
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/ha
4-5 cm
2000 kgDM/ha
6-8 cm
2500 kgDM/ha
8-12 cm
3000 kgDM/ha
>12 cm
Stage
Cover kg
DM/ha
Sward height
(cm)
1650
2450
3
6
Tupping
1800
5
Mid-Pregnancy
Graze down to
1500
3
Lambing
outside
Move onto
1800 4-6
weeks prelambing
6
After weaning
Fat ewes
Thin ewes

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.
2.
3.
Sward Replacement – destruction of old
sward and replacement by reseed (plough
or minimal cultivation)
Sward Renovation - introduction of seed
into an existing sward with little or no
cultivation
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 soils
2. Heavy land that takes time to dry out
3. Where rapid establishment is required
4. Thin swards (silage ground)


Specialist drills/equipment required



Control perennial weeds before overseeding
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 drainage
2. Poor soil fertility
3. Weeds
4. Under-stocking
5. Poor integration of cutting and grazing
6. Poaching
7. 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