生物质炭中盐基离子存在形态及其与改良酸性土壤的关系

为研究生物质炭中盐基离子存在形态及其与改良酸性土壤的关系,通过厌氧热解的方法于300、500和700℃下制备了玉米秸秆炭。考察了热解温度对玉米秸秆炭水溶性、交换性和盐基总量的影响。采用室内培养的方法考察了添加玉米秸秆炭对酸性土壤的改良效果。结果表明:热解温度影响玉米秸秆炭各形态盐基离子含量,玉米秸秆炭总K、总Na、总Ca、总Mg、水溶性K、水溶性Na、水溶性Ca、交换性Ca和交换性Mg含量随热解温度升高显著增加;水溶性Mg和交换性K含量随热解温度升高先增加后下降。玉米秸秆炭中的K和Na主要以水溶态存在,约40%的Ca和30%的Mg以交换态存在,约50%的Ca和70%的Mg以其他形态(主要为难溶态)存在。添加玉米秸秆炭能极显著提高酸性土壤pH和降低土壤交换性Al3+含量,提高和降低幅度随热解温度升高极显著增加。总K+总Na+总Ca+总Mg含量可以作为衡量玉米秸秆炭提高酸性土壤pH能力的间接指标。添加玉米秸秆炭能极显著提高土壤交换性K、Na和Mg含量,能显著提高交换性Ca和总盐基离子含量。玉米秸秆炭总K和总Na含量是提高土壤交换性K和Na含量的决定因素,交换性Ca含量在提高土壤交换性Mg和交换性盐基总量中起决定作用。     

设施蔬菜栽培对土壤阳离子交换性能的影响

以辽宁省沈阳市于洪地区设施菜地及其相邻旱田土壤为研究对象,测定土壤的有机质、阳离子交换量、交换性盐基离子组成和土壤盐基离子饱和度,分析设施蔬菜栽培对土壤阳离子交换量及交换性盐基离子组成的影响。结果表明:(1)与旱田土壤相比,设施土壤有机质含量明显增加,上下层土壤有机质平均含量分别为35.6 g kg-1和18.0 g kg-1,分别是旱田上下层土壤有机质含量的2.1倍和1.8倍;设施土壤阳离子交换量呈上升的趋势,土壤阳离子交换量与有机质含量呈极显著正相关关系(r=0.603**,n=50,r0.01=0.361)。(2)与旱田土壤相比,不同层次设施土壤交换性盐基总量均有所增加,交换性盐基离子中除交换性Ca2+含量变化不大之外,交换性K+、Mg2+、Na+含量均显著增加;不同层次设施土壤交换性K+、Mg2+、Na+饱和度显著高于旱田土壤,但交换性Ca2+饱和度和盐基饱和度呈下降趋势。     

不同栽培管理方式下土壤交换性盐基特征差异分析

为探讨不同栽培管理方式下土壤交换性盐基含量的特征,采用NH4OAC(pH 7.0)浸提-原子吸收分光光度法测定分析了上海郊区大棚及露地栽培体系下有机和常规农业生产系统中土壤不同土层交换性盐基离子(K,Na,Ca,Mg)含量。结果表明,各盐基离子浓度为Ca>Mg>Na>K,有机园艺生产系统K、Na、Ca和Mg/K值及盐基总量(SEB)高于常规生产方式。露地有机园艺管理耕作层各盐基离子浓度高于常规管理,大棚有机生产方式下各盐基含量均显著高于常规生产方式(P<0.05),但容易引起土壤酸化。统计分析结果表明,不同园艺生产系统对Na、Ca和Mg/K值具有显著性影响,且大棚条件下更为明显。因此,不同园艺生产系统的管理方式改变了土壤盐基离子分布及其特性。     

