Dr Stephen Davies1, Mr Wayne Parker1, Dr Gaus Azam1, Mr David Hall1, Mr Tom Edwards1, George Mwenda1, Mr Chad Reynolds1, Mr Glenn Mcdonald1, Bindi Isbister1, Ms Alice Butler1, Mr Andrew Blake1, Mr Peter Newman2, Mr Rob Sands3, Ms Kelly Ryan3, Mr Ben Curtis3, Ms Hilary Bunny4, Mr Chris Gazey1
1DPIRD, Perth, 6000, 2Planfarm, Geraldton, 6530, 3Farmanco, Mundaring, 6073, 4Aglytica, Mount Lawley, 6050
Biography:
Dr Stephen Davies is a Principal Research Scientist with DPIRD, based at Geraldton in the northern Western Australian grain belt. Steve has worked for DPIRD for 20-years undertaking research focussed on developing options for the innovative management and amelioration of soil constraints in cropping systems, with the aims of making cropping more productive, sustainable and resilient while ‘doing his bit’ to help grow the industry and feed the world. Steve is privileged to work with incredibly dedicated DPIRD Soil and Grains research teams and thanks them for their support and their massive contribution to soils R&D.
Abstract:
Over the past 17-years soil amelioration approaches have developed to include one-off (strategic) deep soil mixing or inversion tillage in Western Australian (WA) cropping systems. Deep ripping developments include increased ripping depth to 50-80cm, and topsoil inclusion or subsurface delving capability. Strategic deep tillage is applicable to ~13M hectares of WA’s south-west agricultural soil consisting of deep sands, sandy earths, deep sandy duplex and ironstone gravel. Subsoil acidity, subsoil hardpans, topsoil water repellence, sodicity, poor fertility and low water holding capacity often constrain these soils. DPIRD researchers maintain a database of amelioration responses which contains more than 220 site-year inversion and deep mixing comparisons. Cereal grain yield increases range from 0.56-0.91 t/ha for inversion and 0.52-0.72 t/ha for deep mixing across a range of soil types and seasons after amelioration. Narrow-leafed lupin and canola have similar yield responses of 0.34 and 0.37 t/ha, respectively, for deep mixing and 0.44 t/ha and 0.50 t/ha, respectively, for inversion, with 55-66% of these comparisons having a significant yield increase. A comprehensive 2020 survey indicated 52% of grower respondents undertook strategic deep tillage overall, with 39% ripping, 24% mixing and 16% inverting their soils. For growers using mechanical amelioration 97%, regularly applied lime to manage soil acidity. A DPIRD-commissioned study by consulting firms Planfarm and Farmanco utilised de-identified client financial data to show growers who over the past 10-years had adopted ‘complete’ amelioration packages increased farm operating profit by $100/ha/yr and had 2.6 kg/mm higher wheat water use efficiency than those who hadn’t. Increased value and resilience of WA cropping will come with improved spatial management of refined soil amelioration and profile reengineering practices.