Approximately half of national soils are below the target pH level of 6.3 for productive grassland soils.

When fertilisers are applied to soils with low pH levels, less of the nutrients applied are available for plant uptake, and fertiliser use efficiency by the crop will be lower. The use efficiency of nitrogen and phosphorus fertilisers in particular can be drastically reduced on soil where no lime has been applied for long periods.

Therefore, applying lime to correct soil pH is the first step to soil fertility management.

Lime use in Ireland

Over the last three decades, the sales of lime in Ireland have collapsed compared to the 1970s and early 1980s, where on average 1.7m tonnes of lime was applied annually.

This has led to the current situation, where Irish soils are massively deficient in lime with little or no lime application in some regions of the country.

Over the last 30 years, an average 800,000t lime has been applied annually - less than half of the previous average.

Planning your liming programme

Soil testing is the easiest and most accurate method of determining the lime requirement of the individual fields on your farm.

The soil test will provide information on the current soil pH level and also the tonnes of lime required per hectare to bring the pH levels up to the target: 6.3 for grassland, or 6.5 for tillage soils.

The next step is to develop a liming programme or rotation for the individual fields on the farm. This can be as simple as deciding what fields require lime, at what rate lime is to be applied (t/ha), and when is the best opportunity to apply it.

This simple liming plan can then be communicated with the lime supplier or local lime contractor, so that the correct quantity of lime can be delivered and spread in a timely manner.

Using every opportunity throughout the season to spread lime, if required, is important. As we saw this year, waiting until October to spread lime is risky due to poor weather and un-trafficable soil conditions.

Take advantage of low grass cover after silage cuts and plan to have the paddocks that also need lime grazed out at the same time, so that lime can be applied to both areas.

Lime – return on investment

Lime plays a major role in improving the three fundamentals of soil:

  • Soil chemistry and nutrient availability.
  • Soil physical structural quality.
  • Drainage and soil biological functioning, including earthworm activity etc.
  • Maintaining the correct lime status of your soils will improve overall soil health and fertiliser use efficiency, and in turn, improve your crop yields and farm productivity. Increased grass and grain yields of at least 1.5t/ha are common when soil pH is brought up to the correct level.

    Taking current grain prices (or the average value of 1t grass DM at €160) and the cost of an annual lime maintenance application rate (€22/ha) into account, this represents a return on investment of almost €7 in additional grain yield for each €1 invested in lime, or a 7:1 return. This ratio also holds true for grassland.