A comparison between X‐ray fluorescence and dissolution methods employing lithium metaborate fusion for elemental analysis of soil clays

Abstract

A method employing fusion of soil clay samples with lithium metaborate (1:5 ratio) in a furnace at 1050°C for 1 hr. subsequent dissolution of the fused sample in 4% HNO₃. and elemental analysis for Si, Al, Fe, Ca, Mg, K, and Ti by atomic absorption spectrometry was compared with the X‐ray fluorescence (XRF) fused disc technique for analysis. Duplicated analyses were performed on 15 clay samples from soils of the southern U.S and three API reference samples. The mean total percent recovery by this method was excellent (100.14 ± 2.85). Elemental oxide quantities in terms of SiO₂. Al₂O₃, Fe₂O₃, MgO, CaO and K₂O determined by atomic absorption/flame emission (AA/FE) spectroscopy were in good agreement with values measured by x‐ray fluorescence (XRF) on the same subsamples (r = 0.89^* to 0.98^**). but somewhat more variable on subsamples seperated from different pretreatments (r = 0.70^* to 0.97^** ). The method, which has also been tested on 36 additional clay samples from a variety of Kentucky soils with total percent recoveries ranging from 96.5 ‐ 103.5%. demonstrated no bias due to mineralogy with respect to mixed, montmorillonitic. and siliceous classes. This technique presents numerous advantages over other elemental analysis techniques utilizing fusion, dissolution, or XRF spectroscopy with respect to time, effort and cost. With the introduction of inductively‐coupled plasma (ICP) emission spectroscopy. efficiency can be additionally improved.     

Effect op foliar sprays of sulphuric acid with and without elemental sulphur in the prevention of chlorosis In Peanut (Arachis hypogaea. L.)

Abstract

A field experiment was conducted on an alkaline calcareous soil of Agronomy farm of the College of Agriculture, University of Udaipur to study the effect of sulphur on crop yield, leaf elemental composition, chlorophyll synthesis and activities of haematin enzymes. Application of elemental sulphur 21 days before planting with and without 0.1 per cent foliar sprays of H₂SO₄. increased crop yield by 137 to 197 per cent. Application of all these treatnents had no effect on nitrogen, phosphorus and potassium content of leaves but sulphur content was signficantly increased. Iron content of green leaves was decreased significantly 4 to 5 times together with an increase in the activity of catalase and peroxidase enzymes. Chlorosis in these soils appears to be on account of a reduced physiological availability of iron after absorption.     

西安市郊农田土壤环境地球化学研究

通过取样调查和实验分析,研究了西安市郊农田土壤环境的地球化学特征。土壤中的常量元素和微量元素结果分析显示,CaO、MgO和Na2O含量明显高于陕西土壤、全国土壤中的平均值,重金属元素Pb、Ni、Zn、Cr、Co、Mn、As等严重超标。通过相关分析和聚类分析,探讨了土壤元素间的亲和性及赋存特征,为农业生产、农业结构调整和防治土壤污染提供地球化学依据。     

黑龙江五常水稻产区土壤地球化学特征研究

对黑龙江五常地区的土壤类型与土壤地球化学特征进行分析，研究表明，五常水稻产区特定的土壤条件和土壤地球化学特征是该区水稻优质高产的主要原因。     

Ionomic Profiling of Rice Genotypes and Identification of Varieties with Elemental Covariation Effects

Ionomic profiles are primarily influenced by genetic and environmental factors. Identifying ionomic responses to varietal effects is necessary to understand the ionomic variations among species or subspecies and to potentially understand genetic effects on ionomic profiles. We cultivated 120 rice (Oryza sativa) varieties to seedling stage in identical hydroponic conditions and determined the concentrations of 26 elements (including 3 anions) in the shoots and roots of rice. Although the subspecies effects were limited by the genus Oryza pre-framework and its elemental chemical properties, we found significant differences in ionomic variations in most elements among the aus, indica and japonica subspecies. Principal component analysis of the correlations indicated that variations in the root-to-shoot ionomic transport mechanisms were the main causes of ionomic differences among the subspecies. Furthermore, the correlations were primarily associated with the screening of varieties for elemental covariation effects that can facilitate breeding biofortified rice varieties with safe concentrations of otherwise toxic elements. The japonica subspecies exhibited the strongest elemental correlations and elemental covariation effects, therefore, they showed greater advantages for biofortification than the indica and aus subspecies, whereas indica and aus subspecies were likely safer in metal(loid) polluted soils. We also found that geographical and historical distribution significantly defined the ionomic profiles. Overall, the results of this study provided a reference for further association studies to improve the nutritional status and minimize toxicity risks in rice production.     

