K-soil stock

The K-soil stock figure shows the amount of potassium (K) in the exchangeable fractions. The figures are based on the amount on the cation exchange capacity (CEC) which is considered “exchangeable”. Whilst not as readily available as the K-plant available, the exchangeable part (K-soil stock) would be available to supply the soil solution as it becomes depleted over time. Because of this, there is easily the potential for there to be a large disparity in the two figures given how little K can be present in an exchangeable format any given time compared to what has the potential to become available.