'Soils with optimum pH will grow 10-15% more grass'

Now is the ideal time to spread lime
Now is the ideal time to spread lime
Farming Independent Team

Farming Independent Team

Liming acidic soils (pH <5.5) and improving soil pH to the optimum (pH 6.3) will grow approximately 10-15pc more grass during the growing season, according to Teagasc research.

It says by maintaining soil pH 6.3, soils will release major nutrients (nitrogen (N), phosphorus (P), potassium (K) and sulphur (S)) from soil organic matter and mineral reserves.

For example, soils with an optimum soil pH 6.3 will release up to 80kg N/ha/year. This will reduce fertiliser N bills by up to €80/ha/year.

Research from Johnstown Castle has shown that soil P availability will also be increased in the majority of soils; for example, soil P levels can increase from Index 1 to 2 from lime alone.

This is a low-cost route to improving soil P fertility and increasing the utilisation of P applied as either organic manures or bag fertilisers. In effect, lime is conditioning soils to release and make more major plant nutrients available for grass growth during the growing season.

Teagasc has advised that now is the ideal time to apply lime as soil conditions will be good and it will allow time for the lime to work over the winter months.

"Apply lime only based on the most recent soil test report. Ground limestone is the most cost-effective tool to control soil acidity in the long term. Don’t exceed 7.5t/ha (3t/ac) in a single application," it said.

Which lime to use?

Calcium ground limestone is the most common and is:

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  • fast acting and offers rapid pH adjustment.

Magnesium (dolomitic) ground limestone is:

  • slower to react but has a higher liming value; and,
  • a good source of magnesium for soils with low levels.

With granulated limes, you should consider the costs over a three- to five-year period, but these limes are:

  • finely ground (less than 0.1mm particle size) and very reactive; and,
  • applied as a maintenance product where soil pH is in the optimum range.

Online Editors


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