Advice on Liming

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

Crop type	Target soil pH
Grassland (mineral soils) grass only swards	≥ 6.3
Grassland (mineral soils) with clover	6.8 to 7.0
Grassland (peat soils)	5.5 to 5.8
Cereals	≥ 6.5
Beet/Beans/Peas/Oilseed/Maize	6.8 to 7.0
High molybdenum (Mo) soils	6.0 to 6.2

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 (<3 months) 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