DEAR EDITOR,

At Solohead research farm in 2022, we applied zero kg/ha of nitrogen (N) fertiliser to half the farm while the other half got 45 kg/ha. We were able to do this because since 2017, we had been transitioning to high clover grassland getting low or zero N fertiliser input. The saving in N fertiliser was €25,000 (€450/ha) in 2022 under circumstances of massively inflated nitrogen fertiliser costs. Milk output from the farm was maintained in line with earlier years. It was a profitable year, underpinned by high milk prices.

This research at Solohead terminated at the end of 2023. The legacy of this research is being continued by the Low Carbon Dairy Farmers Discussion Group (AKA the zero N brigade). These farmers have around one third (10% to 80%) of their farms under high-clover grassland getting very low or zero N fertiliser input. The Middle Eastern war is destabilising global energy markets. As we’ve seen in 2022, high energy costs escalate the cost of nitrogen.

Hopefully it won’t come to it, but one way or the other the low-carbon dairy farmers are increasingly hedged against future shocks to N fertiliser costs as they transition to high-clover grassland. Given its importance and faced with current uncertainty, it makes sense to diversify and use clover to free our farms from the stranglehold of being solely dependent on nitrogen fertiliser.