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How can nitric acid be used to make mixed phosphate fertilizers?

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Diagram showing the element phosphorus on the periodic table, with its atomic number 15, symbol P, atomic weight 30.973762, electron configuration, cubic crystal structure, solid state at room temperature, and weakly acidic oxides.
phosphorus

Nitric acid can be used to treat phosphate rock as an alternative to using sulfuric or phosphoric acid in the production of fertilizers.1

When phosphate rock is treated with nitric acid, one of the resulting products is calcium nitrate. Because calcium nitrate is itself a fertilizer, the process yields a variety of mixed fertilizers.1

Furthermore, ammonia can be used to neutralize the mixture, which produces ammonium phosphate. This is considered an improvement over other methods because both the phosphorus and the nitrogen constituents contribute essential fertilizer elements, rather than including the "dead weight" of calcium sulfate that is formed when using sulfuric acid.1