WRI Seminar Series: Dr Therese McBeath and Dr Stephen Davies – Transforming the agricultural productivity of agricultural sandy landscapes in southern and western Australia.

Dr Therese McBeath and Dr Stephen Davies, CSIRO Agriculture and Food Systems Program

Title: Transforming the agricultural productivity of agricultural sandy landscapes in southern and western Australia

Abstract: Sandy landscapes are considered the least productive and most vulnerable agricultural landscapes of Australia. With more than 22 million ha of sandy soils, the principles of conservation agriculture have been widely adopted in Australian cropping systems. However, with yield gaps exceeding 50% of the yield potential, there are constraints to production that need to be addressed to maintain sustainable and profitable crop production on these soils.

The soil-based constraints to production in sandy landscapes include high soil strength preventing root proliferation, topsoil water repellence, acidity and low fertility. To date, the most substantive and consistent crop production responses have been observed with strategic (i.e. one-off or occasional) high disturbance deep tillage techniques (delving, deep ripping, inclusion ripping, inversion ploughing and rotary spading) that break up high soil strength layers and/or mix repellent and acidic layers. The crop yield benefits in ameliorated sands typically range 20-80%. Growers often start with deep ripping and then implement other strategies to further ameliorate soil constraints, including the incorporation of amendments such as lime or clay-rich subsoil, and incorporation techniques such as soil mixing, inversion or delving. Deep tillage techniques are widely adopted, with nearly two-thirds of grain growers in Western Australia undertaking some form of strategic deep tillage in 2023.  

Ensuring that the right soil amelioration technique targeted at the key production constraints for a given site, underpins the stewardship of these techniques. The initial stages of strategic deep tillage increase erosion risk until soil cover is restored and techniques that optimise post-amelioration soil management are an important focus. These techniques include seedbed preparation and subsequent crop agronomy to ensure maximal ground cover and biomass production so that the system can sustain higher fertility turnover and protection of the natural capital at the same time as achieving an overall increase in crop productivity.

Bio: Dr Therese McBeath is a Principal Research Scientist and Team Leader with the CSIRO Agriculture and Food Systems Program at Waite Campus, Adelaide. She has expertise in soil and crop management and works on a range of largely industry funded projects that test strategies to improve productivity and profit-risk outcomes for growers across Australia’s cropping regions.

Dr Stephen Davies has expertise in managing soil constraints in cropping systems with a focus on developing practical tools and options for grain growers. He leads two DPIRD and GRDC funded co-investment projects. Outcomes from these projects include: 1) Optimising management of multiple interacting constraints across variable soils and test the value of re-engineering soil profiles to 80cm+. 2) Optimise amelioration timing, seedbed preparation, herbicide use and crop rotations to maximise the size and longevity of amelioration benefits