Sulphur boosts grass DM yield
SULPHUR applications to grassland could reduce nitrogen leaching by increasing herbage dry matter yields, and consequently nitrogen uptake.
Lorna Brown of IGER North Wyke, Okehampton, Devon, explained to delegates at the BGS winter meeting that sulphur encourages nitrogen uptake by the plant, so there is less nitrogen residue remaining in soil to be washed away.
In plot trials at North Wyke, one site with moderately-drained sandy loam soils showed applying sulphur significantly increased nitrogen intakes by the five-year-old perennial sward, said Dr Brown.
Dry matter yields increased more with sulphur on low nitrogen input sites than high nitrogen input sites, but environmentally both sites showed important findings.
"The high nitrogen site was well above the peak EC limit on nitrates of 11.3mg N/litre. But when sulphur was applied leaching fell below this limit."
Dr Brown concluded that sulphur use in Nitrate Vulnerable Zones may help producers comply with water quality regulations without reducing DM yields.
These findings were supported by Levington Agricultures Ian Richards.
"In the next 10 years sulphur may become a routine application especially in organic or conservation areas."
His companys trial work shows applications of 15kg/ha (12 units/acre) sulphur boosts second cut silage dry matter yields by 0.75t, costing £60/ha (£24/acre). Comparing favourably with nitrogen, sulphur applications shows a 10-12:1 value return on investment, said Dr Richards.
It is hard to predict responses to sulphur for first cut silage, but for second cut there is no reasons not to apply it, he added.