Standard AOAC methods of chemical analysis have been used to characterise the industrial byproducts partly burnt chicken litter ash (CLA), totally burnt chicken litter ash (CLAT), wood ash (WA), and iron smelting slag, for use as a combined liming agent and phosphate (P) fertiliser. These materials are effective liming agents with calcium carbonate equivalence of 93–99%. Total P concentrations of CLA (3.6% P), CLAT (4.75% P), slag (0.26% P), and WA (0.44% P) indicate that they would function as P fertilisers when applied at the high rates required for liming soils. The form of P in slag is unknown; CLA and CLAT consist mostly of mixtures of the phosphate mineral apatite with calcite and quartz. WA consists mostly of calcite, quartz, and various salts. For long extraction times, total P dissolved increased in the sequence CA (citric acid) > NAC (neutral ammonium citrate) > AAC (alkaline ammonium citrate). Little apatite persisted in residues of CLA and CLAT after 120 h of CA extraction but considerable amounts of apatite remained in NAC and AAC residues. A glasshouse P-response experiment was carried out with ryegrass on an acid lateritic soil with the application of various levels of phosphate as chicken litter ash, iron smelting slag, and wood ash. Monocalcium phosphate (MCP), dicalcium phosphate (DCP), and rock phosphate (RP) were included for comparison purposes. Based on plant yield data, the relative agronomic effectiveness (RE) of DCP compared to MCP was 57%, 72%, 73%, and 94%, respectively, for 4 successive harvests, for RP was 24%, 34%, 70%, and 56%, for chicken litter ash was 13%, 16%, 33%, and 39%, for slag was 8%, 9%, 16%, and 10%, for WA was 6%, 9%, and was effectively zero for the final 2 harvests. For no extraction time was the P soluble in the 3 citrate extractants a reliable predictor of the agronomic effectiveness of these materials as P fertilisers established by plant growth measurements.
