Soil aluminium availability in Andisols of southern Chile and its effect on forage production and animal metabolism

Soil acidification limits livestock production in many parts of the world. Two experiments were carried out to investigate the effect of aluminium (Al) on pasture yield and animal production. In experiment 1, the effect of raising soil pH (in water) from 5.1 (acid soil, A) to 5.6 (corrected soil, C) was tested on forage and animal production. In experiment 2, Friesian calves were individually fed either silage with or without the addition of 2000 mg kg^?1 of Al as aluminium sulphate. Al, P, Ca and Mg concentrations were measured in forage, and in animal blood and faeces. Live weight gain (LWG) was also measured. Soil acidification resulted in a 36% overall reduction in pasture yield in the A treatment (9.4 ± 0.31 and 14.7 ± 0.47 t ha^?1 year^?1 for the A and C treatments respectively) and in 15% reduction of the protein concentration in the herbage. No significant differences were found for the individual daily LWG (P > 0.05). Direct Al intake reduced animals daily LWG by 14% (P ≤ 0.05). The correction of soil acidification increased livestock production by 125% when stocking rate was strictly adjusted to grassland production.