  The Lund string fragmentation model is applied in a non-perturbative
calculation of the invariant production cross section of pions from
proton-proton collisions in the soft pT region. Invariant production cross
sections of pions and kaons from proton-proton collisions in the hard pT region
are calculated from the Feynman-Field perturbative QCD parton model.
Parameterizations of these production invariant cross sections are described.
