我国南方不同母质土壤pH剖面特征及酸化因素分析

【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。     

不同母质发育的红壤性水稻土磷素吸附特性及其影响因素的研究

磷是作物生长发育所必需的营养元素,植物吸收利用的是土壤中的有效磷,土壤有效磷的消长取决于土壤磷素的收支状况,而其消长速度则与土壤性质有关[1]。不同质地土壤固相表面的吸附能力不同,因而影响了土壤溶渡中磷的浓度[2]。为确保土壤满足作物吸收所必需的最低磷溶液浓度,就需要对不同土壤固相的吸附性能进行研究。而水稻土常年以淹水和风干状态交替存在,因此水稻土中     

湖南不同母质植烟土壤钾的形态与特征

采集湖南烟区4种主要成土母质的16个具有典型代表性土壤样品,分析各形态钾的含量与比例。结果表明:紫色板页岩发育的土壤钾素库容量大,但有效钾含量相对较低,说明土壤对有效钾的保持能力有限;石灰岩发育的土壤矿物钾数量较少,但非交换性钾和有效钾的含量相对较高;第四纪红土发育的土壤在钾容量和自身补给潜力有限的情况下,维持了较高的有效钾水平,这可能与钾肥的施用及土壤对有效钾的保持有着密切的关系。不同母质发育土壤交换性钾只有27%是有效性较高的非特殊吸附钾,这可能直接限制了土壤短期钾的供应强度。土壤钾素有效性因成土母质的不同具有一定的差异,石灰岩发育土壤钾素有效性最高,其次为板页岩、第四纪红土,紫色板页岩最低。     

The significance of gley features in soils derived from grey parent materials

Detailed observations of gley features in soils derived from grey Upper Greensand rocks have been compared with their moisture regimes as determined by water-levels in dipwells. There was good correlation between the incidence of grey ped face and matrix colours of low chroma, prominent ochreous mottling within the matrix and duration of waterlogging. Careful examination of soil macromorphology can be used, despite inherent greyness, to assess the drainage status and Wetness Class of these soils.
Physical and micromorphological analyses suggest that the wetness of some Upper Greensand soils is due to the combination of low vertical permeability in the underlying rock, and moderate horizontal permeability in the overlying horizons. Such circumstances allow perched water-tables to form in wet weather, sustained by lateral flow when rainfall has ceased.     

上海地区水稻土氮素矿化模拟

Three types of paddy soils, derived from granite, Quaternary red clay and basalt, respectively, were selected to study the effects of Fe and Mn in paddy soils on methane production and emission through pot and incubation experiments. The results indicated that the difference of Fe and Mn in paddy soils was one of the important factors causing obvious differences in methane emission from different soil types. Soil Fe and Mn affecting methane emission from the paddy soils was likely through affecting soil Eh and forming Fe and Mn plaques on rice roots. Different rates and valences of added Fe and Mn significantly affected methane production from paddy soils. Therefore, this study enhanced understanding of processes controlling methane emission from paddy soils and may help to improve modeling and estimating regional and global methane emission from paddy soils.     

Composition of organic solutes and respiration in soils derived from alkaline and non-alkaline parent materials

Parent material greatly influences pedogenesis and soil nutrient availability and consequently we hypothesized that it would significantly affect the amount of organic solutes in soil, many of which have been implicated in rhizosphere processes linked to plant nutrient uptake. Consequently, we investigated the influence of two contrasting parent materials in which calcite was present or absent (alkaline and non-alkaline soils) on the concentrations of dissolved organic carbon (DOC), low-molecular weight organic acids (LMWOA) and glucose in soil solution. Both soils were under Norway spruce. The dynamics of LMWOAs in soil were also investigated using ¹⁴C-labelled citrate and oxalate. Some of the mineral horizons of the alkaline soils showed significantly higher concentrations of DOC, phenolics, and fumarate in soil solution and also a higher basal respiration. No major differences were seen in organic solute status in the organic horizons of the two soil types. LMWOAs were present at low concentrations in soil solution (< 1 to 25 µM). Their mineralization rate significantly decreased with soil depth, however, overall neither their concentration or half-life in soil was markedly affected by parent material. The alkaline soils had significantly higher CO₂-to-soil organic C (SOC) ratios, and consequently SOC in the alkaline soils did not seem more chemically stable against mineralization. Considering possible DOC and CO₂ efflux rates it was suggested that the equal or larger SOC stocks in alkaline mineral soils were most likely linked to a higher net primary productivity. In conclusion, our study found that parent material exerted only a small effect on the concentration and dynamics of organic solutes in soil solution. This suggests that in comparison to other factors (e.g. vegetation cover, climate etc) parent material may not be a major regulator of the organic solute pool in soil.     