植茶年限对土壤团聚体中交换性盐基离子分布的影响

采用野外调查和室内分析相结合的方法,就植茶年限对土壤团聚体中交换性盐基离子分布的影响进行了研究。结果表明：（1）土壤团聚体交换性K 含量随粒径的减小先升高后降低;交换性Mg2 含量在各粒径中分布较均匀;而交换性Na 、Ca2 含量和交换性盐基总量（TEB）随粒径的减小而升高。各粒径团聚体交换性盐基离子平均含量表现为Ca2 > Mg2 > K > Na ;（2）随着植茶年限的增加,各粒径团聚体交换性K 、Na 含量逐渐降低;交换性Ca2 、Mg2 含量和TEB先升高后降低,且均在植茶23 a和31 a含量较高。其中,0～20 cm土层比20～40 cm土层的变化幅度更明显;（3）土壤团聚体（K Na ）/（Ca2 Mg2 ）含量比值随粒径的减小先升高后降低;而团聚体含量随粒径的减小则先降低再升高最后降低。随着植茶年限的增加,各粒径团聚体（K Na ）/（Ca2 Mg2 ）含量比值先降低后升高,植茶23 a和31 a含量比值较低,这与>5 mm团聚体含量的变化规律相反,0～20 cm土层表现更明显。不同粒径团聚体对交换性盐基离子的保持和供应能力存在明显差异,各粒径团聚体交换性K 、Na 含量逐年降低,交换性Ca2 、Mg2 含量在植茶23 a和31 a较高,其后有所降低。因此,在茶园管理中需平衡施用氮、钾肥,植茶23 a后应增施有机肥料,加强水土保持,防止土壤严重酸化以减少Ca2 、Mg2 淋失。     

我国主要菜区耕层土壤盐分总量及离子组成

【目的】评价全国主要菜区温室、 大棚和露地菜田土壤盐分及离子组成状况,为土壤次生盐渍化防治、 蔬菜合理施肥和土壤可持续利用提供一定的理论依据。【方法】在我国北方3个区域(东北、 华北、 西北地区)和南方4个区域(华中、 西南、 华东、 华南地区)主要蔬菜种植区不同栽培方式典型菜田耕层土壤展开调查,共采集501个土壤样品,分析了盐分总量及其离子组成。【结果】 1)全国主要菜区设施(温室和大棚)菜田土壤盐分总量及其各离子含量(NO-3、 SO2-4、 Cl-、 Na+、 K+、 Ca2+、 Mg2+)均显著高于露地菜田土壤,盐分总量平均高69.3%,离子组成增加幅度在36.2%~170.0%之间。2)设施菜田土壤次生盐渍化的土样数比例显著高于露地菜田土壤,但设施菜田土壤盐化程度总体上较轻,居于轻度盐化水平的比例占38.2%,处于中度盐化以上水平的比例仅占4.7%。 3)设施菜田土壤盐分总量及主要盐分离子(NO-3、 SO2-4和Ca2+)含量积累总体上随种植年限的延长呈先增后降并趋于平缓的变化趋势,在连续种植5~6年时达到高峰期,之后因采取的各种管理措施而有所降低,但仍显著高于露地菜田土壤。 4)设施菜田土壤盐分离子组成以NO-3和SO2-4为主,其次是Ca2+,分别占盐分总量的27.9%、 26.9%和15.3%。露地菜田土壤主要盐分离子组成总体上是SO2- 4 NO- 3 Ca2+、 HCO-3,分别平均占盐分总量的29.0%、 21.1%、 16.1%和14.1%,但西北地区露地菜田土壤盐分离子组成以HCO-3为主,其次是SO2-4、 NO-3和Ca2+。【结论】设施菜田土壤次生盐渍化的土样数比例虽然显著高于露地菜田土壤,但土壤盐化程度总体上较轻,盐分离子主要是NO-3、 SO2- 4和Ca2+,NO-3、 SO2-4含量大于Ca2+含量; 露地菜田主要盐分离子是SO2-4、 NO- 3、 Ca2+和HCO-3,含量为SO2- 4 NO- 3 Ca2+、 HCO-3。     

辽西褐土区设施土壤交换性养分累积规律研究

本文自辽宁省西部朝阳地区旱地土壤及设施栽培土壤采集耕层土壤样品,分析了褐土区旱地改为设施栽培后土壤pH、电导率、有机质、速效养分及交换性养分含量的变化。研究结果表明:1)朝阳褐土地区旱地变为设施种植蔬菜后,耕层土壤有机质、碱解氮、速效磷、速效钾含量、土壤电导率均显著增加,土壤pH值则由偏碱性显著下降至中性及微酸性;2)设施土壤交换性盐基总量显著增加,较旱地土壤提高了11.37%,其中设施土壤的交换性Mg~(2+)、K~+含量分别是旱地土壤的1.89倍和2.77倍,均显著增加;土壤交换性Ca~(2+)的含量无显著变化。3)设施土壤中交换性Mg~(2+)和K~+占交换性盐基总量的比例显著高于邻近的旱地土壤,交换性Ca~(2+)的比例则显著低于旱地;设施土壤Ca/K、Mg/K、Ca/Mg比值较旱地土壤均显著下降,其中设施土壤的平均Mg/K比值已低于2,土壤缺Mg现象应得到重视。在设施土壤养分管理过程中,应充分考虑交换性养分的数量及其比例关系。     

