If you had to pick a year to start a project on growing red clover silage in NI, you wouldn’t have picked 2023, AgriSearch general manager Jason Rankin told farmers attending a webinar last Wednesday night.

The online event provided the first update on a new ZeroNsile project involving 12 farms across NI, aiming to grow silage without chemical nitrogen (N). Eleven farms established red clover last year, with three farms in Co Down also trialing Lucerne.

Despite the challenging year, farmers involved said they will persist with the crop. Having established 12 acres on 15 June, Tyrone farmer David Clarke took 51 bales off on 16 August and a further 60 on 2 October.

“The bales were wet, but fed very well,” he said.

Fermanagh farmer Stephen Maguire sowed on 17 May and took 7.5 bales/acre off on 10 August and five bales/acre on 26 October. Rows were “grouped to save the field” and while it is extremely wet silage, intakes have been good.

Across the 11 farms, the red clover was sown out in a mix, with around 3kg included alongside 8kg of perennial ryegrass and 1kg of white clover per acre.

Pros and cons

Outlining the pros and cons of red clover, AFBI scientist Dr David Patterson said it is capable of producing very high yields of over 15t dry matter per hectare (DM/ha).

However, it can’t be grown consistently in a field – after four years there needs to be a four-year break to prevent the build-up of stem eelworm and clover rot. But the main issue with red clover is that it has a crown just above the surface. If the crown is damaged by livestock or machinery, the plant dies, said Patterson.

At harvest he advised farmers not to cut too low and not to tedd out the crop more than once.

“You want preserved red clover leaves in the silage – that is where the protein and other digestible nutrients are contained,” he said. Ideally, three to five cuts should be taken at six to eight-week intervals.

Red clover has a high requirement for potassium and needs phosphorus, however, slurry is quite a well-balanced fertiliser for the crop. No N fertiliser should be applied.

“As soon as you put on N fertiliser, you are turning off the tap of biological N fixation,” said Patterson.

Establishment

Soils should be at least pH 6.5 and when establishing the crop, it needs to be applied to the surface of a fine, firm seedbed. Weeds must be effectively dealt with and the previous crop sprayed off, especially given the lack of clover safe sprays in NI.

Red clover can be sown once soils reach 8oC, which usually means from mid-April onwards, however, sowing date should not slip beyond June.

A series of farm walks relating to the project are to take place later this spring.