Fractionation of Phosphorus in Sludge-Affected Soils
- A. C. Chang,
- A. L. Page,
- F. H. Sutherland and
- E. Grgurevic
Phosphorus accumulated in sludge-treated soils was chemically fractionated by a sequential extraction procedure. Samples used for the study were obtained from experimental plots of a sludge land application site, where composted sludges at rates 0, 22.5, 45, and 90 t ha−1 y−1, and liquid sludges at rates of 0, 3.75, 7.5, and 15 cm/y have been applied for 5 y. There were also experimental plots whose liquid sludge treatments were terminated after 3 y. The experimental field was cropped with winter barley (Hordeum vulgare) after the sludge applications.
In soils not treated with sludges, the Ca-bound P accounted for 50–60% of the total P. An accumulation of Al- and Fe-bound P occurred in all sludge-treated soils. In the top 15 cm of surface soil, after 5 y of composted sludge treatment at a rate of 90 t ha−1 y−1 (1980), the Al- and Fe-bound P was > 60% of the total P. Concentrations of water-soluble P in sludge-treated soils also increased. There were indications that the organically bound P in sludge-treated soils was the most likely form to leach. Three years after the termination of sludge applications, there was little change in the distribution pattern of sludge-borne P in the soil profile.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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