• First year nutrient management critical for new grassland reseeds
  • 25kgDM/ha response to 1kgN on new swards falls to 15kg on older ones
  • £20 return for every £1 spent on Sulphur and up to £12 for every £1 on Phosphorus


With grassland taking a hammering over 2019/20 and many growers now planning extensive reseeding next year, first year fertiliser management will play a critical role in their future performance and longevity, says Ross Leadbeater of CF Fertilisers.

Optimum grassland nutrition can not only improve dry matter yields from new pastures, it can also maximise production throughout their life and extend intervals between re-seeding, he points out.

“It’s important to match variety choice to intended use but once sown, sward management, in particular focusing on Nitrogen and Sulphur applications, can dramatically improve the business returns from reseeds.

“In general terms, producers that carry out regular reseeds produce a litre of milk from grazed grass for around 3p/litre whilst from permanent pasture it’s at least 5p/litre.

“Over a five year period, you can expect reseeded leys to produce a total of 624,000 MJ/ha of energy whereas for permanent pasture this will be more like 440,000MJ/ha.”

With a reseed likely to incur costs of £450 – 500/ha and the potential drop-off in grass energy produced each year after reseeding around 4,500 litres/ha, producers must manage swards carefully to get the most out of their investment, he says.

“Correct use of Nitrogen is key. Reseeded pasture will deliver 25kg grass DM/ha for every kg of Nitrogen applied, whilst with permanent pasture this is only 15kg.

“A good N application programme will ensure plants remain stronger and more abundant, competing better with other pernicious grass species and the grass mix you put in at the start is more likely to be preserved as the years go by.

“Sound nutrition planning, particularly in the early stages, means you could also get an extra 2-3 years out of your reseed adding further to its cost efficiency.”

Paying attention to other key nutrients is also important, Ross Leadbeater points out.

“We’ve seen Sulphur delivering a 30% increase in grass growth in trials for both first and second cuts on reseeds in their first full growing season. And good responses to Sulphur are not just seen on lighter land.

“In trials on medium loam soils in Cheshire, a 190kg/ha application of Nitram (34.5%N) on a reseed gave 9.66t DM/ha in total for first and second cut silage, whilst applying 84 kg/ha of Sulphate as SingleTop (27N + 12SO3) lifted this to 12.45t DM/ha – a 29% increase.

“On the same reseed, using Sulphur for grazing also produced an extra 1.1t DM/ha over the first four grazing rotations – a 14% yield response.

According to ACT fertiliser product manager Tim Ayliffe-Robson, responses to Phosphorus are also beneficial.

“An application of 40kg P2O5 water soluble phosphate has been shown to give 9% more grass DM yield on first and second cut silage and 5% on the first four grazings.

“These responses are occurring when soil P indexes are already at 2 and 3, suggesting that maintenance applications of P in this form are used efficiently and provide a beneficial yield response.

CF True granular NPKS compounds make ideal early season applications for grassland, generally, but are a great way to kick reseeds into life, he explains.

“CropMaster Sulphur (27-4-4 +7SO3) is a good option for getting some early water soluble phosphate into reseeded swards and if you’re looking at more frequent cutting then Multicut Sulphur (23-4-13 +7SO3) would suit best.

“If you’re confident P and K levels are sufficient for optimum growth then CF SingleTop (27N + 12SO3) is a proven all-round performer for grassland.

“New leys produce over 30% more dry matter tonnes/ha when compared to older leys. In addition from a forage quality perspective, older leys will begin to revert to native weed species – for example PRG has a D Value of 73 whilst this can be as low as 58 for Bents.

“Managing reseed nutrition properly is certainly advantageous, with cost/benefit analysis showing a £20 return for every £1 spent on Sulphur and up to £12 for every £1 on Phosphorus – and that’s on top of the extra yield benefits from using N wisely.