Limestone comes in numerous forms, calcium carbonate being one of them. It is one of the most abundant natural resources available in Ireland.
But whether it’s the calcium or the magnesium version of the product that’s being used by farmers, the end result is the same – an increase in soil pH values.
And what a good news story this is for the thousands of Irish grassland farmers whose acidic soils are crying out for a pH uplift.
It’s trendy at times to bash politicians. But it should always be accepted practice that a genuinely good decision made by a government minister is to be applauded.
And such is the case where agriculture minister Charlie McConalogue and his commitment to the 2023 liming programme are concerned.
Further good news in this regard comes in the form of a government commitment to double the programme’s budget – from €8 million to €16 million.
In my opinion, it is one of the most positive developments to have impacted on Irish agriculture in a generation.
It also goes without saying that all farmers eligible for the initiative should commit with all urgency.
However, this would be on the basis that farmers using the lime would justify its application on the back of a current soil test result.
Soil testing and calcium carbonate
It is a scandalous fact that 90% or more of the grassland soils in Ireland have a pH value well below 6.0.
It has been known for years that regular lime or calcium carbonate application was the backbone of every soil management plan.
Research has shown that ground limestone will deliver a plant growth response within two to three months of spreading.
As a rule of thumb, spreading lime at rate of 1.0t/ha will raise soil pH value by approximately 0.3 of a unit.
And, here’s the really good news. Ireland is sitting on trillions of tonnes of the stuff. We don’t have to import one grain of the material. In fact, we could probably supply the world with it.
Lime
Lime is nature’s wonder. It is a soil conditioner/fertiliser that has no peer. If we want to reduce our dependency on bagged nitrogen (N), lime is the answer. It’s as simple as that.
Looking to the future, production agriculture in this country must wean itself off chemical N. And a back-to-basics approach should get us a long way down the road in meeting this objective.
Agricultural lime remains the cheapest and most effective soil quality enhancer that is available to Irish farmers.
All that is required is a soil test to determine the amount of lime that beds to be applied to a particular field.
During the period 1970 to 1985, lime usage in Ireland averaged 1.5 million tonnes annually. For the specific years 1979 and 1985, the actual amount of limestone spread was in the region of 1.7 million tonnes.
According to Teagasc, these figures are indicative of the national lime requirements that are required to maintain soil pH in the optimum zone of pH 6.3 to 6.5 on mineral soils in Ireland.
In contrast, annual lime usage has only exceeded one million tonnes on four occasions during the last 30 years. As a consequence, soil acidity has increased on Irish farms resulting in a large requirement for lime.
Correcting soil pH needs be carried out on an annual basis with ground limestone applications to maintain soil pH in the optimum zone for efficient use of both soil and applied nutrients – manures and fertilisers.
Traditionally, the perceived practice was to treat 20% of available farmland with lime, based on soil test results.
Teagasc confirms that such an approach remains good advice, when it comes to managing soil pH.
So, does committing to an effective liming programme tick every box? I think so.