In 2002 Western Dairy funded a feasibility study with the aim of measuring Feed-on-Offer (FOO) and Pasture Growth Rate (PGR) with satellite imagery in the dairy region of south-west Western Australia.  The dairy region is located in the south west coastal area of Western Australia (figure). 


The focus of this project was to test the accuracy of the remotely sensed pasture information compared with ground measurements and commence delivering it directly to end-users. The application of the information for feed budgeting or optimising spatial variation has significant benefits but would not be addressed in this feasibility study.


The dairy region is ostensibly coastal with state forest bordering the inland eastern areas. Existing dairy farms compete for resources with the infiltration of residential farms and viticulture. Typical pastures measured are composed of clover (Trifolium subterranuem) and annual ryegrass (Lolium spp.), with opportunistic plants such capeweed (Arctotheca calendula) and barley grass (Hordium leporinum). Spatial climate information used in the estimation of FOO and PGR for the dairy region included maximum and minimum temperature, evaporation, rainfall and solar radiation.

Monthly pasture biomass information obtained by Dr Bill Smart of the Department of Agriculture Western Australia from four experimental sites were used to validate outputs of the FOO and PGR models. The position of these pasture paddocks were georeferenced using a GPS.  A recording of pasture biomass was taken using a plate meter every 10m across selected paddocks at each site. Plate meter data were calibrated against oven dried samples taken at each recording for each site. These data were used to calibrate the FOO model. 


Landsat TM images were pre-processed to produce an NDVI map and then subsequently processed to provide a farm and paddock spatial map of FOO. Spatial statistics were applied to provide a paddock average FOO.


PGR were calculated using data derived from the NOAA satellite and validated against field observations obtained by differentially determining the feed biomass on paddocks in the rotation-grazing pattern. This provided paddock average PGR.


Copyright 2003 Pastures from Space
Last modified: October 01, 2003

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