A project led by Dr Caroline Brophy of NUI Maynooth has found that grass yields can be boosted and fertilizer costs slashed by mixing certain types of grass seed together. It has long been known that clover is a beneficial nitrogen fixer, and some farmers already include clover in the seed mix. The study found that the best results, up to 20% increased yields, were achieved with mixtures of legumes like white or red clover, with cock's foot or orchard grass and rye grass.
"What we saw from the study was any kind of mixing gave a strong diversity effect. Think of putting two types of species together. If one is deeper rooted than the other, it is able to go further down for nutrients and water, so you utilise the system better", Dr Brophy said.
In terms of climate fluctuations, this kind of diversity might offset extreme conditions like drought and flooding. The study used thirty-one study sites across Ireland, Sweden, Norway, Switzerland, Iceland and Italy. Large fields could be cut up to five times in one year. Irish Grassland Association member Tommy Moyles from Clonakilty, has already been planting a dense clover content in his grassland. He claims it has reduced his nitrogen needs by over 40% since 2012.