Use of intensity and capacity measurements to assess the potassium supplying power of soils

For depletions of soil exchangeable potassium of between 15 and 50%, potassium concentrations in ryegrass and strawberry leaf were linearly related to pARO K√BCO where ARO K is the equilibrium potassium activity ratio and BCO is the slope, measured at ARO K of the curve relating the quantity of labile potassium and the activity ratio. Potassium supplying power as measured by pARO K√BCO could also be expressed as a function of the equilibrium activity ratio and the mineral component of the cation exchange capacity of the soil.