Land use in the hills of the southern sector of the Lonquimay commune (Chile) and its structural characteristics

Abstract

Soil physical quality indicators were determined on a hillside in the south of Lonquimay commune (38°37’38” South Latitude; 71°05’26” West Longitude) as a uniform physiographic unit subjected to 3 uses: Ñirre (Nothofagus antarctica) grazed forest (BP), Alfalfa (Medicago sativa) sown pasture (PS) and degraded pasture (PD) (Acaena sp., Chusquea sp., Festuca sp., Stipa sp.). The soils are sandy loam (average 60.6% sand, 31.3% silt and 8.1% clay) subjected to goat grazing. They have a high porosity (>52%). There were differences in OM content in the sequence BP>PS>PD. There were differences in macroaggregates (PD>BP>PS) and microaggregates (PS>PD>BP). When measuring the Mean Weight Diameter MWD (mm), as an indicator of aggregate stability, a higher BP value was expected due to the presence of organic matter, which did not occur; all MWD values were <0.2 mm, considered as unstable aggregates. It is concluded that the soils studied show generalised conditions of structural degradation, independent of their use and depth; this occurs due to the additive effect of a series of degradation factors such as low organic matter content, erosion, poor soil structure, low aggregate stability and overgrazing that does not allow for the recovery of vegetation cover; to which are added climatic conditions with low temperatures that slow down biological dynamics.