Manganese retention by selected calcareous soils as related to soil properties

Abstract

Calcareous soils often need supplemental manganese (Mn) to support optimum plant growth, but some reports show that the apparent recovery of applied Mn is very low in such soils, i.e., nearly all of the applied Mn is retained in the soil. This experiment was conducted to find the relationship between the retained Mn and selected properties of calcareous soils. Eleven surface (0–20 cm) soil samples with pH ranging from 7.7 to 8.1 and calcium carbonate equivalent (CCE) ranging from 20 to 50% were used in the Mn adsorption study. Two‐gram subsamples of each soil were equilibrated with 20 mL of 0.01M CaCl₂ solutions initially containing 10 to 200 mg Mn L^‐1. The Mn that disappeared from solution (after 6 h shaking at 25°C) was considered as adsorbed (retained) Mn. The adsorption data showed a highly significant fit to Freundlich and also to the two‐surface Langmuir adsorption isotherms. The coefficients of both isotherms showed significant positive correlations with cation exchange capacity (CEC), organic matter (OM), and CCE of the soils indicating that OM and calcium carbonate are the sites of Mn retention in calcareous soils. Comparison of the adsorption data of this experiment with those of plant Mn uptake of the same soils (published earlier) shows that as the Langmuir second surface adsorption maxima (maximum retention capacity) of the soils increase the plant Mn concentration and uptake decrease.     

典型潮土剖面主要性质和微量金属垂直分布特征

对不同利用方式下石灰性潮土剖面主要性质和微量金属元素含量垂直分异规律进行了初步研究。结果表明,长期耕种的菜地和旱地0～15cm表层土壤有机碳含量高于其他土层,pH和CaCO3含量低于下层土壤;表层土壤Cd已明显积累;但Cd、Pb、Cu、Zn含量均未超过国家土壤环境质量二级标准。几种微量金属全量在菜地和旱地表层土壤之间没有显著差异,但菜地表层土壤DTPA可提取态Cd含量显著高于旱地。从微量金属的剖面分布看,石灰性潮土全量Cd和DTPA可提取态Cd、Pb、Cu、Zn均有明显的表聚现象,这种分布与土壤有机碳含量、pH和CaCO3含量显著相关。聚类分析表明,该区域耕作土壤环境分析样品的采集以表层土壤0～15cm多点混合样品为宜。     

Adsorption isotherms of some heavy metals under conditions of their competitive adsorption onto highly calcareous soils of southern Iran

Recently, application of sewage sludge or effluents resulted in raising the concentrations of some heavy metals in some agricultural soils of Iran. Experiments were conducted to evaluate the competitive adsorption of lead (Pb), copper (Cu), zinc (Zn), and cadmium (Cd) on six calcareous soils. Adsorption characteristics were evaluated by equilibration of 1 g of each soil sample with 20 ml of 0, 10, 20, 30, 40, 50, 100, or 200 mg L^?1 of their nitrate solutions and 0.01 M NaNO₃ as background electrolyte. Furthermore, solid/liquid distribution coefficients (K_d) of studied metals, as an index of soil capacity to resist a change of the soil solution concentration, were calculated. Results indicated that amounts of adsorbed Pb, Cu, Zn, and Cd increased with increase in their concentrations in the contact solutions, but this trend was more pronounced for Pb and Cu than the others. For all studied soils and metals, Langmuir equation described the adsorption behavior fairly well. Furthermore, Langmuir and Freundlich equation parameters were positively correlated to cation exchange capacity (CEC) and smectite contents; whereas, they were negatively correlated to sand content. Considering K_d values, the selectivity sequence of the metal adsorption was Pb > Cu > Zn > Cd. Therefore, the risk of leaching and also plant uptake of Zn and Cd will be higher as compared to those of the other elements.     

