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Mapping the Top End with an eye to agriculture

TERN’s soils facility, the Soil and Landscape Grid of Australia, is in the thick of land evaluations that will map the suitability of northern Australian landscapes for agriculture.

Governments, farmers and industries are keen to explore the possibility of expanding agriculture across northern Australia, and people’s dreams and debates about it feature regularly in the mainstream news media.

Intensifying farming in the Top End needs care and planning. The Director of the Soil facility, Mr Mike Grundy, said the soil information available for northern Australia was nowhere near the level of detail or quality needed to guide the development of a ‘northern food bowl’ from the initial stage, identifying of where to establish industries. As Mike says, to know what to grow, you have to understand the characteristics of the soils and landscapes, and their interaction with the environment and climate. The TERN Soil facility is producing new layers of soil information across Australia – building on the legacy of the past and informed by new remotely sensed landscape information. In northern Australia, however, historical information is scarce and scattered.

‘While the TERN soil project will make the most of this legacy combined with new landscape information, in northern Australia the fundamentals need improving,’ Mike says.

So, there are a number of surveys taking place across the north – and the same detailed landscape information that the TERN Soil facility is using to add value to legacy information can be used to speed up and enhance the surveys. Much of the new information comes from ‘cleaning’, analysing and enhancing data on the earth’s surface collected by the NASA shuttle, at the extremely fine resolution of about 30 metres across the whole country.

‘We are able to visualise a range of characteristics, from quite simple aspects of the landscape such as the degree of slope, to ones that are very complex to produce and which tell you more about landscape function, such as how much solar radiation is received at each point in the landscape,’ Mike says.

‘With solar radiation data, for example, we can model how much water plants use and how much water is available to them across seasons, and estimate evaporation rates. And we have all seen that the vegetation on northern slopes can differ markedly from that on the south – although the type of difference varies across the country. Differences include soil depth, vegetation type and even landscape shape, and they occur because the landscape interacts with the position of the sun.

‘This kind of knowledge can change the way you describe and understand landscapes, and it’s important as we move to establish sustainable agriculture in new areas,’ Mike says.

Other layers inform on landscape processes, for example where sediment is likely to collect, where water will flow, what the sub-surface soil and rock patterns are likely to be, and how soil depth is likely to vary. These layers, combined with carefully planned new soil sampling, help pinpoint land that is likely to be both productive and resilient.

‘All this can be used to inform policy makers and planners where the best places are to grow crops, and what kinds of crops are suited to the soil and climate characteristics of an area,’ Mike says.

These landscape information tools are the first product on the TERN Soil Data Portal. Survey teams are using them to produce new information about how the soil functions to guide choices in investment in northern agriculture, currently in the Burdekin, Flinders and Gilbert rivers and soon, as teams begin to use the new layers, in other studies across northern Australia.

Mike says the Soil and Landscape Grid of Australia has provided the information initially for CSIRO and the Queensland and Northern Territory governments, but with the release through the TERN Portal, they are now widely available.

Meanwhile, the facility is also using the layers to improve Australia’s soil information more generally – and next year will release a new fine-grained soil ‘map’ of soil function for the whole of Australia.

 

Soil sampling and field measurement near Hughenden in Queensland’s Gulf
region to produce new soil mapping. Sampling design and mapping used landscape information produced by the TERN Soil facility.

Published in TERN e-Newsletter July 2013

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