TY - JOUR JF - JCPP JO - VL - 11 IS - 42 PY - 2008 Y1 - 2008/1/01 TI - Soil Phosphorus Forms in Four Toposequences of Isfahan and Shahrekord Regions TT - شکل‌های فسفر خاک در چهار ردیف ارضی از مناطق اصفهان و شهرکرد N2 -   Studying soil phosphorus fractions is useful in understanding soil pedogenesis as well as soil fertility. In this reseach, 20 soil samples were taken from different depths of 0-30 and 30-60 cm of upper-slope, mid-slope and lower-slope positions of four toposequences in arid (Jei and Ziar in Isfahan) and semiarid (Farokhshahr and Shahrekord) regions. In each toposequence, the soil depth was relatively low at the upper-slope position and increased toward the lower-slope. The soils in upper-slope and mid-slope were under scarce native vegetation where the soil in lower-slope was under farming activities. Soil phosphorus (P) fractionation was carried out using sequential extraction. The total soil phosphorus was in the range of 302-1135 with an average of 715 mg/kg. About 65-89% of total phosphorus were inorganic, and 11-35% organic. The amount of inorganic and organic P in the soil samples was in the range of 204-897 with an average of 571, and 70-238 with an average of 114 mg/kg, respectively. The amount of total, inorganic and organic P increased from upper-slope toward the arable lands and decreased from topsoil to subsoil in all toposequences. In the studied soils, apatite ( Ca10-P ), aluminum phosphates(Al-P), octacalcium phosphates( Ca8-P ), iron phosphates (Fe-P), iron oxides occluded phosphates( OC-P ) and dicalcium phosphates( Ca2-P ) were the major constituents of the soil inorganic phosphates, respectively. SP - 463 EP - 472 AU - Dehghan, R. AU - Shariatmadari, H. AU - Khademi, H. AD - KW - Phosphorus fractions KW - Toposequence KW - Calcareous soils KW - Isfahan KW - Shahrekord. UR - http://jcpp.iut.ac.ir/article-1-802-en.html ER -