Abstract. Seventeen field experiments were conducted on alkaline soils in eastern Australia between 1997 and 2000 to evaluate irrigated cotton response to phosphorus (P) fertilisation. Only 3 experiments demonstrated significant (P < 0.05) increases in crop P uptake or lint yield with P application. Comparison of several soil P tests revealed that Colwell (bicarbonate) P provided the best correlation with P uptake at early flowering and lint yield. Soil P may limit cotton growth where Colwell-P concentrations are <6 mg/kg. Soil P concentrations at most of the sites were well above this critical limit, so P fertiliser application was not required. Average P uptake at physiological cut-out and P removal in seed cotton was 21 and 15 kg P/ha, respectively. Apparent P fertiliser recovery was variable (0–67%) and may have contributed to the lack of response that was observed in 14 out of the 17 experiments. It is recommended that at least 40 kg P/ha be applied to soils with Colwell-P concentrations <6 mg/kg to increase soil P reserves. Application rates of at least 20 kg P/ha are recommended where Colwell-P falls between 6 and 12 mg/kg to maintain soil P fertility.