We study the stochastic homogenization of the system -div \sigma^\epsilon =
f^\epsilon \sigma^\epsilon \in \partial \phi^\epsilon (\nabla u^\epsilon),
where (\phi^\epsilon) is a sequence of convex stationary random fields, with
p-growth. We prove that sequences of solutions (\sigma^\epsilon,u^\epsilon)
converge to the solutions of a deterministic system having the same
subdifferential structure. The proof relies on Birkhoff's ergodic theorem, on
the maximal monotonicity of the subdifferential of a convex function, and on a
new idea of scale integration, recently introduced by A. Visintin.Comment: 23 page
