  Inclusive distributions of soft production of mesons in hadronic collisions
are calculated in the valon-recombination model. The new determination of the
valon distributions from hard scattering data makes possible a tightly
interrelated treatment of pion and kaon production in the fragmentation regions
of proton, pion and kaon. Only one free parameter is used in the determination
of the valon distribution in the kaon. No other adjustable parameter is needed
to fit the $x$-distributions of the data on inclusive cross sections, except
for the normalizations since the data are at fixed $p_T$. The success of the
model in reproducing seven inclusive distributions suggests that there are two
important mechanisms at work in soft production. One is that the structure of
the hadron that fragments is highly relevant. The other is that the produced
particles are formed by the recombination of quarks and antiquarks. These two
aspects about hadrons in soft processes can be well described in the framework
of the valon-recombination model.

High Energy Physics - Phenomenology