保护地土壤酸度特征及酸化机制研究

在辽宁省沈阳市于洪地区采集保护地及其相邻露地旱田土壤样品,测定土壤交换性酸、交换性盐基离子组成和土壤pH,研究保护地土壤酸化特征以及土壤pH与潜性酸、交换性盐基的关系。结果表明:（1）建成保护地栽培蔬菜后,保护地土壤酸化趋势明显,土壤交换性酸(交换性H⁺和Al³⁺)呈上升的趋势,土壤pH随着交换性酸的增多而降低;Al³⁺在交换性酸中所占比例随交换性酸总量增加而增大,随有机质含量增加而减小;H+在交换性酸中所占比例则呈相反的变化趋势。（2）保护地各土层土壤交换性盐基总量较露地相应层次土壤均有所增加,其中交换性Mg²⁺、K⁺、Na⁺含量均高于露地,而交换性Ca²⁺含量变化不明显;保护地各土层土壤交换性Mg²⁺、K⁺、Na⁺饱和度较露地相应层次土壤均有所增加,但盐基饱和度、交换性Ca²⁺饱和度下降明显。（3）土壤pH与交换性酸、非交换性酸含量呈极显著负相关,而与盐基饱和度呈极显著正相关,且主要受占优势的交换性Ca²⁺制约。     

大棚栽培番茄不同施肥条件下土壤养分和盐分组成与含量的变化

试验选择具有3年棚龄的大棚和砂壤质地的旱耕人为土,进行不同施肥条件下,土壤养分与盐分变化的冬春两茬西红柿栽培小区试验,对施肥引起的土壤养分与水溶性盐分含量及盐基离子组成的变化进行了系统的定量分析。试验结果表明,在整个生育期采用地膜覆盖的条件下,施用尿素可以快速增加土壤速效N素的含量和水溶性铵盐的含量水平。羊圈厩肥的P、K、Ca和Mg等元素含量较高,其施用会很快增加土壤速效态P、K的含量和土壤水溶性K 、Ca2 、Mg2 等盐基离子的含量。回归分析显示,施用1kg尿素N或1t羊圈厩肥引起土壤电导率增加量分别为6.45×10-4mS/cm和5.45×10-3mS/cm。土壤盐基离子含量的增加,主要由于水溶性NH4 、K 、Ca2 、Mg2 含量的增加而引起。施用尿素不但增加土壤水溶性NH4 的含量,而且通过NH4 的交换作用增加了土壤K 、Ca2 和Mg2 的含量水平。     

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。     

不同利用方式对潮棕壤交换性钾钠及盐基总量的影响

为深刻认识土地利用变化对土壤交换性离子的影响,本文对潮棕壤水稻田、玉米地、撂荒地和人工林地4种土地利用方式经过14年后,在0～150cm剖面中土壤交换性钾、钠、交换性盐基总量的剖面分布及交换性钾钠比值变化进行了比较研究。结果表明,林地和撂荒地各土层交换性K含量及土体中交换性K储量具有高于水稻田和玉米地的趋势;水稻田和撂荒地0～20cm各土层的交换性Na含量显著高于林地和玉米地;林地0～150cm深度土壤交换性Na储量显著高于其他三种利用方式(P<0.05);0～150cm深度内土壤交换性盐基总储量大小依次为林地、玉米地、撂荒地、水稻田;水稻田剖面土壤交换性K/Na随土层深度增加而增大,其他3种土地利用方式则是随土层深度增加而降低。土壤管理和植物自身的特性在土壤剖面中交换性离子的构成以及土壤交换性盐基库的重建等方面可能起到重要作用。     

