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Recovering Fertility of Acidic Volcanic Ash Soils in the Araucania Region (South Chile): Impacts of Liming, Grassland Composition, and P Fertilisation

Recuperación de la fertilidad de los suelos volcánicos ácidos del sur de Chile: Impactos del encalado y fertilización fosfatada

Abstract : The aim of this study was to assess the effect on soil quality of a governmental program whose objective is restoring the fertility of degraded acidic volcanic ash soils. The program consisted of (i) liming, (ii) correction of the P status, and (iii) sowing forage plants. We measured soil fertility of fields after 1 to 4 years since start of the program, and compared these fields against fields under old permanent natural grasslands, used to estimate the baseline soil test values for the properties considered in this study. The survey was conducted in five localities (Lonquimay, Curacautín, Vilcún, Cunco and Villarrica) in the temperate southern part of Chile (Araucania region). The impacts of the program on acidity (pH and exchangeable aluminum) were different among localities. At Cunco, exchangeable aluminum was not affected, while pH increased initially but decreased to its initial value within four years. Instead, at Lonquimay exchangeable aluminum decreased significantly, and pH remained slightly higher than the control values through the first four years. At Lonquimay P-Olsen was initially increased, showing a positive short-term effect of the program, but gradually decreased after the first year, until it returned to the initial level. At Vilcún, an increase with time was observed during the whole period. In Curacautín, Villarrica and Cunco, the P-Olsen content increased during the first years of the experiment but began to decline at the end of the period. This study provided important results for the improvement of the program.