This study was conducted to investigate potassium depletion from soils under intensive cropping of sugarcane (Saccharum officinarum) in Khuzestan Province. Pairwise sampling from 0-30 and 30-60 cm depths was carried out in 30 locations spread throughout farmlands belonging to Haft-Tappeh Agro-Industry, Karun company as well as Sugarcane & By-products Development Corporation. These locations were selected randomly and such that each point was located at the common border between cultivated and non-cultivated soil while considering the supposition that factually cultivated soil is a non- separable part of non-cultivated soil now under sugarcane cultivation. In order to establish the confidence in the similarity of sampled soils, some soil properties such as relative frecuency in soil particles, pH, equivalent calcium carbonate, organic matter and CEC were determined and compared. In addition, mineralogy of some pairs of soil samples were determined through XRD and compared with each other. The similarities among pairs of soil samples, according to the mentioned properties, were established while using Minitab statistical software, as well as Mann-whitney test. In order to investigate potassium depletion, ammonium acetate & nitric acid extractable potassium, as well as exchangeable & nonexchangeable fractions of this element were determined for all soil pairs. Means comparison test indicated that these mentioned forms of potassium in cultivated soils had significantly decreased, at a level of 1% confidence and at 0-30 and 30-60 cm depths, in comparsion with non-cultivated soils. Exchangeable K in cultivated soils of Haft-Tappeh, Karun and Sugarcane & By- products Development Companies, lands has decreased (at the depth of 0-30 cm) to an extent of 21.6%, 43.9% and 73.8% respectively in comparison with adjacent non-cultivated soils. The level of exchangeable & nonexchangeable forms of potassium (in the 30-60 cm layer) in all cultivated soils has decreased as much as 56% and 54.4% respectively as compared with those in non-cultivated ones.
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