Grass is usually measured in kg of Dry Matter Grass availability measured in kg DM/ha Lowland...
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Transcript of Grass is usually measured in kg of Dry Matter Grass availability measured in kg DM/ha Lowland...
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