Quantity/intensity relations in soils and the potassium nutrition of the strawberry plant (Fragaria SP)

In glasshouse pot experiments over two years, the strawberry plant used potassium primarily from sources which were in instantaneous equilibrium with the soil solution. Leaf potassium concentration at flowering and fruiting was highly correlated with the initial equilibrium potassium activity ratio (AR ) of the soil, and a linear relationship existed between 1/Leaf‐K and 1/AR Yield of fruit was less well correlated with AR than with the quantity of labile potassium in the soil. the gradient of the straight line part of the quantity/intensity (Q/I) graph was increased for 2 of the 5 soils after the period of intensive cropping; this could be related to an increase in the amount of exchangeable calcium+magnesium in the soil.