New trial results announced at the Livestock Event show sulphur delivered a 29 per cent increase in grass growth for first cut grass in 2016, with swards remaining responsive to further applications as the season progresses.
Dr. George Fisher, independent grassland specialist, said: “Like 2015, 2016 is turning out to be a very sulphur responsive year but we are seeing significant responses to phosphorus, too.
“The overriding message for farmers is to consider using a sulphur-containing fertiliser this year and do not cut back on maintenance applications of phosphorus.”
The trials, which took place in Cheshire and Devon, were commissioned by CF Fertilisers as part of their commitment to independent and replicated grassland research.
The work follows trials from 2014 to 2015 in which useful responses in grass yield to sulphur, even on heavier soils, and to maintenance applications of phosphorus on P index 2 and 3 soils, were seen.
In the latest trials on medium loam soils in Cheshire, a 100kg/ha application of straight N (Nitram) delivered a yield of 4.55t DM/ha for first cut silage while the addition of 44 kg/ha of sulphate (as SingleTop) lifted this to 5.85t DM/ha– a 29 per cent increase.
These applications also produced an extra 0.8t DM/ha for early grazing.
On a heavier clay loam at the Devon trials site, response to sulphur was 10 per cent for the same levels of application as the Cheshire site, whilst when sulphur and phosphorus were added together, yields increased from 4.2t DM/ha from the straight nitrogen to 5.2t DM/ha – an impressive 24 per cent lift.
At a time when getting the most out of home-grown feed has never been more important, the results are highly significant, Dr Fisher said.
He said: “If you assume a 75 per cent utilisation rate from field to feeding, this extra 1t/ha DM for first cut silage at 11 MJ ME contains enough energy to produce 1,530 litres of milk or 175kg of liveweight gain. Well worth having.
“Similarly, an extra 0.5t/ha DM for early grazing at 12 MJ ME and an 85 per cent utilisation rate, produces enough energy to produce an 845 litres of milk or 110 kg liveweight.”
The responses to phosphorus are also very interesting with an application of 40kg P2O5 (water soluble phosphate) giving up to 17 per cent more grass DM yield on first cut silage and 8 per cent on the first two grazings, he points out.
He said: “These responses are occurring when soil P indexes are already at 2 and 3, suggesting maintenance applications of P in this form are used efficiently and provide a highly beneficial yield response.
“All in all, it shows livestock producers need to think much more about their land’s nutritional needs if they want to produce the highest cost-effective yields of forage.
“Doing so is certainly advantageous, with the cost benefit in milk production showing a £20 return for every £1 spent on sulphur and up to £12 for every £1 on phosphorus.”