Zinc distribution in Zimbabwean soils and its relationship with other soil factors

Abstract

The distribution of zinc in some major Zimbabwean soils was studied using 120 profiles taken from 22 different locations. The total zinc status (TL‐Zn) of the horizons of soils studied was low (8 ppm), and the range was narrow (3.7 to 16.3 ppm). The residual zinc (RS‐Zn) fraction was about 65 percent of the total zinc found in the soils, while 15 percent was organically bound zinc (OG‐Zn), 14 percent was available zinc (MG‐Zn), and 6 percent was zinc associated with hydrous metal oxides (OX‐Zn). The total zinc status of the soils was related to parent material. Generally, texture had a significant effect on zinc distribution with heavier textured soils having more zinc in most fractions than the lighter textured soils. A decrease in zinc down the profile was observed for available, residual, and total zinc. If cropped intensively, 32 per cent of the soils with less than 1 ppm available zinc have the potential for zinc deficiency. Multiple stepwise regression analysis showed that organic matter, silt and clay contents, available copper, and resin P₂O₅ contents were important for predicting the available zinc content of the soils, while texture and organic matter content were important in predicting total zinc content.     

Boron adsorption characteristics of some acidic alluvial soils in relation to soil properties

Abstract

We investigated boron (B) adsorption characteristics for 16 acid alluvial soils as a function of equilibrium B concentration (0–80 μg/mL) and the effect of soil properties on such adsorption. The adsorption data for the soils could be described by Freundlich, Temkin, and BET isotherm equations over the entire concentration ranges studied, and by Langmuir and Eadie‐Hofstee equations only over a limited range. In general, the B adsorption capacity and the energy of retention of the soils calculated from different equations are low, the average Langmuir adsorption maxima and bonding energy constant being 21.47 μg/g and 0.113 mL/μg, respectively, making B susceptible to leaching losses. Simple and multiple regression analysis show that the adsorption capacities are significantly influenced by organic carbon (C), cation exchange capacity (CEC), and different forms of aluminium (Al) content in soils. The energy related constants are also influenced by the forms of Al in soils. Existence of significant correlations between constants obtained from different equations confirmed the adsorption characteristics of the soils.     

Effect of land use and topography on soil properties and agronomic productivity on calcareous soils of a semiarid region,Iran

In this research, the effects of land use and slope position on soil properties and its agronomic productivity were studied in a greenhouse experiment. The study also covered the effects of water stress, fertilizer treatment and their interactions. Eight soil samples were collected from four slope positions along hill slopes from two adjacent land use types of rangeland and dry farmland in a semiarid region of Iran. Soil samples were analyzed for their physical and chemical properties and yield and yield components of wheat were measured as indices of soil agronomic productivity in a replicated pot experiment. Soils of the dry farmland showed higher fertility and better quality than the soils from the adjacent degraded rangeland, especially at the upper slope positions. The results indicated that yield components of wheat were all higher for the dry farming land compared to the degraded rangeland, and at the bottom of slopes compared to the top. The effect of land use and slope position on agronomic productivity of soil was influenced by water supply. The actual impact on soil productivity of soil degradation, induced by land use and slope position, was overshadowed by the dominating effect of water stress. While both chemical fertilizer and fertilizer + manure treatments enhanced the agronomic productivity of all soils, their effects were much more pronounced on the degraded soils of the rangeland. Water stress reduced fertilizer efficiency on all the soils used in this study. Copyright © 2011 John Wiley & Sons, Ltd.     

Density separation of soil organic matter across three land uses in calcareous soils of Iran

ABSTRACT

The aim of this study was to examine the usefulness of physical and chemical fractionation in quantifying soil organic matter (SOM) in different stabilized fraction pools. Soil samples from three land use types in Lorestan province, Southwest Iran were examined to account for the amount of organic carbon and nitrogen in different SOM fractions. Size/density separation and chemical oxidation methods were applied to separate the SOM fractions including particulate organic matter (POM), Si + C (silt and clay), DOC (dissolved organic C), rSOM (oxidation-resistant organic carbon and nitrogen) and S + SA (sand and stable aggregates). The values obtained for TOC, TN, and HWC were highest in forest lands followed by the range and agricultural lands. Among the SOM fractions, S + SA showed the highest values (5.75, 5.77 and 20.6 g kg^?1 for agriculture, range and forest lands respectively) followed by POM, Si + C, rSOM, and DOC. The concentrations of C and N in the labile fractions obtained the higher values than in the stabilized fractions. Forest lands had the highest amounts of organic C and N among all fractions whereas agricultural lands showed highest values for inorganic C content of soils in different fractions.     

