喀斯特山区退耕地水稳性团聚体演变特征及土壤养分效应

Dynamics of Soil Water Stable Aggregates and Their Relationship with Soil Nutrients on Converted Land in Karst Areas

以贵州省六盘水市钟山区喀斯特山区不同年限退耕还林地为研究对象,以中度石漠化样地和自然恢复松林为对照,采用时空替代法,分析探索了其水稳性团聚体演变特征及与土壤养分的协调效应关系。结果表明,喀斯特山区坡耕地退耕还林5～8a后,>0.25mm水稳性团聚体在土壤中的含量明显提高,最低含量已达60%以上,粒径多集中在5～2mm,且有向大粒径明显转化的趋势。通过对水稳性团聚体与土壤养分相关性和回归分析显示,>0.25mm水稳性团聚体与土壤有机质、全氮、全钾及速效钾显著相关,相关系数达0.7～0.97;与碱解氮、全磷相关性不显著。在喀斯特山区退耕还林过程中,适当考虑种植对土壤磷素返还作用明显的植物,避免人为干扰,将有利于退耕地林木的健康生长。

In order to understand the dynamics of soil water-stable aggregates and the relationship with soil nutrients on the land from the converting cropland into forest land project in the karst hilly area of Guizhou Province, 4 kinds of the land with 5 to 8 years conversion age in the Zhongshan area of Liupanshui City were selected for a systematical study through the approach of substituting the temporal serial for spatial serial. In addition, the land of moderate rocky desertification and natural restoration pine samples were selected as controis. Results showed that the content of soil water-stable aggregates increased promptly in the forest stage years, and The water-stable aggregates were mainly in the range from 5 to 2 mm and there was an obvious tendency that water stable aggregates were in the transformation to a greater particle size. ~0.25 mm aggre- gates were significantly correlated with soil organic carbon, total K, and quick acting K, but not with alka- line hydrolysis nitrogen and total P. It was necessary to keep soil organic carbon in a good balance in order to improve soil structure on the arable land in converting cropland into forest land project.