Effect of potassium fertilizer application on the potassium and its equilibrium in tea-grown soils

5-year successive field and pot experiments were carried out to study the effect of potassium fertilizer application on the potassium pools and its equilibriums in tea-grown soils.The soils used in pot experiment were yellow sandy soil,yellow lime stone soil and purple acidic soil,respectively,and the soil in field experiment was a yellow sandy soil under 25 year's tea cultivation.The results indicated potassium fertilization increased significantly potassium pools in soils.However,the absolute content of the soil potassium trended to decrease year by year.The changes of potassium in soil depended on soil type,and the increment magnitude of yellow lime stone soil yellow sandy soil purple acidic soil.The amount of potassium removed by tea from soils without potassium application were both 0.10 g/kg every year in pot experiment and field experiment.Annal quantities of removed potassium were 0.18 g/kg(yellow lime stone soil),0.09 g/kg(yellow sandy soil) and 0.07 g/kg(purple acidic soil) in pot experiment,respectively,thus potassium fertilizer should be applied to meet the K equilibrium in soil under tea planting.