Soils Of Different Origin Research Articles

Comparative analysis of volume change behavior of expansive road subgrades stabilized with waste paper sludge

Expansive soils have a high tendency for volume change in case of fluctuations in moisture content, potentially causing significant damage to light structures, particularly road pavements. This paper investigates the influence of waste paper sludge (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS$$\\end{document}) as an alternative sustainable stabilizer on the volume change behavior of expansive road subgrade soils of different origins. For this purpose, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS$$\\end{document} was added to the expansive soils at ratios of 3%, 6%, 9%, 12%, and 15% by dry weight of the soils. A series of Atterberg’s limit, swelling, shrinkage, compaction, and consolidation tests were performed on pure soils and soil specimens with \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS$$\\end{document} to attain a comprehensive understanding of the role that \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS$$\\end{document} plays in the volume change behavior of expansive soils. The experimental test results showed that the addition of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS\\:$$\\end{document} led to a considerable decrease in the plasticity and swell-shrink potentials of subgrade soils. The consolidation settlement of expansive road subgrades was also reduced to some extent with \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS$$\\end{document}. Moreover, the statistical analysis of the test data indicated a significant relationship among different swelling-shrinkage parameters. The experimental results presented here suggest that the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:WPS$$\\end{document} may be a cost-effective, environmentally friendly, and sustainable stabilizer to reduce the volume change sensitivity of expansive road subgrade soils.

Use of DMT and CPTU tests in the evaluation of shear modulus G 0 for soils of different origin

Use of DMT and CPTU tests in the evaluation of shear modulus G 0 for soils of different origin

Combined Column Test for Characterization of Leaching and Transport of Trace Elements in Contaminated Soils

Environmental assessments are required prior to remediation and redevelopment of contaminated sites. To date, regulatory guidelines are commonly based on total concentrations. Occasionally, simple leaching procedures are included in environmental assessment. Despite being essential for quantification of contaminant transport, analysis of hydraulic conductivity is rarely considered. Cost-effective methods that reflect both contaminant leaching and hydrogeological properties of contaminated soils are needed to ensure proper soil management. The aim of this study was to simultaneously evaluate contaminant leaching and hydraulic conductivity in soil using a combined column test (CCT) and compare this to the leaching results from batch tests (BT) and transport estimates derived from the empirical Hazen equation. Two soils of different origin were characterized using the CCT. By including physical and chemical factors affecting the release and retention of contaminants, the CCT provides an integrated assessment of leaching and transport of trace elements from soils. Additionally, the effect of soil compaction was investigated as a physical treatment to reduce leaching and transport in contaminated soils. Soil compaction did not demonstrate reduced leaching, but a less extensive contaminant transport was observed due to reduced hydraulic conductivity in the soil.

Soil origin and duration of a garden experiment affect competitive outcomes between dominant grassland species

AbstractQuestionsTo explore whether temporal variation and context dependency of competition may explain alternations in dominance of four dry‐grassland species. The species Anthericum ramosum, Brachypodium pinnatum, Bromus erectus, and Inula salicina coexist in one region, each dominating some sites, and have similar habitat affinities and ecological optima.LocationDry grasslands of northern Bohemia, Czech Republic, Europe.MethodsWe assessed interspecific competition at the end of each year of a three‐year garden experiment, in all pairwise combinations of species and in a mixture of all species, using multiple competition designs to test for robustness of the observed competitive outcomes. We replicated the experiment in soils from two localities, differing in structure and chemical composition.ResultsBased on a single harvest at the end of the experiment, Brachypodium was the strongest competitor, both in terms of competitive effect and competitive response, and Bromus and Inula the weakest. However, the competition outcomes changed over time: during the first two experimental years, Bromus was the strongest competitor, followed by Inula. Competitive outcomes also depended on soil origin: Bromus was a stronger competitor when grown in soil resembling soil at the sites it naturally dominates while Inula showed the opposite pattern.ConclusionsWe showed that variation in competitive abilities of individual species over time, under different competition scenarios and in soils of different origin provide the opportunities for each species to locally dominate over the others.

