A graph G is called edge-magic if there is a bijective function f from the set of vertices and edges to the set {1, 2, . . . , |V (G)| + |E(G)|} such that the sum f (x) + f (xy) + f (y) for any xy in E(G) is constant. Such a function is called an edge-magic labeling of G and the constant is called the valence of f . An edgemagic labeling with the extra property that f (V (G)) = {1, 2, . . . , |V (G)|} is called super edge-magic. In this paper, we establish a relationship between the valences of (super) edge-magic labelings of certain types of bipartite graphs and the existence of a particular type of decompositions of such graphs.