To provide a phosphate fertilizer produced by blending a calcium-based material such as poultry manure incineration ash and quick lime to a phosphate-based fertilizer such as calcium superphosphate, magnesium phosphate fertilizer or the like to convert the water-soluble phosphate contained in the phosphate fertilizer to be water-insoluble and 2% citric acid-soluble phosphate to be free from the bonding to allophane or the like in soil, the run off of the phosphate to the outside of a soil layer and the generation of ammonia gas even when mixed with a fertilizer containing an ammonium salt such as ammonium sulfate.

The citric acid-soluble phosphate fertilizer is produced by blending 10-250 pts.wt. calcium-based material to 100 pts.wt. phosphate fertilizer containing water-soluble phosphate.