南方茶园土壤酸化特征及交换性酸在水稳性团聚体中的分布

通过采集浙江省杭州西湖龙井茶园土壤,研究茶园土壤剖面的酸度特征、养分变化以及交换性酸在水稳性团聚体中的分布特征,以了解南方茶园土壤的酸化过程。结果表明:茶园表层土壤(0-20cm)酸化严重,最低的pHH2O值达到4.0,并且有明显的深层化趋势;表土的有机质和速效磷含量较高,速效磷含量最高可达138.2mg/kg;表土团聚体分级表明茶园土壤有良好的团聚体结构,具有良好的水稳性;除了交换性H+在0.5～0.25mm和0.25～0.106mm水稳性团聚体之间没有明显差别外,交换性酸总量、交换性H+和交换性Al 3+含量均随着水稳性团聚体粒径的减小而降低;水稳性大团聚体中交换性Al 3+相对交换性H+占有明显的优势,而在0.106～0.05mm水稳性微团聚体中交换性H+占有明显的优势。交换性酸总量、交换性H+和交换性铝主要分布于>2mm和2～0.5mm水稳性团聚体中,同时在不同粒级团聚体中的分布随粒径的减小而降低。     

Exchangeable Cs/K ratio in soil is an index to estimate accumulation of radioactive and stable Cs in rice plant

Pot and field experiments were conducted to clarify the effect of soil exchangeable potassium (K) and cesium-137 (¹³⁷Cs) on ¹³⁷Cs accumulation and to establish soil index in rice (Oryza sativa L.). Four paddy soils in Fukushima Prefecture, Japan, showing different transfer factors for radioactive Cs derived from the accident of Fukushima Daiichi Nuclear Power Station in the field were compared in terms of ¹³⁷Cs accumulation in rice in a pot experiment. ¹³⁷Cs accumulation in shoots and brown rice widely varied among soils with the transfer factor ranging from 0.018 to 0.068 for shoots and 0.004 to 0.065 for brown rice. ¹³⁷Cs concentration in brown rice and shoots tended to decrease with higher levels of soil exchangeable K, and they were more closely related to the exchangeable Cs/K ratio. Similar relationships between the Cs/K ratio and Cs accumulation in plants were obtained for the stable isotope cesium-133 (¹³³Cs). The distributions of ¹³⁷Cs and ¹³³Cs in grains were also similar and variable among soils. The transfer factors obtained in pot experiments mostly agreed with field observations. The results imply that the exchangeable ¹³⁷Cs/K can be a potential soil index to estimate ¹³⁷Cs accumulation in rice.     

Potassium isotherm partitioning based on modified quantity‐intensity relation and potassium buffering characterization of soils of North India

Background : Potassium (K) availability in soil and plant uptake is restrained by the dynamic interactions among the different pools of K. Aims : To understand these interactions, a study was undertaken to assess the quantity–intensity (Q/I) and buffering characteristics of rainfed maize (Zea mays L.) growing soils. Ten contrasting soils were evaluated for K partitioning changes in exchangeable K (ΔEK) and non‐exchangeable K (ΔNEK) pools in the soil‐solution phase and buffering characteristics using a modified version of Q/I approach. Results : The partitioned Q/I isotherms showed strong adsorption with the increase in K concentration ratio (CR^K) and the changes due to ΔEK were higher than changes due to ΔNEK. Total buffering capacity (PBC^K) significantly correlated (r = 0.92, p <0.01) with clay content with a major share contributed by buffering capacity owing to non‐exchangeable K ( ${\mathrm{PBC}}_{\Delta \mathrm{NEK}}^K$) rather than exchangeable K ( ${\mathrm{PBC}}_{\Delta \mathrm{EK}}^K$). The fixation capacity (β) factor, the magnitude of added K converted into a non‐exchangeable pool, ranged from 41 to 63%, whereas release (α) factor, the magnitude of added K converted to the exchangeable pool, ranged from 19 to 36%. Both threshold solution K (CK_r) and threshold exchangeable K (EK_r) values were found to be high in Satran clay loam (S2) and lower in Doon silty clay loam (S3) soils. The equilibrium exchangeable K (EK_o) was found close to minimum exchangeable K (E_min) in Doon silty clay loam (S3) and Babaweyl sandy clay loam (S1) soils and overall E_min constituted about 8.94 to 0.57% of the EK_o. Conclusion : It may be concluded that K Q/I isotherm partitioning provides a valuable insight to assess the dynamic relations. The ratio of α/β (K recharge index) could be used to evaluate the K enrichment capacity of soil to K additions while EK_r and E_min can be potentially useful in the elucidation of exchangeable K as K fertility index especially in soils with poor K fertilizer management.     

