【Objective】In the past few decades, soil potassium has received less attention than nitrogen and phosphorus, despite that potassium loss in farmland is a common issue due to large crop demand and the relatively small application amount. Soluble potassium resources are relatively unabundant in China. The low self-sufficiency rate and high reliance on imports led to the high cost of potassium fertilizers. Due to the importance of potassium in crop production and the cost and environmental consequences of applying potassium fertilizer, it is worth paying attention to mineral potassium in future agricultural production. It has been found that there is a unique potassium release mechanisms of layered silicate potassium-rich minerals in paddy soils. However, there is currently a lack of systematic research on the changes and influencing factors of different potassium transformation thresholds during the formation of paddy soils, which greatly limits the establishment and development of potassium transformation models for these soils. 【Method】This study selected "potassium-rich" purple paddy soil and "potassium-poor" red paddy soil, and investigated the evolution characteristics and influencing factors of different potassium transformation thresholds during their formation through time series analysis. The aim was to provide theoretical support for reducing the dependence on soluble potassium fertilizers in rice fields. 【Result】 For "potassium-rich" purple paddy soil, traditional rice cultivation in the early stages (within 0-20 years) significantly reduced the total amount of water-soluble potassium and exchangeable potassium in the plow layer (about a 28% decrease). After this period, the transformation thresholds between water-soluble potassium and exchangeable potassium, and between exchangeable potassium and non-exchangeable potassium, remained relatively stable, with thresholds stabilizing between 61±4 and 106±9 mg·kg-1, respectively. For "potassium-poor" red paddy soil, the total amount of water-soluble potassium and exchangeable potassium also decreased significantly in the early stages of rice cultivation (within 0-100 years), reaching very low levels (about a 30% decrease). Subsequently, the transformation thresholds between water-soluble potassium and exchangeable potassium, and between exchangeable potassium and non-exchangeable potassium, stabilized, with thresholds remaining between 32±4 and 64±4 mg·kg-1, respectively. 【Conclusion】During the formation of paddy soils, the potassium forms and transformation thresholds in these soils are closely related to the potassium-rich minerals in clay and silt particles. The potassium release mechanisms of layered silicate potassium-rich minerals can remain stable over a long period during the formation of "potassium-rich" paddy soils. For red paddy soils, especially those with over 200 years of rice cultivation, it is necessary to increase potassium fertilizer input in a sustainable and potassium-balanced manner to avoid negative potassium balance in the fields. There is great potential in using gravel-rich layered silicate potassium minerals as an alternative to traditional potassium fertilizers in paddy fields.