active ingredients. Several previous studies showed that K organic acids increased the solubility K of mineral. Results of Bevan and Savage (1989) showed that addition of oxalic acid increased the solubility of K-feldspar on pH 4 and 9, which indicated that the mechanism solubility of feldspar are increased was not due to preferential complexion of aluminium, but rather by an increase in the overall solubility of feldspar in the neutral pH region. Organic acid in medium can be as buffering agent to keep on neutral pH