A pot culture experiment involving 2 harvests of corn and 1 harvest of rape within 2 years had been conducted to explore the responses of corn and rape to the application of potassium sulfate,mineral potassium fertilizer and rock powder with abundants potassium content (totally,3 treatments involved in the experiment )fertilized in Huangsannitu(yellow sandy loam),which is deficient in potassium nutrition.And the changes of the soil potassium nutrition under the situation of continuous application of potassium fertilizers had been studied by means of testing the continuous extraction curve and the quantity/intensity curve for the quickly available and slowly available potassium of the soil after the experimentation.The results showed that the treatment of potassium sulfate not only greatly promoted the growth and yield of the crops but also the plant potassium content and the total absorption rate of potassium Were obviously higher than other treatment.The application of potassium sulfate mainly contributed to the increase of the exchangeable soil potassium content;and the mineral potassium fertilizer and the rock powder with abundant potassium,however,enlaryed the storage of slowly available potassium in the soil.The corn plantes for the treatment of potassium sulfate had begun to absorb the slowly available potassium since the head sprouting stage and it amounted to 23%-42%of the total potassium absorption rate.