Soil amelioration in Western Australian cropping systems: a review of the benefits, adoption, and value

Document Type

Conference Proceeding

Publication Date

10-2024

Conference Title

Agronomy Australia Conference 2024: Adaptive Agronomy for a Resilient Future

Place of Publication

Albany, WA

Keywords

Soil amelioration, soil constraints, grain yield, profit, adoption

Disciplines

Agricultural Science | Agronomy and Crop Sciences

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 (i.e. mechanical amelioration) is applicable to ~13 M 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 0.14-0.91 t/ha for inversion and 0.21-0.73 t/ha for deep mixing across a range of soil types and seasons after amelioration. Narrow-leafed lupin yield responses to deep mixing or inversion range from 0.19-0.54 t/ha and canola from 0.21-0.49 t/ha. Comprehensive grower surveys in 2020 and 2024 showed an increase in from 52 to 66 % of grower respondents undertaking strategic deep tillage, with 51 % ripping, 24 % mixing and 17 % inverting their soils in 2023-24. For growers using mechanical amelioration 97 %, regularly applied lime to manage soil acidity. A DPIRD-commissioned study by consulting firms Planfarm and Farmanco utilised deidentified client financial data to show growers who over the past 10-years had adopted ‘complete’ amelioration packages increased farm operating profit by $100 /ha/year and had 2.6 kg/ha.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.

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