Phosphate sorption in some representative soils of Bangladesh Mohammad E. Hossain a *, Sirajul Hoque b and Khan T. Osman a a Department of Soil Science, University of Chittagong, Bangladesh; b Department of Soil, Water and Environment, University of Dhaka, Bangladesh (Received 21 October 2010; final version received 20 January 2011) An experiment was conducted to observe the phosphate sorption potential of some soils of Bangladesh. Three soil series of calcareous origin, namely Sara (Aquic Eutrochrept), Gopalpur (Aquic Eutrochrept) and Ishurdi (Aeric Haplaquept), and two soil series of non-calcareous origin, namely Tejgaon (Rhodic Paleustult) and Ghatail (Aeric Haplaquept), were selected. The soils were equilibrated with dilute solution of calcium chloride containing graded concentrations of phosphate (0, 1, 2, 5, 10, 25 and 50 mg P mL 71 ), and the amount of phosphate sorbed or desorbed was determined. Although all the soils showed potential for sorbing phosphate from applied phosphorus, their ability to sorb phosphorus differed. Increasing rates of phosphate application increased the amount of P sorption but reduced phosphate sorption percentage in all soils except Tejgaon. Phosphate was sorbed by the soils in the order: Tejgaon 4 Ghatail 4 Ishurdi 4 Gopalpur 4 Sara at 50 mg P mL 71 application. Soils possessing higher amounts of free iron oxide and clay sorbed more phosphate from applied phosphorus. Keywords: phosphate; sorption; Bangladesh Introduction Phosphorus sorption–desorption characteristics reflect the partitioning of P between soil solid phase and soil solution. Understanding sorption–desorption of P on soil gives insight into the mechanisms of soil P retention and release (Li et al. 2007). From an agricultural viewpoint, maintaining soil P concentrations in an optimum range for plant growth is essential to sustain soil fertility and ensure the production of plants. Environmental concerns associated with P focus on its stimulation of biological productivity in aquatic ecosystems, being transported from agricultural fields to surface waters. The sorption and desorption mechanisms of phosphorus are inextricably linked with a number of factors, including the amount and type of clay, the amount and type of hydrous oxides of Al and Fe, inorganic and organic ions, the pH of the system and reaction kinetics (Hedley et al. 1995). Phosphorus is sorbed to a greater extent by 1:1 (e.g. kaolinite) than by 2:1 clays (e.g. montmorillonite). The greater amount of P fixed by 1:1 clays is probably due to the higher amounts of Fe and Al oxides associated with kaolinitic clays that predominate in highly weathered soils *Corresponding author. Email: ena_swe@yahoo.com Archives of Agronomy and Soil Science Vol. 58, No. 9, September 2012, 959–966 ISSN 0365-0340 print/ISSN 1476-3567 online Ó 2012 Taylor & Francis http://dx.doi.org/10.1080/03650340.2011.557370 http://www.tandfonline.com