Raúl Meneses R.1, Fernando Squella N.2 y Christian Crempien L.2
From 1981 to 1987, at Los Vilos Subexperimental Station (INIA, Chile, 31º 52' lat. S, 71º 28' long. W), a sheep production system was evaluated, to know the biological productivity of a native pasture used with excluded and deferred paddock, in order to improve the traditional system used at the coastal strip of the arid zone. The system included 45 ha of native pasture and 17.7 ha of native pasture reinforced with Atriplex repanda and Atriplex nummularia. A vegetational map was stablished initially and dry matter production, botanical composition, bare soil and pasture value were evaluated each season. The dominant formation were herbaceous, low-Iigneous, and lowligneous- herbaceous. Dominant species were: Piptochaetium stipoides, Vulpia megalura, Avena barbata, Erodium cicutarium and Medicago polimorpha. The highest dry matter availability was always observed in excluded paddocks. 1985 presented the lowest productivity, due to the extreme drought of that year. The botanical composition of all paddock were improved, through the increase of poáceas. D.M. disponibility, botanical composition, pastoral value and bare soil were equal or higher than the obtained at the zone, using a traditional system. Shrubs' contribution was considered low. Pastoral values were classified as very low and low. Bare soil varied from 4.5 to 72.5% the later was observed under a very dry year. The praire management realized allowed the improvement of its condition.
1 Subestación Experimental Los Vilos (INIA), Casilla 40, Los Vilos, Chile.
2 Estación Experimental La Platina (INIA), Casilla 439, Correo 3, Santiago, Chile.