Potassium chemistry in some important paddy soils of Bangladesh

Abstract

Ten important paddy soils, seven from floodplains and three from terrace areas, were studied for different forms, and release and fixation behavior of potassium (K). Floodplain soils had higher amounts of total K [39.2 to 68.5 cmol(+)kg‐1] than did terrace soils [25.8 to 37.6 cmol(+)kg‐1]. Almost the same trend was observed for mineral and nonexchangeable K. Six out often soils were found to be deficient in available K. Release and fixation behavior of K varied due to variation in the contents of minerals affecting K chemistry in the soils. Based on K form and release and fixation behavior, soils were characterized in relation to K fertility. All three terrace soils had low reserves of both mineral and nonexchangeable K and the release potential was also low, available K was low in two and medium in the other. Soils of Old Brahmaputra Floodplain and Meghna Estuarine Floodplain had available K below the critical level, medium mineral K, low nonexchangeable K, low release potential and high fixation rate. Overall condition of K fertility of these soils could be termed as “bad.” The condition of two soils of Ganges Tidal Floodplain was “best,” having high mineral, nonexchangeable and available K, high release potential and medium fixation rate. Other soils could be termed as “medium.”