不同母质发育的红壤电荷特性研究

研究了3种不同母质发育的红壤中电荷的差异,比较了不同母质对电荷的影响。结果表明:3种母质发育的红壤中,紫色土发育的红壤中全部负电荷含量明显高于花岗岩发育的红壤和第四纪红色黏土发育的红壤;第四纪红色黏土发育的红壤中正电荷的含量明显高于花岗岩发育的红壤和紫色土发育的红壤;第四纪红色黏土发育的红壤、花岗岩发育的红壤和紫色土发育的红壤中正电荷与pH呈显著性负相关;第四纪红色黏土发育的红壤正电荷与有机质呈显著负相关,花岗岩发育的红壤和紫色土发育的红壤中正电荷与有机质含量呈显著正相关;第四纪红色黏土发育的红壤和紫色土发育的红壤正电荷与黏粒含量呈一元二次线性关系,花岗岩发育的红壤正电荷与黏粒含量呈极显著负相关;紫色土发育的红壤吸附的NH4+-N含量最高,第四纪红色黏土发育的红壤吸附的NO3--N含量最高。通过对3种母质发育的土壤电荷特性的研究,可为不同母质的红壤进行合理施肥与管理提供科学依据。     

Red soils derived from limestone contain higher amounts of trace elements than those derived from various other parent materials

The concentrations of 48 trace elements (Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, Zr, Nb, Mo, Ag, In, Cd, Sn, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Tl, Pb, Bi, Th and U) in 14 soils derived from limestone, sampled at three sites, are compared with the concentrations in 500 soil samples derived from a variety of other parent materials. The 500 samples were collected from 75 sites nationwide in order to include the wide range of common soil types in Japan. Most analytical results were obtained by inductively coupled plasma mass spectrometry (ICP-MS), but Cr, As, Br, Zr, Sn, and I concentrations were determined by energy dispersive X-ray fluorescence spectrometry (EDXRF), because the acid dissolution techniques employed in this study were found to be incapable of recovering these elements completely. In order to examine the reliability of analyses, the concentrations of many elements were also determined by EDXRF, inductively coupled plasma-atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS). Box and whisker diagrams (Tukey plots), constructed using log-transformed values of each element, show clearly that geometric means of nearly all the trace elements in soils derived from limestone are higher than those in soils derived from other parent materials. The only exceptions are Sr, Ag and Eu, though statistical analysis (Student’s t-test) shows that the differences for these three elements were not significant at p < 0.05. Similarly, the observed differences of geometric means for Sc, Br and Ba between limestone soils and other types of soils were also not significant at p < 0.05. It can be concluded, therefore, that the concentrations of the above-mentioned 48 trace elements in soils derived from limestone are significantly higher than those in other types of soils, with the exception of Sc, Br, Sr, Ag, and Ba, though it was necessary to exclude 81 soil samples, developed on scoriaceous (basaltic) volcanic ash from Mt. Fuji, as an exceptional group for comparisons of V and Cu, as these soils contain higher levels of these two elements. The above results can be attributed to the gradual accumulation of trace elements in the limestone soils due to the intense weathering processes.     

Potassium availability in soils from different parent materials in the subhumid zone of Nigeria

Abstract

Potassium (K) availability was assessed in 21 soil samples from four different parent materials (alluvium, iron pan materials, Nupe sandstones, and colluvial materials) across the subhumid zone of Nigeria. It was found that the Nupe sandstone soils gave the lowest proportion of the various forms of K with respect to total K in the topsoil. While water‐soluble K was the lowest in the soils of all the parent materials, one normal hydrochloric acid (1 N HCl)‐extractable K was the highest in the soils of all the parent materials. The one normal ammonium acetate (1 N NH₄OAc)‐extractable K (exchangeable K) was correlated (P<0.05) with exchangeable calcium (Ca) and magnesium (Mg) in the alluvial, iron pan material and colluvial material soils and with clay in the soils of all the parent materials. The K fixed in the 42 days of incubation was highly correlated (P<0.01) with the K added in the colluvial material soils.     