Principles underlying the practice of determining lime requirements of acid soils by use of buffer methods

Abstract

A buffer is generally a mixture of a weak acid and a salt of the same weak acid. Hence it can neutralize both acids and bases, and thus resists marked changes in pH of a system. Yet systematic change in pH of a buffer caused by addition of an acidic substance can be used to indicate the total acidity represented by the change in buffer pH. Since acid soil is itself a buffer, when it is added to a buffer mixture for the purpose of measuring its acidity or lime requirement (LR), the resulting double‐buffer suspension (soil‐buffer) is a relatively complex system. Much of the complication in interpreting the changes in buffer pH brought about by mixing soil and buffer stems from the facts: i) that much of the acidity is pH‐dependent, and ii) that quick‐test methodology involves reaction of only a fraction of the total soil acidity with the buffer. Marked change in relative amounts of H ions dissociating from the soil‐SMP‐buffer system at soil‐buffer pH 6.9 and above accounts for relatively wide variations between buffer‐indicated and CaCO₃ incubation‐measured LR of low LR soils. Similarly, decreased reactivity of H⁺ in high organic matter soils and increased reactivity of H in acid‐leached soils cause errors in buffer‐indicated LR. Awareness of these principles helps avoid pitfalls of existing buffer methods, and has led to incorporation of the double‐buffer feature for improving the SMP method.     

通过施用碱性矿渣和作物残茬生物炭以促进酸性老成土中盐基饱并降低土壤酸度

This investigation was conducted by using alkaline slag and crop straw biochars to reduce acidity of an acidic Ultisol through incubation and pot experiments with lime as a comparison. The soil was amended with different liming materials： lime（1 g kg^-1）,alkaline slag（2 and 4 g kg^-1）, peanut straw biochar（10 and 20 g kg^-1）, canola straw biochar（10 and 20 g kg^-1） and combinations of alkaline slag（2 g kg^-1） and biochars（10 g kg^-1） in the incubation study. A pot experiment was also conducted to observe the soybean growth responses to the above treatments. The results showed that all the liming materials increased soil p H and decreased soil exchangeable acidity. The higher the rates of alkaline slag, biochars, and alkaline slag combined with biochars, the greater the increase in soil p H and the reduction in soil exchangeable acidity. All the amendments increased the levels of one or more soil exchangeable base cations. The lime treatment increased soil exchangeable Ca^2＋, the alkaline slag treatment increased exchangeable Ca^2＋ and Mg^2＋ levels, and the biochars and combined applications of alkaline slag with biochars increased soil exchangeable Ca^2＋, Mg^2＋ and K^＋ and soil available P. The amendments enhanced the uptake of one or more nutrients of N, P, K, Ca and Mg by soybean in the pot experiment. Of the different amendments, the combined application of alkaline slag with crop straw biochars was the best choice for increasing base saturation and reducing soil acidity of the acidic Ultisol. The combined application of alkaline slag with biochars led to the greatest reduction in soil acidity, increased soil Ca, Mg, K and P levels, and enhanced the uptake of Ca, Mg, K and P by soybean plants.     

黑垆土非代换性钾剖面分布特征的研究

本文初步研究了黄土高原黑垆土主要亚类非代换性钾的变化、分布,表明其符合指数回归方程,是草原地带黑垆土主要特征之一。粘黑垆土剖面非代换性钾分布呈“S”型,是森林地带塿土向草原地带黑垆土、黑麻土和黑焦土过渡的森林草原地带的土壤,从形态上兼有塿土剖面非代换性钾分布某些特征,但量上有所差异。草原地带的墹地、沟掌地和川台地的黑垆土剖面非代换性钾分布具有森林草原地带黑垆土的特征。本研究从土壤非代换性钾剖面的变化为黑垆土分类和岩石地层的划分提供科学依据。     

Ability of different soil extraction methods to predict potassium release from soil in ley over three consecutive years

