Greener Pastures: soil acidity

Page last updated: Wednesday, 17 January 2018 - 2:20pm

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The Greener Pastures project was set up to assist the Australian dairy industry meet the two major challenges in managing high performing pasture systems: maintaining profitability while meeting the expectations of a community that is increasingly sensitive to environmental issues. This page discusses the major findings from a program to correct a soil acidity problem which had the potential to compromise the production of intensively grazed ryegrass pastures.

Soil acidity messages for farmers from Greener Pastures:

  • 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 pHCa of the top 10cm of soil to 5.5 or greater.
  • Where possible, lime should be incorporated into 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 fertiliser nitrogen after each grazing.
  • Once the target pH has been achieved, monitor soil pH and re-apply lime when pHCa declines below 5.5, requiring smaller amounts of lime (1t/ha) to return soil pHCa to 5.5 or greater.
  • Do not allow soil pHCa to decline much below 5.5 to avoid a major re-liming program to ameliorate the problem.