伊朗一些石灰性土壤中锌解吸动态研究

Desorption of zinc (Zn) from soil is an important factor governing Zn concentration in the soil solution and Zn availability to plants. Batch experiments were performed to study the kinetics of Zn desorption by diethylenetriaminepentaacetic acid (DTPA) from 15 calcareous soil samples taken from Golestan Province in northern Iran. Soils were equilibrated with 0.005 mol L-1 DTPA solutions for 0.25 to 192 h. The results showed that the extraction process consisted of rapid extraction in the first 2 h followed by much slower extraction for the remainder of the experiment. Desorption kinetic data was fitted to pseudo-first-order kinetic model. The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 2 h. The model of two first-order reactions was fitted to the kinetic data and allowed to distinguish two pools for Zn: a labile fraction (Q1 ), quickly extracted with a rate constant k1 , and a slowly labile fraction (Q2 ), more slowly extracted with a rate constant k2 . The applicability of pseudo-second-order model in describing the kinetic data of Zn desorption was also evaluated.     

Effects of soil properties and trace metals on urease activities of calcareous soils

A study was conducted to investigate the relationship between urease activity and some physical, chemical, and microbiological properties of soils from central Iran. Inhibitory effects of Cr, Cd, and Pb on urease activity were also studied. Results indicated that no significant difference was observed between urease activity of field-moist and air-dried soils. Soil organic C and total N correlated highly significantly with urease activity, with r values of 0.899*** and 0.797***, respectively. There was also a significant correlation between urease activity and the number of bacteria grown on urea-agar media, with r value of 0.470*. A significant negative correlation (r =–0.492*) was observed between urease activity and electrical conductivity of saturation paste extracts. There were no significant correlations between urease activity and soil textural properties, pH, calcium carbonate equivalent, cation exchange capacity, and populations of soil bacteria on nutrient agar and population of soil fungi on potato dextrose agar. Both Cd and Pb inhibited urease activity to a similar extent and to a greater extent than did Cr.     

伊朗中部伊斯法罕地区土地利用对石灰性土壤磁性质和重金属的空间分布的影响

Anthropogenic activities have caused the accumulation of heavy metals in the soil environment. Pollution of the soils significantly reduces environmental quality and affects human health. In many recent studies, magnetic susceptibility measurements have been used for pollution monitoring. The objective of this research was to determine the spatial variability of magnetic properties and selected heavy metals and the effects of land use on their variability in the surface soils of the Isfahan region, Central Iran. A total of 158 composite surface (0-5 cm) samples of calcareous soils were collected from an area of about 700 km2, located along a cross-border transect from Isfahan City to a steel plant, covering urban, industrial, agricultural and uncultivated land uses. Concentrations of copper (Cu), zinc (Zn), lead (Pb), manganese (Mn), iron (Fe), nickel (Ni), chromium (Cr), and cobalt (Co) and magnetic parameters, magnetic susceptibility at low frequency (χlf), natural remanent magnetization (NRM), saturation isothermal remanent magnetization (SIRM), and isothermal remanent magnetization at the field of 100 mT (IRM100mT) and the backfield of 100 mT (IRM-100mT), were measured in all the soil samples. Results showed that magnetic susceptibility in the urban and industrial land topsoils (0--5 cm) samples was significantly higher than that in the agricultural and uncultivated land soils in the study area. Concentrations of Cu, Zn, Pb, Mn, and Fe were positively correlated with magnetic properties (χlf, IRM100mT, SIRM, IRM-100mT, and NRM), which could be attributed to their inputs from traffic emissions and industrial activities at the study sites. Ni and Cr concentrations showed significant negative correlations with magnetic properties. No significant correlation was found between Co concentration and magnetic parameters. The Tomlinson pollution load index (PLI) showed significant correlation with the magnetic properties (χlf, IRM100mT, SIRM, IRM-100mT, and NRM). The spatial distribution of the selected heavy metals and χlf in the study area suggested that activities at the urban and industrial land sites caused greater pollution as compared to that at the study sites of other land uses. The concentrations of Cu and Zn seemed to have been affected by anthropogenic sources, whereas Ni, Cr, and Co were mainly controlled by natural sources in the study area. Moreover, the concentrations of soil Pb and Fe in the study area could be affected by both lithologic and anthropogenic sources. The magnetic parameters appeared to be a proxy measure for the degree of heavy metal contamination and could be a potential method for the detection and mapping of contaminated soils.     

