Characterization and variability of the interior dryland natural pasture in the subhumid Mediterranean zone of Chile

Hernán Acuña P.1, Julia Avendaño R.2, Carlos Ovalle M.1

During three yearperíods, total annual productivity (and the botanical composition) of the herba ceous strata was measured in 31 sites of the dryland range of the Chilean Mediterranean subhumid zone. The initial contents of nitrogen, phosphorus and potassium in the soil were determined, as well as other vegetation and soil parameters. Average annual productivity of the herbaceous strata for ah sites and years was 1,611 kg of dry matter (D.M.) per ha (S.D. ± 1,005). Locahities with initial soil nitrogen contents higher than 20 ppm produced 59.2% more D.M./ha than those sites with lower soil nitrogen; when the soih potassium was equal or higher than 0.4 meq/ 100 g, the productivity was 90.2% higher than with lowercontents. Soils classífied in Classes VI and VII produced 914 kg D.M./ha; while those in Class III, were 231% more productive. Non eroded soils reached a productivity 187% higher than those with severe or very severe erosion. At sites with a Iow woody strata of vegetation (dominant species is Acacia caven L.), or without it, production was 1,169 kg of DM/ha; while sites with a tail woody strata of vegetation (higher than 1.70 m) reached 2,223 kg D.M./ha. Pastures that had been plowed within the last 10 years produced 1,236 kg D.M./ha, compared to 2,293 kg of D.M./ha produced by those with more than 10 years without plowing.

1 Estación Experimental Quilamapu (INIA), Casilla 426, Chillán, Chile.
2 Subestación Experimental Cauquenes (INIA), Casilla 165, Cauquenes, Chile.