With the escalation in fuel, fertiliser and other input costs we have calculated that the true cost of establishing a new sward is now in the region of £450 -500/ha or £180 – 200/acre. However, it is key to ensure grassland is productive as the volume of nutritious grass that is grown and utilised is key to profitability. Therefore it is recommended to reseed 10 – 15% of grassland each year.
Reseeding is a good way of replacing swards badly affected by weed, removing compaction problems and improving production from swards that have become open and gappy. However, these problems will soon reappear in the new ley if grassland management practices are not improved to prevent this type of deterioration again.
When to reseed?
Autumn reseeds are generally more successful than Spring reseeds due to moisture availability to the young seedlings. There is plenty of moisture in the soil at the moment offering an idea opportunity to start reseeds. We normally work on a cut off for Autumn reseeds of mid September.
Using a break crop between grass leys will disrupt the cycle of grass specific pest and diseases, eliminate pasture based animal parasite and enhance weed control opportunities. Break crop options could be either a cereal or maize crop, alternatively a winter brassica followed by a Spring reseed.
Of course, if your soils are not poached and do not need to be ploughed, establishing the crops with min till will make the establishment even cheaper.
how to reseed dairy grass in the autumn?
soil acidity
Before you start you need to know soil status for acidity, phosphate,potash, magnesium and organic matter. If you do not have a soil analysis (from auger to depth of 6”) in the past 3 years then do one so you can rectify any issues prior to reseeding.
Grassland soil pH should be maintained between 6.0 – 6.5 and you should aim for the higher end of this for reseeding. To prevent trace element lockup, you should not apply more than 2.4 t/ha lime per application – if the pH of your soil is very low you may need to lime for a couple of years before you invest in the reseeding. Liming should be done onto the ploughed surface, not before, as this is where the seeds will germinated.
compaction
Heavy soils are prone to compaction, particularly due to grazing in wet conditions, buffer feeding out in the fields, and heavy silage machinery travel in not ideal conditions. But light soils can suffer from compaction too!
Compaction must be corrected prior to reseeding, otherwise soil structure will jeopardise the success of your reseed and how long it will last.
Ensure you use a spade to dig some holes and find the depth of the compaction in the field, and then set the subsoiler up so that it works under this level.
The best time to subsoil is when the top soil has some moisture and the subsoil is dry. Do not subsoil in wet conditions, otherwise you will smear the soil and affect future drainage.
Some farmers subsoil on top of ploughing to get down deep and with less resistance.
sward destruction
Spray with Roundup to kill perennial weeds and weed grasses and allow 5 – 7 days for a complete kill before cultivating/applying manure.
organic manure
After subsoiling and sward destruction, organic manure can be applied.
If you have any FYM it is a good idea to put this onto reseeding ground prior to ploughing as it is a good source of N, P and K, the fibre will aid soil structure, and it is a good way to bury the manure residues.
For autumn reseeding there is no requirement for nitrogen so you need to be able to demonstrate a crop need for the manure and stay within the permitted nitrate leaching rules. If you are not sure how much manure you can put on give us a call.
Make sure you work out the crop nutrient need from the soil analysis, what the manures will supply and whether you need to top up with artificial fertiliser. There is no point in going to all the expense of reseeding and not give the plant what it needs to establish well.
cultivations
Once the manure has been spread,plough the field, ensuring you bury the previous sward and manure residues –apply any lime required onto the ploughed surface.
Prepare a fine, firm, level seed bed around 5 -8 cm deep and roll. Either broadcast the grass seed onto a Cambridge rolled surface and then work in with a light harrow to a depth of 6 – 8mm, or cross drill at half the seed rate in each direction at a depth of 15 cm.
Finish off with consolidation using a combination of flat and Cambridge rolls if possible. Do not roll in wet conditions. It is key to ensure a good seed to soil contact.
Dairy grass seed mixtures
The cost of grass seed is less than 25% of the full expense of re-seeding and most will be down for several years. Taking time to select the right varieties will reap benefits for productivity and persistency and is well worth doing.
Use a reputable merchant displaying the NIAB-TAG logo, get the details of the grass mixes they recommend for your situation, then go to the AHDB website and download the 2024/25 RGCL handbook which will show all the details of the NIAB approved varieties so you can decide which is the best mix for you. Alternatively send us the mixes you are considering and we will advise.
The inclusion of clover will reduce your reliance on bought in fertiliser and increase the levels of homegrown protein. It is also key for a number of the Sustainable Farming Incentive options.
You should select medium to large leaf white clover varieties for medium to long term leys. For short term leys for cutting, include red clover.
There are a number multispecies SFI compliant mixes suitable for SAM3 – Herbal Leys available, these vary depending grazing or cutting mixes.
For long term leys (5years+) select a mix of perennial ryegrasses which are more persistent – use amix of early/mid or mid/late depending upon how early your farm is.
For medium term leys (3 –5 years) select a mix of perennial ryegrasses and hybrid ryegrasses.
For short term leys (1 - 2years) use Italian ryegrasses/diploid perennials for cutting, or hybrid/perennial ryegrasses for grazing.
Timothy is good to include if you are an extended grazer, if you make hay, or if your farm tends to lie wet.
Protecting your reseed
- FritFly– a particular risk with autumn grass reseeds following grass, and direct drilled crops are most at risk. Risk of attack can be reduced by allowing a gap of at least 4-6 weeks between sward destruction and reseeding – if you can afford the time!. Attacks cause patches of stunted yellow plants, and the larvae may be seen feeding at the base of the stem. Reason able control can be achieved by chemical treatment with chlorpyrifos at emergence in high risk situations, or at the very first sign of damage.
- Leatherjackets–damage is usually seen in spring when the larvae are feeding just below ground level. Attack results in patches of yellowing plants which usually die. Dig just below the soil surface to see if you can find larvae to confirm. Treatment is chlorpyrifos.
- Slugs–are a high risk in wet autumns where seedbeds are rough. Leaves are often shredded or torn close to the ground with thin strips eaten out, and slime maybe present. Keep an eye on your reseed and apply slug pellets as soon as damage is seen.
Short term ryegrasses sown early in the autumn may need to be grazed or cut prior to winter to avoid winter kill.
Heavy infestations of chickweed will need spraying either in late autumn or the spring to prevent too much competition with the grass.
In Spring, walk the reseed and look for perennial weeds, they are easier and cheaper to control the younger you catch them – spray if necessary.
For more help and advice from our dairy consultants please follow the link below
