Effect of a fly ash and gypsum mixture on rice cultivation

Abstract

The salt titration (ST) method was evaluated as a method to determine ZPC in comparison with the potentiometric titration (PT) method for 26 soils with variable charge clays, i.e., Oxisols and Ultisols from Thailand and Andisols from Japan. In addition to the determination of ST-pH₀ as the zero point of charge, a calculation procedure (STPT method) was adopted here in order to acquire more information from the titration curve. Furthermore, for the purpose of cross-checking of ZPC determined by the PT method, the ST procedure was successively applied to the samples analyzed by the PT method (PTST method).

The soil to solution ratios of 1: 10 to 1: 5 gave almost an identical ST-pH₀ value for every soil. The values of both ST-pH₀ and PT-ZPC ranged from 4.7 to 6.3 for the Andisols, while for the Oxisols and Ultisols, they were always below 4.2. The difference between the values of ST-pH₀ and PT-ZPC was only slight for the Andisols, whereas it was sometimes large (0.4 pH unit) for the Oxisols and Ultisols. Nevertheless, it was concluded that the ST method with its modification (STPT) was comparable to or even better than the PT method for the soil characterization work due to its convenience and simplicity.     

Pedogenesis and surface charge of some Andic soils in Washington,U.S.A.

Chemical and surface charge characteristics were determined for three soils that were formed in a mantle of volcanic tephra along a bio-climatic gradient in forest in northcentral Washington state. The soils are Nevine silt loam (Typic Vitrandept), Manley silt loam (Entic Cryandept), and Moses silt loam (Andic Cryochrept). Selective dissolution analyses for Al, Fe, and Si suggests that the weathering products in the ash mantle are poorly crystalline aluminosilicates, hydrous and crystalline Fe-oxides, and Al-humus complexes in decreasing order of abundance. The chemical and physical data indicate that Moses silt loam has undergone a greater degree of weathering than either Nevine silt loam or Manley silt loam, and we attribute this to differences in the weathering environment. The measured points of zero charge parameters are typical for soils that are dominated by amphoteric surfaces: the soils exhibit charge reversal, and charge magnitude is dependent upon pH and electrolyte concentration. The point of zero salt effect ranged from 5.1 to 5.3, and the point of zero net charge ranged from 4.3 in Nevine silt loam to 5.4 in Moses silt loam. Pedogenesis has not caused large enough differentiation among the soils to allow us to use zero charge parameters as indicators of the degree of pedogenesis.     

我国几种地带性土壤无机胶体的表面电荷特性

研究了用返滴定法测定我国七个不同地带土壤无机胶体的表面电荷特性。结果表明 :( 1 )返滴定法测定的供试土壤无机胶体可变电荷量随纬度升高而逐渐上升。这主要与供试土壤粘土矿物、铁铝氧化物组成及含量有关。一般来说 ,土壤层状硅酸盐粘土含量越多 ,永久负电荷量和其可变负电荷量越大 ;铁铝氧化物含量越高 ,可变负电荷量越低。( 2 )七个地带性土壤无机胶体的Qv pH曲线上在pH5左右有一峰值 ,这可能与供试土壤胶体中铁铝氧化物的ZPC及供试土样层状硅酸盐的边面Si OH基吸附H 及Al OH基离解H 有关     

有机-无机复合体的电荷零点

Five soil samples collected from China and two soil samples from Pakistan with widely different origin and characteristics were used to study the zero point of charge (ZPC) of soil colloids. The results showed that the value of zero point of charge of H-clay complexes was lower than that of H-clays in all the samples. Natural clay complexes had the highest ZPC as compared to H-clay complex and H-clay in alfisol, closer to H-clays rather than H-clay complexes in oxisol and udult. The delta value of ZPT (zero point of titration) to ZPC was higher in H-clay complexes than in H-clays.     

Field and chemical Evaluation of volcanic ash deposition in some soils of Malaysia

A study was conducted to determine the extend of volcanic ash deposition and distribution in some soils of Malaysia. A total of 12 soil types of different geology and locations from Peninsular Malaysia and West Sarawak were collected and analysed for their physico‐chemical and dissolution analysis. All soils under study belonged to either the order of Inceptisols, Ultisols or Oxisol. They were acidic and had relatively low CEC and exchangeable bases. The Al saturation percent were higher in the Ultisols as compared to the Oxisols. Field and laboratory investigations, and the dissolution analysis comprising of the binary ratio, ferrihydrite percent and allophane content, suggested that the soils under study were highly weathered and non‐allophanic. The soils of West Sarawak, however, may contain a reasonable deposits of the volcanic ash materials, as shown by the higher pH_NaF values of near 9.4, but other laboratory analysis were still not conclusive of the result.     

