Will lime be left until next year—again?

Will lime be left until next year—again?

We all know lime is important, but it is one of those jobs we often never get around to. There is always silage to cut, slurry to spread or another urgent job waiting.

Lime has always provided a good return on investment. However, with feed and fertiliser costs increasing and continued uncertainty in global markets, correcting soil pH is now more important than ever.

The next 14 days could provide valuable opportunities to spread lime on farms where ground conditions allow. If last spring is anything to go by, we cannot assume that another suitable opportunity will come along soon.

Another year can quickly pass

It is easy to say that lime can wait until spring—but spring brings the rush to get slurry spread. Before long, first-cut silage is approaching and lime is postponed again because of the risk of contaminating the crop.

Suddenly, another season has passed and lime is still on the list. Meanwhile, another year of applying slurry and fertiliser to low-pH fields means poorer nutrient efficiency and less value from every pound spent on nitrogen, phosphorus and potassium.

That is why any suitable opportunity to spread lime should not be missed.

Give it one hour

On the next wet day—or even over a couple of tea breaks—set aside one hour to open your Soil Nutrient Health Scheme results.

Instead of losing that half hour scrolling through TikTok or checking MartEye—important as that may be—use it to identify the fields that need lime.

You do not need to tackle the whole farm at once. Start with the five fields showing the greatest lime requirement or those expected to produce the most grass next year. Prioritise the fields with the lowest pH and make a practical plan for getting them limed.

Aim for pH 6.2 on mineral grassland and pH 5.5 on peat soils. Farms trying to obtain more benefit from clover or multispecies swards may want to consider a higher target pH of around 6.5. Always follow the recommendation for each individual field.

You already have the results—use them now rather than waiting until they are out of date.

Low pH reduces fertiliser utilisation

The cost of low soil pH can be seen in fertiliser utilisation.

At a soil pH of 5.0–5.5, only 77% of nitrogen, 48% of phosphorus and 77% of potassium may be utilised. Overall, this suggests that up to 32% of the fertiliser applied may not deliver its intended value.

Even at pH 5.5–6.0, the estimated figure is still 21%. Put simply, for every £100 spent on fertiliser, as much as £21–£32 may fail to provide the expected return where soil pH is below target.

With fertiliser becoming increasingly expensive, can any farm afford that level of inefficiency?

More grass from the same ground

Correcting soil pH does not just improve fertiliser efficiency—it can also increase the amount of grass grown.

Increasing soil pH from 5.5 to 6.3 can produce at least one additional tonne of grass dry matter per hectare annually or in other words ~2 silages/acre. The increased grass production has been valued at a minimum of £150 per hectare each year.

Across 50 acres—approximately 20 hectares—that could mean around 20 additional tonnes of grass dry matter annually, with a feeding value of at least £3,000 each year.

That additional grass could help fill a silage shortfall and reduce the amount of purchased feed required next year.

The financial case is difficult to ignore

At approximately £50 per acre, spreading lime across 50 acres would cost around £2,500.

Northern Ireland analysis has estimated a return of almost £7 for every £1 invested in lime over five years. On that basis, a £2,500 investment could potentially deliver around £17,500 in feeding value through additional grass production and improved nutrient efficiency.

Who knows how much feed or fertiliser £2,500 will buy next spring or summer? Whatever it buys, it is unlikely to offer the same potential return as investing that money in lime now.

Doing nothing also has a cost. Applying expensive fertiliser and slurry to low-pH soil means the grass may not make full use of those nutrients. Correcting soil pH helps every pound spent on fertiliser work harder.

Make the plan now

If fields still need to be cut, cut them first. Apply slurry after cutting, allow at least 10 days and then spread the lime.

Give your lime contractor a heads-up now so they can plan ahead and be ready when the fields become available. If everyone waits until the last minute, contractor availability could become another reason the job does not get done.

Liming is not just a job for reseeding, and it does not have to be an all-or-nothing project.

There is no time like the present. Before you finish today, open your SNHS results, identify five priority fields and phone your lime contractor.

Do not leave lime on the list for another year. The information is available, suitable opportunities may arise and the financial case has rarely been stronger.