【摘要】 【目的】母质是影响土壤理化性质的主要因素之一,研究不同母质土壤pH的剖面特征及主要影响因素,为防治土壤酸化提供依据。【方法】选取湖南祁阳白茅草植被下七种母质(第四纪红土、红砂岩、板页岩、花岗岩、石灰岩、紫色页岩、河流冲积物)发育的土壤,测定不同层次(0—20、20—40、40—60、60—80和80—100 cm)土壤pH,通过比较表层(0—20 cm)与底层(60—100 cm) pH的差异来表征表层土壤是否酸化及酸化程度;测定0—20 cm土层的酸碱缓冲容量、有机质含量、阳离子交换量、比表面积及颗粒组成,分析影响表层酸化的主要因素。【结果】石灰岩剖面土壤的pH (8.46～8.72)最高,呈强碱性,其次为河流冲积物(7.37～7.87)、紫色页岩土壤(7.41～8.00),呈碱性;花岗岩、第四纪红土、红砂岩、板页岩四种母质发育的红壤呈酸性或强酸性,以花岗岩红壤pH (5.31～5.70)较高,其次为第四纪红土(4.62～4.97)、红砂岩红壤(4.31～4.67),板页岩红壤pH (4.25～4.49)最低。比较表层(0—20 cm)与底层(60—100 cm)土壤的pH,发现七种母质剖面土壤的表层均出现了pH降低,说明表层已出现酸化现象,酸化程度大小依次为:紫色页岩土壤>河流冲积物土壤、花岗岩红壤>第四纪红土、红砂岩红壤>石灰岩土壤、板页岩红壤。对表层土壤的比表面积、颗粒组成(黏粒、粉粒、砂粒含量)和pH、酸碱缓冲容量、阳离子交换量、有机质含量共八种理化因素进行逐步线性回归分析,由于多种因素的相互影响,七种母质土壤并未发现影响表层酸化的主要因素,但在四种母质(第四纪红土、红砂岩、板页岩、花岗岩)发育的酸性红壤中阳离子交换量是影响表层酸化的主要因素。【结论】土壤阳离子交换量与表层红壤酸化差值呈显著负相关,是影响第四纪红土、红砂岩、板页岩和花岗岩四种酸性红壤表层酸化的主要因素之一。更多还原

【Abstract】 【Objectives】To investigate changes in pH at different depths of soil derived from seven parent materials to help prevent soil acidification.【Methods】Soil samples at layers of 0–20, 20–40, 40–60, 60–80 and 80–100 cm were collected from seven sites with different parent materials(Quaternary red earth, Red sandstone, Plate shale, Granite, River alluvial material, Limestone, and Purple shale) under Imperata cylindrica meadow, in Qiyang County, Hunan Province. Soil pH, soil acid and alkaline buffering capacity, soil organic matter, soil cation exchange capacity, soil specific surface area, and particle size were measured, and soil acidification was estimated by the difference in the soil pH between 0–20 cm and 60–100 cm layers.【Results】The pH values of red soil from Quaternary red earth, red sandstone, plate shale and Granite were below 6.0, river alluvial material soil(pH 7.37–7.87) and purple shale soil(pH 7.41–8.00) were neutral with pH7.0–8.0, and limestone soil was strongly alkaline with pH 8.46 – 8.72. For all the seven parent materials, the average acidification rate of red soils was in the order: purple shale soil > river alluvial material soil, granite red soil > Quaternary red earth red soil, and red sandstone red soil > limestone soil, plate shale red soil. Based on analysis of pH, soil acid and alkaline buffering capacity, soil organic matter, soil cation exchange capacity, soil specific surface area and particle size, no key factors were found in the seven parent materials that led to soil acidification. However, soil cation exchange capacity was found to be the key factor for soil acidification in four parent materials, including Quaternary red earth, red sandstone, plate shale and granite.【Conclusions】Soil cation exchange capacity is negatively correlated with the soil acidification, which is one of the main factors limiting the acidification in four parent materials, including Quaternary red earth, red sandstone,plate shale, and granite.更多还原