Claire Mc Auliffe, Teagasc Listowel Dairy Advisor, discusses the benefits of applying lime and the role lime has to play in correcting soil pH. Lime is mainly lost from the soil through rainfall and drainage which reduces soil pH.
The soil pH, which is a measure of the level of acidity in the soil, can be established through taking soil samples on your farm. Soil samples should be taken at least every four years to ensure accurate readings. These soil samples will give a reading of the soil pH and will also indicate the amount of lime that will be required to correct the soil pH. These results can also be used to generate colour coded maps from the Teagasc nutrient management programme. These colour coded maps will indicate which plots of land are on target for soil pH and which fields require lime.
The target soil pH for grassland is 6.2 pH with peat soils having a lower target of 5.7 pH. Lime is mainly lost from the soil through rainfall and drainage which reduces soil pH. Correct soil pH will make better use of fertilisers applied to land either organic or chemical. Having a correct soil pH also makes nutrients more available for plant growth, research shows average grass production response of at least 1.0 t/ha from lime alone.
When is Lime Time:
We recommend applying lime on a three or four programme on your farm so as to build up soil pH and also maintain soils that are at correct soil pH. Follow this lime plan based on the most recent soil samples available. Target fields with the largest requirements first but do not exceed 7.5 tonne of lime per hectare in a single application. Lime can be applied all year round, with this time of year being ideal after second cut silage has been removed if no more cuts are planned on that ground, or where there is ten acres grazed tight. It is ideal to apply lime onto bare ground.
Urea or slurry should be applied ten days before lime application if required and avoid spreading after lime as it can lead to nitrogen loss.
For derogation farmers it is now mandatory to correct soil pH on their farms and this can be done by applying lime.
It is important to say that lime costs in the region of €25 per tonne spread but has a potential return of seven times this which has been proved through research.