板栗品质与土壤地球化学关系研究进展

板栗具有较高的经济价值,但其地域性较强,品质差异较大。综述了近年来板栗营养品质的评价指标体系的研究进展,板栗品质与土壤性质的关系以及板栗品质和土壤地球化学元素间关系的研究进展,并对板栗产量、质量和施肥技术间的关系进行了分析和论述,最后指出了存在的问题,并对提高板栗营养品质提出了几点建议。     

中国西南地区几种土壤的元素地球化学特征

研究西南地区变性土、铁铝土及水稻土７个剖面的地球化学和矿物学特征的结果表明：铁铝土在元素地球化学分类上可划为铝质富铝化类型，变性土也表现了一定的富铝化趋势，而水稻土最明显的特征是Ｆｅ、Ｍｎ及Ｃａ均相对富集。变性土粘土矿物以蒙脱石为主，铁铝土则以高岭石占优势，水稻土矿物组成取决于母质来源。根据主组元分析结果，可以探讨成土过程中不同剖面的元素分异和相关性，以及元素地球化学的演变趋势。     

Soil organic matter in urban soils: Estimation of elemental carbon by thermal oxidation and characterization of organic matter by solid-state C nuclear magnetic resonance (NMR) spectroscopy

To reduce soil destruction by urban sprawl, land use planning has to promote the use of soils within cities. As soil functions are now protected by law in Germany, urban soil quality has to be evaluated before soil management. We studied contributions from elemental carbon (EC) and soil organic matter (SOM) quality in topsoil horizons at seven sites in Stuttgart, Germany, differing in impurities by technogenic substrates. The most disturbed site was found at a disused railway area while high-density areas, public parks and garden areas showed varying degrees of disturbance by anthropogenic activities. For most soils, compounds derived from plant litter dominated organic matter (OM) quality characterized by nuclear magnetic resonance (NMR) spectroscopy. Although high contents of EC (up to 70% of soil organic carbon) were indicated by thermal oxidation, this was not confirmed by aromatic C intensities in NMR spectra. Only for the highly aromatic railway soil were results for elemental carbon by thermal oxidation and NMR similar. As other technogenic substrates beside EC like plastics may also contribute in the long-term to OM in urban soils, new analytical techniques are therefore required. This knowledge will promote the evaluation of urban soil properties and their sustainable use.     

Effects of previous elemental sulfur applications on oxidation of additional applied elemental sulfur in soils

Oxidation of elemental sulfur (S⁰) in 20 Chinese agricultural soils was tested and the effects of previous S⁰ applications on the oxidation of additional applied S⁰ in selected soils were investigated using laboratory, greenhouse, and field experiments. Results showed that sulfur oxidative capacities presented great variability among 20 tested soils, with a coefficient of variation of 92.4%. There were no significant relationships between S⁰ oxidation and physical and chemical properties of the selected soil. Previous S⁰ amendment significantly increased the oxidation rate of additional applied S⁰. These stimulatory effects after the first applications of S⁰ were greater than those after two applications. The percent increase in S⁰ oxidation rate due to S⁰ pretreatment was negatively correlated with the oxidation capacities of soils before S⁰ pretreatments. The significant reduction of sulfur oxidation in autoclaved soils and significant increase in S⁰ oxidation after inoculation with S⁰-treated soil suspension demonstrated that microbial oxidation was mainly responsible for the enhancement of soil oxidation ability after previous S⁰ amendments.     

淮河上游全新世黄土-古土壤序列元素地球化学特性研究

在野外考察研究的基础上,对河南禹州全新世风成黄土-古土壤剖面系统采样,利用X-荧光光谱仪测定了常量元素和微量元素的含量及其变化,并与磁化率曲线、粒度变化曲线对比分析发现:常量元素氧化物比值钾钠比、残积系数和以Rb为代表的微量元素含量等随剖面层次呈规律性变化,即在古土壤层(S0)中含量最高,表土层(MS)中次之,在黄土层(L1、Lt、L0)中最低。硅铝率和Sr的含量表现出相反的变化规律。表明在全新世古土壤层和表土层形成时期,气候温暖湿润,成壤作用和次生粘化作用较强;在黄土堆积时期,气候比较干旱,沙尘暴频繁,成壤作用微弱。这些化学参数与磁化率曲线可以进行对比,表明成土过程中元素的迁移变化受全新世以来气候变化和成壤环境变化的控制。与黄土高原腹地的洛川剖面相比,淮河上游禹州剖面中绝大多数常量元素的含量较高,而绝大多数微量元素的含量偏低,磁化率也显著偏低,绝对值差别很大,粒度组成当中细沙成分含量很高,这说明淮河上游黄土物质来源与黄土高原地区明显不同。联系全新世时期黄河频繁泛滥、改道、沉积与黄淮平原盛行东北风形成流沙地的事实,认为淮河上游的黄土是黄河泛滥沉积物质经过风沙活动改造,由东北风力系统搬运而来的近源粉尘堆积,再经过就地风化或者成土改造而形成。