旱耕地土壤磷垂直迁移机理的研究

Study on Mechanisms of Phosphorus Downward Transfer in Arable Soils

为了解磷素在土壤剖面中淋溶及迁移机理,选择有较长施肥历史的3个旱地土壤,用亮蓝溶液染色鉴定了优势流途径,并分离和采集被染色剂染色和不染色的土样,分析了土壤全磷、有效磷的垂直分布。结果表明,供试土壤中磷的迁移存在基质流和优势流2种途径,心土层以下染色部分土壤的磷含量明显高于不染色部分土壤,基质流迁移磷的深度与土壤磷的饱和吸附量成反比;土壤中优势流区域从上至下变小,但优势流磷迁移比基质流深得多,优势流磷迁移深度与基质流磷迁移深度的比值随土壤粘粒含量的增加而增加。

Leaching of phosphorus （P） from soils is a potential environmental hazard. Understanding movement mechanism of P in the soils is important to manage the soils. In this study, Brilliant Blue was used as the dye tracer to identify preferential path in three arable soils with a long fertilization history. Both dyed and non-dyed soils were separated for analyzing total and available P. The results showed that P in the soils could be downward transferred in both matrix and preferential flows. The concentrations of P in subsurface soils were significant higher in dyed component than in non-dyed component. The downward transfer depth of P with matrix flow in the soils decreased with increasing the maximum capacity of soil to P. The area of preferential flow decreased with increasing depth. However, the P downward transfer was much deeper in preferential flow than the matrix flow. The ratio of P downward transfer depth by preferential flow to that by matrix flow increased with the increasing of soil clay content. The results suggested that preferential flow played an important role in downward movement of P in the soils.