Modelling Livestock Production
The latest downscaled climate change projections that were used to develop future climate scenarios (see CSIRO ozclim for more information) were applied to biophysical models to predict the impact of changed climate conditions on plant and animal productivity, plus emissions of CH4 and N2O and soil C balance. There are a range of such production models that have been developed in Australia – each with a slightly different focus.
The models used during SLA2030 included:
GrassGro is a biophysical grazing systems model focussed on the wool and meat (sheep and beef) industries in southern Australia. It is largely applicable for sown pasture to address questions such as best time for lambing / calving; appropriate stocking rates; and likely gross margins. GrassGro can quantify the variability in pasture and animal production in response to climate and management changes so that farmers and natural resource managers can assess the profitability impacts and risks that variable weather or changing management systems imposes on a grazing system.
GrassGro uses daily climate data and characteristics of the grazing property (soil profile characteristics and moisture holding capacity, pasture species) and animal enterprise (including genotype, production system and grazing management system including rules for the feeding of supplements). Seasonal and year-to-year variation in pasture and animal production and gross margins are presented in comprehensive reports which enables some analysis of risk associated with climate and management decisions.
For more information on Grassgro:
SGS Pasture model (including DairyMod)
The SGS Pasture Model and related DairyMod are mechanistic biophysical pasture simulation models. The models include pasture growth and utilisation by grazing animals (up to 5 pasture species in any simulation – annual, perennial e.g. C3 or C4 and legumes), animal metabolism and growth (sheep, beef cattle and dairy cows), water and nutrient dynamics (N, P, K, S and soil organic matter), and options for pasture management, irrigation and fertilizer application.
The underlying processes in these models are identical but they have livestock and management systems customised for different industries:
- DairyMod for dairy;
- SGS Pasture model for sheep and beef; and,
- EcoMod (primarily used in New Zealand) for dairy, sheep, beef and deer systems.
These models can be used to investigate climate and management impacts on pasture and animal production in point-based simulations. They have been used to simulate sown and native pasture based systems from SW Western Australian to SE Queensland. To date, these models have mostly been used within the agricultural systems research community.
Greenhouse Gas Calculators (GHG’s)
There are also a range of GHG’s freely available on the web that are available for use. These include:
- FarmGAS Scenario Tool
- Dairy Greenhouse gas Abatement Strategies Calculator (DGAS)
- Decision Support Frameworks for Greenhouse Accounting on Australian Dairy, Sheep, Beef or Grain Farms produced by the University of Melbourne – The Dairy (D-GAF), Beef (B-GAF), Sheep (S-GAF) and Grains (G-GAF) Farm Greenhouse Accounting Framework Tools