Potassium (K) is the third of the indispensable macronutrients required for all life, alongside nitrogen (N) and phosphorus (P). All three of these macronutrients play a fundamental role in our food production. However, around one-fifth of all agricultural soils face severe potassium deficiency. Whilst we know that potassium is critical to maintaining healthy ecosystems and supporting global food production, there is still more that we need to discover about potassium supply, consumption and pollution risk.