Pastures from SpaceTM has been redeveloped for Western Australia by Landgate and DPIRD and now provides more features for producers to understand their pasture growth on a weekly and annual basis. The map allows the selection of a property and gives FOO, PGR and cumulative PGR as an average across the property. The graph component allows users to turn on and off years of data from 2004 and gives median, 25% and 75% percentile growth curves against the selected years. This allows an analysis of how seasons vary across the property, the shape of the growing season, the total pasture grown in any year and the current and historical FOO. In the graph function there is an option to download the data to a csv file.
Although the tool doesn't have the option to identify and select individual paddocks, users can zoom in on a pixel (6.25 ha) and find all historical and current pasture data for that area.
The technology to estimate FOO (kg DM/ha) has been developed and calibrated since 1995 in the southwest of Western Australia and is based on the relationship between normalized difference vegetation index (NDVI) and ground-truthed data to explain seasonal response patterns. FOO is the above-ground green pasture biomass and PGR is the current rate of pasture growth. The cumulative PGR or total dry matter is the sum of the weekly PGR multiplied by 7 days and is expressed as kg DM/ha.
The map can also be used to view Feed on Offer and Pasture Growth Rate for the whole of the South West agricultural region on a weekly basis, including the last seven years of data. The vegetation (plantations and native vegetation) overlay is updated annually, however, it may not reflect current land use.
The technology to estimate FOO (kg DM/ha) has been developed and calibrated since 1995 in the southwest of Western Australia and is based on the relationship between normalized difference vegetation index (NDVI) and ground truthed data to explain seasonal response patterns. FOO is the above-ground green pasture biomass expressed as kg/ha and PGR is the current rate of pasture growth in kg/ha per day.
The primary information for this application comes from the MODIS satellite. The MODIS satellite passes over Western Australia at least 14 times a week at a resolution of 250 m by 250 m or 6.25 ha. More information on how FOO and PGR are calculated. Although Sentinel satellites can provide more detailed data (10x10m) it is affected by cloud cover and has limited value during our wet and cloudy winter days.
Using the current and historical FOO and PGR curves
The site will show the current year’s FOO alongside historical FOO curves for each year to 2004 allowing comparisons between seasons. Years can be turned on or off or all years displayed by clicking on the expanded chart button. At a property/location level this can give a picture of likely seasonal growth, particularly if years with a similar start to the season are displayed.
Using the pixel function can allow a certain area of a paddock to be queried for its pasture growth, with years that were in crop turned off for more accurate estimation of the paddocks potential production. It is also a useful function to evaluate the impact of new practices, fertiliser application and new pasture establishment.
The cumulative PGR option in the chart function shows an estimated total pasture growth for the season by adding the weekly PGR across the year. This can be useful to identify the total production in the estimation of potential stocking rate or productivity of an area on the property (pixel function) or the whole of property growth potential. Please be aware that the property summary data includes paddocks that are cropped. Cropping growth is similar to pasture in the early part of the season but as daily production grows over 2000 kg DM per day the ability of the satellite image to determine differences is limited.
How to use the new Pastures from SpaceTM mapping tool
Selecting your property and base map
This can be done using the map either by:
- using the map and zooming into your general area and clicking on your property, or
- by using the icon on the main toolbar and entering in your PIC/Property ID combination and selecting the correct combination from the drop down list.
Once your property has been selected and the boundary is drawn on the map with a thick dark line, a chart will appear at the bottom of the screen showing your property's history.
Displaying FOO or PGR on the main map
Choose either FOO or PGR. The map will automatically default to the most recent image available (weekly) but you can change the image by clicking on the date button to access the last 6 years of weekly pasture growth rate (PGR) and green feed on offer (foo) imagery covering the South West corner of WA. The supplied imagery is 250m x 250m pixel data, and is created from daily satellite passes into a weekly image minimise cloud-cover.
You can zoom in and out to see how the values change across the SW corner of the state.
You can also change the opacity of the imagery, using the slider located to the right of the PGR & FOO buttons. This will allow you to see what is satellite imagery is representing on the ground, especially when you change the base map to one of the aerial imagery options.
To turn the satellite imagery off, reselect either of the active FOO or PGR imagery buttons and the image will disappear.
Using the graph function
A chart will appear on the bottom of the screen once a property is selected. Use the drop down menu on the left hand side of the graph to toggle between FOO, PGR or cumulative PGR. The median of the property will be displayed by week for the current year alongside the average, 25% and 75% growth percentiles since 2004. Toggle on and off years to understand the variation across seasons.
When first displayed, the chart is shown in condensed mode and displaying the "Property History" values showing the current years' data as a black line with triangular markers on it, and the previous years' data as a blue line. An additional 4 years worth of data is available by clicking on each of the years listed on the right hand side of the chart. This is the average of the property at each date.
Click the expand button on the right top of the chart screen to expand the graph and see options for all historical data to 2004. Also on this screen is the opportunity to download all of the selected data to a csv file. Click the close button on the right hand side to remove the chart display.
To re-display the chart, simple click on your property on the map.
When you select the "Pixel History" option, you can then click any spot on the map to see the history of that location over time. To swap back to Property History mode, simply click "Property History" option in the top-left hand corner of the chart's header bar.
Select a pixel of interest on the main map. A pin will mark the pixel selected. The chart screen will now display data from that pixel in the same way it displays data at a whole of property level.
These instructions are also available when the map is first opened. Clicking the question mark icon on the top right hand corner of the screen will give you the option of seeing these instructions again.
Pastures from SpaceTM is proudly brought to you by DPIRD, Landgate and CSIRO.