三江平原位于我国东北端,是由黑龙江、松花江、乌苏里江和兴凯湖冲积而成的低平原,总面积约51300平方公里。由于平原内部地势平坦,地面坡降小,土质粘重、渗透困难,沼泽土壤广泛发育,是我国沼泽土壤集中分布的地区之一。沼泽土壤主要分布在浓江、别拉洪河、挠力河、七星河、阿布沁河、七虎林河、穆棱河、松阿查河的河漫滩及阶地上的低洼地,水城子古河道,以及大小兴凯湖湖滨。面积13700余平方公里。

Sanjing Plain is situated in the northeast part of China.It is one of the areas where marshy soil is widely spread.The area qf marshy soil is over 13,700 km²,about one fourth of the total plain area.Most of the marshy area of Sangjiang Plain belong to the marshy soil without peat accumulation.There is a rom humus horizon(10-20cm thick)between the grass-root and the gley horizon. The marshy soil of Sanjiang Plain may be divided into two great groups, six sub-groups and ten kinds. The textures of most of the marshy soil belong to loam clay—clay.The volume weight of surface stratum is 0.1—0.8 g/cm³.The content of organic matter varies with different sub-groups of marshy soil.The exchangeable cation is about 30—70 m.e/100g,the exchangeable base is 20-40 m.e/100g.The nitrogen content of the marshy soil is sufficient,but contents of phosphorus and potassium are not sufficient;the pH value is 5—7. The marshy soil is a kind of valuable soil resources by which after reclamation,we can develop agriculture,animal husbandry,reed breeding and fertilizermaking,etc.