Soil constraints that quietly cost yield
Acidity, salinity and sodicity rob crops long before you see visual symptoms. Roots slow down. Nutrients lock up. Water infiltration drops. The fix starts with the right tests at the right depths, followed by a practical plan that suits your soil type, rainfall and rotation.
What to test and where
- pH in CaCl2 at 0 to 10 cm, plus subsoil layers such as 10 to 30 cm and 30 to 60 cm
- Electrical conductivity for salinity risk
- Exchangeable cations and ESP for sodicity risk
- Texture and CEC to understand buffering and amendment needs
Why it matters
- Acidity reduces root growth and availability of P, Ca, Mg and Mo. Alongside nitrogen management, deep nitrogen testing is also critical for reliable yield and protein.
- Aluminium toxicity becomes a risk as pH falls.
- Salinity stresses seedlings and reduces water uptake, often seen as patchy emergence on saltier rises or depressions.
- Sodicity disperses clay, which collapses soil structure, reduces infiltration and causes hard-setting surfaces.
Target ranges that guide decisions
- pH CaCl2 commonly targets around mid 5s in the topsoil for most cereals and pulses, with higher targets for sensitive crops
- EC kept in safe ranges for establishment on your soil type
- ESP reduced where structure and infiltration are compromised
Practical fixes
Liming for acidity
- Use a quality lime with a fine particle fraction for faster reaction
- Apply ahead of a break in season or incorporate where the system allows
- Lift pH in stages rather than trying to fix multiple layers in one hit
- Recheck pH in two to three years to confirm the lift and adjust maintenance rates
Gypsum for sodicity
- Apply gypsum where ESP is high and surface sealing or crusting is a problem
- Place ahead of rainfall for movement into the profile
- Combine with stubble retention and controlled traffic to protect structure gains
Managing salinity
- Choose tolerant crops or varieties for saltier zones
- Improve drainage where practical
- Keep groundcover to reduce evaporative concentration at the surface
Zonal thinking pays
Do not treat a whole paddock the same if the constraints are not uniform. Map the risk zones, confirm with targeted coring, then allocate lime or gypsum where it will return the most.
Monitoring and follow up
- Repeat pH, EC and ESP testing in the same layers and GPS points
- Track crop performance in treated and untreated zones
- Adjust rates as soils respond and rotations change
Our Independent Agronomy help you tailor liming, gypsum use and crop choice to your conditions.
Ask Dawson Ag to profile pH, salinity and sodicity across your key paddocks and build a staged plan for lime and gypsum.
