Understanding crop development and yield responses to mitigate high soil strength in Australian soils

Outcomes

By June 2026, growers have the knowledge to improve profitability of high strength and compacted soils through crop selection, soil amelioration and/or a combination of both.

Outputs

Output 1: By June 2026, develop new resources and strategies incorporating crop choice and amelioration management that maximise return on investment for growers.

Output 2:  By June 2026, improved crop specific metrics quantifying the impact of high soil strength and compaction on growth, development, and yield of key crops wheat, canola, barley, oats and narrow leaf lupin.

Project Objectives
We will use a combination of glasshouse and field studies to develop a better understanding of relationships between root growth and soil strength using the latest in-situ 3D imaging technology. This research aims to (i) establish penetrometer benchmarks for root growth for key grain crops and potential ‘primer crops’, (ii) confirm the relevance of these benchmarks in key soil types, (iii) test the hypothesis that HSS reduces growth of crops via inhibited tillering or branching as well as decreased ability to extract soil water and nutrients, and iv) examine the potential for primer crops to improve root penetration in HSS to improve productivity of subsequent crops. Developing critical soil penetrometer benchmarks for different crop species requires other potential confounding factors to be controlled. We will achieve this by using a multi-pronged approach to study the morphological mechanisms by which different crops overcome HSS and quantify comparative differences in root anatomy, shoot growth and yield as they relate to HSS.

Project objectives have been framed around these broad themes:

Objective 1: Understanding relationships between soil strength, bulk density, and water contents at different water potentials to plan glasshouse experiments to repack cores and to assess at what conditions water availability or soil strength become limiting factors for root growth on different crops.

Objective 2: Comparing comparative differences between different species: A range of soil strengths will be generated using small cores of an artificial ‘model’ soil containing no chemical or nutrition constraints. Root and shoot growth of wheat, canola, barley, oats, narrow leaf lupin, faba bean,  chickpea, lentil, sorghum, lucerne and safflower will be compared under a range of increasing soil strengths between 1 and 4 MPa.

Objective 3: Effect of HSS over the crop life cycle: The relative effect of HSS on root growth of different species identified in objective 2 will be extended to the entire life cycle, using large PVC cores using both ‘reconstituted’ cores and ‘intact’ cores.

Objective 4: Field experiments aimed to (i) identify crop production in relation to root growth limiting factors associated with high soil strength and water availability (ii) confirm the relevance of penetrometer benchmarks developed in the glasshouse for root growth for key grain crops and potential ‘primer crops’ in key soil types, (iii) examine the potential for primer crops to improve root penetration in HSS to improve productivity of subsequent crops.

Objective 5: Characterise genetic diversity in wheat to understand interactions between soil strength, texture and water with the aim to determine which (i) root traits are most important in HSS and how these affect water and nutrient extraction; ii) which wheat varieties have greater ability to penetrate HSS; and iii) how much reduction in root growth in HSS reduces shoot growth, independent of water and nutrient supply.

Objective 6: Test the hypothesis of Unkovich et al (2023; FCR 291, 108792) that HSS reduces growth of crops via inhibited tillering or branching as well as decreased ability to extract soil water and nutrients, that cereal crop responses to deeper tillage are primarily due to a direct effect on crop tillering caused by hormonal responses rather than via increased crop water use (evapotranspiration).

Objective 7:  Project outreach: Broader extension material developed and delivered into industry specific networks.