电解质对喀斯特地区土壤团聚体稳定性的影响

为研究电解质对喀斯特地区土壤团聚体稳定性的影响,及为喀斯特石灰土地区的土壤结构改善和该地区的农林生产提供理论参考,选取广西南宁马山县3种用地的石灰土作为研究对象,分析土壤团聚体在各浓度(0.00、0.05、0.10、0.20、0.50、1.00 mol/L)电解质(KCl、NaCl、MgCl₂)溶液中的稳定性和破碎过程。结果表明：(1) 电解质浓度＜0.10 mol/L时,随着电解质溶液浓度增大,破碎团聚体中5–3 mm粒径组分含量著降低,＜0.25 mm组分含量均明显增加。(2) 破碎实验中团聚体基本在第1 min内完成大部分团聚体的破碎,纯水中的团聚体破碎速率明显慢于电解质溶液。(3) 本研究在MWD值的基础上提出“团聚体动态稳定指数”概念,根据团聚体动态稳定指数可得,各土壤团聚体稳定性大小表现为：柑橘园＞桉树林＞坡耕地。综上,电解质显著影响喀斯特土壤团聚体稳定性,且在＜0.10 mol/L时团聚体稳定性随电解质浓度增大而先快速降低后缓慢降低；电解质溶液会显著提升团聚体的破碎量和破碎速度。

Effects of Electrolytes on Stability of Soil Aggregates in Karstic Limestone Areas

In order to explore the effects of electrolytes on the stability of soil aggregates in karst areas, limestone soils under three land-use types (citrus groves, eucalyptus plantations and sloping cultivated land) from Mashan County, Nanning, Guangxi, were selected as research objects to analyze the stability and fragmentation process of soil aggregates at various concentrations of (0, 0.05, 0.10, 0.20, 0.50, 1.00 mol/L) electrolyte (NaCl, KCl, MgCl₂) solutions. The results showed that: 1) The stability of the aggregates decreased as the concentration of the electrolyte solution increased. The particle size distribution of the aggregates decreased in the range of 3 ~ 5 mm and increased in the range of<0.25 mm. The stability of the aggregates decreased slowly after the electrolyte concentration>0.10 mol/L. The influences of different electrolytes on the stability of aggregates were: NaCl>KCl>MgCl₂. 2) Most of soil aggregates in the fragmentation experiment were fragmented within the first minute, and the rate of aggregate breaking in electrolyte solutions was significantly faster than in pure water. 3) The study of the "Dynamic Stability Index of Aggregates", based on MWD values, showed that the dynamic stability of soil aggregates when disturbed by electrolytes was higher or lower in the following order for different land types: citrus groves, eucalyptus forests and sloping arable land. In summary, electrolytes significantly affected the stability of karst soil aggregates, and the stability of soil aggregates gradually was decreased with the increase of electrolytes concentration. The results of the study can provide a theoretical basis for soil erosion control in karst areas.