Can lime be applied to grazing fields?

Yes, once fields have been grazed off and grass covers are low, it is an ideal time to apply lime.

For example this could require ordering a load of lime (20t) after each grazing rotation to correct soil pH.

Where lime sticks to the grass, will it affect grazing animals?

Ideally, apply lime to low grass covers to reduce pasture contamination with lime.

Rainfall will typically wash most of the lime from the grass down to the soil. Where a small amount of lime remains on the leaf, this will not affect grazing animals.

What is the best way to manage lime on soils that are prone to becoming soft at the surface

To minimise these effects apply lime on “a little and often basis” and improve soil pH in stages over time.

Don’t exceed 5t/ha in a single application or apply split applications (2.5t/ha) over a number of years.

When should lime be applied to silage fields?

Leave sufficient time (~ 2 months in dry weather) between applying lime and closing for grass silage. This will enable the lime to be fully washed into the soil and reduce the risk of lime entering the silage bales or the silage pit.

How long should I leave between lime and slurry applications?

Spreading cattle slurry on fields that have received lime recently and where the lime has not had sufficient time or rainfall to be washed into the soil, can result in a loss of some of the available N in the slurry. To minimise these slurry N losses, apply the slurry first and then apply the lime seven to 10 days later.

How long should I leave between lime and urea applications?

For urea, a similar situation arises to cattle slurry where increased N loss (ammonia-N volatilisation) may occur where straight urea fertiliser is applied on recently limed land. Therefore, apply urea first and apply the lime seven to 10 days later to reduce the risk of N losses. However, where protected urea is being applied, research work indicates that it is safe to apply protected urea to fields that have been limed recently.

What is the lime advice for high molybdenum soils?

Where farms are affected by high Mo soils aim to maintain soil pH between 6.0 and 6.2. Alternatively, apply lime as recommended and supplement animals with copper.

How fast will lime work?

Once lime is applied and is washed in to the soil, it starts to adjust soil pH. At least 35% of ground limestone (350kg/t) has a particle size < 0.15mm and is very fast-acting.

The remaining 65% lime (650kg/t) provides a long-acting source of lime to neutralise soil acidity over time.

This courser fraction of lime will be broken down in the soil in the medium term (six to 24 months) and helps to maintain soil pH levels in the longer term until the soils are resampled in years four to five.

What is the return on investment from lime?

Research shows that liming acidic soils increases grass production by 1.5tDM/ha.

On a drystock farm, this is valued at €105/t DM and €180/t DM on a dairy farm.

An application of 5t/ha of ground limestone to correct soil pH represents a cost of €25/ha/year over five years. The return on investment from lime gives €6 to €10 worth of extra grass for every €1 invested in lime.

What types of ground limestone are available?

There are two types of ground limestone that are available nationally – calcium and magnesium. Calcium lime is most widely available, while magnesium is only available in the southeast.

On soils that are low in Mg, magnesium limestone is a good source for both soil pH correction and to provide Mg for plant growth.