Zinc desorption kinetics from some calcareous soils of orange (Citrus sinensis L.) orchards,southern Iran

Zinc (Zn) desorption is an important process to determine Zn bioavailability in calcareous soils. An experiment was performed to assess the pattern of Zn release from 10 calcareous soils of orange orchards, southern Iran and the soil properties influencing it. For Zn desorption studies, soil samples were extracted with diethylene triamine penta-acetic acid solution at pH 7.3 for periods of 0.083–48 h. Suitability of seven kinetic models was also investigated to describe Zn release from soils. Generally, Zn desorption pattern was characterized by a rapid initial desorption up to 2 h of equilibration, followed by a slower release rate. The simple Elovich and two-constant rate kinetic models described Zn release the best, so it seems that Zn desorption is probably controlled by diffusion phenomena. The values of the rate constants for the superior models were significantly correlated with some soil properties such as soil organic matter (SOM) content, cation exchange capacity (CEC), and soil pH, whereas carbonate calcium equivalent and clay content had no significant influence on Zn desorption from soils. SOM had a positive effect on the magnitude of Zn release from soils, while soil pH showed a negative effect on Zn desorption. Furthermore, the initial release rate of soil Zn is probably controlled by CEC in the studied soils. Finally, it could be concluded that SOM, CEC, and soil pH are the most important factors controlling Zn desorption from calcareous soils of orange orchards, southern Iran.

Abbreviations: Soil organic matter (SOM); Cation exchange capacity (CEC); Calcium carbonate equivalent (CCE); Zinc (Zn).     

Factors affecting potassium fixation in calcareous soils of southern Iran

Potassium fixation capacity and mineralogical analysis of 24 representative soils, collected from southern Iran, were studied. Potassium fixation analysis was performed by adding six rates of K from 0 to 1000 mg kg^?1 soil in a plastic beaker and shaking for 24 h. Mineralogical analysis showed that the clay fractions were dominated by smectite, chlorite, mica, palygorskite, vermiculite and quartz. In general, the studied soils fixed 8.5–55% of the added K. The potassium fixation capacity of the studied soils was significantly correlated with smectite content (r ² = 0.87), clay content (r ² = 0.60), cation-exchange capacity (r ² = 0.79) and NH₄OAc-K. Wetting and drying treatment and incubation time had significant effects on K fixation. The average percentage increase in K fixation following the wetting and drying treatment was 24 and 30% for surface and subsurface soils, respectively. The average percentage increase in K fixation with increasing residence time was 79 and 56% for surface and subsurface soils, respectively. Because K fixation is a diffusion process, time and increased concentration of soluble K (because of soil drying) are factors affecting the rate of K diffusion from a soil solution to the interlayer positions of the expansible 2:1 clay minerals.     

The relationship between copper accumulated in vineyard calcareous soils and soil organic matter and iron

The intensive use for over 100 years of copper sulphate (Bordeaux mixture) to fight mildew in vineyards has led to a substantial accumulation of copper (Cu) in surface soils. To assess the effects of such large concentrations, the surface soils of 10 Burgundy vineyards were sampled and analysed for total organic matter (carbon and nitrogen) and metal (copper and iron) contents. Physical (i.e. size fractionation) and chemical (sequential extraction) methods were used to determine the distribution of these elements. The most Cu‐contaminated plots showed the largest accumulation of organic carbon and Cu in the coarse sand and fine sand fractions. Copper was strongly correlated with organic carbon and organic nitrogen in the coarse sand fraction and with organic nitrogen in the fine sand fraction. Copper was also highly correlated with both Fe and organic nitrogen in the clay fraction but not significantly with organic carbon. The sequential extraction showed that Cu was bound mainly to the Fe oxides. However, in the most Cu‐contaminated plots, a part of added Cu was bound to organic matter. This study suggests that Cu protected indirectly the organic matter present in the coarse fractions against biodegradation, and therefore modified the distribution of organic carbon among the particle‐size fractions. Iron appeared as the main factor responsible for Cu accumulation in the clay fraction, mainly through inclusion of Cu in Fe oxyhydroxides and possibly in clay–humus complexes.     

