模拟酸雨对砖红壤盐基离子迁移和释放的影响

对发育于玄武岩的砖红壤进行了室内模拟酸雨淋溶试验,结果表明：（1）酸雨淋溶土壤会引起土壤盐基离子的大量淋失。以土壤中的K＋最易于淋失,Ca^2＋、Mg^2＋的淋失量最大。酸雨pH愈低,Ca^2＋、Mg^2＋、K^＋的迁移量愈大。酸雨淋溶土壤的时间越长,盐基离子的迁移量越大。（2）土壤经≥5d的酸雨淋溶后,土壤交换性盐基离子的含量均随淋溶时间的增加而减少。酸雨的pH不同,则土壤交换性盐基离子所受的影响不同。（3）与原土壤相比较,短期（≤5d）的酸雨淋溶,可使土壤交换性Ca^2＋、K^＋以及强酸性（pH≤3.0）酸雨淋溶的交换性Mg^2＋增加;土壤被酸雨较长时间（≥10d）淋溶后,则会降低土壤交换性Ca^2＋、Mg^2＋、K^＋的含量;不同时间的酸雨淋溶,均会降低土壤交换性Na^＋的含量。（4）土壤经酸雨淋溶后,某些矿物会发生风化,释放出盐基离子,也会使部分交换性盐基离子转成非交换态。     

微地形作用下紫色母岩发育土壤的酸化特征

为揭示丘陵地区微地形作用下紫色母岩及其不同地形部位发育土壤的酸化特征,在西南丘陵地区采集土壤样品并分析其基本理化性质。结果表明:西南丘陵地区的紫色土已经出现了一定程度的酸化,土壤酸化后使交换性酸含量增加,交换性盐基离子总量和盐基饱和度降低。从丘陵地区的坡顶至坡底,紫色土的发育程度逐渐增加,土壤中维持土壤pH在碱性范围内的碳酸盐遭受到的淋溶作用依次增强。因此,从坡顶至坡底,紫色土的酸化范围逐渐增大。由于酸化后的紫色土pH开始受阳离子交换反应所控制,而在微地形的作用下,受盐基离子遭受淋溶过程和复盐基过程的相对强弱不同的影响,从坡顶至坡底,紫色土的总体酸化程度并未增加。可见,对西南丘陵地区的紫色土的开发利用需考虑到其较为独特的酸化特征。     

模拟酸雨对果园土壤主要形态酸变化的影响研究

采用室内淋溶的方法研究了模拟酸雨对果园土壤pH（H2O）、pH（KCl）、交换性酸（EA）、交换性铝（EAl）、可滴定酸度（BNC）等各形态酸的变化影响,并依据淋溶前后各形态酸的含量评价了土壤酸度的变化。试验结果表明：以土壤pH（H2O）值作为供试土壤酸化指标,pH≤4．5的模拟酸雨淋溶促进了土壤酸化,而pH≥5．5的酸雨淋溶缓冲了土壤的酸化;以土壤pH（KCl）值、交换性酸（EA）、交换性铝（EAl）或可滴定酸度（BNC）作为土壤酸化的指标,pH2．5的酸雨淋溶促进了土壤酸化,而pH≥3．5的淋溶处理缓冲了土壤的酸化,土壤酸度减弱。     

几种低分子量有机酸淋溶对土壤铝、硅及盐基离子淋失的影响

采用50cm原状土柱进行模拟淋溶实验,比较研究了模拟酸雨和几种低分子量有机酸对红壤Al、Si及盐基离子淋失的影响。结果表明,模拟酸雨淋洗后土壤中有极少量的Al和一定量的Si及盐基离子淋出。与去离子水对照相比,pH3.5和pH4.5模拟酸雨处理Si的淋出总量分别增加了6.52%和3.26%;K 、Na 、Ca2 和Mg2 等盐基离子淋出量增加了2.41%~96.80%。100μmol/L的柠檬酸、苹果酸和草酸处理Al、Si的淋出量与模拟酸雨处理相差不大,而10mmol/L的柠檬酸、苹果酸和草酸处理则比模拟酸雨处理有显著的增加。有机酸淋洗后淋出液中各盐基离子含量均要高于模拟酸雨处理,盐基离子淋出总量是模拟酸雨处理的1.58~9.27倍。实验结果说明低分子量有机酸在酸化土壤方面比酸雨有更大的威胁。由于盐基离子的大量淋失,模拟酸雨和有机酸淋洗后淋出液pH均要高于原淋洗液pH。     

