High soil strength and soil compaction-related issues are widespread in Australia’s western and southern grain growing regions, leading to reduced root growth in crops and restricting their access to soil nutrients and water.
A new Grains Research and Development Corporation (GRDC) investment will explore the capabilities of different crops and varieties to overcome high strength soils, examining which crops could be introduced into farming system rotations as an alternative management option to amelioration.
The $4.5 million project will be led by The University of Queensland, with partners La Trobe University, South Australian Research and Development Institute, University of Adelaide, Agriculture Victoria, the Western Australian No-Till Farmer Association, Murdoch University and Ag Communicators.
Project lead Dr Yash Dang from The University of Queensland says the team’s focus is on discovering which crops and crop varieties have the greatest ability to penetrate high strength soils as well as root traits that are most important and how these affect water and nutrient extraction.
“The project will consider the particular plant species or cultivars that have the ability to penetrate their root systems through? high strength soils,” Dr Dang says.
“This new information will give growers the ability to select the crops that can most effectively extractmoisture and nutrients from high strength soils.”
All grain cropping soils in Australia are susceptible to problems of high soil strength in the surface and the subsoil, with tenosols, chromosol, calcarosols and sodosols the most susceptible.
The largest areas of tenosols and chromosols are in Western Australia, while calcarosols are most common in South Australia. Sodosols occurs throughout Australia but are widespread in Victoria and large sections of WA.
Dr Dang says that until now, the grains industry had focused on using soil amelioration strategies such as deep ripping or spading to maximise crop productivity in problematic soils.
“Currently, most growers are relying on deep ripping to manage these soils, and there has been less focus on crops with enhanced ability to grow in high strength soils,” Dr Dang says.
“But several questions remain around deep ripping, including where deep ripping should occur, how consistent is the response, as well as whether it increases erosion risks.
Dr Dang says recent progress in the development of root imaging systems, such as MRI and X-ray CT, was providing new alternatives to traditional methods to visualise root–soil interactions.
“These new procedures, especially when combined with the use of intact soil cores that maintain the physicochemical integrity of the soil profile, allow an in-situ 3D visualisation of roots growing in soil,” he says.
The three-year project will include glasshouse and field experiments, looking at crops including wheat, canola, narrow-leafed lupin, sorghum, chickpea, lentil and three ‘primer-crop’ species (safflower, lucerne, and sulla).
Field trials will collect data on rainfall, temperature, changes in profile soil water and shoot biomass at critical crop development stages and analyse root architecture from ‘intact’ soil cores providing the 3D analyses of the root systems throughout the growth period.
GRDC sustainable cropping solutions manager – west, Dr Rowan Maddern, says that the project would provide growers with new resources and strategies to use crop choice, soil amelioration, or a combination of both, to maximise the profitability of their farming system.
“With improved knowledge of crop types that perform well on high strength soils, growers can make improved soil management decisions that could extend the longevity of their soil amelioration and, ultimately, improve on-farm yield and productivity,” Dr Maddern says.
“A major outcome of the project is to provide growers with some fundamental information on abilities for crop species to penetrate a high strength soil and provide a ranking scale that will aid grower decision making.”
The project also includes two PhD students from The University of Queensland and La Trobe University looking more specifically into the relationship between soil moisture, bulk density, shoot physiological responses as well as genotypic variation in wheat.
The project Understanding crop development and yield responses to mitigate high soil strength in Australian soils will run until 2026, with results to be available via fact sheet, podcast, video and GRDC’s Groundcover magazine.