Irrespective of soil type and location, many paddocks were badly damaged by poaching in 2012. This damage will reduce grass dry matter production in 2013.
On some farms, these paddocks cannot be reseeded within the grazing rotation and in other cases, cashflow will not allow for them to be reseeded this year.
However, it is possible that over-seeding of these swards in early spring could help increase perennial ryegrass content. Over-seeding can be used as a short-term avenue to full reseeding.
It probably should only be considered when the farmer can carry out the tractor work themselves and minimise operation costs.
If over-seeding is being considered, its success is dependent on getting as much seed-to-soil contact as possible and having moist conditions post-germination.
Use a tetraploid (bigger seeds) grass variety, at a seeding rate of 6-8kg/acre. Roll with a ring roller, which can follow the undulations of the paddock.
The more open the pasture, the more likely that over-seeding will be successful.
The best time for over-seeding is late April or mid-summer (after silage cuts), but this is not possible on all farms.
Ensure the paddock is grazed at light covers for the remainder of the year.
It will only be on the third or fourth rotation that the new plants will start making a contribution to the sward.
Here, we outline two methods of over-seeding which could be used on farms this year to improve grass production.
Method 1: Grass harrow and fertiliser spreader combination
Ensure the pasture is grazed off well, clean to the base.
Harrow with a grass harrow to ensure a levelling of the divots and disturbance of the soil surface.
Spread grass seed (6-8kg/ac) with the fertiliser spreader, then spread compound fertiliser (1-2 bags/ac) of 18:6:12 or 10:10:20. Roll pasture with a Cambridge roller (if available) or a light roller.
Spread a light coating of slurry (1,000-1,500 gallons/acre). Ensure pasture is grazed frequently thereafter.
Don't expect to see major differences within the pasture instantly, as it will take time for the new seeds to establish.
Ensure the pasture is grazed at light covers to assist seedling germination and tillering.
It is advisable to use a tetraploid variety because tetraploid seed sizes are much larger than diploids.
Over-seeding will not work if seeding is followed by dry conditions so, if this happens, continue to spread light levels of slurry (1,000-1,200 gallons/ac) or soiled water after grazing.
These swards may require a post-emergence spray upon establishment.
Method 2: Guttler or stitching-in machines
Graze off pasture well to 3.5cm. If this is not possible, mow pasture down tight to this height.
Use a guttler or stitch-in seeder across the pasture at a seeding rate of 6-8kg/ac. Spread compound fertiliser (1.5-2 bags/ac), either 18:6:12 or 10:10:20.
Roll the pasture with Cambridge or other light ring roller. Apply a light coating of slurry (1,000-1,500 gallons/ac).
These swards may require post-emergence spraying upon establishment.
When using a stitching-in machine, it is advisable to use slug pellets (Draza) at sowing.
Ensure frequent grazing thereafter until new seedlings have emerged. Graze with lighter stock if possible.
Dr Michael O'Donovan is a senior grassland researcher working with Vincent Griffith at Teagasc Moorepark, Cork