Researchers studied different forms of potassium in soil under rice cultivation in India. They found that water soluble, exchangeable, and non-exchangeable potassium levels were highest with a specific treatment. Water soluble potassium decreased from early to late stages of rice growth, while exchangeable potassium decreased in one season but increased in another. Non-exchangeable potassium increased as the rice plants grew. Adding lime to the soil increased all forms of potassium compared to a standard treatment. Potassium levels decreased with soil depth and were lower in one season compared to the other. The amount of potassium taken up by the rice plants correlated with specific forms of potassium in each season.