The increased cost of chemical fertiliser and summer drought has made the use of red clover silage (RCS) swards popular on many farms.

But there is still a large number of farmers that have concerns regarding the use of red clover, most notably the need for reseeding more regularly.

Red clover silage

Speaking at the Irish Grassland Association (IGA) dairy conference earlier this week, Teagasc researcher Michael Dineen outlined a recent study conducted by Teagasc on the cost saving that can be achieved using RCS.

Michael Dineen

Dineen firstly outlined research that was conducted at Teagasc Grange, which showed that, over a six-year period, a RCS sward that received no chemical nitrogen (N) had a similar annual dry matter (DM) production (15,000kg of DM/ha) to a grass sward receiving up to 412kg of N/ha/year.

Dineen noted that although the sward had seen clover content drop from 75% in year one to 44% in year six, the annual DM yields were showing no signs of decline.

Economic savings

Dineen then discussed more recent research that looked at the economic savings that can be obtained when using RCS swards.

Red clover replaces the chemical N fertiliser with biologically fixed N (equivalent to 150-300kg N/ha).

Three different systems were looked at in this trial: A grass silage two-cut system, RCS three-cut system with 0-7-30 being used, and a red clover three-cut system – all slurry.

Grass silage
two-cut system
Red clover silage
three-cut system, with 0-7-30
Red clover silage
three-cut system – all slurry
€/bale (€ t DM)€/bale (€ t DM)€/bale (€ t DM)
Fertiliser (Including spreading)€11.89 (€59)€7.10 (€34)€4.16 (€20)
Harvesting cost (Including plastic)€24.48 (€122)€23.69 (€113)€23.69 (€113)
Other (feeding, herbicides etc)€2.49 (€12)€2.64 (€14)€2.64 (€14)
Fixed cost (reseeding/facilities)€2.77 (€14)€4.78 (€23)€4.78 (€23)
Total cost (excluding land charge)€41.60 (€208)€38.30 (€184)€35.30 (€170)
Four-year to six-year persistency for red clover€-2.10 (€-11)€-2.00 (€-11)
Total costs (excluding land charge)€41.6 (€208)€36.20 (€173)€33.30 (€159)
25% reduction in fertiliser price €-2.1 (€10)€-1.10 (€6)€0.00 (€0)
Source: Teagasc

Based on chemical fertiliser prices of €1,100/t and €883/t for protected urea and 0-7-30 respectively, RCS was €3.30/bale cheaper to produce compared to grass swards.

When the grass sward and slurry-only red clover swards were compared, there was a €6.30/bale saving to be seen.

In a scenario where chemical fertiliser prices dropped by 25% (i.e. €825/t and €662/t for protected urea and 0-7-30 respectively) the cost benefit of red clover over grass swards silage is €2.30/bale.

This was based on the red clover needing to be reseeded every four years, based on a six-year reseeding programme there was a €5.40 saving for RCS three-cut system, with 0-7-30 and a saving of €8.40 for slurry only RCS.

Takeaway message

Using red clover has an environmental benefit to farmers, but based on this research it also has a significant cost-saving benefit – even with more regular reseeding being required.

Based on this research, for every 100 bales of silage produced on a farm there is a economic saving of between €630 and €840.