With the aim of obtaining more efficient phosphate fertilizers than those traditionally used with calcareous soils, new coated slow-release fertilizers were produced at laboratory scale. Calcium triple superphosphate was used as the basic fertilizer and Kraft pine lignin for coating. The products obtained with a coating percentage of between 5 and 26% were evaluated by means of laboratory tests for solubility in water at a constant temperature as well as by carrying out physical tests regarding handling and transport. It was found that the rate of P contribution to the water solution is less in the coated products than in the uncoated superphosphate and that the rate constants of the nutrient release process decrease with increasing coating percentages of the fertilizers. The nutrient release in these coated products follows a kinetic equation of the first order. Finally, an incubation test of the experimental fertilizers was carried out in a calcareous soil for 3 mo. It was confirmed that available phosphorus increases with the application of coated phosphate fertilizers in inverse proportion to the coating percentage of the fertilizer. The greatest increase occurs with the product SPL-11 (11% coating) 30 days after its application.