An experiment was carried out to find out the effect of fused-P and rock-P applications to mixed pasture species (Orchardgrass; Dactylis glomerata, and ladino clover; Trifollum repens) grown in Cheju volcanic ash soils. Black soil when compared with very dark brown soil, is generally lower in available phosphorous. Phosphorus uptake in pasture species lowers its dry matter yield. In the case of carrier free, phosphorus application increased dry matter yield more than no phosphorus, while carrier was treated (0.5 mole KH₂PO⁴) there was no difference in the dry matter yield and available phosphorus between no P and P applications. When applied to pastures, fused-P compared with rock-P gave higher dry matter yields and increased P-uptake.