The Rainfall and Pasture reports provide historical rainfall, pasture growth and pasture cover information for a selected Lot or Lots on Plan. Rainfall is estimated from surrounding rainfall stations, pasture cover from satellite imagery and modelling, and pasture growth from modelling alone. Time-series of pasture growth and cover are shown for the entire Lot on Plan.
There are two rainfall and pasture reports available on FORAGE:
The Rainfall and Pasture report calculates pasture growth using Queensland Government’s GRASP (Grass Production) model. Calculations use daily inputs of interpolated rainfall, solar radiation, minimum and maximum temperature, vapour pressure and potential evapotranspiration.
The Rainfall and Pasture by Land Type report calculates pasture growth using the GRASP grazing systems model based on Grazing Land Management (GLM) land type parameters. Calculations use daily inputs of interpolated rainfall, solar radiation, minimum and maximum temperature, vapour pressure and potential evapotranspiration.
The Rainfall and Pasture report includes:
The Rainfall and Pasture by Land Type report also includes summary statistics for individual land types on the selected area for simulated (modelled) pasture growth and pasture cover.
Pasture growth for GLM land types across Queensland is based on modelling conducted by Department of Agriculture and Fisheries (DAF). This modelling was the best available at the time of release and will be periodically updated as improvements are made based on comparison with available data sets.
Report sample is available online here.
Report sample (by land type) is available online here.
For a selected Lot/s on Plan or adjoining Lots on Plan in Queensland, both the ‘Rainfall and Pasture’ and ‘Rainfall and Pasture by Land Type’ reports:
Provide recent and historical rainfall and pasture growth statistics
Pasture growth statistics are calculated using Queensland Government’s GRASP (Grass Production) model from daily inputs of interpolated rainfall and climate.
|Elements||Rainfall and Pasture report||Rainfall and Pasture by Land Type report|
|Availability||Available Queensland-wide||Available Queensland-wide|
|Parameter set used to simulate pasture growth and ground cover||The GRASP model uses a broad-scale parameter set for simulating pasture growth for the whole Lot on Plan||GRASP model uses different parameter sets for different land types within the Lot on Plan|
|Parameter for tree density in the model||Uses a broad estimation||Calculated for each 30m*30m pixel within the Lot on Plan based on remotely sensed tree density based on Foliage Projective Cover (FPC)|
|Presentation of model simulation results||Presented as a whole for the Lot/s on Plan||Presented separately for each GLM land types|
|Total Standing Dry Matter||Provided based on GRASP model outputs||Not provided|
|Ground cover - model calculations||Ground cover is the average for the whole Lot/s on Plan obtained from the AussieGRASS model outputs||Ground cover is calculated for each of the land types within the Lot/s on Plan based on calculations from the GRASP model|
|Ground cover – satellite observations||Not provided||Based on dry season images from each year. The ground cover value for each point is the average of the image for the area covered by the Lot on Plan boundary|
indicate the range in annual district rainfall and pasture growth over time
provide an historical context for assessing current pasture conditions
provide an historical context for assessing ground cover dynamics as influenced by rainfall and grazing management.
The climate information is obtained from Queensland Government’s SILO database. SILO contains Australian climate data from 1889 (current to yesterday) which are interpolated from station observations reported to the Australian Bureau of Meteorology.
Rainfall is interpolated from rainfall observations processed by the Bureau of Meteorology across Australia. This will include rainfall stations on or surrounding the Lot on Plan which report, or have reported, rainfall to the Bureau of Meteorology.
The key parameters/factors used to calculate pasture growth include climate (rainfall, temperature, evaporation), soil characteristics (such as soil texture, water holding capacity, soil nutrients), pasture community (or land type) including the type of grasses/trees and tree density, and grazing management information such as livestock numbers.
The livestock numbers used as input to Queensland Government’s GRASP (Grass Production) pasture model, for these calculations, are regional averages derived from the Australian Bureau of Statistics (ABS). Livestock numbers are reported on a local statistical area basis, but redistributed spatially according to the productivity of land types, Foliage Projective Cover, exclusion of grazing from national parks, etc.
Grazing pressure has an impact on pasture growth calculations. So any difference between the redistributed livestock numbers and the actual livestock numbers on the specific Lot(s) on Plan, will be a source of error in the pasture growth calculations.
The information provided in the reports can be used to assess the climate and pasture growth variability over the last few decades for the selected Lot(s) on Plan. This information can support grazing land managers in their decision making, (e.g. in estimating safe carrying capacity).
The historical ground cover information also provides an indication on how rainfall and stocking management influence ground cover which may be useful in land condition assessment.
Satellite imagery derived Foliage Projective Cover (FPC) is used to account for tree density in the model.
Without setting up specific conditions, it is not possible to monitor or measure pasture growth. What you see in a paddock is termed Total Standing Dry Matter (TSDM) and is the result of pasture carried over from previous years and pasture growth, pasture detachment and pasture intake (by livestock and other grazers) in the current year.