Microbiome composition of disturbed soils from sandy-gravel mining complexes with different reclamation approaches

Activities connected to mineral mining disrupt the soil layer and bring parent rock material to the surface. It leads to altering the environmental conditions and leaves behind vast areas of disturbed lands. Returning these lands to natural ecosystems is an important contemporary challenge, which can be acquired by reclamation practices. Soil microbiome composition reflects changes happening to disturbed lands; thus, its analysis is a powerful tool for evaluating the disturbance degree and estimating the effect of the implementation of reclamation techniques. Additionally, factors connected to the characteristics of a particular geographical region have a certain impact on the microbiome and should be taken into account. Thereby, studies of soil microbiomes of disturbed soils of different origins are essential in understanding the dynamics of soil restoration. Here, we focus on soil microbiomes from two sandy-gravel mining complexes in mountainous areas with a moderate continental climate of the Central Caucasus. These quarries share the same parent rock material, but differ in benchmark soil type and reclamation approach - one was left for passive recovery and the other was technically reclaimed with overburden material. Comparative analysis of microbiome composition, based on sequencing of 16S rRNA gene libraries, showed that region and disturbance are the key factors explaining microbiome variation, which surpass the influence of local factors. However, the application of reclamation techniques greatly reduces the dissimilarity of soil microbiomes caused by disturbance. Linking of soil chemical parameters to microbiome composition showed that the disturbance factor correlates with a lack of organic carbon. Other chemical parameters, like pH, ammonium, nitrates and total carbon explain microbiome variability on a smaller scale between sampling sites. Thus, while regional and disturbance factors reflected differentiation of soil microbiomes, soil chemical parameters explained local variation of certain groups of microorganisms.

Miscanthus × giganteus Phytoremediation of Soil Contaminated with Trace Elements as Influenced by the Presence of Plant Growth-Promoting Bacteria

The phytoremediation of industrial crops is becoming popular for the revitalization of land contaminated by trace elements (TEs). This approach combines biomass production with the improvement of soil health. To implement phytoremediation and derive sufficient dry biomass, crop production must be adequately supported by agricultural practices, including the application of bioinoculants. The current study aims to test the influence of several plant growth-promoting bacteria (PGPB), isolated from TEs-contaminated soil—i.e., Stenotrophomonas maltophilia KP-13, Bacillus altitudinis KP-14, and Pseudomonas fluorescens KP-16 and their consortia on the phytoremediation of the industrial crop M. × giganteus cultivated in the same TEs-contaminated soil. Contrary to expectations, the effects of PGPB on the biomass harvest were low. The most significant increase was detected in leaf biomass treated with a consortium of tested PGPBs. More significant effects were detected in the uptake of individual TEs. The phytoparameters of translocation factor, comprehensive bioconcentration index and uptake index were used to characterize the behavior of the TEs; Cr; Mn; Ni; Cu; Zn; Sr; V; and Pb in the presence of isolates. Plants treated with PGPB strains accumulated minimal concentrations of Cu and Pb in their aboveground biomass, while a tendency for Zn accumulation in the leaves and stems, and Sr accumulation in the leaves was observed. The obtained results reveal the combinations of isolates that lead to the minimal uptake of TEs into the stems and the simultaneous increase in DW. This study provides more insight into the leading factors of phytoremediation supported by PGPB and can be helpful when M. × giganteus is grown on TEs-contaminated soils of different origins.

Identification and validation of early genetic biomarkers for apple replant disease.

Apple replant disease (ARD) is a serious threat to producers of apple trees and fruits worldwide. The ARD etiology is not unraveled and managing options are either economically not applicable or environmentally harmful. Thus, interest is given in biomarkers that allow to indicate ARD situations at early time points in order to classify soils according to ARD severity but also to analyze the effectiveness to potential countermeasures. This study aimed at (i) identifying ARD biomarkers on the transcriptional level in root tissue by analyzing the expression of previously identified candidate genes in ARD soils of different origin and texture and (ii) testing the specificity of these marker genes to ARD. In vitro propagated M26 plantlets were submitted to a bio-test with three ARD soils, either untreated or disinfected by γ-irradiation. Expression of seven candidate genes identified in a previous transcriptomic study was investigated by RT-qPCR in a time course experiment. Already three days after planting, a prominent upregulation of the phytoalexin biosynthesis genes biphenyl synthase 3 (BIS3) and biphenyl 4-hydroxylase (B4Hb) was observed in the untreated ARD variants of all three soils. The phytoalexin composition in roots was comparable for all three soils and the total phytoalexin content correlated with the expression of BIS3 and B4Hb. The third promising candidate gene that was upregulated under ARD conditions was the ethylene-responsive transcription factor 1B-like (ERF1B). In a second experiment M26 plantlets were exposed to different abiotic stressors, namely heat, salt and nutrient starvation, and candidate gene expression was determined in the roots. The expression levels of BIS3 and B4Hb were highly and specifically upregulated in ARD soil, but not upon the abiotic stress conditions, whereas ERF1B also showed higher expression under heat stress. In conclusion, BIS3 and B4Hb are recommended as early ARD biomarkers due to their high expression levels and their high specificity.

