A pot experiment was catried out to study alleviation of soil acidity and Al toxicity by applying an
alkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acid
sandy loam (pH 4.5). Barley (Hondeum vulgare L. cv. Forrester) was used as a test crop and was grown
in the sewage sludge-amended (33.5 t sludge DM ha-1) and unamended soils. The results showed that the
alka1ine biosloids increased soil pH from 5.7 to 6.9 for the clay sandy loam and from 4.5 to 6.0 for the sandy
loam. The sludge product decreased KCl-extractable Al from 0.1 to 0.0 cmol kg-1 for the former soil and
from 4.0 to 0.1 cmol kg-1 for the latter soil. As a result, barley plants grew much better and grain yield
increased greatly in the amended treatments compared with the unamended controls. These observations
indicate that alkaline-stabilised biosolids can be used as a liming material for remedying Al phytotoxicity in
strongly acid soils by increasing soil pH and lowering Al
