Changes of soil physical and chemical properties of albic soil in the meadow of Sanjiang Plain after rice planting.

The changes and renewal of soil quality are the criteria for judging agricultural development and soil management. The albic soil is the main paddy field soil in Sanjiang Plain. There is limited knowledge about the changes of soil quality after the dry field was changed into the paddy field. Taking albic soils from different years of rice planting as study objects, the changes of soil physical and chemical properties were investigated. The results showed that the total amount of soil organic carbon and reducing substances increased in the ploughing layer (16-23 cm thick) and the bottom ploughing layer (6-8 cm thick). The depth of ploughing layer gradually increased with the increases of rice planting years. There was no significant change after the bottom layer was changed into the paddy field. There was no significant difference in the subsoil layer (20 cm thick) compared with dryland. The Fe and Mn in the soil tended to migrate downward, but only to the plough bottom layer. The ratio of soil solid phase of the ploughing layer and the ploughing bottom layer increased after rice planting, with the ratio of soil solid phase of the ploughing bottom layer increased from 47.8% to 70.0% and the bulk density increased from 1.22 g·cm to 1.77 g·cm. Decreases of the total amount of soil porosity, increases of the proportion of micropores, and cohesive leaching deposition in the albic soil were observed after rice planting. The changes of soil physical and chemical properties of albic soil after rice planting were generally consistent with the evolution of paddy soil except for several particularities.