Soil attribute regulates assimilation of roxarsone metabolites by rice (Oryza sativa L.)

Roxarsone (ROX), an organoarsenic feed additive, and its metabolites, can be present in animal manure used to fertilize rice. Rice is prone to absorb arsenic, and is subject to straighthead disorder, which reduces rice yield and is linked with organic arsenic compounds. This study aims to elucidate how soil property affect arsenic accumulation in rice plants fertilized with chicken manure containing ROX metabolites. Manures of chickens fed without or with ROX, designated as control manure and ROX treated manure (ROXCM), respectively, were applied in eight paddy soils of different origins, to investigate the assimilation of arsenic species in rice plants. The results show that inorganic arsenic (arsenate and arsenite), monomethylarsonic acid and dimethylarsinic acid (DMA) were detected in all brown rice and husk, trace tetramethylarsonium and trimethylarsine oxide were occasionally found in these both parts, whereas all these arsenic species were determined in straw, irrespective of manure type. ROXCM application specifically and significantly increased brown rice DMA (P = 0.002), which remarkably enhanced the risk of straighthead disease in rice. Although soil total As impacted grain biomass, soil free-iron oxides and pH dominated arsenic accumulation by rice plants. The significantly increased grain DMA suggests manure bearing ROX metabolites is not suitable to be used in soils with abundant free-iron oxides and/or high pH, if straighthead disorder is to be avoided in rice.

Interrelationship between Undrained Shear Strength from DMT and CPTU Tests for Soils of Different Origin

Abstract The article presents test results on the use of the flat dilatometer test (DMT) to evaluate changes in undrained shear strength su in soils of various origins. Reference values for the undrained shear strength calculated with Marchetti’s original formula were su values obtained from the piezocone penetration tests. The tests were conducted at eight investigation sites in Poland, where five groups of soils were separated: loess-deluvial, loess-deluvial cemented, young till, aged till, and Pliocene clay. The soils exhibited varied overconsolidation effects. The study results revealed that the factors influencing the relationship between undrained shear strength and the KD coefficient from DMT test were various because of the origin, grain size distribution of the soils and cementation. In order to include the influence of overconsolidation and grain size distribution in calibration of su from DMT, a modified KD1 coefficient was introduced into the formula describing this relationship. The final solution was obtained with multiple linear regression. A relatively high statistical evaluation of this relationship was determined for aged till and deluvial and uncemented loess.

API ZYM assay to evaluate enzyme fingerprinting and microbial functional diversity in relation to soil processes

Soil properties, enzyme activity, and microbial functional diversity coevolve with soil processes. Consequently, activity and diversity of soil enzymes could be used for evaluating the natural processes in ecosystems and their changes but, for applied management strategies, useful cost-effective methods and synthetic indicators are required. The aim of this study was to use API ZYM (API) assay to evaluate the fingerprint of soil enzyme activity and microbial functional diversity in relation to soil processes. To strengthen the results, a parallel measurement of enzyme activities was performed with microplate-fluorometric (FA) assay. Seven soil profiles classified as Haploxeralf, located in two Mediterranean areas under xeric moisture and mesic temperature soil regimes, were selected. The Synthetic Enzyme Index (SEI) was calculated as the sum of 16 enzyme activities determined according to the two methods (SEI–API and SEI–FA). Moreover, the enzyme activities were used to assess the microbial functional diversity through the calculation of the Shannon’s diversity index (H’ API and H’ FA). The results showed a relationship between SEI–API and SEI–FA which was described by a linear model. Moreover, a significant linear regression was also found between the Shannon’s diversity indices calculated according to the two methods, H’ API and H’ FA. Significant differences were found from surface A to deep Bt genetic horizons in a decreasing gradient of enzyme activity and microbial functional diversity. For subsurface horizons, the SEI–API was significantly higher in E than AB horizons, suggesting that API method can detect the different biochemical behaviour in eluviation processes occurring in Haploxeralfs. API ZYM assay proved to be suitable for a general biochemical evaluation and for assessing microbial functional diversity in soils of different origin, composition, and land uses. For this reason, it can be proposed as a simple cost-effective method to use during the soil survey.

