Phosphorus (P) | Mineral element vital to plant growth. One of three macro-nutrients (‘NPK‘) needed for photosynthesis and overall plant health and yield (eg. wine grapes). See also nitrogen and potassium. Calcareous soils whose clay content is high may be low in phosphorus (Ian d’Agata, 2019, p.337)
Dr Ian d’Agata, Native Wine Grape Terroirs of Italy (University of California Press, 2019).