Digital soil assessment: Guiding irrigation expansion in Tasmania, Australia
Kidd, DB and Webb, MA and Grose, CJ and Moreton, RM and Malone, BP and McBratney, AB and Minasny, B and Viscarra-Rossel, RA and Cotching, WE and Sparrow, LA and Smith, R, Digital soil assessment: Guiding irrigation expansion in Tasmania, Australia, Digital Soil Assessments and Beyond: Proceedings of the Fifth Global Workshop on Digital Soil Mapping, 10-13 April 2012, Sydney, Australia, pp. 3-8. ISBN 978-0-415-62155-7 (2012) [Refereed Conference Paper]
Digital Soil Assessment is being used to model land suitability in recently commissioned irrigation schemes in Tasmania, Australia, in support of Government agricultural expansion policy. The Wealth from Water pilot program commenced in 2010 within a 20,000 ha irrigation district in the Meander Valley in northern Tasmania. The modelling requires comprehensive soil, climate and terrain parameters to rate the suitability of land for seven test enterprises (alkaloid poppies; carrots; hazelnuts; barley; blueberries; pyrethrum; and industrial hemp). Digital soil mapping techniques were used to produce soil information at 30 m resolution for pH, EC, clay and stone content, drainage, and depth to sodic and/ or impeding layer based on sampled soil cores and explanatory spatial data. Sites were located using a stratified random sampling design, with environmental covariate datasets including a digital elevation model and derivatives, gamma radiometrics, legacy soil mapping, surface geology, and satellite imagery. Individual soil properties were predicted using MIR and NIR analyses using an Australian calibration dataset, and a sample sub-set with conventional chemical analyses. Temporal climatic grid inputs of frost risk, growing season, chill hours, and rainfall intensity were generated using available weather stations and explanatory terrain data, and improved in resolution and certainty by the collection of spatially intensive temperature and rainfall data from additional temporary field sensors. The land suitability for each enterprise was determined by interrogating each soil and climate parameter with a series of suitability rules. The preliminary soil, climate and suitability surfaces are being evaluated through restricted access by key personnel from Tasmanian Government, academia and industry, with suitability mapping planned for public release in 2012 through a Tasmanian Government web-based Spatial Portal, (the LIST, www. thelist.tas.gov.au).