Mussel shells | Soil amendment permitted in organics and used in wine-growing by a number of wine producers in New Zealand. ‘The mussel shells are normally combined with composted or composting grape marc,’ says New Zealand-based organics consultant Bart Arnst told me in Oct 2019. ‘The mussel normally arrives with some mussel meat attached which provides a food source initially for the micro-biology. If you crush the shells down to a powder you have the same calcium content as agricultural lime, plus the trace elements which come from the ocean. My assessment is that it’s a positive option to improve soils and therefore wine quality, and I’ve dug many a hole to check.’

The first time I saw mussel shells being applied to vineyards was at the Yealands winery on Tuesday 14th July 2015.