12 February 2022

Advice on Liming Factsheet

Teagasc recently published a compendium of 20 factsheets providing the latest technical advice on soils, nutrients and fertiliser. The second of these is about Liming and can be read here. All 20 will be published here on Teagasc Daily

Farmers are urged to focus on Nutrient management planning, optimisation of soil fertility, using organic manures strategically and increasing clover in swards, all balanced with prudent fertiliser usage.

The benefits of liming

Release of soil nitrogen (N) for early grass growth (up to 80 kg N/ha, 64 units/ac per year)
Increase the availability of soil phosphorus (P) and potassium (K)
Grow an extra 1.5 t grass dry matter (DM)/ha annually

Target soil pH for different crops

Return on investment (ROI) from ground limestone use

Research shows an average grass production response of ~1.5 t DM/ha from lime alone
This is worth ca. €181/t DM on a dairy farm and €105/t DM on a drystock farm
An investment of €27/ha to maintain soil pH in the optimum and returns €150/ha
This represents a return of €6 – 10 for every €1 invested in lime

Advice on spreading lime

How much?

Test soils on a regular basis (every three to five years) to determine lime requirements
Only apply lime based on a recent soil test report
Don’t exceed 7.5 t/ha in a single application

When?

Prepare a farm liming plan. This will identify where lime is needed, and when and at what rate lime should be applied
Lime can be spread all year round. Having a lime plan in place will open up opportunities to get lime applied over the year when conditions are suitable and land is available

How Often?

Apply lime often as per the soil test report
On very acidic soils apply 50% now and the remainder in two years’ time
Apply lime to 20% of the farm annually

Which lime to use?

Calcium ground limestone is most common
- Fast acting ( < 3months) and rapid pH adjustment
Magnesium (dolomitic) ground limestone is available
- Somewhat slower to react but higher liming value
Granulated limes
- Finer lime (less than 0.1mm particle size) and very reactive
- Apply as maintenance product when soil pH >6.0

Lime and high molybdenum soils

Soils with high Mo status may give rise to copper deficiency in grazing animals
Increasing soil pH >6.2 increases Mo availability
To reduce elevated Mo levels maintain a somewhat lower soil pH 6.0 to 6.2

Lime & slurry/urea

The type of N in slurry and urea is ammonical N and prone to loss if applied to freshly limed soils. To avoid N loss the following is recommended:

Leave seven days between applying urea or slurry before applying lime
Leave three months between applying lime and following with urea or slurry application
No interval required between liming and protected urea

Deirdre Hennessy, Seamus Kearney, Mark Plunkett, David Wall, Mark Moore (Editor), Pat Murphy, Stan Lalor, were the main contributors to this series of leaflets. Numerous colleagues from Teagasc AGRIP, CELUP, REDP, Signpost, PR dept. and advisory service also participated.

To access the entire compendium of 20 factsheets see Soils, Nutrients and Fertiliser Factsheets Find more information on this topic in Soil & Soil Fertility