Optimized procedure for the determination of P species in soil by liquid-state 31P-NMR spectroscopy

Abstract Background Liquid-state 31P-NMR spectroscopy becomes progressively an important role for studying phosphorus (P) dynamics in soil. Soils of different origin and organic matter content were used to optimize sample preparation and re-dissolution procedures to improve characterization of P species in soil by 31P-NMR spectroscopy. The efficiency of P extraction from an untreated fresh soil was compared to that from freeze-dried and air-dried soil samples. Results A freeze-drying pretreatment not only provided the greatest extraction yields of total and organic P from both farmland and forest soils but also enhanced the intensity of signals for inorganic and organic P species in 31P-NMR spectra, except for polyphosphates. Re-dissolution of freeze-dried soil extracts in relatively dilute alkaline solution and addition of a small aliquot of concentrated HCl to the NMR tube prior to analysis improved the quality of NMR spectra. Finally, the visibility of relatively weak P signals, such as for phosphorus diesters, phosphonates, polyphosphate, phospholipids, and DNA were reproducibly enhanced when 31P-NMR spectra were generated after at least 15 h of acquisition time. Conclusion The optimized procedure presented here ensured the greatest detectability of inorganic and organic P species by liquid-state P-NMR spectroscopy in soil extracts.

Equilibrium isotherm and kinetics modeling of U(VI) adsorption by natural soil systems

This research examined the adsorption capability of natural soils of different origin for U(VI) at soil–water interface and the mechanism involved. Adsorption kinetics study indicates that adsorption followed the pseudo-second order kinetics irrespective of soil types and was not solely controlled by the diffusion step rather surface complexation and ion-exchange plays major role. Study of adsorption isotherms indicates adsorption involves chemisorption and soil with high Fe and Mn content better fit to Langmuir model. The study provides a better insight for site selection for radioactive waste (uranium) disposal facilities as well as soil suitable for back fill or permeable reactive barrier to inhibit migration of U(VI).

