The Pasture Growth Model (PGM) is one of the seven eco-hydrological modelling tools included in the CLASS catchment-modelling framework. PGM can be used at a daily time step either as a stand-alone tool at a paddock scale or as part of the CLASS catchment model wherein PGM simulates pasture growth for all grid cells under pasture in a catchment and provides growth information to the catchment hydrology model. PGM can be used to simulate growth of composite pasture types of multiple pasture species that may be summer or winter active, perennial or annual. The model simulates green and dead dry matter, green LAI, root biomass and ground cover for a range of climate, soil and management conditions. CLASS PGM provides a Windows based user-friendly graphical user interface (GUI) which guides the user through each step.

The model is designed for use by environmental science professionals including scientists, researchers, State and Federal NRM organisations, Catchment Management Authorities, consultants and students.

CLASS PGM is designed for use by professionals with varying levels of expertise in pasture growth and recharge modelling. It can be used by expert scientists, modellers and agronomists to simulate pasture growth. Advanced users with measured field data and a sound understanding of pasture dynamics and soils can update parameter files and apply PGM to their own applications. In the absence of field data and parameters, default parameters inbuilt in PGM database can be used.

CLASS PGM has been implemented on data from the Delegate Catchment (Snowy River basin, New South Wales) under the project ?Landscape Strategy for the Snowy Monaro Region?. PGM has also been implemented on pasture growth data from the experimental catchments at Wagga Wagga Research Centre, DIPNR and the results were compared with the observed pasture yield and species composition.

Main features of this product are:

1. CLASS PGM provides a Windows based user-friendly graphical user interface (GUI).
2. Capability to simulate growth of composite pasture types of multiple pasture species that may be summer or winter active, perennial or annual
3. Seamless integration with the Richards? equation based hydrology, an established and proven technology for accurate water balance simulations
4. The ability to simulate interactions between pasture growth and water balance using robust plant physiology and unsaturated zone hydrology concepts
5. The model uses adaptable sub-daily simulation time steps by sensing transient nature of the atmospheric conditions and attempts to overcome the divergence problems usually associated with solution of the Richards? equation.