土壤胶体中氧化物表面性质的初步研究

我们以蒙脱石为对照,测定了以水合氧化物型表面为主的试样四个方面的表面性质:电荷零点(ZPC)、滴定曲线、羟基释放量及不同pH条件下对NH₄⁺和Cl^-的吸附。结果表明,在pH 4—9范围内,氧化物型表面提供可变正电荷1—8 meq/100g,提供可变负电荷3—15meq/100g;三二氧化物使土壤的ZPC升高,而永久负电荷和有机质使土壤的ZPC降低。作为粘土酸,氧化物表面的酸性较弱,其表面质子逐步解离,使滴定曲线不出现突跃。氧化物表面的羟基和水合基密度很高,增加了土壤对离子的专性吸附能力。土壤中常见的氧化物型表面主要来自Fe,Al氧化物及非品质矿物,就它们的化学式而言,主要有Si—OH、Fe—OH及Al—OH,它们可存在于同一土壤中,在土壤常见的pH范围内,具有低ZPC的Si—OH亚表面提供可变负电荷,具有高ZPC的Fe—OH和Al—OH亚表面提供可变正电荷。     

Ion adsorption mechanisms in oxidic soils; implications for point of zero charge determinations

In order to clarify the adsorption mechanisms for various ions (e.g., P, K, Ca, Mg), ion adsorption studies were carried out on a range of soils of widely different mineralogical compositions. The soils were classified as: Hydrandept, Gibbsihumox, Eutrustox and Haplustoll and belonged, respectively, to the Honokaa, Halii, Wahiawa and Waialua soil series in Hawaii.Soils containing mostly hydrous Fe and Al oxides, thus colloids of the variable-charge type, retain ions through various types of adsorption mechanisms. As a result, certain interactions between cation adsorption and anion adsorption occur which affect the ion exchange processes and thereby the determination of the point of zero charge (PZC).In this study adsorbed phosphate increased the adsorption of cations and lowered the PZC and adsorbed Ca interfered with PZC determinations unless these were carried out with CaCl₂ as supporting electrolyte. It is likely that this latter interference will have influenced the results of many earlier studies because of the very strong adsorption of Ca by oxidic colloids. In this study only part of the adsorbed Ca could be recovered from the two most highly weathered soils, by repeated extractions with NH₄-acetate at pH 7.The results indicate that many soils of the tropics can be characterized effectively by their PZC's. One should be aware, however, of the effects of strongly adsorbed ions commonly present in these soils and thus use those supporting electrolytes for the PZC determinations which counteract these effects.     

Charge distribution of selected venezuelan soils with some pedogenic and agrotechnological implications

Abstract

A study of the electrical charge distribution of selected Venezuelan soils (two Oxisols, two Ultisols, and one Alfisol) by potentiometric titration (PT) and ion adsorption (IA) procedures, showed that all soils have a predominance of negative charge at their natural pH level and within the experimental pH range used (3.5–7.5). The only exception was the Amazonas 2 soil, which has a point of zero net charge (PZNC) at pH 3.5. Potentiometric titration (PT) results allowed us to find the point of zero salt effect (PZSE) of these soils, which is related to their pedogenetic development. The order found, from older to younger, was: Guanipa (Oxisol) > Amazonas (Oxisol) > Lomas de Cubiro (Ultisol) > Altos de Pipe (Ultisol) > Barinas (Alfisol). The Stoop's method, used to determine the PZSE of the soils, was found to be a more efficient and shorter way than PT for this purpose. Ion adsorption (IA) was a more realistic way than PT to determine charge distribution for the studied soils. The soils were classified according to their charge distribution, following Gillman and Sinclair (4), as type 1 (Barinas, Lomas de Cubiro, Altos de Pipe, Amazonas 1) and type 2 (Amazonas 2 and Guanipa). This classification has agrotechnological and management implications related to the effect of added amendments, fertilizer and pollutants that would interact as ions in these soils. The low anion exchange capacity (AEC) of all these soils means low absorption capacity for non‐specifically adsorbed anions, and therefore, their probable ease of leaching down through the soil profile.     

Surface charge characteristics of volcanic‐ash‐soils from Spain. Effect of organic matter and mineralogical composition

Abstract

Surface charge characteristics of several Spanish Andosols were investigated. The relationship between these characteristics and the mineralogical composition and organic matter content of the soils were also taken into account.

The electro‐chemical behaviour of the soils was similar to that of many metallic oxides, in which the surface charge is determined exclusively by the activity of potential determining H and OH^‐ ions in the bulk solution.

