The wet conditions throughout the winter and early spring period have caused further damage to already hard-hit grassland and delayed reseed plans for many, but there are still many options open for rejuvenating swards in 2024.
One of the most important jobs for grassland farmers this spring is assessing which underperforming fields need to be re-seeded or overseeded during the year and making a plan for when the best time to do this is, says Agrii National Grass, Roots, and Environmental Seeds Manager Adam Simper.
“Persevering with an existing sward that is winter-damaged or now full of weed grasses is always a false economy, with both yield and quality likely to be reduced.
“Timings might not be ideal, but this is a year where some difficult decisions need to be taken and compromises made.
“A full reseed will not only boost overall yield, improvements in D value, ME, protein and sugar content will help maximise milk yield and DLWG, delivering better returns from grazing and forage.”
Three key considerations
Three key areas will be particularly important this season, he points out.
“Firstly, it’s important to ensure old swards are successfully killed off with a glyphosate- based product before preparation of the seedbed begins.
“Ensure there is sufficient new growth for the chemical to be taken up and that an appropriate rate is applied under correct conditions. Whilst this treatment will control actively growing plants, it will not kill dormant weed seed in the soil.
“Next on the list is to think about nutrition requirements. The high levels of rainfall will have potentially washed key nutrients from the soil and mineralisation of nitrogen is likely to have been low to date.
“It’s therefore important to sample the fields to determine pH, P,K and Mg indices. Walk in a ‘W’ around the field taking soil samples to a depth of 15cm if ploughing or 7.5cm if only cultivating the surface.”Any problems seen will then need addressing with lime and an appropriate fertiliser regime.
“Finally, seedbeds will also need careful preparation following the challenging conditions with the aim of preparing a firm, fine seedbed, making sure ring rolling is carried out after drilling to maximise seed to soil contact.”
Another important factor is to make sure the right grass seed mixture is chosen based on its intended end use and individual growing conditions, Adam Simper advises.
“Select mixtures with a high proportion of new grass and clover varieties which have recently been added to the Grass and Clover Recommended List in order to maximise advances in breeding programs and help increase on-farm profitability from home grown forage.
“Our approach is to pick the best varieties from a range of breeders to capitalise on individual characteristics such as cutting and grazing yields, D value, ground cover scores, disease resistance and seasonal growth. It’s also important to choose a no clover mixture if significant weed problems are expected – you can always introduce clover at a later date once a herbicide has been applied to the sward.”
New sward suitability
Once established, suitability for grazing can be established by pulling gently at the grass blades between thumb and finger, he explains.
“If the root system is pulled out then the plant is not ready to be grazed. If the roots stay in the ground and the grass blades rip off, then graze periodically from 8-12cm down to 4-6cm.
“This will encourage the plant to tiller out and help achieve a dense leafy sward. Gentle first grazings also allow sunlight to reach and stimulate the grass tiller buds and the clover’s growing points.”
Overseeding can be an option in some cases, he points out, as it is a simple but effective way to rejuvenate old or damaged grass leys at a lower cost than a full reseed, he adds.
“Overseeding can also be more efficient and reduce the amount of time that home-grown grass forage is out of production.
“Timing is key with the main aim being to minimise competition from the existing sward. Overseeding can take place up until the end of April, but later summer is also a good option as grasses are not growing as vigorously as in May or June.
“Careful consideration also needs to be given when choosing where to overseed, an open sward is needed, as a thick old sward will be very hard to open out to allow the seeds to reach the soil so then a full reseed may be a better option.”
