Fig. 7

Response surface of pH in calcareous soil amended with four sources of phosphorus for applying distilled water (a) and acidified water (b): bone char (BA), bone ash (BC), phosphate rock (PR), and single superphosphate (SSP).
Response surface of pH in calcareous soil amended with four sources of phosphorus for applying distilled water (a) and acidified water (b): bone char (BA), bone ash (BC), phosphate rock (PR), and single superphosphate (SSP).