Reducing the environmental risk from the soluble P present in sludge-amended soils is essential for increasing the soil's capacity to utilize sewage sludge beneficially. Fresh dewatered anaerobically digested sewage sludge (FSS) was stabilized using three chemicals: ferrous sulphate (FeSul), calcium oxide (CaO) and aluminium sulphate (alum), with different chemical ratios, or by composting. Designations for the stabilized sludges are as follows (respectively): FeSul-SS, CaO-SS, alum-SS and BSC.  Phosphorus phytoavailability was studied during a 100-day incubation period of the sludge materials with alluvial soil in comparison to KH₂PO₄-amended soil by a newly-developed bioassay, which corresponded to the inorganic content P (P_i) of tested plant. The dynamics of water-soluble P (WSP) and Olsen-P were also investigated in the amended soils. Phosphorus phytoavailability was notably linked with incubation time, the chemicals used, and their rates in the sludge. In general, P phytoavailability at equal rates of P addition was KH₂PO₄ >> alum-SS > BSC ≥ FSS > CaO-SS >> FeSul-SS, and was positively related to the added P rates, although the pattern of the increase differed among the sludge products. The amount of inorganic WSP (WSP_i) extracted from the soil increased following the application of FSS or BSC, and additional P mineralization further increased its concentration during incubation. In contrast, in most cases the chemically stabilized sludges, especially the FeSul-SS, showed considerably reduced WSP_i concentrations relative to the untreated soil. No correlation was found between the WSP content in the sludge and in the soil amended with sludge. The total WSP, Olsen-P and organic WSP (WSP_o) were positively correlated with P phytoavailability. It is concluded that all the three chemically stabilized sewage sludges with propriety ratio of chemicals can effectively control WSP_i in soil but still supply P for plant growth.