Contributions of different parent materials in soils developed from periglacial cover‐beds

Soils frequently develop from mixtures of different parent materials. We quantified the contributions of different parent materials to the substrate for recent soil development using trace metal concentrations and Pb isotope ratios as input data for end‐member mixing analyses (EMMAs). We examined six transects (320–775 m) at two sites in the Rhenish Slate Mountains. Soil types ranged from acid Cambisols to stagnic Luvisols developed from periglacial cover‐beds. Sixteen O, 11 A, 120 B and 10 C horizons were analysed for total trace metal concentrations and partly also ²⁰⁶Pb:²⁰⁷Pb ratios. Most metal concentrations in the B horizons were in the background range, except for Pb, which partly had elevated concentrations of up to 135 mg kg⁻¹. The depth distribution of metal concentrations and ²⁰⁶Pb:²⁰⁷Pb ratios suggested that metals deposited from the atmosphere had hardly reached the B horizons. A principal component analysis (PCA) of the trace element concentrations in the 120 B horizons identified four main metal sources of the B horizons, which we interpreted as bedrock (slate), loess, Laacher See tephra (LST) resulting from the last volcanic eruption in the Eifel mountains and ore veins. The slate was characterized by Cr and Zn, the loess by Zr, the LST by Nb and the ore veins by Pb. Based on EMMAs with four end‐members using two different sets of tracers (Set 1: concentration ratios of Zr:Cr, Nb:Cr, Pb:Cr, Set 2: Zr:Zn, Nb:Zn, and Pb:Zn), slate, loess and LST contributed, on average, 39–40, 22–24 and 37–38%, respectively, at Site 1 and 19–21, 53–63 and 18–26%, respectively, at Site 2. In contrast, the ore contribution was consistently estimated at 0%. An additional EMMA with two end‐members based on the ²⁰⁶Pb:²⁰⁷Pb ratios estimated the contribution of the ore at 0.02%. We conclude that EMMAs based on trace element concentrations and isotope ratios provide a tool for determining the contribution of different parent materials to the substrate from which soils develop, at least at a small regional scale and if an appropriate tracer that distinguishes all the considered substrates is found.     

氮、磷、锌肥对纤维亚麻产量的效应

本文研究了南方主要母质发育的水稻土对硅酸盐的吸附与解吸特征。结果表明:吸附资料能很好地用Freundlich方程拟合,Temkin方程次之。不同浓度下的吸附过程可能存在两种吸附机制,解吸过程均呈抛物线型。连续解吸可提高土壤吸附Si后的解吸率。     

不同母质发育的柑橘园土壤团聚体及有机碳分布特征

作为土壤结构的基本单元和土壤肥力的组成部分,土壤团聚体对其物理、化学和生物学特性均具有重要影响。选取湖南省永兴县5种典型母质发育的柑橘园土壤,采用湿筛法研究不同成土母质的柑橘园土壤团聚体结构变化和有机碳分配规律。结果表明:(1)研究区不同母质发育土壤以>0.25 mm粒径团聚体为主,占85.94%～95.89%,其中板页岩风化物发育的黄泥土中大团聚体含量最高;(2)不同母质柑橘园土壤团聚体的水稳性大小为板页岩风化物(黄泥土)>第四纪红色粘土(红黄泥)>石灰岩风化物(灰红土)>砂砾岩风化物(红砂土)>河流沉积物(河砂泥);(3)不同母质柑橘园土壤团聚体有机碳含量、团聚体有机碳储量和团聚体对土壤有机碳的贡献率均随着团聚体粒径的减小而减少;(4)平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)和土壤可蚀性(K)与>2 mm团聚体间的相关系数最大,表明>2 mm团聚体含量是影响土壤团聚体稳定性的主要因子;(5)>2 mm团聚体有机碳贡献率与土壤团聚体MWD和GMD呈显著正相关,与土壤K值呈显著负相关,与土壤D值呈显著负相关。总体而言,目前南方柑橘果园施肥管理应注重增施有机肥,提高土壤结构的稳定性,从而降低水土流失的风险。     

不同酸性物质对石灰性土壤的酸化效果研究

采用室内模拟试验研究了酸性物质对石灰性土壤的酸化效果。结果表明,磷酸能有效地降低石灰性土壤的pH,要使土壤pH由8.89降至6.0左右,最佳酸用量为3.27g/100g土。对于pH较高的石灰性土壤,只用低pH(pH=5.5)的酸水溶液在短时间内降低土壤pH是不切实际的。磷酸二氢铵不仅具有很好的酸化效果,且具有很好的缓冲性能,每100g土壤加入2.3g磷酸二氢铵可使石灰性土壤pH从8.89降低到6.39,并能维持较长的酸性环境。施用5%的硫磺可在30d内使土壤pH降低到7.0～7.5之间。     