模拟雨水连续淋洗下土壤化学性状动态变化特征的研究

本文从研究正常降雨对土壤性状的影响出发,进行了模拟雨水对酸性紫色土和石灰性紫色土的连续淋洗试验。试验结果表明在模拟雨水连续淋洗150天的过程中,土壤中钙、镁、钾、钠等盐基离子几乎都显示出一定程度的净淋溶特征,土壤中各盐基离子的动力学变化特征几乎都与抛物线扩散方程吻合。淋洗结束后土壤酸度未发生显著变化,但两种土壤CEC值均有所降低。     

模拟酸雨对果园土壤交换性阳离子迁移及其对土壤酸化的影响

采用短期室内淋溶的方法研究了模拟酸雨对供试果园土壤交换性Ca^2＋、Mg^2＋、K^＋、Na^＋、交换性盐基总量（BS）、阳离子交换量（CEC）、电导率（EC）等变化的影响。试验结果表明,土壤交换性Ca^2＋（pH2.5）、Mg^2＋、K^＋、Na^＋、BS（pH2.5）、CEC（pH≥3.5）含量较酸雨淋溶前增加,且随着剖面深度表现出较好的层次性;淋出液中Ca2＋、Mg^2＋、K^＋、Na^＋含量随着模拟酸雨酸度的增强而依次增加,其中pH2.5酸雨处理与其它淋溶处理间淋出液Ca^2＋、Mg^2＋、K^＋、Na^＋含量差异显著;以土壤交换性Ca^2＋、BS、CEC、盐基饱和度（BSP）与EC为指标衡量土壤的酸化,pH 2.5酸雨处理导致了淋溶土柱表层和中间土层的土壤酸化,其中交换性Ca^2＋、BS、BSP指标表征pH 3.5的酸雨处理引起了表层土壤酸化,而pH≥4.5的酸雨淋溶缓冲了土壤的酸化,土壤的酸度减弱。     

模拟酸雨和几种低分子量有机酸淋溶对土壤交换性盐基的影响

采用原状土柱进行模拟淋溶实验,比较研究了模拟酸雨和几种低分子量有机酸对红壤交换性盐基的影响。结果表明:与去离子水对照相比,pH 3．5和pH 4．5模拟酸雨淋洗后,0-20 cm土层土壤交换性K 、Na 、 Ca2 和Mg2 含量增加了5．19％-14．65％,而这种增加主要发生在10-20 cm土层。100 μmol／L和10 mmol／L的柠檬酸、苹果酸和草酸淋洗后,0-20 cm土层土壤交换性K 、Na 、Ca2 和Mg2 含量与模拟酸雨淋洗后的结果相差不大,有的层次甚至还要稍低;而在20-50 cm土层则增加了10．42％-96.41％。有机酸淋洗后,土壤交换性盐基的增加受矿物溶解和盐基迁移两方面的影响,而下层的增加可能主要是盐基迁移的影响,由此可见有机酸或许加快了盐基离子向下迁移的速度和土壤酸化过程。     

酸性紫色土的阳离子交换特征及其对酸缓冲容量的影响

明确酸性紫色土的交换性阳离子组成特征及其对土壤后续酸化进程的影响有助于评估紫色土的潜在酸化风险。为此,在重庆市合川区采集了38个酸性紫色土,进行了理化性质分析与酸缓冲容量测定,探讨了阳离子交换特征对土壤酸缓冲容量的影响。结果表明:部分紫色土的酸化程度较为严重,但酸性紫色土仍具有较高的交换性盐基阳离子含量和阳离子交换量(CEC)。紫色土的交换性Ca~(2+)和交换性Mg~(2+)含量分别为红壤的5.9倍和3.9倍。紫色土CEC也显著高于红壤和砖红壤。丰富的黏土矿物组成,尤其是较高的蒙脱石含量,是紫色土具有较高盐基阳离子含量和高CEC的主要原因。酸性紫色土的酸缓冲容量大小为3.18～25.6mmol·kg~(–1)·pH~(–1)。酸缓冲容量与交换性盐基总量和CEC间均呈极显著的正相关性。较高的盐基阳离子含量和CEC有助于增加紫色土的酸缓冲容量,减缓土壤的酸化速度。因此,尽管部分紫色土酸化较为严重,但受成土母质和发育程度的影响,丰富的盐基阳离子含量能对进入土壤中的酸进行缓冲,减缓紫色土酸化速度。这是紫色土相对于其他地带性酸性土壤所具有的独特酸化特征。     

