As grass varieties are constantly improved, reseeding can produce over £500/acre potential extra milk production. Using new improved varieties can give 33% more yield than a typical five year ley. Over the next four years, DM yield will be 10% higher.
The benefits of reseeding
- Improves pasture yield and quality, reducing bought in feed requirements/
- Introduces new varieties with improved productivity, durability and disease resistance.
- Increased palatability
- Increased protein
- Increases sward response to fertiliser, through using more nitrogen efficient varieties.
- Opportunity to review soil compaction and any weed issues
- Less disease – cycles are broken
- Extends grazing season
Assess the sward
The benefits of a new ley can last many years over an existing one. However, over time these benefits will decline. The rate that a ley declines will depend on:
Nutrition - Maintaining the swards nitrogen, phosphate, potash and sulphur requirements.
Soil health - Maintaining correct soil pH and avoiding compaction.
Weed Control - Maintaining an appropriate weed control programme
Grassland Management - reducing ingress of native species (weed grasses) which are of lower production and nutritional quality.
The amount of ryegrass (or other sown species) is a better indicator for a need to reseed than the actual age of the ley. As the ley increases in age, the yield potential falls to as much as 50% after five years. Reseeding should be considered before sown species fall below 50%. Weed grasses e.g annual meadow grass make up the rest. These offer less yield, poor feed quality and low response to nitrogen.
Although there is obviously a cost in reseeding this will be quickly gained back in extra milk or meat produced. It is also important to address other issues that might reduce output, before reseeding, to ensure maximum benefit.
Weed grasses in the sward
The amount of weed grasses in the sward increases over time reducing productivity.
Yield losses
The potential yield losses from weed grasses compared to perennial ryegrass can be seen below:
Nitrogen response
The perennial ryegrass and weed grass response to nitrogen is shown below:
Average benefits in first production year
4000kgDM/acre x extra 1 MJ/kgDM quality (11MJ/kgDM ‘v’ old ley@ 10MJ) = 4000MJ/acre extra
Plus yield 20% DM/acre = 800kgDM@11MJ/kg DM = 8800MJ/acre
At 40p / L = £966 / acre additional milk
Selecting the correct mix
By selecting a recommended listed grass mix you will benefitfrom scientifically proven yield benefits and allows you to capitalise on the strengths of different species.
Using the recommended list provides information on the best performing grasses and clovers available. Varieties on the list have been independently tested.
The recommended list allows selection for quality:
Yield and quality performance - Dry matter and energy.
Field performance - Disease resistance and persistence.
Feed performance - Grass fibre (NDF), cell wall digestibility (CWD), water soluble carbohydrate (WSC), protein
Select a mix for your system e.g silage only, grazing only or dual purpose.
Reseeding step-by-step
- Pre-sowing
- Soil test before reseeding – correct the pH and any nutrient deficiencies
- Check the subsoil for compaction from both livestock and machinery
- Burn off old swards with glyphosate
- Sow in early spring once the soil is warm and has sufficient moisture, or in the autumn up until end of September (weather permitting)
- Mixtures with clover should be sown by the end of August
- Cultivate to create a fine, firm seedbed. Sow no deeper than 15mm and give good soil to seed contact to aid faster development.
- Ideally sow into warm, moist soil
- Post sowing
- Cambridge roll to consolidate the seedbed
- Monitor for Fritfly Fly, Leatherjacket and Wireworm attack
- Monitor for slug activity and treatif required
- Control broad leaved weeds e.g. chickweed by light sheep grazing or suitable weed killers
- Early management ofthe new sward is key to encourage tillering. Grazing is preferable to cutting in the first instance
Typical costs for seed bed preparation and sowing
Other costs may include liming, seed bed fertiliser, spraying, finance charges, bringing the cost to £225-£275 per acre. However, some of these are annual costs when not reseeding.
*NAAC 2022 costs