Improving grazing management using the GRASP model

Summary

The objectives of the project were to: 
(1) develop an updated and fully documented version of the pasture growth model GRASP so that it can be used by pasture scientists across northern Australia; 
(2) support the model with a comprehensive parameter library for different land-types in northern Australia; and 
(3) train more than twelve pasture scientists in the use of the model and its supporting tools. 
In the project the following tasks were successfully achieved: 
1) Improved computing code and modelling environment were developed; 
2) Approximately forty pasture scientists were trained in three major workshops in the use of the model and the new interfaces; 
3) The model was improved by the addition of alternative runoff models and also sub-models addressing the varying dilution of available nitrogen by pasture; 
4) New pasture growth datasets and historical grazing trial data from across northern Australia were added to the database; 
5) New approaches to calculate animal intake and utilisation in grazing trials were demonstrated; 
6) Parameter sets were developed for about 250 land-types in Queensland and close liaison was established with the pasture science teams in the Northern Territory and Western Australia who are conducting similar exercises; 
7) The pasture growth model GRASP has been linked to the CSIRO SE herd/economics model ENTERPRISE; 
8) A more formal network of pasture scientists across states and institutions was established; and 
9) The results of the model development have been communicated through the Grazing Land Management education package (GLM), on-line model documentation, workshops for pasture scientists, and publications by CSIRO SE. 
The achievements of the project provide a basis and a legacy for the future development of models of pasture growth and their application to the northern Australian grazing industry.