The ZPC of the soils varies between 3.7 and 5.1 and always remains below the zero point of titration (between 0.6 and 10 meq/100g). These low ZPC values seem to be related to the high content of organic matter in the soils, but no clear correlation between both values has been found.

The mineralogical composition and the percentage of amorphous oxides in the soils, on the other hand, had an effect on the charge characteristics’. A correlation coefficient (r=0.801) was found between the Al₂O₃% and ZPC value of the soils.     

可变电荷土壤中铜离子的解吸

研究了我国四种可变电荷土壤红壤、赤红壤、砖红壤和铁质砖红壤以及二种恒电荷土壤黄棕壤和黑土中吸附性铜离子的解吸特征。研究结果表明 ,可变电荷土壤吸附的一部分铜离子可以被去离子水解吸 ,而且在pH～解吸率曲线上在一定pH值时出现解吸率最大值。在最大值时不同土壤中铜离子解吸率的大小与土壤中氧化铁的含量有关。氧化铁的含量越高 ,在最大值时铜离子的解吸率越大。当用中性电解质解吸可变电荷土壤吸附的铜离子时 ,电解质的浓度越大 ,解吸率越低。与此相反 ,恒电荷土壤吸附的铜离子不能被去离子水解吸 ,只能被中性电解质解吸 ,且电解质的浓度越高 ,解吸率越大。这表明 ,可变电荷土壤中吸附性铜离子的解吸规律 ,完全不同于恒电荷土壤中者。本文初步讨论了其原因     

Mineralogy and factors controlling charge development of three Oxisols developed from different parent materials

Three Oxisols, developed from serpentinite (Sungai Mas Series), basalt (Kuantan Series) and andesite (Segamat Series), selected to represent the most common Oxisols in Malaysia were sampled and studied. The objectives of this study were: (i) to determine mineralogical composition and factors responsible for changes in point of zero charge (pH₀) of the variable charge component of three Oxisols; (ii) to use pH₀ values to assess degree of chemical weathering; and (iii) to determine the magnitude of variable charge using corrected back-titration technique. The mineralogical composition was determined by X-ray diffraction analysis (XRD). The pH₀ was determined by potentiometric titration in different electrolyte strengths. The magnitude of variable charge generation as a function of soil pH was measured using corrected back-titration to allow elimination of charge overestimation caused by solid dissolution and hydrolysis reactions. The results showed that the mineralogical composition were similar (kaolinite, goethite, hematite and gibbsite) between profiles but different in proportion, except for gibbsite which was absent in the andesite-derived soil. The sequential removal of soil organic matter (SOM), iron oxides and SOM together with iron oxides resulted in the changes of pH₀ from 3.9–5.7 to 5.3–6.7, 2.6–3.7 and 3.3–4.5, respectively. These pH₀ changes indicate SOM and sesquioxides are masking mineral surfaces and are factors responsible for lowering and increasing pH₀ values, respectively. Regression correlation (R² = 0.87^??) showed that for every 1% organic C may decrease 1.0 unit of pH₀ value. The pH₀ values, after SOM removal, are in the order of Sungai Mas ～ Segamat > Kuantan Series. This suggests that the serpentinite and andesite-derived soils have achieved a relatively similar degree of chemical weathering and they are more weathered than the basalt-derived soil. The charge measured by corrected back-titration is 1.5–3.8 cmol_c kg^? 1 at pH 4.5 and increases to 4.2–10.8 cmol_c kg^? 1 at pH 6.5, indicating that the three Oxisols mainly bear variable charge. Charge overestimation resulted from dissolution and hydrolysis reactions during potentiometric titration ranges from 36 to 160%, depending on pH values (the lower the pH the higher is the overestimation). Hence, back-titration is a reliable technique to correct charge overestimation when using the traditional potentiometric titration for highly weathered tropical soils.     

Grade of weathering and fertility of volcanic ash soils of Aso volcano

Texture is one of the major criterions in soil classification, probably because it has a decisive influence on soil properties. This is particularly true for volcanic ash soils. Most ashes are largely composed of sand and silt particles with little clay (11, 15). The ash weathers very rapidly (1), and clay site particles less than 2 microns in diameter occur even within a few months, as shown by Ishii at the authors' laboratory. Those clay size particles produced in the early stage of weathering are slightly weathered ones (2), and are still subject to rapid weathering, losing bases and silica under humid and well drained conditions. In consequence the clay fraction of volcanic ash soils is composed of particles which vary in degree of weathering from slightly altered glass and feldspar to true clay mineraloids and minerals. The clay fraction of younger soils as a whole is less and that of older ones is more weathered. Weathering brings a remarkable change in the properties of volcanic ash soils; for example, an inerease in soil acidity, lowering of base saturation and bulk density, or accumlation of organic matter. These changes must exert a great influence on soil fertility directly or indirectly.     

