When to reseed
Both spring and autumn provide opportunities for a successful reseed; deciding which is best for you will depend largely on your land and farming system.
Although the timing of a spring reseed is more likely to be influenced by the weather, spring usually provides the widest window due to better weather and soil conditions. When reseeding in the spring, good soil conditions allow the chance to use post-emergence herbicide sprays and control weeds effectively. A spring reseed also means a break or catch crop such as a winter grazing brassica can be grown, and this can be a useful technique to reduce the threat of leatherjackets. It’s important to remember though, a spring reseed initially offers a lower yield potential and, depending on the method used, can mean the soil might be too tender to travel or graze early.
Conversely, the time period available for a successful autumn reseed is usually narrower, but it does allow time over winter for the ley to reach its full production potential and give the soil a chance to settle before travel or grazing. An autumn reseed also means a full season’s yield can be taken from a field before reseeding followed by a full yield the following year. Break crops can also be grown before an autumn reseed with options including brassicas being grazed during mid-summer when grass growth is often lower.
Preparing the seedbed
Before deciding how you’re going to reseed, preparing the ground is critical. Aim to produce a fine, firm and level seedbed. This is key to maximising the seed-to-soil contact and gives you the best chance of successful germination.
In many cases the actual method used to reseed has little impact on yield in the first full year. More important is making sure whichever method you use is done properly and managed well post-drilling.
Ploughing remains one of the most commonly-used methods of cultivation to provide a firm and level seed bed. It’s a particularly good option where soil compaction is an issue. It allows you to remove soil pan and bury both trash and farmyard manure, releasing nutrients back into the soil. It also ensures good seed-to-soil contact.
But ploughing can be expensive and dry out lighter soils, damaging soil biology. There is also a risk of bringing less fertile soil towards the surface, as well as disturbing weed seed banks, bringing them up to where they can germinate. Docks, for example, can lie dormant in the soil for up to 50 years, but still germinate and grow if disturbed.
Minimum tillage (Min-till)
Min-till is often cheaper and allows a quicker return to grazing. It involves very little disturbance of the topsoil so ideal in stony and shallow soils where you’re trying to avoid bringing stones up to the surface.
There are a wide variety of drills on the market, including disc drills, slot seeders and air drills, all of which have their place and work well in the right circumstances. Preparation prior to drilling is particularly important and has a substantial impact on the success of min-till. It is vital any thatch or trash is sufficiently broken up and buried in order to create a fine, level seed bed.
Direct drilling is a particularly useful method of renewing pastures used for rotational grazing. Preparation is important here too and gives the best chance of successful establishment.
Start by grazing the ley off tightly and spraying with herbicide at around 2,800kgDM/ha. Wait for the herbicide withhold period before removing dead material by either grazing or for silage. The removal of dead material before drilling is important. If left, it can rot down creating an acidic surface layer which can scorch or kill seedlings as they emerge. Before drilling, check the soil pH and apply quick-action lime if necessary, before spreading fertiliser and direct drilling the grass seed. Weeds should be dealt with wherever possible and the new ley grazed off as soon as the mixture stands the pull test, normally at 3-6 cm.
Cereals as a break crop
Cereals as a break crop is useful for establishing a new grass ley and gives you a winter forage crop. But the focus needs to remain on the grass ley you are establishing rather than the crop. This means when you drill the cereal, only use up to two thirds of the normal drilling seed rate and reduce the fertiliser inputs. This helps ensure the cereal crop doesn’t grow too thick a canopy reducing the amount of light reaching the grass seedbed below.
When harvesting the cereal, aim to chop at around 40% DM and 30% starch and use as a fermented silage whole crop. By the time the cereal is harvested, the grass ley underneath should be well established.
To find out more about choosing the right mixture for your next reseed, contact Ben Wixey on 07990 578550.