模拟酸雨淋溶下强风化土壤矿物风化计量关系研究

矿物风化计量关系对于定量土壤酸化速率至关重要。我国亚热带地区矿物风化强烈,土壤的酸敏感性高。为获取强风化土壤在矿物风化过程中元素释放特征及其化学计量关系,选取花岗岩发育的富铁土,先用EDTA-乙酸铵溶液洗脱土壤胶体上吸附的盐基离子,然后采用改进的Batch法,将洗脱盐基土壤与未洗脱盐基土壤同时进行模拟酸雨淋溶。结果表明:(1)洗脱盐基土壤与未洗脱盐基土壤的盐基离子(K~+、Na~+、Ca~(2+)和Mg~(2+))释放情况存在显著差异,洗脱盐基后土壤在淋溶中释放的盐基来源为矿物风化,释放缓慢而平稳;(2)未洗脱盐基土壤在淋溶初期,盐基的释放量较大,随着淋溶的进行,释放量迅速下降,淋溶后期的释放速率与洗脱盐基土壤接近,这说明未洗脱盐基土壤在淋溶初期释放的盐基主要来源于阳离子交换过程,后期则主要来源于风化过程;(3)洗脱盐基土壤和未洗脱盐基土壤经酸雨淋溶释放的各盐基化学计量关系(K~+∶Na~+∶Ca~(2+)∶Mg~(2+))以及盐基离子与硅的化学计量关系(BC∶Si)差异较大,由于未洗脱盐基土壤受到阳离子交换的影响,因此只有洗脱盐基土壤的矿物风化计量关系可以作为定量估算土壤酸化速率的依据。     

酸化环境对紫色母岩风化产物交换性盐基离子及其酸缓冲容量的影响

为了分析研究酸化环境对紫色母岩风化产物交换性盐基离子及其酸缓冲容量的影响规律。本研究以侏罗纪紫色岩层中的遂宁组(J3s)、沙溪庙组(J2s)和蓬莱镇组(J3p)为研究对象，设置pH分别为2.5、3.5、4.5、5.6等4个酸性环境，以及去离子水（pH=7.0）为对照处理（CK），采用循环浸泡试验和模拟淋溶试验，研究酸性环境对紫色母岩风化产物特征的影响。结果表明，通过酸化环境处理后，3组紫色母岩风化产物交换性盐基离子及其总量均随酸化环境的pH降低而减小，且3组紫色母岩风化产物的酸缓冲容量与其交换性K+、Na+、Ca2+、Mg2+含量以及交换性盐基总量均呈极显著正相关关系(P<0.01)。以pH =7.0 (CK)处理为对照，循环浸泡处理后的遂宁组(J3s)、蓬莱镇组(J3p)和沙溪庙组(J2s)风化产物中交换性盐基总量的减小幅度分别为8.75%～18.21%、10.83%～23.18%和5.85%～18.41%。而且模拟淋溶24次后，遂宁组(J3s)、沙溪庙组(J2s)和蓬莱镇组(J3p)风化产物中交换性盐基总量较模拟淋溶12次时分别减小为1.77%～24.85%、8.99%～25.75%和8.05%～25.66%。此外，在同一酸度处理下，风化产物中的交换性盐基离子均表现为Ca2+> Mg2+> Na+> K+。本试验中淋溶处理下风化产物酸缓冲容量、交换性盐基离子及盐基总量低于浸泡处理。可见，丘陵地带坡面的矿物或养分的迁移以淋溶作用为主，平地的矿物或养分的迁移以浸泡作用为主。因此，酸沉降可能在一定程度上加速坡面土壤侵蚀的发生，进而导致平原化进程的加速。     

微地形下紫色土的矿物组成和pH的耦合特征

为了研究微地形下紫色土的矿物组成和土壤酸度之间的关系,采集了重庆合川丘陵地区典型的紫色土壤,通过电渗析模拟酸化,并通过X射线衍射光谱分析电渗析前后的矿物组成以及酸度变化。结果表明:不同地形部位的紫色土随着地形部位的降低,土壤原生矿物的比重逐渐降低,土壤的发育程度越来越高。紫色母岩及其发育的土壤pH大小关系为母岩石骨子土半沙半泥土豆瓣泥。pH变化与土壤中的方解石、钠长石和钾长石等矿物的含量有紧密关系。电渗析模拟土壤酸化后发现,石骨子土和半沙半泥土的pH分别降低了4.3,3.8个单位,同时土壤原生矿物分解风化,表明土壤原生矿物(如长石类矿物)可以缓冲土壤的酸化。     

