A SoilQuality Australia fact sheet “ Optimising Crop Root Systems” outlines soil conditions affect the development of crop root systems.

One way to optimise plant uptake of nutrient reserves in the soil is to maximise the area crop roots come into contact with the soil and ensure they can access nutrients and water down the soil profile. This is especially important for leachable nutrients such as nitrogen and sulphur, and nutrients with significant reserves in the subsoil. The abundance and depth of crop roots can be increased by recognising and improving conditions that inhibit root development or performance.¹

The Soilquality Australia fact sheet goes onto to outline soil conditions that inhibit optimal crop root structures.

Subsoil compaction can reduce the extent of crop root systems by restricting root penetration. Poor aeration leads to anaerobic conditions where root growth and biological activity are restricted more often and for longer periods compared to a similar but better aerated soil. This can mean roots are unable to access nutrients such as nitrogen from the subsoil and results in poor nitrogen use efficiencies.¹

Sodic soils are characterized by a high proportion of sodium ions relative to other cations, which significantly impacts soil structure and can lead to poor drainage as well as reduced water infiltration. Sodic soils can restrict root growth and performance by restricting the uptake of water and some nutrients while allowing other nutrients to be taken up in excess of the crop requirements. The exchangeable cation balance can be corrected with applications of gypsum, lime and organic matter.¹

Diseases that affect plant roots can substantially reduce a plant’s ability to access water and nutrients from the soil. Waterlogging or water stress encourage the development of many root diseases. ¹

Good soil structure allows drainage of excess water and allows oxygen into the soil profile in wet condition, maximises plant available water in dry conditions, and provides suitable conditions for soil biology. Healthy populations of diverse soil organisms reduce the ability of disease organisms to spread and dominate within the soil, and this can reduce crop damage even when disease is present.¹

Ways to improve soil conditions include applying agricultural lime for soil acidity. ¹ Building soil organic matter, through applications of compost as well as growing and incorporating cover crop residue, will improve the buffering of soil pH and help build soil biology.

Applying gypsum at moderate rates over a number of years will assist to improve soil aggregate structure for clay as well as compacted soils, reduce sub soil compaction as well as sodium build up in sodic soils.  The calcium in gypsum also supports soil biology and earthworm populations.

For guidance on using gypsum, consult your local fertiliser advisor for advice on application rates based on a recent soil test.

Gypsum for soil and plant health. Gypsum is BioGro certified.

References

Optimising Crop Root Systems - NSW | Fact Sheets | soilquality.org.au