Prof. Roger Armstrong1, Wilhelm Nigel2, Ehsan Tavakkoli3, Dr Bianca Das4, Dr Katherine Dunsford1, Wayne Pitt3, Pete Johnstone4, Dr Daniel Hendrie1, Dr Garry O’leary5, Craig Beverly1, Geoff Dean4, Brian Hughes2, Murray Hart3, Peter Sale6, Kerry Stott1, Felicity Pritchard1
1Agriculture Victoria Research, Horsham, Australia, 2SARDI, Clare, South Australia, 3NSW DPI, Orange, New South Wales, 4Tasmanian Institute of Agriculture, University of Tasmania, Sandy Bay, Tasmania, 5The University of Melbourne, Melbourne, Victoria, 6LaTrobe University, Melbourne, Victoria
Biography:
Roger is a Senior Research Scientist with Agriculture Victoria based at Horsham and an Adjunct Professor at LaTrobe University. His research aims to improve water and nutrient use efficiency of dryland farming systems. He has undertaken extensive research on overcoming soil-based constraints using both amelioration and genetic solutions. Other research interests include reducing the carbon footprint of cropping systems, identifying new root ideotypes for southern Australia and is the custodian of Australia’s longest running rotation-tillage field experiments. He has authored > 130 journal articles and is a regular presenter at grains industry forums such as Adviser Updates and national conferences.
Abstract:
Ameliorating poorly structured clay soils with organic and/or inorganic amendments can often produce large increases in crop productivity but can also result in little or no yield improvements in the southern grains region. The substantial upfront costs and logistical complexities associated with soil amelioration require growers to have a high level of confidence in the expected outcomes before adopting this strategy on a commercial scale.
Knowledge developed from a range of field and controlled environment experiments and biophysical simulation modelling was utilised to develop a decision support tree (DST) based on key biophysical properties to assist growers and their advisers select management options. The field trials encompassed different amendment sources (organic, inorganic and combinations of both), placement methods, soil types and environments (annual rainfall ranging from 325 to 690 mm) across 49 site-by-year combinations.
Key factors when considering to ameliorate include (i) whether crops consistently fail to meet water limited yield potential, (2) the likelihood that the combination of rainfall and surface soil texture will result in sufficient soil moisture to enable activation/decomposition of the ameliorant in the amelioration zone, and (3) the depth in the soil profile where constraints become potentially limiting to the crop. Maximising economic benefit generally required spatially targeted application of ameliorants to specific soil conditions within a paddock. When utilised with an associated economic decision framework, growers now have the capability to optimise productivity and profitability for soil management within the southern grain region.