Introduction to Grassland
- Some Definitions
Botanical Composition:
–The range of plants growing in an area.
Indigenous Species:
–Species of plants that grow naturally in an area. - How Important is Grassland?
70% of world’s agricultural land.
91% of agricultural land in Ireland.
Main source of feed for cattle and sheep. - Grassland Ecology
Natural vegetation of Ireland is deciduous forest.
There is a natural progression through stages:
–bare soil
–grass
–shrubs
–forest.
Grazing stops this natural progression at the grass stage. - Types Of Grassland
- Rough Mountain and Hill
18% of agricultural land
Rock outcrops – difficult to lime, fertilise and reseed
Variable botanical composition – poor grasses, heather and gorse
Low stocking rates
Low productivity - permanent Grassland
51% of agricultural land
Variable botanical composition but generally dominated by perennial ryegrass
Heavily stocked and fertilised
High productivity - Temporary Ley
22% of agricultural land
Grass as part of a rotation – will only be in grass for a few years
Little variability in botanical composition – mainly the sown variety
High stocking rates and productivity as very good land - How do we encourage growth of top quality grasses?
Top quality grasses are short and leafy as they have a high concentration of sugars an starch.
We encourage their growth by:
–Intensive grazing
–High levels of soil fertility
So for all grass types keep stocking rates to a maximum to prevent the grass from becoming long and stemmy.
Use lime and fertiliser as necessary. - Dry Matter in Grass
Dry Matter: The matter remaining in a sample of food after the water has been removed. It is usually abbreviated to DM.
Dry Matter Digestibility (DMD): The amount (percentage) of dry matter that can be digested by an animal.
Dry Matter Intake (DMI): The amount of feed an animal consumes excluding its water content. - What makes a Good Grass?
Productivity
- Produce large quantities of herbage
- Respond to fertiliser and lime
Palatability
- Tastes good
- Cattle and sheep will eat it
Digestibility
- Retained and assimilated (used) in the body
- Contributes to production of milk, meat or wool - Digestibility
When grass is in vegetative stage (short and leafy) it has a high concentration of soluble carbohydrates and proteins which are highly digestible.
As the grass starts to produce stems to support seed heads there is an increase in the amount of fibre in the plant which is less digestible.
The plant can go from 80% digestibility to only 50% digestibility one month later.
Some grasses have better digestibility's than others. - Perennial Ryegrass
High productivity, palitibility and digestibility
Long growing season
Aggressive grass that tillers vigorously and is persistent
Likes free draining, high pH (> 6.0) moderate/high fertility soil. - Italian Ryegrass
Very long growing season
Less aggressive and does not tiller as vigoursly
Main use is for silage
Also requires good soil and liberal fertiliser use. - Hybrid Ryegrasses
A result of a cross between different species of ryegrasses, usually PRG and IRG.
They are crossed to produce a grass with hybrid vigour (has the desirable characteristics of both parents)
They are combined to produce a strain with the high production level of IRG and the persistence and long growing season of PRG. - White Clover
Protein rich legume that fixes atmospheric N (up to 130kg/ha/yr)
Very palatable
Suitable for grazing situations as stolons root easily when trodden into soil.
Heavy fertiliser N use will reduce the amount of clover in the sward - Red Clover
Not as important
Used in short term leys cut for silage
Otherwise similar to white clover - So what should we Sow?
For Grazing
–uniform growth pattern (steady supply)
–high feeding value
–easy management
–mixture of perennial ryegrasses with range of heading dates and white clover
For Silage
–large amounts of digestible dry matter at the same time
–single strain of perennial ryegrass or strains with similar heading dates
