What are the benefits of reseeding?

Currently only 5% of agricultural grassland is reseeded and permanent grass leys plays a significant role in UK production. Well managed grass is the lowest cost feed for ruminants. Renewing swards regularly is important to maximise poductivity and maintain feed quality.

Dairy Nutrition

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.

Grass yield over the years

Weed grasses in the sward

The amount of weed grasses in the sward increases over time reducing productivity.

Weed Graph

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:

Yield Losses

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

Reseeding 1st year benefits 2

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

Benefits of reseeding

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