It is envisaged that lime usage on Irish farms will double over the coming years. Moreover, this enhanced usage level must be maintained.
The driving force in making this happen comes back to two key factors – the inherently acidic nature of Irish soils and the fact that improving soil pH values will significantly reduce greenhouse gas (GHG) emission values.
At a recent webinar on soil fertility, Teagasc soil fertility specialist, Mark Plunkett said: “Last year lime usage levels dropped in Ireland dropped to around 750,000t, back from the 1Mt recorded in the previous two years.
“However, I am very optimistic that lime usage will bounce back in 2024. It should be possible to reach a 1.5m to 1.7m tonnes usage rate between now and Christmas.”
Ireland’s Marginal Abatement Cost Curve (MACC) target for 2025, where lime usage is concerned is 1.7 million tonnes.
“As we move towards 2030, this figure rises to some 2.5 million tonnes on an annual basis,” Plunkett commented.
Lime usage
Significantly, the Teagasc representative is also linking the enhanced use of lime over recent years to the general improvement in soil phosphate levels, identified during the same period.
“Around 50% of our soils are at Index 1 or 2 for phosphate. Index 3 is the sustainable level where phosphate is concerned and the good news is that 30% of Irish soils meet this condition,” Plunkett continued.
“The remainder of our soils are at an Index 4 for phosphate.”
According to Plunkett, approximately 30% of Irish soils do not need applied potash.
“Again, Index 3 is the sustainable level where the availability of potash in soils is concerned,” he said.
The current MACC projection figure for applied chemical phosphate sits at 46,000t/yr.
“Irish farmers were meeting this target between 2028 and up to the fertiliser crisis of 2022/2023,” Plunkett commented.
“At that stage, both phosphate and potash application rates fell back by around 33%. This trend is a concern in terms of both maintaining and building soil fertility.
“We need to get back on track in terms of national phosphate and potash application rates. The target here is to improve soil fertility levels. By taking this approach, farmers will also be improving nitrogen use efficiency levels.”
Plunket added that there will be a very clear crop response secured to phosphate and potash fertiliser additions to Index 1 and 2 soils.
“For index 3 soils, a maintenance fertiliser dressing is all that’s required. Index 4 soils should not receive additional phosphate or potash.”