Tips for choosing the right site, preparing the ground, controlling weeds and sowing
The benefit of multi-species swards is that they can maintain a steady growth rate with reduced fertiliser. A sward with a clover content of 20-50pc can allow fertiliser application in the summer to be halved.
The inclusion of plantain and chicory in the mix can prevent losses of nitrogen on the farm, through better use of N by animals and reduced farm leaching.
The recent Department of Agriculture multi-species sward scheme got good interest from farmers.
Here are some tips about how to establish multi-species swards on your farm.
Choosing a site and preparation
Choose grazing paddocks over silage fields, and go for paddocks with low weed burden.
Avoid commonage and land designated as Natura 2000 as they are excluded from the DAFM scheme.
Also avoid replacing areas of existing biodiversity (naturally diverse permanent pasture that is not designated) or unused land on the farm with new multi-species swards.
It is important that soil fertility is good, ie pH 6.2-6.5 and Index 3+ for P & K.
The seed mixture required for the DAFM scheme is listed below.
Address weed issues with herbicide before sowing — no post-emergence spray can be applied to the whole field once multi-species / clover swards are established.
After reseeding, the only methods for weed control are spot spraying/weed licking/wiping (using a spray that targets the most prevalent weed eg, for thistles use Thistlex); mechanically picking/removing weeds; or regular topping to reduce annual weeds.
Direct drilling results in lower weed emergence, as does good establishment.
Method of reseeding
Similar to grassland reseeding, the best conditions for sowing are without drought or frost, and ideally a warm, moist seedbed (around 10°C) between April and August.
■ Spray off the existing sward as per normal reseed. Then cut the existing sward as tight as possible while complying with the prescribed interval between spraying and cutting.
■ Cultivate soil as you choose (disc/harrow/plough).
■ Lime should be applied, if necessary. If using minimum cultivation apply 5t/ha (2t/ac) to the desiccated sward pre-cultivation. If ploughing address any lime requirement post-ploughing.
■ Apply normal seed bed fertiliser at sowing (P and K with N) based on soil test results.
■ Sow the multi-species seed mix at a rate of 12kg/ac (30kg/ha) at around 1cm deep (choose the seeder carefully to avoid seed separation).
■ Roll to get a fine firm seed bed and good soil and seed contact.
■ Allow 6-8 weeks before the first grazing to let the herbs establish strong taproots — only graze if new plants are strong enough to withstand grazing.
Direct drilling into stale seed bed/minimum cultivation
This is environmentally beneficial because it retains more soil organic matter than a full reseed.
■ Graze/cut off existing sward as tight as possible.
■ Spray-off with glyphosate as per normal reseed.
■ Comply with the interval between spraying and grazing/cutting prescribed on the herbicide label.
■ Sow at approx. 1cm deep (choose drill carefully to avoid seed separation).
■ Roll to ensure soil and seed contact.
■ Apply seed bed fertiliser and lime as normal for reseed.
■ Allow 6-8 weeks before the first grazing to let herbs establish strong taproots, only graze if new plants are strong enough to withstand grazing
Over-sowing into an existing sward:
This is another option but can be less reliable than a full reseed. It has the advantage of being cheaper, taking fields out of production for a shorter duration, and better protecting soil carbon.
When done correctly (and with favourable conditions), it can be very successful.
However, for the Department’s MSS Scheme, the grass component must be included as part of the seed mix, so over-sowing will be a less relevant option.
Note that the principles are almost identical to those for over-sowing of clover into a grass sward.
Aoife Forde is a Teagasc B&T drystock advisor, based in Galway/Clare