Obtaining an optimal soil fertility status is a key pillar to the success of dairy production systems or any farm production system.
Over the last four decades, lime has in some way been the forgotten fertiliser, as we are only applying 50% of our national annual lime requirement.
This is in spite of soil tests from dairy farms showing that 39% of soil samples have sub-optimal soil pH levels for grass production (over 6.3) and 61% of soils are sub-optimal for clover productivity of over 6.5.
The ground conditions at the moment are still very trafficable as, despite the few days of rain, the prolonged dry spell has held up ground conditions for now, so this is the time farmers should be applying lime.
Having good soil fertility will help with the uptake of nutrients and is key to utilising soil and reducing your emissions efficiently.
Now is the time to take action and use soil sample information to plan soil fertility in order to get the best out of your grass in 2026.
Soil fertility
Lime is required on a regular basis to regulate soil pH for productive mineral soils, as a ‘little but often’ approach is the key to maintaining soil fertility.
Soil fertility is always going to be a key driver of production and is even more essential now with nitrogen (N) and phosphorus (P) allowances being tightened, as utilising the fertiliser available to you is going to boost herbage production.
Increasing your soil pH has the potential to reduce your N fertiliser requirements by 50-70kg N/ha per year, according to Teagasc.
For the establishment of clover, the soil fertility needs to be at optimum levels in order for the plant to persist and survive – soil pH for clover should be between 6.3-6.5, while soil indexes for P and potassium (K) should be three or four.
Over the last number of years, farmers have learned that establishing and maintaining clover in grass swards can be difficult and can take a lot of extra management to be successful with the legume.
However, the biggest problem with clover is its initial establishment as if the soil pH is not optimal, the plant will struggle to establish and persist, so areas of the farm that are marked for reseeding need to be targeted for soil fertility correction.
Neglecting the fertility of your soil will likely lead to the running down of soil nutrient reserves, which will negatively impact N use efficiency and grass yields in the coming years.
Action
There should be no reason for not having your soil tested, as you cannot apply accurately to the soil if you do not know what nutrients are lacking.
If you do not have any soil tests already, you should be aiming to go soil sampling later on in the year when nutrients are fully out of the soil. A plan should be put in place now to curate a proper nutrient management plan.
Farmers should firstly focus on correcting soil pH, and secondly on getting the most out of their slurry and manures by identifying what is needed most.
Applying lime as soon as possible after a cut of silage is essential to reduce the risk of lime residues. The aim should be to avoid high grass covers of over 800kg DM/ha.
Lime should be applied without exceeding 5t/ha in a single application, and so a split application of 2.5t/ha over a number of years will allow you to build up soil pH in stages over time.
It is not just silage fields that may require lime at this time of the year – any field with a low pH should be targeted after a tight grazing or after it is mowed for surplus bales.
Lime should be spread to correct soil pH, and farmers can spread slurry before the lime application, but it is advised to leave a 10-day gap between the two applications.