长期施用氮磷钾肥和石灰对红壤性水稻土酸性特征的影响

利用34年的长期定位施肥试验,研究不施肥(CK)、施氮磷钾肥(NPK)和氮磷钾化肥配施石灰(NPK+Ca O)对红壤性水稻土不同形态酸、土壤盐基离子及水稻植株阳离子吸收量的影响,探讨土壤交换性H+和Al3+占交换性酸的比例、土壤盐基离子、植株带出阳离子数量与土壤酸度的关系。结果表明,长期NPK处理早、晚稻土壤p H较CK处理分别降低0.2和0.3个单位,交换性酸提高2.3倍和4.2倍,水解性酸提高35.4%和40.0%;NPK+Ca O处理早、晚稻土壤p H较NPK处理分别提高0.5和0.7个单位,较CK处理分别提高0.3和0.4个单位,交换性酸、水解性酸均显著低于NPK和CK处理(p0.05)。土壤交换性H+、Al3+含量高低顺序均为NPK+Ca OCKNPK。土壤交换性盐基离子以交换性Ca2+所占比例最大(81.8%~89.3%),NPK+Ca O处理交换性Ca2+较CK和NPK处理分别提高40.1%和62.9%。交换性Ca2+、交换性盐基离子、盐基饱和度与土壤p H正相关,与交换性酸、水解性酸负相关,交换性Mg2+与交换性酸、水解性酸负相关,交换性Na+与水解性酸负相关。植株移出带走的钙、镁、钾、钠离子量及其总量对土壤p H、交换性酸和水解性酸有一定影响,但其相关性均不显著。研究表明长期施用化肥条件下通过配施石灰可有效缓解稻田土壤的酸化,促进酸性稻田土壤的生态修复与改良。     

Differential soil acidification caused by parent materials and land-use changes in the Pearl River Delta region

Soil acidification occurs widely across the world, which has been partly attributed to land-use change. However, measureable effect of land-use change as well as parent materials on soil acidification remains poorly understood. Here, a typical area with intensive land-use change in the Pearl River Delta of China was chosen for this study. Topsoil (0–20 cm) and subsoil (20–40 cm) samples (n = 169) under different land uses (paddy fields, vegetable lands and orchards) and parent materials (granite and alluvial sediment) were collected in 2020. Soil pH, exchangeable base cations, exchangeable acidity and pH buffering capacity were measured to evaluate the status of soil acidification. The change of soil pH over the last 15 years was evaluated via comparing with historical data (n = 329) in 2005. The results showed a higher exchangeable acidity and lower pH buffering capacity and exchangeable base cations of soils derived from granite compared with soils derived from alluvial sediment in 2020. In the last 15 years, significant soil acidification under different parent materials was observed under vegetable lands and orchards but not paddy fields. Faster pH decline was found under land-use change from paddy fields compared with the unchanged vegetable lands or orchards. Furthermore, stronger acidification under the same land-use change was observed for soils derived from granite compared with soils derived from alluvial sediment. These results indicate that land-use change induced soil acidification is dependent on parent materials. This study implies that cropping management such as suitable rotation operation may slow soil acidification, and measures including straw returning may ameliorate acidified soils.     

Classification schemes for the acidity,base saturation,and acidification status of forest soils in Switzerland

Soil chemical parameters related to soil acidity were determined for 1450 soil samples taken from individual mineral soil horizons in 257 forest soils in Switzerland, 196 developed from carbonate‐containing and 61 from carbonate‐free parent material. The distribution of pH values and exchangeable base cations in corresponding pH ranges were related to the capacity and rate of buffer reactions in the soil. Based on this, five acidity classes for individual soil samples were defined. To describe and classify the status of soil acidity and base saturation (BS) of an entire soil body, the pH and the BS of the total fine earth in the soil were calculated from the pH and BS, respectively, of the individual soil horizons and the estimated volumetric content of fine earth. The status of soil acidification of soil profiles was assessed primarily using the total amount of exchangeable acidic cations in percent of the CEC of the fine earth in the entire soil profile. As a second factor, the gradient between the acidity class of the most acidic soil horizon and the estimated acidity class at the beginning of soil formation was used. The application of these classification schemes to our collection of soil profiles revealed the great influence played by the type of parent material. The acidification status of most soils on carbonate‐containing parent material was classified as very weak to weak, whereas soils on carbonate‐free parent material were found to be strongly to very strongly acidified. In terms of parent rock material, microclimate, and natural vegetation, the results of this study and the proposed classification schemes can be considered appropriate for large parts of Europe.     