To avoid over‐fertilization of potassium (K) and thereby a mineral composition in the grass crop not optimal for animal health, estimation of K release from soil is important. The analytical methods should therefore predict the total K release. Furthermore, to minimize costs for the farmers they should provide information which remains valid over a period of several years. The relationship between different soil extraction procedures for K and K uptake in ley for three subsequent years after soil sampling was studied in 19 field experiments on a range of mineral soil types in Norway. Potassium determined with solutions that extracted exchangeable K or parts of exchangeable K (0.01 M CaCl₂, 0.5 M NaHCO₃, 1 M NH₄oAc, or ammonium acetate lactate) was significantly (p < 0.05) related to the K yield only in the 1st yr after soil sampling. Potassium extracted with boiling in 1 M or 2 M HNO₃ was significantly related to the K yield only in the 2nd and 3rd yr. Potassium extracted with cold 2 M HCl, boiling 0.1 M HNO₃ or 0.5 M HNO₃ was significantly related to the K yield in all 3 yr after soil sampling. Among these extractants, 0.1 M and 0.5 M HNO₃‐extractable K were better predictors of K uptake than 2 M HCl‐extractable K. These three extractants release some non‐exchangeable K in addition to exchangeable K. The fraction of 1 M HNO₃‐K extractable with 0.1 M HNO₃ varied from 4% to 45%, whereas from 15% to 78% of 1 M HNO₃‐K was extractable with 0.5 M HNO₃. Consequently, the more easily releasable fraction of K extracted by boiling with 1 M HNO₃ varied considerably between different sites.     

The effect of lime levels on the growth of beans and maize and nodulation of beans in three tropical acid soils

Abstract

A study to investigate the effect of lime on dry matter yield of maize (Zea mays) and beans (Phaseolus vulgaris) and nodulation of beans grown in three tropical acid soils (two humic Nitosols and one humic Andosol) was carried out in a greenhouse. The soils ranged from 4.2 to 5.0 in pH; 1.74 to 4.56 in %C; 21.0 to 32.0 meq/100g in CEC; 5.10 to 8.10 meq/100g in exchange acidity; 0.60 to 3.20 meq/100g in exchangeable (exch.) Al and 0.13 to 0.67 meq/ 100g in exch. Mn.

Exchange acidity and exch. Al decreased with increasing levels of lime in the three soils. Exchangeable Al was reduced to virtually zero at pH 5.5 even in the soils which had appreciable initial amounts. Exchangeable Mn also decreased with increasing levels of lime in the two Nitolsos. Exceptional results, however, were obtained with the Andosol where exch. Mn increased ten‐fold with the first level of lime and then decreased with subsequent levels.

In all the soils, mean dry matter yield of beans and maize, and mean nodule dry weight of beans generally increased significantly with increasing lime levels up to pH value of 6.0. The dry matter yield of beans and maize, and nodule weight of beans, however, decreased progressively with increasing lime levels beyond pH 6.0 value. pH range of 5.5 to 6.0 was considered optimum for the growth of maize and beans, and nodulation of beans in these soils.     

铜仁市植烟土壤交换性钙镁空间分布特征及其影响因素分析

为明确贵州省铜仁市植烟土壤中交换性钙和镁的状况,以铜仁2019年植烟耕层土壤交换性钙镁为研究对象,利用多元统计学和地统计学方法分析了土壤交换性钙镁空间变异特征及其影响因素。结果表明,铜仁植烟土壤交换性钙、镁含量整体丰富,平均值分别为1.72、0.27 g·kg^-1,但仍有19.31%的交换性钙和27.59%地区的交换性镁含量处于低与极低水平。植烟土壤中钙镁比处于适宜范围的比例仅占29.70%,说明钙镁比失调较严重。土壤交换性镁含量总体呈现由西北向东南逐渐增加的趋势,土壤钙镁比总体呈现由中部向东南和西北逐渐减小的趋势,思南中部钙镁比处于最高值,江口南部与松桃南部钙镁比处于最低值。植烟土壤交换性钙、镁含量及其比值的空间变异是由结构性因素和随机性因素共同作用的结果。pH对交换性钙、镁空间变异的影响最大,分别能够独立解释其变量的41.6%、55.7%,且与交换性钙、镁分别呈现幂函数和三次函数关系,随着pH值升高,土壤中交换性钙和镁含量升高。综上,贵州铜仁植烟土壤空间分布不均匀、差异性较大,钙镁比失调比较严重,pH值对交换性钙、镁空间变异的影响最大,并与其呈极显著正相关。因此,铜仁烟区在指导钙镁施肥时要注意其空间差异性、做到分类指导,可以通过调控钙镁肥料施用量或含钙镁的改良剂调节土壤pH值来达到平衡土壤养分的目的。本研究可为铜仁市烟田钙镁养分管理提供科学依据。