Aims Potassium (K) nutrition is essential in grasslands, but soil K buffering capacity is highly soil-specific, making generic fertiliser recommendations challenging. Highly K-buffered soils have a greater capacity to store and resupply exchangeable K, often resulting in minimal observable changes in soil test K (STK) in response to applications of mineral fertiliser K (MNK). Conversely, low K-buffered soils typically show gre...