Overwintering soil temperature may influence crop response to phosphorus (P) and indices of P availability in the humid, temperate, transitional climate of Tennessee. The effects of P fertilization and soil incubation temperature on sorghumsudangrass (Sorghum bicolorxS. Sudanese) grown on a Typic Hapludalf was investigated in a greenhouse study. In order to determine the effect of temperature on P availability, soils were incubated prior to cropping, at a constant temperature of 6°C or an average diurnal temperature of 24 and 36°C. Reagent grade Ca(H2PO4)2.H2O was used as the fertilizer source and applied at rates of 0, 10, 20, and 30 mg P kg‐1for the first test and 0, 20, 40, 60, and 80 mg P kg‐1for the second test. Critical P concentration in the shoots for optimum yield was found to be 1.3 mg g‐1, corresponding to soil solution and labile P concentrations of 5.5 μmol L‐1and 167 μg g‐1, respectively. Optimum yield occurred for applications of >65 mg P kg‐1and was unaffected by soil incubation temperature. Applied P rates affected extractable P by five chemical extractants (Bray I, Bray II, Mehlich I, Mehlich III, and Mississippi), but soil incubation temperature had no affect. The extractants, however, were poorly correlated to plant P uptake and no one extractant appeared preferable to the others as an indicator of P availability.