A preliminary examination of the spatial distribution of acidic soil and required rates of ameliorant in the Avon River Basin, Western Australia

摘要

Soil acidity is a major constraint to agricultural production in the south-west of Western Australia. This paper will examine a simplistic approach to mapping the spatial distribution of soil acidity in the Avon River Basin (ARB) of Western Australiaand discuss the implication this has on liming requirements in this region. Soil pH_(Ca) at 0.1 m intervals to a maximum depth of 0.3 m was analysed at 39480 locations across the ARB. The geo-location of these samples was recorded and soil pH_(Ca) distribution mapped using soil-landscape polygons. Nearly seven million hectares of topsoil (0-10 cm) is estimated to be extremely to moderately acidic (pH_(Ca) 4.3-5.5) and nearly four million hectares of shallow subsurface (10-30 cm) is estimated to be extremely to highly acidic (pH_(Ca) <4.8). At these levels of acidity, it is calculated that the ARB will require nearly twelve million tonnes of agricultural lime to increase the topsoil to pH_(Ca) 5.5 over a shallow subsurface of pH_(Ca)4.8.