The metal atom, which is present in superphosphate, is

Superphosphate is a widely used phosphorus fertilizer produced by reacting phosphate rock with sulfuric acid [t1][t5]. The primary active ingredient in both single superphosphate (SSP) and triple superphosphate (TSP) is monocalcium phosphate, chemically represented as Ca(H2PO4)2 [t1][t4]. In the production of single superphosphate, the reaction also generates calcium sulfate (gypsum) as a byproduct, which remains in the final mixture [t1][t7]. Consequently, the metal atom fundamentally present in the chemical structure of the active nutrient-supplying component (monocalcium phosphate) and the associated byproduct (calcium sulfate) is calcium (Ca) [t4]. While other macronutrients like potassium and magnesium are essential for plant growth, they are not the defining metal constituents of the superphosphate chemical compound [c5][t4].

Sources

1. [1] https://www.sciencedirect.com/topics/chemistry/superphosphate
2. [2] Indian Economy, Nitin Singhania .(ed 2nd 2021-22) > Chapter 9: Agriculture > FERTILISERS > p. 302