Pastures from Space Plus

Pastures from Space (PFS) provides estimates of pasture production during the growing season by means of remote sensing. Satellite data is used to estimate pasture biomass and combined with climate data to produce pasture growth rate estimates.

District estimates are directly available from, whilst individual farm data is available by subscribing to a paid service. Landgate have just, in the last few weeks, released a new version - Pastures from Space Plus. The program is now more user friendly and provides the option of getting high resolution imagery (Landsat 900m2 as well as the standard Modis 62,500m2 imagery).

Despite Pastures from Space being available for over 12 years, very few producers are actively using it. Feedback from producers indicates that there is a general lack of understanding on how they can best use the information available and uncertainty about the accuracy of the data.

The key value of PFS is the opportunity for producers to benchmark their property’s pasture production across seasons, with 10 years of data being available. To analyse this information a simple spreadsheet can be used – the key data that is considered is the week of break, growing season rainfall (GSR), total dry matter (TDM), water use efficiency (i.e. kg DM/mm GSR), potential stocking rate, potential total dry matter, unrealised TDM, and potential TDM/dry sheep equivalent (DSE).

Potential stocking rate (S/R) was calculated from TDM minus residue required at end of the season divided by 550 (the assumed kilograms DM consumed by a sheep). Potential TDM was calculated from GSR multiplied by 30 (the target kg DM/mm GSR). Figure 1 provides data from a case study property.

Figure 1. Potential and Actual Stocking Rate

The graph shows the property’s actual stocking rate (S/R) expressed as DSE/WGHa and the S/R that the TDM produced would support. When the actual S/R exceeds the potential from TDM, the deficit is filled with supplementary feed, overstocking will reduce the leaf area and hence the capacity of the pasture to grow. There has to be a balance between growing pasture and utilization and the best compromise is when actual stocking rate is slightly less than potential stocking rate. It shows the importance of being flexible with stocking rate to adapt to seasonal variability.

The impact of high stocking rates is reflected in the WUE, with the property only achieving 8 to 12 kg DM/mm GSR. A target WUE of 30 kg DM/mm GSR has been used – is this too high? Having analysed a number of farms with this method, changes in management can result in significant increases in WUE. Brad Wooldridge (producer from WA) has achieved a 180% increase in WUE over a 10 year period (taking it from 10kg DM/mm GSR in 1994 to 28kg/mm in 2014 at same S/R).

The week of break drives TDM in some areas, but with the case study property it does not make a significantly reliable indicator. However, the season break reasonably consistently occurs around week 15, which makes planning practices such as pasture deferment easier. There are obviously other key seasonal indicator points and with local knowledge, breaking the season’s productivity into different periods may allow the implementation of management practices that target key seasonal components where the greatest response will be achieved. Thus the focus may become sub season rather than the individual season as a whole.

By analysing the bigger picture farm system results using PFS data, the impact of management on the productivity of the pasture system and its capacity to cope with seasonal variability and the effectiveness of strategies adopted over the past 10 years can be analysed. This provides extremely useful information for future planning and setting of strategies to deal with the variable seasons.

Whilst the Landsat (high resolution) data provides an opportunity to further fine tune strategies to the paddock level there are issues with receiving the data. The Landsat satellite passes over every 16 days, therefore no information is available if it happens to be a cloudy day. However down the track more consistent data availability will take pasture and grazing management to the next level.

For further information on Pastures from Space plus see or contact Ian McFarland on 0437 659 353.