Distribution and forms of phosphorus and aluminium in acidic topsoils under pastures in south-eastern Australia [Victoria; New South Wales]

McLaughlin, M.J.; James, T.R. . Div. of Plant Industry; Baker, T.G.; Rundle, J.A.

Distribution and forms of phosphorus and aluminium in acidic topsoils under pastures in south-eastern Australia [Victoria; New South Wales]

1990

McLaughlin, M.J. | James, T.R. (Commonwealth Scientific and Industrial Research Organisation, Canberra (Australia). Div. of Plant Industry) | Baker, T.G. | Rundle, J.A. (Victorian State Chemistry Lab., East Melbourne (Australia))

Examination of soils at 15 sites showed significant amounts (35-65 percent) of the total P were present in organic forms (Po). Some 20-40 percent of this Po was extractable using 0.5 M NaHCO3, and is regarded as easily mineralizable and a potential source of P for plant uptake. Substantial amounts of Al were present in crystalline and non-crystalline oxides (2000-6000mg per kg) and complexed to organic matter (up to 400 mg per kg). Sampling and analysis of soils for determining P fertilizer requirements and diagnosing acidity and related problems should take into account the relative heterogeneity in soil properties in the top 100 mm of the profile.

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