PLEASE NOTE:  The current APSIM Rice Model is unavailable for Commercial Use. 

The APSIM Rice module is an implementation of the Oryza2000 model produced by IRRI.

Please see the official IRRI documentation for Oryza2000 for more information.

IRRI official site

There is also a Text Book called “Oryza2000: Modeling Lowland Rice”
by B.A. Bouman, M.J. Kropff, T.P. Tuong, M.C.S. Wopereis, H.F.M. ten Berge, H..H. van Laar. ISBN is 971-22-0171-6