This report is based on annual soil testing over 10 years of 48 dairy paddocks at Vasse Research Centre in the south-west of Western Australia.
The main messages for farmers from this part of the study were:
- Soil test all paddocks to obtain pH values to assess if soil acidification is likely to be reducing pasture production.
- If soil acidification is identified as a problem, start liming with as large levels of good quality lime as can be afforded until the desired pH is achieved.
- Soil acidification is ameliorated by applying sufficient good quality lime to raise the pH of the top 10cm of soil, as measured in calcium chloride, to 5.5 or greater.
- Where possible, lime should be incorporated into the soil after application to increase its effectiveness.
- Soil acidification continues, both while liming and after liming has been successfully completed, particularly for intensively grazed pastures top-dressed with nitrogen after each grazing.
- Once the target pH has been achieved, monitor soil pH and re-apply lime when pH declines below 5.5, requiring smaller amounts of lime (1t/ha) to return soil pH to 5.5 or greater.
- Do not allow soil pH to decline much below 5.5 to avoid a major re-liming program to ameliorate the problem.