a degraded pasture of Brachiaria humidicola and its influence in the physical and chemistry properties of the soil. The treatments used were: pasture without tillage (WT), conventional harrow (CH), and one pass of harrow plus one pass of sub-soiling at 40 cm of deep (H+S), using a randomized block design, with three repetitions of 1100 m². At the beginning of the experiment it was applied 400 kg of acidulated phosphate rock and three months later, 100 kg/ha of urea and 100 kg/ha of K₂SO₄ were applied. The second year it was applied urea, K₂SO₄, and MgSO₄, using 100, 100, and 50 kg/ha, respectively. It was measured the aerial biomass production, and the disponibility of P₂O₅, K₂O, CaCO₃, and MgO. It was also measured soil acidity, compactation, and humidity. Root density of the pasture was measured at 18 months. It was observed that the aerial biomass production of B. humidicola was increased independently of the tillage system used. In the systems HC and H+S were obtained higher production and it was hold up through on time. In the system with tillage the humidity and soil compactation were only affected at the beginning of the experiment. These systems influenced the availability of phosphorus, potassium, calcium, and magnesium with reduction through time, and their higher concentrations were associated to the stratum of 0 at 10 cm of depth.

Keywords : Degraded pasture; Brachiaria humidicola; tillage.