三江平原草甸白浆土种稻后土壤理化性质变化

土壤质量变化与更新是农业发展和土壤管理的判断准则.白浆土是三江平原主要水田土壤,但旱田改水田后缺乏对其土壤质量变化规律的研究.本研究以不同种稻年限白浆土为调查对象,探讨其土壤理化性质演变特征.结果表明: 白浆土种稻后,耕层(厚16~23 cm)和犁底层(厚6~8 cm)土壤有机碳、还原物质总量增加,耕层深度随种稻年限增加呈逐渐增加趋势,犁底层无明显变化,心土层(厚20 cm)与旱田无显著差异;土壤中Fe²⁺和Mn²⁺有向下迁移现象,但只迁移到犁底层;耕层和犁底层土壤固相比率比种稻前增加,犁底层固相比率由47.8%增加到70.0%,容重由1.22 g·cm^-3增加到1.77 g·cm^-3,土壤孔隙总量降低,微孔隙比例增加,白浆土种稻后有黏粒淋溶淀积现象.白浆土种稻后,土壤物理和化学性质的变化特征与水稻土的演变规律既有一致性,又有其特殊性.

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 Fe²⁺ and Mn²⁺ 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^-3 to 1.77 g·cm^-3. 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.