可变电荷土壤中特殊化学现象及其微观机制的研究进展

综述了近年来可变电荷土壤化学研究的进展,着重总结了可变电荷土壤中的盐吸附、铁铝氧化物对土壤自然酸化的抑制作用和离子强度对离子专性吸附的影响等特殊化学现象及其微观机制的研究进展。用颗粒表面扩散层重叠导致有效电荷数量减小的原理解释了盐吸附现象和铁铝氧化物对土壤自然酸化的抑制作用。阐明了可变电荷土壤和矿物中介质离子强度影响离子专性吸附的机制,用四层吸附模型解释了离子专性吸附随离子强度增大而增加的现象,并根据胶体zeta电位随离子强度改变而变化的趋势进一步证明了离子强度增大使胶体专性吸附面上静电电位的绝对值减小,是离子专性吸附随离子强度增大而增加的主要原因。带电颗粒表面双电层结构和双电层相互作用的深入研究,有助于阐明可变电荷土壤中一些特殊化学现象的微观机理,从而进一步完善土壤化学理论。     

磷的吸附和表面电荷特征及其与华南地区某些土壤矿物的关系

The phosphate adsorption and surface charge characteristics of the tropical and subtropical soils derived from different parent materials in China were determined, and their relations to soil mineralogy were analysed. The results showed that all soil phosphate adsorption curves were well fitted by Freundlich equation and Langmuir equation. The maximum buffering capacity of P ranged from 66 to 9 880 mg kg^-1, with an increasing order of purple soil, skeletal soil, red soil, lateritic red soil, yellow soil and latosol; and the highest value was 149 times the lowest value, which indicated great differences among these soils in phosphate adsorption and supplying characteristics. The pH₀ (zero point of charge) values obtained by salt titration-potential titration varied from 3.03 to 5.49, and the highest value was found in the latosol derived from basalt whereas the lowest value was found in the purple soil. The correlation analysis indicated that the main minerals responsible for phosphate adsorption in the soils were gibbsite, amorphous iron oxide and kaolinite; and the pH₀ was mainly controlled by kaolinite, gibbsite and oxides.     

Adsorption of silica in river waters by soils in central Chile

The adsorption of the silica in water by soils was investigated using principal river waters and soils collected in central Chile from about 34° to 41° south latitude. The adsorption of silica in water (y) was linearly proportional to the silica concentration in river waters (x) as shown by the following equation:

y=bx-a

where a and b were constants being subject to the nature of the soils. The silica contentration in river waters appeared to relate closely to the rocks in the catchment area. and was high in rivers from volcanic ash areas. However, the salt concentration had no correlation with the silica concentration, and tended to lower to the southward with an increase in annual precipitation and a decrease in annual mean temperature. Sulphate appreciably lowered the adsorption of silica by soils, although chloride and nitrate had little effect on the adsorption. The a-value, dissolution of silica in pure water, was the largest in paddy and alluvial soils, and both the a- and b-values were less in surface soils .in comparison with those of lower horizons. Soils caused neither adsorption nor dissolution of silica at a certain silica concentration. This silica zero adsorption concentration differed greatly from soil to soil, and the largest value which was observed in the surface soil of an irrigated paddy soil was so large that it could not adsorb silica from any river water in the central Chile. In contrast to this soil, an imogolitic subsoil of an Ando soil exhibited the highest adsorption concentration, i.e. it was possible to adsorb silica from every river water in the central Chile. Humus seemed to protect soil silica from dissolution and at the same time to prevent adsorption of silica by soils. Allophanic colloids were labile in water without humic-material, readily releasing silica into the water.     

恒电荷土壤及可变电荷土壤与离子间相互作用的研究 Ⅱ.共存体系中Cl-的吸附特性

对 3种可变电荷土壤和 4种恒电荷土壤在陪伴阳离子分别为Na 、K 、NH 4 、Mg2 、Ba2 、Al3 和共存SO2 -4下Cl- 的吸附量进行了测定。结果表明 ,供试土壤的Cl-吸附量顺序均为AlCl3>BaCl2 和MgCl2 >KCl和NH4 Cl>NaCl,其中可变电荷土壤的差异较大。不同电解质溶液中Cl- 吸附量的顺序与土壤所带正电荷量的顺序一致。Langmuir方程的K值较小 ,且在不同介质中的差异不大。随SO2 -4浓度的增大 ,可变电荷土壤对Cl- 的吸附量减少 ,平衡液的pH值增大 ,而恒电荷土壤则变化甚微 ,说明共存的SO2 -4使可变电荷土壤的表面负电荷增加 ,但对恒电荷土壤则影响不大。这些结果说明 ,Cl- 以电性吸附的机理不因介质而变。可变电荷土壤在一价阳离子存在时 ,除土壤本身所带的正电荷外 ,还有一价阳离子吸附后产生的正电荷以及由此引起的对Cl- 的协同吸附。在二、三价阳离子存在时 ,还有Cl- 的离子对吸附 ,而恒电荷土壤在所有介质中 ,似乎总是以与Cl- 的协同吸附为主     

