Rice pot experiment was conducted with red earths and their paddys derived from graniteand basalt to study the differences in their P fertilizer zvailability and soil chemistrycharacteristics. It was found that for the red earth and its paddy soil derived from granite.the P availability was mainiy related to Fe and Al while for those from basait the Pavai-lability was related to not only Fe and Al,but also Mn. The mechanism of P fertiliser avai-lability in red earths affected by Fe and Mn in the soil-plant system was discussd.