Lime can be applied to land at any time of the year, however mid-summer and autumn are identified as the most ideal time of year, as soils appear dry and firm.
Teagasc recommends that at least 3 months should be left between liming and harvest of silage.
The following advice has been sourced from a recent publication by Teagasc.
Which Lime to Use?
Calcium ground limestone is most common
- Fast acting and rapid pH adjustment
Magnesium (Dolomitic) ground limestone is available
- Slower to react but higher liming value
- Good source of magnesium for soils with low levels
- Finely ground lime (less than 0.1mm particle size) and very reactive
- Apply as maintenance product where soil pH is in the optimum range
- Consider costs over a 3 to 5 year period
Lime & High Molybdenum (Mo) Soils
- High levels of Mo in grass can reduce copper uptake in grazing animals
- On soils with high Mo status there is higher risk of copper deficiency occurring
- Increased soil pH (especially > 6.2) increases Mo availability
- Minimise soil Mo by maintaining soil pH at a slightly lower range 6.0 - 6.2
Poaching & Soil Types
- As the soil pH increases following lime application to permanent pasture the rate of breakdown of the grass sod may also increase due to elevated biological activity
- On wetter and more poorly drained soils this may increase the risk of poaching occurring in the short term
- To reduce the risk of “softening the sod” lime should be applied at a reduced rate using a little and often approach
Lime & Slurry /Urea
- The type of N supplied in slurry and from urea is ammonical N and is prone to loss if applied to freshly limed soils.
- To avoid N loss the following is recommended
- Wait at least 3 months after liming before applying
Urea or slurry application
Wait 10 days after slurry or urea application before applying lime
Farmers who spread lime report positive results on their farms
John Leahy, Athea, Co. Limerick
– Farms heavy clay mineral & peat soils
– Increased mineral soil pH from 5.5 to 6.3 over 3 years across the whole farm
– Applied 100t lime per year on 40ha costing €2,600/yr
– Increased average grass production by 1.5t DM/ha/yr (valued at €272/ha)
– Average lime applied per year 7.5t/ha (Costing €65/ ha/year)
–This represents a return on investment of €4 in extra grass for every €1 in lime
The Benefits of Liming
- Increase grass production annually
- Release up to 80kg N/ha/year n Unlock soil phosphorus (P) and potassium (K)
- Unlock soil phosphorus (P) and potassium (K)
- Increase the response to freshly applied N, P & K Lime
Lime is a soil conditioner and controls soil acidity by neutralising the acids generated from N fertiliser and slurry applications and following high rainfall.
Soil pH has a large influence on soil nutrient availability. Aim to maintain mineral soils in the pH range 6.3 - 7.0 and peat soil in the pH range 5.5 - 5.8 to maximise nutrient supply.
Soils below the target pH will have reduced nutrient availability of N, P & K in the soil and poorer response to applied nutrients.
Maintenance Lime Requirements
- High annual rainfall leads to a large removal of lime each year
- Typical maintenance lime requirement of 2.5 to 5.0 t/ha once every 5 years depending on regional location and rainfall (i.e. typically higher rates may be required in the West)
- Apply maintenance lime to 20% of your farm on an annual basis
Importance of soil pH for Grass Production
- Correcting soil pH from 5.2 to 6.3 increased grass production by at least 1.0 t/ha
- The application of 5t/ha ground limestone produced similar grass yields compared to the application of 40 kg/ ha P fertiliser alone on soils with low pH
- The addition of lime + P fertiliser in combination produced the largest grass yield response (1.5 t/ha more grass than the control in the season of application)
- Lime increases the availability of both stored soil P and freshly applied fertiliser P
Return On Investment (ROI) From Ground Limestone Usage
- Research shows average grass production response of at least 1.0 t/ha from lime alone
- This is worth €181/tonne of grass dry matter (DM)
- Return on investment - maintenance lime application costing €25/ha/yr enabling the production of at least €181/ha/yr of extra grass
- At farm level every €100 investment in lime equates to approximately €700 in extra grass production annually Spreading Lime
How much lime?
- Test soils on a regular basis (every 3 to 5 years) to determine lime requirements
- Only apply lime based on a recent soil test report
- Don’t exceed 7.5t/ha in a single application
- Application rates >7.5t/ha, apply 50% now & remainder in 2 years
- Prepare a farm liming plan
- Target fields with largest requirements first n Lime can be spread all year round
- Ideally apply to bare soils (after grass silage harvest)
- Apply at reseeding time & incorporate into seedbed
- Apply lime as per the soil test report
- On very acidic soils with high lime requirement apply 50% now and remainder in 2 years’ time
- Apply lime to 20% of the farm annually