Soil pH is one of the biggest factors affecting crop production in this country. According to Teagasc, only 20% of soils have optimum soil pH levels.
Optimum soil pH levels can result in increased nutrient use efficiency and, therefore, improved water quality and reduced greenhouse gas emissions.
For example, moving from low soil pH levels to optimum soil pH can result in a doubling of nitrogen use efficiency on grassland.
It is important to plan ahead and apply lime in advance of crops that need it. For example, beet crops react sensitively to soil pH so lime should be applied earlier in the rotation and not the year the beet is planted in order to reach the optimum soil pH.
Loss of lime
Farmers on light soils most likely need to pay more attention to their soil pH levels as lime can be lost through water draining from the soil.
Crop production will also cause lime levels to deteriorate, so intensive grassland or tillage production systems are likely to lose lime faster than low-intensity systems.
Best time to apply lime
On grassland, lime can be applied once there is not a strong cover on the soil and grass can be grazed once rain has washed the leaves clean.
If applying to a grass reseed, it is best to apply after ploughing and to incorporate the lime into the top layer of soil.
On tillage crops, where large amounts of lime are required growers sometimes split the application and apply half before ploughing and half after ploughing.
Lime requirement will vary based on soil test results and farmers should consult with their adviser if unsure.
The soil pH along with the SMP buffer are both needed to calculate the requirement.
Optimum soil pH