Carlos Ovalle M.1, David Contreras T.2, Loreto Martrnez S.3 , Juan Gastó C.4 y Julia Avendaño R.5
Dry matter production, botanical composition and pastoral value of five types of pastures, with and without annual fertilization, were compared during eight growing seasons (1979-1986), in the dryland area (annual rainfall 695 mm) of Cauquenes.
The pastures were: 1) naturalized; 2) successional (pasture that grows after a wheat crop); 3) phalaris; 4) subterranean clover and 5) subterranean c1over- phalaris-annual ryegrass association.
A split-split-plot design was used, the fertilization treatments being the subplots (1,000 m2) and years the sub-sub-plots. Fertilization was 32 kg of N and 22 kg of P/ha/year. Evaluations were done by cuttings and the plots were individually grassed by sheep, after evaluation.
Significant differences (P < 0.05) among pastures and fertilizer treatments were observed. The fertilized plots yielded 73% more than the unfertilized ones.
Interactions pasture - year and fertilization - year were also significant. No treatment effects were observed in the years with a low rainfall. Treatments 1) and 2) yielded less than the sown pastures (872 to 2,475 and 1,424 to 3,900 kg of D.M./ha/year, respectively).
Changes in botanical composition and pastoral value, during the experimental period were anaIyzed, in each pasture type.
1 Estación Expertmental Quilamapu (INIA), Casilla 426, Chlllán, Chile.
2 Facultad de Agronomía, Universidad de Chile, Casilla 1004, Santiago, Chile.
3 Memorante Facultad de Agronomía, Universidad Católica de Valparaiso, Casilla 4, Quillota, Chile.
4 Facultad de Agronomia, Pontificia Universidad Católica de Chile, Casilla 6177, Santiago, Chile.
5 Subestación Experimental Cauquenes (INIA), Casilla 165, Cauquenes, Chile.