1. Leaving Certificate Agricultural Science
Sowing and Reseeding Grassland

2. Reasons for Reseeding Grassland
The aim of reseeding grassland is to improve the quality of the grass sward
Weed Infestation
After many years, weeds can start to take over a pasture, reducing its overall productivity, e.g. Dock leaves
Low ryegrass content/high content of poor quality grass
Troublesome weed grasses such as scutch grass and bent grasses can start to dominate sward. They compete with good quality grasses and they lower productivity, palatability and digestibility

3. Livestock may have poached land leading to poor quality pasture
Continued
Addition of clover
Reseeding allows a farmer to increase the clover content of the pasture
Animal activity
Livestock may have poached land leading to poor quality pasture
Can also undergraze or overgraze land, which can cause problems for pasture quality
Poor soil fertility
Before reseeding, soil tests should be carried out and lime and fertiliser requirements should be determined

4. Benefits of reseeding Improves grass quality Improves silage quality
Increases meat and milk production
Higher output allows increased stocking density on land
Better response to N fertilisers
Longer grazing season reduces the need for winter fodder (reduces costs)
Excess grass as a result of increased productivity could be cut for silage and sold

5. Methods of Sowing and Reseeding Grassland
There are several methods of sowing or reseeding grassland
They include
Direct Sowing
Undersowing
Direct drilling
Slurry seeding
Slit seeding

6. Sowing Leys Direct Sowing Best and most reliable way to obtain a ley.
The seedbed is prepared by ploughing and harrowing.
It should be very fine, finer than that for cereals.
Fertiliser should be broadcast and worked in during the final seedbed preparation.
The seed is sown using a combine drill, in lines 10cm apart and 2cm deep.

8. Sowing Leys - 2
They may also be broadcast over the soil and covered over using a chain harrow.
The land should be rolled after sowing to improve seed – soil contact and better germination rates.
Spring sown leys should be sown before May 1st due to the risk of drought.
Autumn sown leys should not be sown after Mid – September.

9. Cultivating direct drilling
Plough to a depth of 15 – 18 cm
Harrow to a fine tilth
Spread fertiliser – 350Kg of /ha
Roll to form a firm seed bed
Sow grass seed at 25Kg/ha using a combine drill
Chain harrow
Roll again

10. Ploughing

11. Power Harrow

12. Sowing Seed

13. Chain Harrow: (buries seed under soil so birds can’t eat seed)

14. Rolling (Pushes seed down and levels field)

15. Sowing Leys - 3 Undersowing
Undersowing is used by farmers who employ tillage / grass rotations.
The grass seeds is sown with a tillage crop, usually a spring cereal (nurse crop).
Over the summer the two crops grow together and after harvesting, the grass takes over.
The land is ploughed and the seedbed prepared in the usual manner.
The grass is sown directly after the cereal (using a drill) and then the land is rolled.

17. Sowing Leys - 4
Spring Barley is the most suitable “nurse crop” as the competition between the two crops is less due to short straw and early harvesting.
Lodging is a problem with this method, so N application should be lessened by 30%.
Tillage yields are reduced using this method also.
Undersowing grass with arable silage (oats / vetch) is good farming practice.
The silage is cut early and the grass has a good chance of establishing itself.

18. Cultivating Undersowing
Plough to a depth of 15 – 18 cm
Power harrow to a fine tilth
Sow cereal and apply fertiliser
Roll to form a firm seed bed
Sow grass using a combine drill
Give a light chain harrow and roll again

19. Sowing Leys - 5 Direct Drilling
This technique involves drilling seeds into unploughed ground.
The drilling machine cultivates a small strip of soil and sows the seed in it.
No problems occur if direct drilled into stubble. (grass is grazed bare)
But if direct drilling into grassland, problems and/or competition can occur.

22. Sowing Leys - 6
The grassland should be grazed bare or mown and killed with a herbicide before direct drilling.
Slug pellets and fertiliser are added with the seed in order to help its establishment.
Direct drilling is most successful on shallow soils where ploughing is difficult.

23. Sowing leys - 7 Slurry seeding
this involves the mixing of grass seeds with the slurry and then spraying back on to the land using slurry tank
This can be very successful on grounds damaged by machinery or poached by animals, provided it is spread before rain in mild weather
Disadvantage is that expensive grass seeds can become trapped in humus in periods of drying after spreading

24. Sowing Leys - 7 Stitching In / Slit seeding
This system is almost the same as direct drilling, except the old sward is not killed.
The seed is drilled using a similar drill, along with slug pellets and fertiliser.
If the seeds establish themselves then they become the dominant species in the sward.
This system is not as predicable as direct drilling and the old sward can often win out.

25. Grassland Establishment
This refers to the development of the seedlings into a thick, densely packed pasture.
The most significant process in the establishment of a good sward is tillering.
Tillering is promoted by damage to the main shoots of the plants.
Newly sown pastures should be lightly grazed to encourage tillering and promote growth.
The best animals for this are sheep or calves, as cows would damage the crop.

26. Grassland Establishment - 2
This works well for spring sown grassland (not under-sown), as the land is dry when grazed.
Annual weeds can be controlled by grazing or topping, as tillering is then promoted and the weeds get little chance to establish themselves.
Perennial weeds like dock can be partially controlled by topping, but a selective herbicide may be required in extreme cases.