Several authors have observed that the availability of soil potassium (K) is affected by environmental and soil factors,e.g.moisture content although the extent of the effect is still uncertain. In a pot experiment carried out with corn(Zea maysL.) for five weeks, effects of two K dosses at two soil moisture levels were studied on the K uptake of young plants. Soils were collected from plots of long‐term fertilization trials representing different K levels. Results of the experiment show that amounts of K taken up by the plants were greatly dependent on soil moisture and available K levels. Soil moisture did not affect the very close linear relationship between dry matter production and K uptake of young corn plants.