Effects of acid deposition on acidity and exchangeable cations in podzols of the Kola Peninsula

Response of soil and soil water of podzols in the Kola Peninsula to acid deposition was estimated under both field and laboratory conditions. A significant increasing trend of exchangeable acidity in organic (O) horizons and exchangeable Al in podzolic (E) horizons of podzols with distance from the nickel smelter was observed. The simulated rain at pH 4.5 did not alter chemical properties of soils and soil solutions. As much as 95–99% of the applied H⁺ ions were retained by soils and appeared in the percolates after a treatment period that depended on acid load and soil thickness. Ca and Mg in soil solutions were highly sensitive to acid loading. Simulated acid rain enhanced the leaching of exchangeable base cations out of root zone. Acid inputs resulted in decreased pH, amount of exchangeable base cations and base saturation, in elevated exchangeable acidity and it's Al fraction in soil solid phase. The most significant changes occurred in O and E horizons. Substantial amounts of both Ca and Mg can be lost from the root zone of podzols in the north-western Kola, subjected to acid deposition, thus leading to forest productivity damage.     

武陵山地植烟土壤酸度特征及影响因素——以湖南省湘西自治州为例

为了解多年种植烤烟的山地土壤酸度特征,研究了湘西自治州的土壤酸度指标特征及其关系以及植烟年限和土壤类型、有机质、黏粒对土壤酸度的影响。结果表明:(1)植烟年限对土壤酸度的影响大于土壤类型;随植烟年限增加,土壤pH下降,潜性酸度增加,黄棕壤土的交换性盐基、阳离子交换量和盐基饱和度下降。(2)土壤pH与交换性酸为幂函数关系,交换性铝是土壤交换性酸的主体,土壤交换性酸强度随交换性铝及其相对比例的增加而增加。(3)土壤pH与交换性盐基、阳离子交换量、盐基饱和度为二次曲线关系,当pH6时,随土壤pH增加,交换性盐基和阳离子交换量下降,盐基饱和度增加;当pH6时,随土壤pH增加,交换性盐基和阳离子交换量增加,盐基饱和度变幅小。(4)土壤交换性盐基离子主要是交换性钙,其次是交换性镁;对土壤pH影响较大的盐基离子是交换性钙。(5)有机质和黏粒主要影响土壤pH、阳离子交换量、交换性盐基和交换性钙。     

Impacts of acid precipitation on coniferous forest ecosystems

This paper summarizes the results from current studies in Norway. One main approach is the application of artificial acid ‘rain’ and of lime to field plots and lysimeters. Application during two growth seasons of 50 mm mo^?1 of ‘rain water’ of pH 3 to a podzol soil increased the acidity of the humus and decreased the base saturation. The reduction in base saturation was mainly due to leaching of Ca and Mg. Laboratory experiments revealed that decomposition of pine needles was not affected by any acid ‘rain’ treatment of the field plots. Liming slightly retarded the decomposition. No nitrification occurred in unlimed soils (pH 4.4-4.1). Liming increased nitrification. The soil enchytraeid (Ohgochaeta) fauna was not much affected by the acidification. Germination of spruce seeds in acidified mineral soil was negatively affected when soil pH was 4.0 or lower. Seedling establishment was even more sensitive to increasing soil acidity. Analysis of throughfall and stemflow water in southernmost Norway reveals that the total deposition of H₂SO₄ beneath spruce and pine is approximately two times the deposition in open terrain. A large part of this increase is probably due to dry deposition. Increased acidity of the rain seems to increase the leaching of cations from the tree crowns. Tree-ring analysis of spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) has been based on comparisons between regions differently stressed by acid precipitation and also between sites presumed to differ in sensitivity to acidification. No effect that can be related to acid precipitation has yet been detected on diameter growth.     

