Over-seeding grass leys could be a valuable option for livestock producers wanting to maximise forage yields and quality this year – while avoiding the hassle of full reseeding.
Using Westerwolds or a tetraploid-based grass mix to breathe new life into flooded and waterlogged pasture could be a simpler option if conditions prevent a full reseed, says Jim Juby of Horizon Seeds.
“Many people have had grassland under water for some weeks now and it’s inevitable that much of this will have suffered due to the anaerobic conditions,” he says.
“Even when water levels have gone down it will take a long time for earthworms, the soil biology and grass to return fully – and the grass that returns will be of very poor quality nutritionally.”
Reseeding a proportion of your grassland is usually the ideal tactic. But for many farmers it won’t be possible to get in with a plough until later in the season – even though it would be highly advantageous to rejuvenate damaged swards before first cut if possible.
“If you can get on using a small tractor with a light footprint, one option is to use a tined cultivator then spin the grass seed on and roll the seed in. An Einbock grass harrow or similar would be ideal as you could carry out all operations in one pass.
“A tetraploid-based mix would be the seed of choice for this approach, as this has seed twice as big as diploid varieties which means twice as much stored energy to help the new seedling establish fully. A seed rate of 20-25 kg/ha would be ideal.”
Using Westerwolds annual rye grass would be another option, says Mr Juby.
“Both a shorter-term ley and a longer one will grow at the same rate so you should be able to get three good cuts during the year whichever option you take. You can then look at a full reseeding programme later in the year when, hopefully, soil conditions are better.
“But it does all depend on the condition of your fields. If it’s not too bad in the next few weeks, you should still consider a spring reseed under a cover crop of spring barley which you could then take for wholecrop in July to boost home-grow feed resources.”
Replacing non-productive grass varieties with a reseed or rejuvenating swards by over-seeding will always deliver benefits, suggests Mr Juby. In fact, one of the biggest improvements comes from greater nitrogen utilisation efficiency, he says.
“A modern perennial ryegrass will give a 50% better response to nitrogen than something like Yorkshire Fog or most of the other weed grasses that thrive when reseeding is delayed or swards are damaged.
“So, if you don’t address your grassland issues in the short term, you’ll effectively be wasting half the nitrogen you apply and that’s a cost few businesses can live with in the present circumstances.”
Return on investment
Farmers who are considering a full reseed should adopt a risk management approach and choose inputs wisely to ensure they get the most out of the investment. Regardless of the intended use, growers should ask some basic questions to make the best decisions when it comes to choosing the right varieties for a reseed.
Mixes are much more robust than single species varieties and have a greater resilience to disease threats as well as better ability to cope with diverse growing conditions, says Mr Juby. A good starting point is to make sure all the varieties in a mix are in the current Recommended List.
“A lot of advances have been made in recent years especially in critical areas such as performance consistency and response to nitrogen inputs. Understanding what is in your mix will also help you establish what the likely milk yield you can expect from your grass and allow comparison of different options to be made.”