Pig slurry was treated by addn. of H3PO4, H2SO4, superphosphate and milk of lime optionally under heating to remove solid phase recommended as fertilizer. The solid phase was studied for content of soluble P2O5, total ammonium N, macro and microelements as well as for BOD and COD, microbial purity and phase compn. The studied solid phase met all requirements for P-contg. fertilizers for agriculture.