Quantitative relationship between soil properties and adsorption of dissolved organic matter onto volcanic ash and non-volcanic ash soils

The formation of soil organo-mineral complexes is a key reaction in the carbon cycle in soil, since organic materials acquire a resistance to decomposition due to the formation of the complexes. Adsorption of dissolved organic matter (DOM) onto soil minerals provides a model of this important process. Adsorption of DOM onto samples from Andisols, Inceptisols, and Entisols in batch experiments was compared in terms of the quantitative relationship between the soil properties and the adsorption behavior of DOM. Adsorption behavior was effectively described by a linear initial mass (IM) isotherm, indicating that the adsorption efficiency did not appreciably decline in the range studied even though a large amount of DOM was applied to the soil samples. Samples from Andisols showed a particularly high efficiency of adsorption compared with those from other soils which contained a comparable amount of organic carbon. Explanatory variables useful to predict the efficiency parameter were investigated in 2 steps: firstly the degree of carbon accumulation in the soil samples was examined, and next an index for the amount of ligand exchange sites was examined in combination with the former indices. As a result, an index comprising the total carbon/clay (or total carbon/specific surface area) ratio and the amount of hydroxy ions in the soil extracts with NaF solution was eventually detected. The former represents the degree of carbon occupation on the soil surface, and the latter the amount of ligand exchange sites on labile aluminum. Although the mechanisms involved in the adsorption varied among soils, the selected index was significantly correlated with the adsorption efficiency.     

Impacts of land use on soil organic matter and degree of compactness in calcareous soils of central Iran

This study was conducted to investigate the impact of land use (dryland farming, grassland and irrigated farming) on bulk density, (ρ_b) and relative bulk density (ρ_b‐rel), and to study the relationships between ρ_b and ρ_b‐rel, respectively, and soil organic matter content (OM) and soil texture at 100 locations in calcareous soils of central Iran. The ρ_b–rel was expressed as the ratio of ρ_b to a reference bulk density, ρ_bef. By considering ρ_b‐ref an inherent soil property that is dependent on soil texture but not on OM, the combined effects of OM due to land use and compaction (due to agricultural machinery) on the degree of compactness could be explored. Multiple linear regression was used to derive pedotransfer functions for predicting ρ_b and ρ_b‐rel. It was found that ρ_b‐rel is strongly affected by OM, and a strong correlation was obtained between ρ_b‐rel and the ratio of OM to clay content. The predictive performance of the multiple regression models was poorest for irrigated farming, which might be explained by intensive soil disturbance by tillage in irrigated farming. The main effect of land use was on OM, and consequently, the degree of compactness was mainly controlled by OM. The greatest OM and least ρ_b‐rel were measured in irrigated farming. Dryland farming had the least OM and the greatest ρ_b‐rel.     

Transformation kinetics of inorganic P forms in relation to calcareous soil properties of western Iran

This study was conducted to investigate the effect of time on chemical forms of P in 10 calcareous soils of western Iran. Phosphorus was added to soils at the rate of 200 mg kg^?1 as KH₂PO₄. The samples were incubated for 1, 7, 15, 30, 60, 90 and 120 days at 25°C and constant moisture. After incubation, P was fractionated by the sequential extraction procedure: soluble and exchangeable P (NaHCO₃-P) Al + Fe-P (NaOH-P), Ca-P (HCl-P) and residual P (Res-P). The distribution of added P into different fractions consisted of two phases involving initial rapid retention followed by a slow continuous retention. In general, the majority of the P applied entered mostly in the HCl-P and Res-P fractions. After 120 days incubation, the HCl-P fraction remained the most dominant in all soils. A combination of silt and sand content of the soils together explained between 88.5 and 83.3% of the variance inNaHCO₃-P and HCl-P transformation rates, respectively, 76.6 and 72.8% of which is explained by silt alone. CaCl₂-P and electrical conductivity (EC) together accounted for 66.3% of the variation in the rate constant of NaOH-P. The release rate of Res-P was not significantly related to soil properties.     

