Choosing whether to go for a full reseed or to overseed can feel like another difficult decision - so feel free to use our field indexing system as a guide.
Generally we suggest that:
Field Indexing 2 – 4 = overseeding
Field Indexing 1 = reseeding
Don’t be afraid of overseeding - A short- to medium-term fix
Currently only around 2% of UK grassland is being oversown. Overseeding is a short- to medium-term option but it does provide a quick fix and is ultimately an effective method of improving productivity - while keeping investment costs to a minimum.
Overseeding is ideal for farmers who need to improve grassland performance to help boost profits but, understandably, feel nervous about investing in a full reseed or taking a field out of rotation.
While brand new swards will always outperform older grasses, overseeding can help to increase dry matter yields short-term – reducing farm reliance on expensive bought-ins and even improving live weight gains. Implemented carefully, overseeding has the potential to improve pasture productivity by between 30 to 40% for between three to four years, depending on field quality.
When overseeding, it is crucial to use a mixture designed specifically for this purpose. Any existing productive grasses in the ley already have an established root system and an established leaf canopy to capture light for photosynthesis. Any new grass seed that is introduced needs to be able to work with these conditions and overseeding mixtures are blended accordingly. Typically, they contain tetraploid perennial ryegrass varieties whose seeds are larger, have more aggressive growth habits and are faster to establish within an existing sward. As well as tetraploid-based varieties, introducing clover could be another option.
Clover can fill in gaps to reduce weed ingress. It can also improve nitrogen levels – encouraging tillering, which makes swards denser. Crucially, clover can also encourage higher voluntary intakes, improving live weight gains.