不同母质类型水稻土酶活性及其与理化性质的关系

将选自湖南双季稻区6种典型成土母质发育的水稻土置于长沙市郊同一生态条件下,通过7年定位池栽试验,研究了不同母质类型对土壤酶活性的影响以及酶活性与土壤理化性质之间的关系。结果表明：不同母质类型对土壤蔗糖酶活性的影响达到显著水平(P<0.05),对酸性磷酸酶、脲酶及过氧化氢酶活性的影响达到极显著水平(P<0.01)。主成分分析表明不同母质发育的水稻土酸性磷酸酶及脲酶作为综合评价土壤酶活性的指标要优于蔗糖酶及过氧化氢酶。6种不同母质水稻土土壤酶综合得分排序为：板页岩>河流沉积物>花岗岩>第四纪红土>紫色页岩>石灰岩。相关性分析表明,土壤蔗糖酶活性与有机质、全氮含量呈显著的正相关关系(P<0.05)。脲酶活性与硝态氮、铵态氮含量呈显著的正相关关系(P<0.05),与pH值呈显著的负相关关系(P<0.05)。酸性磷酸酶活性与速效磷含量呈显著正相关关系(P<0.05),与pH值呈显著负相关关系(P<0.05)。     

New buffer pH method for rapid estimation of exchangeable acidity and lime requirement of soils

Abstract

A new buffer pH method (BpH) for the rapid estimation of unbuffered salt‐exchangeable acidity (ACe) and lime requirement (LR) has been developed. The buffer reagent, consisting of sodium glycerophosphate, acetic acid, trletlianolamine, ammonium chloride and barium chloride, was useful within the pH range 3.8 to 6.6. Delta values from BpH were converted into buffer pH acidity values (AC) and calibrated against ACe of 91 mineral soils and 100 acid Histosols. The correlation coefficients between AC and ACe were 0.966 and 0.956 for the mineral soils and Histosols, respectively. The corresponding regression equations in terms of meq/100 cm were ACe ‐ ‐0.54 + 0.96 AC and ACe = ‐7.4 + 1.6 AC for mineral soils and Histosols, respectively.

To predict lime requirement of mineral soils a curvilinear equation was required. The equation, LR in meq CaCO₃/100 cm³ = 0.1 (AC)² + AC, was tested successfully against rates of lime carried out under laboratory conditions and against crop response in the greenhouse. Field studies on acid Histosols with maize and soybeans showed optimum yield when the rate of lime added was approximately equivalent to ACe.     

Composition of clay minerals and their pedogenetic and taxonomic implications for Stagnic Anthrosols derived from different parent materials in Hunan Province,China

Purpose

The aims of this study were to investigate the composition of clay minerals in soils derived from different parent materials and to elucidate how parent materials and pedogenic environment affect the distribution of clay minerals and reveal the implications for pedogenetics and taxonomy in Stagnic Anthrosols.

Materials and methods

Clay mineralogy and physicochemical properties of the Hydragric horizon of Stagnic Anthrosols derived from granite (GR), plate shale (PS), quaternary red clays (QRC), limestone (LS), purple sandy shale (PSS) and fluvial-lacustrine deposit (FLD) located in Hunan Province of China were analysed to explore the relationships between the conditions influencing the formation of the soil and the composition of clay minerals.

Results and discussion

Results indicated that the composition of clay minerals is closely related to both parent material and type of Stagnic Anthrosols: the soils derived from GR, PS and QRC, which are mostly classified as Fe-accumulic-Stagnic Anthrosols, are dominantly 1:1 type kaolinite and vermiculite and illite/vermiculite mixed layer minerals of widespread distribution. However, soils derived from LS, PSS and FLD were mainly classified as Hapli-Stagnic Anthrosols and are mainly composed of 2:1 type illite/smectite mixed layer minerals, where chlorite is commonly found. Illite is widely distributed and its content varies the least among different parent materials. An extremely significant relationship between pH and kaolinite, chlorite and mixed layer minerals was noted, and the two kinds of mixed layer minerals showed highly significant negative correlation.

Conclusions

This study revealed that the types and quantities of clay minerals in the soil are closely related to the types of parent material. This reflected better direction and degree of development in Stagnic Anthrosols, which is related to the physicochemical properties of parent material and can be used as one of the bases for the classification of soil groups and subgroups within the soil family for Stagnic Anthrosols in Chinese Soil Taxonomy.

