Abstract:The chemical behavior of manganese (Mn) in paddy soils has been paid increasingly more attention since 1950‘s due to its nutritional and environmental effects under rotation of rice and upland crops or transition of upland to paddy soil. A long term experiment, conducted at Hunan Agricultural University since 1982, was used to evaluate the effects of rice based cropping system, amount of organic manure and groundwater level on distribution of several chemical fractions of Mn in the profile of paddy soil d...