不同产地黄芩中无机元素含量及其与根际土壤无机元素的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 不同产地黄芩中无机元素含量及其与根际土壤无机元素的关系 DOI: 10.5846/stxb201304160722 作者: 作者单位: 中国中医科学院中药资源中心,成都康宏药业集团股份有限公司,中国中医科学院中药资源中心,中国中医科学院中药资源中心,中国中医科学院中药资源中心,中国中医科学院中药资源中心,中国中医科学院中药资源中心,中国中医科学院中药资源中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（81130070）；国家科技支撑项目（2012BAI29B02，2012BAI28B002） The contents of inorganic elements of Scutellaria baicalensis from different origins and its relationship with inorganic elements in relevant rhizosphere soil Author: Affiliation: National Resources Center for Chinese Material Medica, China Academy of Chinese Medicinal Sciences,,National Resources Center for Chinese Material Medica, China Academy of Chinese Medicinal Sciences,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:药用植物中各无机元素含量的不仅影响药用植物的生长发育，也是药材有效成分的构成因子。通过对全国范围内16个不同产地（即居群）的92个野生黄芩（Scutellaria baicalensis Georgi）样本及其相应的根际土壤中10种无机元素含量的分析，发现不同产地黄芩及其根际土壤无机元素都有很大变异，且不同产地黄芩根际土壤中无机元素的变异远大于黄芩药材中无机元素的变异。总体来看，黄芩中Mg（9级）含量较其他植物含量高；P（1级）、K（2级）、Mn（3级）含量与其他植物相比处处较低水平；黄芩对Sr（富集系数达到3.52）有较强富集。并且通过无机元素分布曲线分析建立了无机元素指纹谱，主成分分析筛选出黄芩主要特征无机元素为Mg、K、Ca、Fe、Zn。本研究还表明，黄芩对各元素的吸收能力受产地的影响较大，提示黄芩对无机元素的吸收与各产地根际土壤无机元素有一定关联性。 Abstract:Inorganic elements in medicinal plants not only affect the growth and development of medicinal plants, but also are important constitutes of its active ingredients. The present study examined the content and variability of inorganic elements in Scutellaria baicalensis and its relevant rhizosphere soils, as well as the plant's absorption characteristics for various inorganic elements, to explore the relationship between inorganic elements in rhizosphere soil and inorganic elements in roots. A total of 92 S. baicalensis plant and its 92 relevant rhizosphere soil samples, derived from 16 different origins across China, were employed in this experiment. Ten different inorganic elements were detected in the plant samples and the analyses of their corresponding rhizosphere soils. The inorganic element contents of plants from different origins and their corresponding rhizosphere soils varied significantly, and the variation among soils of different origin was much greater than in plants. The ANOVA showed that, in addition to Zn, the contents of other inorganic element in the samples and their corresponding rhizosphere soils were significantly different according to origin. For example, the Cr contents in the samples from Durbat, Heilongjiang were significantly higher than those of samples from other origins and nearly eight times greater than the study average. The rhizosphere soils from Weichang, Hebei and Chicheng, Hebei, contained significantly more Cr, Fe, K, Mn, and Sr than did samples from other areas. The coefficients of variation for Cr, Fe, K, Mn, P and Sr in the plant samples from the 16 origins were significantly greater than those in the rhizosphere soil. However, no significant differences were observed between the coefficients of variation of the inorganic elements for their overall distribution in the plant samples and in the corresponding rhizosphere soils. Furthermore, the content of Mg (9 level) in S. baicalensis (9) was relatively higher than in other plants, while the P (1 level), K (2 level), and Mn (3 level) contents were relatively lower. S. baicalensis also showed a strong concentration of Sr (with an enrichment coefficient of 3.52) and a weak concentration of P (with an enrichment coefficient of 1.27). At the same time, the enrichment coefficient of each inorganic element varied significantly according to origin. Additionally, we obtained the fingerprint spectra of the inorganic elements of S. baicalensis using inorganic element distribution curve analysis and filtered out the characteristic inorganic elements using principal component analysis. Mg, K, Ca, Fe and Zn were the characteristic inorganic elements of S. baicalensis, while Ca, K, Mg, Mn and Zn were the characteristic inorganic elements in the rhizosphere soil of S. baicalensis. Overall, the study showed that the absorption capacity of S. baicalensis for each element varied with origin and that the absorption capacity for each inorganic element was tied to the plant's growth demands and the absorption characteristics of the element. These results also suggested that a correlation existed between the absorption of inorganic elements and the inorganic elements in the rhizosphere soil. This study provided a comprehensive understanding of the geographic variation of nutrient quality for S. baicalensis and a theoretical basis for choosing appropriate planting habitats. 参考文献 相似文献 引证文献

Comparison of the thermodynamic and correlation criteria for internal standard selection in laser-induced breakdown spectrometry

The use of the reference line of an internal standard in LIBS is a usual way to eliminate or reduce the fluctuations of plasma parameters from pulse to pulse as well as from sample to sample. Thermodynamic criterion, i.e. closeness of excitation potentials of the analytical line and the reference one, is often used to select an appropriate reference line. In this work, we propose an alternative criterion based on searching the best correlated pairs of lines under the variations of laser energy. Two criteria were compared for high-alloy steels and soils of different origins. The discrepancy among the values of plasma temperature calculated from Fe I, Mn I and Cr I transitions was found under the conditions of slightly changed laser fluence on steel samples. On the other hand, the agreement between plasma temperatures, obtained for Fe I and Mn I transitions, was demonstrated in plasma on soil samples. Calibration results obtained for manganese in steels and lead in soils show that thermodynamic criterion can be an appropriate way for choosing an internal standard only under LTE conditions. Two lines of Mn I at 403.07nm and 404.14nm and Pb I at 405.78nm were the analytical lines for the quantification of manganese in steels and lead in soils, respectively. The use of the correlative criterion seems to be suitable for internal standardization under LTE or non-LTE conditions. Probable limitations of the correlative criterion and its possibilities to identify weak lines are discussed in the article.