Spatial variability of physico-chemical properties and hydraulic characteristics of a gravelly calcareous soil

Due to the existence of gravelly soils and the lack of sufficient research on such soils, this study was carried out on a gravelly calcareous soil. Selected physico–chemical and hydraulic soil attributes were determined at 69 points on a nested-sampling design. Hydraulic characteristics including unsaturated hydraulic conductivity (K _ψ) and sorptivity coefficient (S) at six applied tensions of 0 to 0.2 m, and sorptive number (α) and macroscopic capillary length (λ) at five applied tensions of 0.03 to 0.2 m were determined using a tension disc infiltrometer. Hydraulic and chemical soil attributes were the highest and the lowest variants, respectively. The maximum and minimum values for the coefficient of variation (CV) in all the measured physico-chemical and hydraulic soil attributes were obtained for α_0.2 and soil pH, respectively. Minimum, maximum, mean and variance values of K _ψ, S and α decreased as applied tension increased. Although the pattern was reversed for λ. The majority of soil attributes showed the spatial structure with dominant spherical and exponential models for physico-chemical and hydraulic attributes, respectively. Range values of semi-variograms were obtained between 4.6 m (for α_0.03) and 211 m (for clay, gravel content and soluble Mg). In general, range values were 99.60, 82.05 and 40.2 m for physical, chemical and hydraulic soil attributes, respectively, indicating that the physical soil attributes influenced neighboring values over greater distances than the other soil attributes. This enables soil scientists to use measured soil physical data over greater distances to estimate attributes in the unsampled locations.     

Mercury content in volcanic soils across Europe and its relationship with soil properties

Purpose  

Volcanoes are a natural source of Hg, whose deposition can occur in neighbouring soils. This study examines the role of soil compounds in the geochemical behaviour of total Hg (Hg _T ) in volcanic soils. An estimation of Hg from lithological origin is also assessed to ascertain the relevance of other sources in Hg _T accumulated in volcanic soils.     

有机质含量对石灰性黄潮土和砂姜黑土磷吸附–解吸特性的影响

通过往土壤中添加不同量小麦秸秆,经好气培养1年后,获得不同有机质含量梯度的系列土壤,研究有机质含量对石灰性黄潮土和砂姜黑土磷（P）相关吸附参数和不同水土比下解吸溶液P浓度的影响。结果表明,Langmuir方程能够较好地拟合不同有机质含量的两种土壤对P的等温吸附曲线,拟合度均达到显著（P 0.05）或极显著（P 0.01）水平。黄潮土和砂姜黑土P最大吸附量（Xm）、吸附结合能常数（K）、最大缓冲容量（MBC）、吸附饱和度（DPS）及相同水土比下P解吸溶液浓度与有机碳含量间均呈显著或极显著的二次抛物线关系。抛物线拐点之前,随有机质含量的提高,P的吸附能力增强,解吸能力降低;拐点之后,吸附能力降低,解吸能力增强。各水土比条件下,P解吸溶液浓度与Xm、K、MBC呈显著或极显著负相关,与DPS呈显著或极显著正相关。随有机质含量的提高,土壤P植物有效性和P流失风险呈先降低后增强的抛物线趋势;土壤供P缓冲能力则先增强后降低。砂姜黑土Xm、K、MBC均明显高于黄潮土,DPS明显低于黄潮土;且其抛物线拐点滞后,拐点横坐标有机碳含量明显高于黄潮土。不同有机质含量的解吸曲线较黄潮土排列紧密;砂姜黑土黏粒含量、碳酸钙含量明显高于黄潮土,全P和Olsen-P含量明显低于黄潮土,这可能是影响两种石灰性土壤P吸附–解吸特性差别的主要原因。     

Zinc requirement of corn grown on two calcareous soils of Pakistan

In greenhouse studies, corn (Zea mays L.) growth increased with Zn fertilization of two alkaline calcareous soils. Zinc concentration and total uptake increased with Zn application. Very high correlations were recorded between plant tissue Zn concentration, total Zn uptake and soil Zn levels determined by DTPA and AB-DTPA soil tests. Correlation between Zn concentration in plants and relative yield was poor. However, close relationships were revealed between extractable soil Zn and relative yield. Near maximum dry matter yield of corn was associated with a fertilizer rate of 2 mg Zn/kg soil. Plant tissue Zn-requirement was 27 mg/kg in 15 days old plants and 32 mg/kg in corn shoots of 40 day age. Critical soil test Zn level was 1.2 mg/kg by DTPA and 1.7 mg/kg by AB-DTPA method. Use of AB-DTPA soil test is suggested for evaluating Zn status of calcareous soils.