     

不同母质发育水稻土N2O消耗潜力及环境影响因素

土壤是N2O的源和汇,在淹水和厌氧条件下具有消耗N2O的能力。稻田土壤长期处于淹水状态,为N2O的消耗提供了有利的环境,从而减少了N2O排放。目前,有关稻田土壤N2O排放的相关研究已有很多,但关于稻田表层土壤N2O的消耗能力及其与环境因素之间的关系研究较少。研究采集了第四纪红壤母质发育的壤土、湖积物砂土发育的砂质壤土、冲积土发育的粉砂质黏壤土3类土壤的各3个表层(0～5 cm)水稻土,风干后将其回填至具有5 cm深土柱的培养装置内,在土柱底部添加N2O和添加氦气(He,对照)两个处理,于28℃下恒温淹水厌氧培养96 h。培养期间监测各土壤N2O、N2的动态变化,以及培养前后土壤养分的变化,量化N2O消耗量和N2增量,以期揭示稻田表层土壤N2O的消耗能力及其与环境因素之间的关系。结果表明,土壤剖面积累的N2O有95.01%～99.92% 被稻田表层土壤吸收,其中被还原为N2的N2O量占总消耗量的64.50%～83.64%,表明淹水厌氧状态下,不同的水稻土均具有很强的N2O吸收和消耗能力。研究还发现,3类土壤N2O的消耗存在一定差异,其中影响砂质壤土N2O消耗的主要环境因子为土壤砂粒含量,且两者之间存在显著的线性相关关系(R2=0.964,P=0.000);土壤黏粒、粉砂粒、pH是粉砂质黏壤土N2O消耗的主要环境影响因素,其中土壤黏粒与其消耗量呈显著线性相关(P<0.05);土壤速效钾和铵态氮增加量是影响壤土N2O消耗的主要环境因子,其消耗量与速效钾之间在0.01水平上显著正相关。这些结果表明,土壤可溶性有机碳、土壤质地、土壤速效钾等是影响稻田土壤N2O消耗的重要环境因子,且不同土壤N2O消耗的环境影响因子存在差异,这将为调节土壤N2O排放提供重要参考。     

Availability of exchangeable and non-exchangeable K in Argentine soils with different mineralogy

There were two objectives in the study: 1) To determine exchangeable K and non-exchangeable K in soils with different potassium depletion levels and mineralogy as plant sources 2) To establish a relationship between the mineralogy vs exchangeable K (Ke) and non-exchangeable K (Kne) mobilization. An extraction experiment of soils was carried out in a greenhouse, with a total of 6 consecutive crops of ryegrass. Different supply rates for plant K were determined by Ke and Kne mobilization according to the soil intensity of use. The contribution of the Ke was greater and generated higher amount of K uptake during maximum availability period (from 0 to the 1st harvest) than in the later period when soil K was already depleted. For this the initial exchangeable K and the illite concentration of soils accounted for almost 100% (R² = 0.981 P=0.01) of the K taken up by ryegrass. For the following period (from the 2nd harvest to the 6th), Kne forms became more important. Plant K supply was not only a result of initial exchangeable K and illite concentration but presumably also of primary K-bearing minerals.     

Characterization of Rhizobium trifolii isolated from soils of different pH

Rhizobium trifolii were isolated from soils along a transect covering a range of soil pH (3.6–5.6) using two varieties of white clover by either growing seedlings directly in soil or in nutrient solution in tubes inoculated with soil. Rhizobia were present at pH 4.5 but absent at pH 3.9. Neither nodule number nor effectiveness were influenced by the method of isolation and the clover variety on which the strain was isolated. There was no relationship between the pH of the soils and either the number of nodules or the effectiveness of the isolates from those soils. Screening the isolates for tolerance of acidity and Al showed that multiplication was unaffected at pH 5.0 but was slowed for all strains at pH 4.5. Multiplication at pH 5.5 was unaffected by 10 μM Al but was inhibited by 50 μM Al. At pH 4.5 all but 16% of the isolates were inhibited by 10 μM Al; none multiplied with 50 μM Al. The strains which multiplied at pH 4.5 with and without Al were isolated equally from soils in the range pH 4.5–5.6. They were also isolated in almost equal proportions from the two varieties of clover and by the two isolation methods. Overall there was little variation in the effectiveness and acid- and Al-tolerance of isolates from these soils of different pH.