Soil heterogeneity generated by plant–soil feedbacks has implications for species recruitment and coexistence

Summary Most studies of soil heterogeneity have focused on underlying abiotic factors such as soil nutrients. However, increasing recognition of plant–soil feedback (PSF) effects on plant growth, combined with the observation that PSFs operate at small spatial scales, suggests that heterogeneity due to PSF could affect plant population and community dynamics. The consequences of PSF‐generated heterogeneity for coexistence depend on heterogeneity's effects on vital rates and how those vital rates influence population‐level recruitment dynamics. We measured vital rates and recruitment dynamics of three congeneric pairs of introduced perennial plants grown as monocultures in experimental PSF‐generated soil environments. Field soils collected from conspecifics and congeners were alternated in patches or mixed together to produce heterogeneous and homogeneous soils, respectively. We quantified the effects of PSF‐generated heterogeneity on germination and establishment and determined how these vital rates affected recruitment. We calculated net pairwise interaction coefficients to predict whether PSFs could mediate coexistence between congeners. Soil heterogeneity altered the relationship of vital rates to recruitment dynamics for some species. For example, Solanum dulcamara recruited later into heterogeneous than homogeneous soils, and germination was a stronger predictor of the timing of recruitment in heterogeneous soil, while mortality was a stronger predictor in homogeneous soil. Contrasts between soils of different origin suggest that mixing soils had non‐additive effects on vital rates (e.g. Rumex crispus mortality was higher in homogeneous than in conspecific or congener soil). Interaction coefficients predicted that PSFs in heterogeneous soils might mediate stable coexistence only of Rumex congeners. Synthesis. Heterogeneity generated by PSFs had species‐specific effects on vital rates, with consequences for recruitment dynamics. Mixing soils of different origin often resulted in non‐additive effects, which may indicate an interaction between soil abiotic and/or biotic properties and could predict non‐additive responses to soil disturbance. Finally, quantifying the reciprocal effects of PSFs on congeners suggests that PSF‐generated heterogeneity may promote coexistence of certain species, which was not evident from individual PSF responses. Future studies should determine whether such mechanisms might operate for more distantly related species.

Independent variations of plant and soil mixtures reveal soil feedback effects on plant community overyielding

Summary Recent studies have shown that the positive relationship between plant diversity and plant biomass (‘overyielding’) can be explained by soil pathogens depressing productivity more in low than in high diverse plant communities. However, tests of such soil effects in field studies were constrained by experimental limitations to manipulate soil community composition independent of plant community composition. Here, we report of an experiment where feedback effects to plants were tested for both plant and soil monocultures and mixtures. Our results demonstrate that overyielding is the result of plant species in mixture being more growth‐limited by ‘own’ soil biota than by soil biota of other plant species. This effect disappeared when the soils had been sterilized by gamma‐irradiation. Mixing plants themselves did not result in overyielding except when grown in the soil of one of the species (Leucanthemum vulgare), where growth of one species disproportionally increased in mixture compared to monoculture. Soil nutrient availability could not explain differences in growth between the non‐sterilized soils. Therefore, our results suggest that plant species–specific soil biota rather than the plants have contributed to the plant community overyielding. Species biomass ranking in mixtures highly differed between non‐sterilized soils of different histories of soil conditioning, whilst the ranking was more consistent in sterilized soil. Sterilized soils of different origin differed significantly in nutrient availability. These results suggest that shifts in competitive hierarchies depend on plant species–specific interactions influenced by soil biota and cannot be induced by mineral nitrogen. Synthesis. Our results show that overyielding in four plant species mixtures can be due to species‐specific interactions between plants and their specific soil biota. Neither mixing the plant species alone nor the differential responses of species to mineral nitrogen influenced community productivity, but mixing soil biota did.

The tandem analytical method of flow injection diode array spectrophotometry and flame atomic absorption spectrometry (FI-DAD(vis)-FAAS) in iron speciation studies using 1,10-phenanthroline complexes

The article presents the new analytical method of determination of the content of selected iron forms in soil and sediment extracts. The presented tandem analytical system uses the molecular and atomic absorption and works in the flow injection mode. The system is equipped with two detectors: the spectrophotometric detector of diode array and the atomic absorption spectrometer. The new analytical system allows for the determinations of the content of ionic iron forms: Fe(II) and Fe(III), as well as the content of non-ionic forms complexed in the extracts of soil and sediment solid samples. The determination limits of 0.2, 0.9 and 0.9μgmL−1 were obtained, for Fe(II), Fe(III) and for iron in acid leachable fraction in solid sample extracts respectively, and the precision of determinations fell within the range of 1.8% - 2.4%. The developed and optimised analytical method was applied in the studies of iron speciation in the acid leachable fraction of sediments and soils of different origin.