有机肥替代化学氮肥提升红壤抗酸化能力

  【目的】  长期过量施用化学氮肥加剧了红壤区农田土壤酸化,严重制约着该区域农业的可持续发展。施用石灰和有机肥是防治红壤酸化的主要措施,我们研究了有机无机肥配合提高红壤抗酸化能力的作用与机理。  【方法】  本研究基于2009年在湖南祁阳中国农业科学院红壤站开展的有机肥替代化学氮肥长期定位试验,其中4个处理分别为单施化肥(由于酸化严重,于2018年底添加石灰改良)、有机肥替代化肥氮20%、40%和60%,供试有机肥为猪粪。采集2018和2020年的土壤样品,分析各施肥处理红壤pH、交换性酸铝、阳离子交换量、有机质、酸缓冲能力等指标的变化及相互关系。  【结果】  至2018年,单施化肥处理较试验之初土壤pH降低了0.48个单位,交换性酸、铝分别增加了2.74和1.06 cmol/kg;添加石灰改良后,土壤pH升高了0.58个单位,交换性酸、铝分别降低了2.62和1.45 cmol/kg。有机肥替代化肥氮40%和60%处理均可有效防治红壤酸化,其中以替代60%处理效果最佳;至2020年60%有机替代处理土壤pH较初始值提高了0.78个单位,交换性酸和交换性铝分别降低了1.10和1.25 cmol/kg。有机肥替代化肥氮40%和60%处理较单施化肥处理显著提高了土壤阳离子交换量,而石灰改良前后土壤阳离子交换量无显著变化。土壤酸缓冲曲线表明,土壤交换性铝含量随着pH的降低而显著升高,单施化肥、有机肥替代化肥氮20%、40%和60%处理的斜率分别为2.71、2.42、1.93和0.16;土壤交换性铝对pH响应斜率与土壤pH、交换性镁、阳离子交换量、交换性钾、有机质含量呈极显著或显著负相关关系。  【结论】  有机肥替代40%以上化学氮肥既能防治红壤酸化,又能提升红壤抗酸化能力。土壤阳离子交换量和有机质可能是导致土壤交换性铝对pH响应差异的主要因素,即阳离子交换量和有机质含量高的土壤pH降低1个单位时,交换性铝增幅较小,但其作用机理还有待进一步研究。     

工业副产品对红壤酸度改良的研究

选择4种工业副产品(粉煤灰、碱渣、赤泥和磷石青),通过室内培养实验研究了它们对酸性红壤的改良效果.结果表明碱渣和赤泥能降低土壤溶液中的毒性形态的Al、可溶性Al以及交换性Al,增加土壤pH、交换性盐基和ECEC,可成为石灰的替代品作为酸性土壤的改良剂,且长期施用不会像石灰那样加剧土壤Mg、K的缺乏.粉煤灰的改良效果不太理想,而磷石青虽然能增加土壤交换性盐基和ECEC,降低土壤的交换性Al,但增加土壤溶液中的毒性形态的Al和可溶性Al,因此不利于表层土壤酸化的改良.加入质子消耗量与土壤交换性酸量等当量的碱渣和赤泥时,红壤pH升高到5.81～6.26,土壤Al的饱和度降低到15%以下,即可消除Al的毒害.根据碱渣和赤泥的质子消耗容量和红壤的交换性酸量来确定改良剂的施入量是估算改良剂用量的可行方法.     

积盐对设施栽培土壤酸度及酸组成的影响

[目的]探讨盐渍化对土壤酸度的可能影响,为了解设施栽培土壤的酸化过程提供依据。[方法]采集了不同酸化特征的设施栽培土壤、露天栽培土壤和自然酸性土壤等3类表层土壤和剖面分层土壤样品,通过化学分析和室内添加肥料盐及土壤洗盐模拟试验,比较研究设施栽培土壤、露天栽培土壤与自然酸性土壤中活性酸、潜性酸、盐基饱和度之间关系差异及其受土壤盐分积累的影响。[结果]与自然酸性土壤相比,设施栽培土壤的酸是人为输入式,其酸化主要发生在表层,土壤剖面呈自上而下下降。在相同交换性酸水平的条件下,设施栽培土壤的pH值最低,其次为露天栽培土壤,而自然酸性土壤的pH值相对较高。在相同土壤pH值的情况下,自然酸性土壤的盐基饱和度明显低于设施栽培土壤和露天栽培土壤,而设施栽培土壤的盐基饱和度高于露天栽培土壤;设施栽培土壤的交换性酸中活性酸组成比例高于自然酸性土壤。增加中盐的积累可显著降低设施栽培土壤pH值;设施栽培土壤的盐分淋洗过程在降低土壤盐分的同时也降低了土壤的活性酸(提高了土壤的pH值)。[结论]盐分的积累增强了设施栽培土壤中潜性酸向活性酸的转化,高量施用化肥不仅可直接通过酸性物质的输入促进土壤pH值的下降,同时由此引起的盐分也可在一定程度上进一步降低土壤的pH值。