Grass is usually measured in kg of Dry Matter

Grass availability measured in kg DM/ha

Lowland ground has the potential to produce 12 tonnes DM per hectare per year

However, due to lower inputs and poor grazing management typical utilisation in NI is 5.0 tonnes DM/ha

Well managed farms 8-10 tonnes DM/ha realistic target

Daily grass growth varies from 5kg DM/ha in February to 100kg DM/ha in May

Includes what is left after grazing Number of methods used

1.Sward assessment using rising plate meter

2.Visual assessment

3.Sward heights

As rod is lowered into pasture, plate is supported by height and density of grass

This is averaged out over a paddock/field taking number of readings across field

Walk each field in ‘W’

Take 30-40 top leaf readings

Calculate field average and record

Keep record each week

1500 kgDM/ha4-5 cm

2000 kgDM/ha6-8 cm

2500 kgDM/ha8-12 cm

3000 kgDM/ha>12 cm

Stage Cover kg DM/ha

Sward height (cm)

After weaning Fat ewesThin ewes

16502450

36

Tupping 1800 5

Mid-Pregnancy Graze down to 1500

3

Lambing outside

Move onto 1800 4-6 weeks pre-lambing

6

Options

1.Apply nitrogen

2.Introduce supplementary feeding

3.Sell stock or cull unproductive animals

Options

1.Increase stocking rate

2.Close up area for silage/Take area out for round bales

3.Reduce supplementary feeding

4.Reduce fertiliser rate

Options

1.Pre-mowing or topping

2.Higher stocking rate

3.More measurement & management

Grass growth varies throughout the season

Grow and graze leafy grass Assess swards regularly Take prompt action when surplus/deficit appears

Maximise utilisation

Higher stocking rates and silage yields.

Higher grass growth response from fertiliser nitrogen.

Improved grass digestibility and palatability

Higher grass sugars and improved ensilability

ME (MJ/kg) Yield (t DM/ha)

Perennial Ryegrass 11.7 12

Yorkshire Fog 9.8 9.6

Creeping Bent 9.8 7.2

RSMG 9.3 7.8

PRG has 20% higher ME content & 50% more yield

The sheaths and backs of the leaves are smooth and shiny

Red stem base

Upper surface of leaf is strongly ribbed

Walk a ‘W’ and assess at points how much PRG is in a sward.

If PRG below 70% - then some work to improve sward will be required

If PRG below 50% then reseed needs to be considered

If % of broadleaved weeds is high action will be required

1. Sward Replacement – destruction of old sward and replacement by reseed (plough or minimal cultivation)

2. Sward Renovation - introduction of seed into an existing sward with little or no cultivation

3. Sward Rejuvenation - gradual improvement to sward by better management.

Required if % of PRG in sward is poor Most reliable and conventional method of

replacing a sward Spring reseed is usually end March to mid

May Autumn reseed between mid July to late

August Spring reseeds often have a heavier weed

burden than late summer reseed

If high % of scutch/bent grasses or weeds like dock/thistles then old sward should be destroyed by Glyphosphate herbicide

Poor seedbed preparation is most common cause of failure

Seedbed to be fine and firm

Consolidate without compacting

Sow 6-12mm deep

Roll to maintain moisture in top layer of soil

Watch out for pests (slugs, frit fly, leatherjackets)

Alternative to conventional method of plough and reseed

Suitable for;1.Stony soils2.Heavy land that takes time to dry out3.Where rapid establishment is required4.Thin swards (silage ground)

Specialist drills/equipment required

Control perennial weeds before over-seeding

Minimise competition from existing sward. Graze hard or cut silage immediately beforehand

Conditions need to be good (not too dry or wet)

Graze lightly when grass seedlings are 10cm high. Graze often for short periods thereafter.

Do not allow long intervals between grazings or closing for silage

Similar to over-seeding

Suited to Italian or hybrid silage swards that have thinned due to continuous cutting

Graze hard or cut for silage

Prepare a shallow tilth by discing and/or harrowing prior to broadcasting or drilling of seed

Identification and correction of poor management practices

Reasons may include;1.Poor drainage2.Poor soil fertility3.Weeds4.Under-stocking5.Poor integration of cutting and grazing6.Poaching7.Excessive use of slurry

Sward Replacement

with ploughing

Sward Replacement

without ploughing

Sward Renovation by

stitching-in(Over-seeding)

£/acre £/acre £/acre

Soil analysis 1 1 1

Spray 23 23

Cultivations 67 42 20

Seed & sow 98 98 64

Fertiliser - sowing 38 38 38

Lime – 2t + application

51 51 51

Total/acre 278 253 174

Factors to be considered

1.Sward life – short, medium or long term

2.Sward purpose – Grazing or cutting

3.Growth season/area – early, intermediate, late

4.Soil type – dry & light or heavy & wet?

5.Always use recommended list varieties

Use varieties with similar heading dates and dates which correspond with intended cutting date

Short term leys – use Italian ryegrass Long term leys – perennial ryegrass Clover inclusion of little benefit if intensive

silage system (2-3 cuts) Hybrids and tetraploids to be considered for

high sugar content

Persistence and ground cover are very important

Clover can have a role to play

Use mostly diploid varieties (more persistent)

Include some Timothy if ground is heavy

Why include clover?

Improves digestibility and intakes Increased animal performance Higher protein % than grass Increased mineral content of sward Can reduce need to spread chemical N

fertiliser

Weeds cause economic loss in several ways;

1.They compete with grass for nutrients and light

2.Area taken up by weeds is not available for grazing

3.Silage made from weed-infested pasture will have lower palatability and energy

4.All lead to poorer than optimum animal performance

Chickweed – annual, can be grazed out Redshank – annual, common in spring

reseeds Ragwort – biennial, extremely poisonous Thistles – perennial, topping not very

effective Dock – perennial, deep tap roots, keep

spraying Rush – perennial, common in poor, acidic,

wet land, spraying very effective