ОСОБЕННОСТИ ИНЖЕНЕРНО-ГЕОЛОГИЧЕСКИХ ИЗЫСКАНИЙ ПРИ ЗАСТРОЙКЕ ГОРОДСКИХ КВАРТАЛОВ И КРУПНЫХ ЗАГОРОДНЫХ ТЕРРИТОРИЙ

The authors discuss peculiarities of engineering geological surveys of contaminated urban and rural soils. The authors provide examples of the influence produced by the scope and composition of geological engineering surveys on the reliability of foundation soils. The authors also provide their assessments in terms of deformation-related properties of filled soils and their employment as immediate foundation soils for a residential house in Marfino. The article is polemical, and it may raise animated discussions of the problem. The authors believe that geological engineering tests held in urban areas and preceding the implementation of any construction projects should not be limited to cone penetration and field tests of soils limited to the grid, and at the stage of the project design, any tests shall be held within the perimeter of a designed building according to the effective legislation. In the course of field tests, geologists must pay special attention to the identification of contaminated soils of different origin, especially if the foundation is made of plates. The depth of the contamination may reach 10 meters in Moscow and in the Moscow Region. Identification of backfill soils may be particularly difficult.

Root-induced Changes in the Rhizosphere of Extreme High Yield Tropical Rice: 2. Soil Solution Chemical Properties

Our previous studies showed that the extreme high yield tropical rice (Padi Panjang) produced 3-8 t ha-1 without fertilizers. We also found that the rice yield did not correlate with some soil properties. We thought that it may be due to ability of root in affecting soil properties in the root zone. Therefore, we studied the extent of rice root in affecting the chemical properties of soil solution surrounding the root zone. A homemade rhizobox (14x10x12 cm) was used in this experiment. The rhizobox was vertically segmented 2 cm interval using nylon cloth that could be penetrated neither root nor mycorrhiza, but, soil solution was freely passing the cloth. Three soils of different origins (Kuin, Bunipah and Guntung Papuyu) were used. The segment in the center was sown with 20 seeds of either Padi Panjang or IR64 rice varieties. After emerging, 10 seedlings were maintained for 5 weeks. At 4 weeks after sowing, some chemical properties of the soil solution were determined. These were ammonium (NH4+), nitrate (NO3-), phosphorus (P) and iron (Fe2+) concentrations and pH, electric conductivity (EC) and oxidation reduction potential (ORP). In general, the plant root changed solution chemical properties both in- and outside the soil rhizosphere. The patterns of changes were affected by the properties of soil origins. The release of exudates and change in ORP may have been responsible for the changes soil solution chemical properties.Keywords: Ammonium, electrical conductivity, iron, nitrate, oxidation reduction potential, pH, phosphorus [How to Cite: Purnomo E, D Choiron, R Yulia, H Halim, Krisdianto, A Hairani and M Osaki. 2012. Adding Organic Matter Enhanced the Effectiveness of Silicate Rock Fertilizer for Food Crops Grown on Nutritionally Root-induced Changes in the Rhizosphere of Extreme High Yield Tropical Rice: 2. Soil Solution Chemical Properties. J Trop Soils, 17 (3): 67-74. doi: 10.5400/jts.2012.17.3.189][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.3.189]

Applicability of Liquid Chromatography with Time-of-Flight Mass Spectrometric Detection for Determination of Cyanuric Acid in Soil

Abstract. Cyanuric acid (2,4,6-trihydroxy-1,3,5-triazine, CA) is a highly polar and hydrophilic degrada-tion product of symmetric triazine herbicides, fairly stable under environmental conditions. We investi-gated the applicability of reversed-phase liquid chromatography coupled to time-of-flight mass spectrome-try (LC-ToF-MS) for qualitative and quantitative determination of CA in soils of different origin and pe-dological characteristics. CA was ultrasonically extracted from soils either with a mixture of acetone and n -hexane (volume ratio = 2:1) or with methanol and analysed on a LiChrospher 100 CN column with ψ(acetonitrile,water) = 50:50 as the mobile phase for isocratic elution. The efficiency and selectivity of LC-ToF-MS determination, using the electrospray ionisation in negative mode and selective monitoring of deprotonated CA molecule ( m/z 128), was evaluated with respect to injection volume, extracting solvent, and possible soil matrix interferences. The advantage of LC-ToF-MS over conventional HPLC with UV-diode array detection was the high ion detection selectivity minimising the interferences of coeluting spe-cies and the unambiguous identification of CA in soil extracts by accurate mass measurements of deproto-nated molecule. (doi: 10.5562/cca2109)