典型热带土壤时间序列的电荷零点变化特征及其土壤发生意义

本研究选取海南岛北部玄武岩上不同发育时间的土壤进行研究,通过电位滴定法测定土壤的电荷零点,并结合XRD衍射测定土壤中的黏土矿物,探讨热带地区电荷零点随土壤发育程度的变化及其指示意义。结果表明:热带地区土壤电荷零点随土壤发育时间延长而升高,土壤中黏土矿物含量的变化和金属氧化物的增加是导致这一现象的主要原因,另外黏土矿物的种类和结晶程度也会影响到电荷零点的大小。电位滴定曲线的数据表明,随着土壤发育程度的加深,土壤永久负电荷减少,土壤的缓冲性能和保肥能力下降。对比其他指示土壤发育程度的指标,电荷零点大小能更好地表征热带地区土壤发育时间的长短,评估土壤发育程度强弱。     

Zero Point of Charge of Organo—Mineral Complexes

Five soil sapmles collected from China and two soil samples from Pakistan with widely different origin and characterstics were used to study the zero point of charge(ZPC) of soil colloids.The results showed that the value of zero point of charge of H-clay complexes was lower than that of H-clays in all the samples.Natural clay complexes had the highest ZPC as compared to -Hclay complex and H-clay in alfisol,closer to H-clays rather than H-clay complexes in oxisol and udult.The Delta Value of ZPT(zero point of titration )to ZPC was higher in H-Clay complexes than in H-Clays.     

Solubility control of KCl extractable aluminum in soils with variable charge

Abstract

Solubility and kinetic data indicated that concentrations of aluminum (Al) extracted with 1 M KCl are determined by the solubility of a precipitated A1(OH)₃ phase in soils dominated by variable charge minerals. Kinetic studies examining the release of Al on non‐treated and KCl treated residues indicated the precipitation of an acid‐labile Al phase during the extraction procedure. The log ion activity products estimated for the KCl extracts ranged between 8.1–8.6 for the reaction Al(OH)₃ + 3H⁺ < = > Al³⁺+ 3H₂O, which was similar to the solubility product of several Al(OH)₃phases. The mechanism proposed for Al precipitation indicated that Al released by exchange with added K⁺ hydrolyzed and released H⁺ that was readily adsorbed on surfaces of variable charge minerals. The increased ionic strength of the extracting solution further increased the amount of H⁺adsorbed to the variable charge surface and reduced the H⁺ concentration in the aqueous phase. Consumption of H⁺ induced further hydrolysis of Al, resulting in supersaturation of the extracting solution and formation of polynuclear hydroxy Al species. It was concluded that the 1 M KCl extraction does not quantitatively extract salt exchangeable Al from variable‐charge soils.     

从高山火山灰中提取铝, 铁和有机碳的可供选择的方法

Montane volcanic ash soils contain disproportionate amounts of soil organic carbon and thereby play an often underestimated role in the global carbon cycle.Given the central role of Al and Fe in stabilizing organic matter in volcanic ash soils,we assessed various extraction methods of Al,Fe,and C fractions from montane volcanic ash soils in northern Ecuador,aiming at elucidating the role of Al and Fe in stabilizing soil organic matter(SOM).We found extractions with cold sodium hydroxide,ammonium oxalate/oxalic acid,sodium pyrophosphate,and sodium tetraborate to be particularly useful.Combination of these methods yielded information about the role of the mineral phase in stabilizing organic matter and the differences in type and degree of complexation of organic matter with Al and Fe in the various horizons and soil profiles.Sodium tetraborate extraction proved the only soft extraction method that yielded simultaneous information about the Al,Fe,and C fractions extracted.It also appeared to differentiate between SOM fractions of different stability.The fractions of copper chloride-and potassium chloride-extractable Al were useful in assessing the total reactive and toxic Al fractions,respectively.The classical subdivision of organic matter into humic acids,fulvic acids,and humin added little useful information.The use of fulvic acids as a proxy for mobile organic matter as done in several model-based approaches seems invalid in the soils studied.