The researchers studied different fractions of potassium in semi-arid soils. They collected soil samples from two soil groups and found that exchangeable potassium was strongly linked to potassium saturation, organic carbon, and other factors. Water-soluble potassium had a negative correlation with organic carbon and soil pH. Nitric acid extractable potassium was closely related to total potassium and other soil properties. Overall, the study showed that different forms of potassium in the soil are influenced by various factors like organic carbon content and soil texture.