Soil structural indices' dependence on irrigation water quality and their association with chromophoric components in dissolved organic matter

Irrigation with treated wastewater (TWW) may affect soil structure and stability and the characteristics of dissolved organic matter (DOM) of the soil solution. The objectives of our study were (i) to evaluate the impact of TWW irrigation, as compared with fresh water (FW) irrigation, on aggregate stability and saturated hydraulic conductivity (indices of soil structure stability) and (ii) to determine whether these indices can be associated with the chromophoric indicators of water‐extractable DOM in TWW‐ and FW‐irrigated soils. We studied aggregate stability and soil hydraulic conductivity (HC) of four different soil types irrigated with either TWW (for at least 5 years) or FW. The results were linked to earlier published data on the concentration scores of fluorescent chromophoric DOM components (obtained from excitation‐emission matrices of flouorescence coupled with parallel factor analysis), dissolved organic carbon (DOC) concentration and absorbance at 254 nm (Abs254). These were all obtained from water extracts of the same soils as those used in the current study. Irrigation with TWW decreased aggregate stability, in comparison to irrigation with FW, in the sandy clay and clay soils, while in the loamy sand TWW increased aggregate stability. The apparent steady state HCs in the TWW‐irrigated samples in the loamy sand, sandy clay and clay soils were similar to, or significantly less than, those obtained in the FW‐irrigated samples. In the sandy loam the opposite trend was noted. Results of principal component and classification analyses showed that the aggregate stability indices were directly associated with soil organic matter and DOM attributes in the coarse‐textured soils, while in the fine‐textured soils inverse associations were noted. Only in the fine‐textured soils were the HC attributes associated (directly) with some of the DOM characteristics. Our results suggest that structural indices of fine‐textured soils are more sensitive than those of coarse‐textured soils to the composition of water extractable DOM.     

Influence of homogenized residues of anaerobic digestate on the physicochemical properties of differently textured soils

Because of the focus on renewable energy, new biogas digesters are being built with the consequence of an increased production of anaerobic digestates (AD) as a by‐product. Although they can be used as organic fertilizer on arable fields, negative impacts of these digestates also may occur. Therefore, it was the aim of this laboratory study to investigate the effect of a normally applied volume of 30 m³ ha^?1 of anaerobic digestates derived from a ground input substrate of maize (Zea mays L.) , sugar beet (Beta vulgaris L.), and wheat (Triticum aestivum L.) in different ratios (100 /80 / 20%) on the properties of two soils. The soils, which were homogenized (sieved to ≤ 2 mm) and placed in columns with a defined bulk density of 1.45 g cm^?3, were a Cambic Luvisol (sandy loam) derived from glacial till and a Podzol (sandy sand) derived from glazial outwash. Physicochemical parameters [pH, electrical conductivity (EC)] and the wetting behavior of the soils were analyzed by measuring the contact angle (CA) by using the Wilhelmy–Plate‐Method (WPM) and the Repellency Index (RI) from the sorptivity of water and ethanol. To determine the risk of soil dispersion as a consequence of digestate amendment, the amount of readily dispersible clay (RDC) was determined by detecting the turbidity of a soil suspension. The application of 30 m³ ha^?1 of AD decreased the wettability of the sandy sand as compared to the untreated soil, while the wettability of the loamy sand remained unaffected by the digestate amendment. The amount of RDC was higher in the loamy sand compared to the sandy sand, but the AD‐amended soil did not exhibit a significant change in dispersibility. While the loamy soil exhibited acidification of the soil after digestate application, the sandy soil showed an alkalinization of soil columns. Overall, the soil texture was identified to be a main factor controlling the effect of the digestates on soil properties. The results of this lab study showed that this study can be used as a first approach for the quantification of digestate amendment under practical conditions.     

毛管埋深和层状质地对番茄滴灌水氮利用效率的影响

为了确定不同质地土壤中地下滴灌的适宜毛管埋深,通过两年日光温室滴灌施肥灌溉试验,研究了毛管埋深、土壤层状质地和施氮量对番茄产量、品质及水分利用效率（WUE）、氮肥表观利用率（AFUE）和氮肥偏生产力（PFP）的影响。研究结果表明,均质壤土中,毛管埋深、施氮量及其交互作用对番茄产量和WUE影响不显著,地下滴灌番茄Vc含量比地表滴灌低;番茄AFUE随毛管埋深增加而降低,施氮量由150 kg/hm2增加到225 kg/hm2时,番茄PFP显著降低。对均质壤土,建议毛管埋深15 cm、施氮量150 kg/hm2,以获得较高的PFP。土壤的层状质地结构明显降低番茄的产量、WUE和PFP,与均质壤土处理相比,上砂下壤和砂土夹层处理WUE分别低32%和11%,产量和PFP分别低33%和12%,从提高水氮利用效率的角度出发,建议在上粗下细（上砂下壤）的层状土壤中慎重使用地下滴灌。     

Fate of 15N-Labeled Potassium Nitrate in Different Citrus-Cultivated Soils: Influence of Spring and Summer Application

The fate of ¹⁵N-labeled potassium nitrate (8.5% ¹⁵N excess) was determined in 3-year-old Valencia orange trees grown in 1-m³ containers filled with different textured soils (sandy and loamy). The trees were fertilized either in spring (24 March) or summer (24 July). Spring fertilized trees gave higher fruit yields in sandy than in loamy soils, which exceeded summer fertilized trees in both cases. Summer fertilized trees had greater leaf biomass than spring fertilized trees. Fibrous root weight was 1.9-fold higher in sandy than in loamy soil. At the end of the cycle, tree N recovery from spring application was 45.7% for sandy and 37.7% for loamy soil; from summer fertilization, N recovery was 58.9% and 51.5% for sandy and loamy soils, respectively. The ¹⁵N recovered in the inorganic soil fraction (0?C90?cm) was higher for loamy (1.3%) than for sandy soil (0.4%). Fertilizer N immobilized in the organic matter was lower in sandy (2.5%) than in loamy soil (6.0%). Potential nitrate leaching from fertilizer (¹⁵NO ₃ ^? ?CN in the 90?C110-cm soil layer plus ¹⁵NO ₃ ^? ?CN in drainage water) was 34.8% higher in sandy than in loamy soil. The low N levels in sandy soil resulted from both higher NO ₃ ^? ?CN leaching losses and higher N uptake of plants grown in the former. The great root mass and higher soil temperatures could account for raised plant N uptake in sandy soil and in summer, respectively.     

Acidity Changes of Foreign Acidic Soils Introduced into Calcareous Soil Environment

Abstract

Many tropical plant species originated in areas with acidic soils and do not grow well in calcareous (high pH) soils. It is impossible to acidify soils that have high contents of calcium carbonate in south Florida. Replacing calcareous soils with acidic soils obtained from distant regions is an alternative. Unfortunately, such introduced acidic soils may eventually be neutralized by irrigation and ground water that is saturated with calcium carbonate. The objective of this investigation was to examine the acidity changes and buffering capacities of three types of acidic soils (silica sand soil, red loamy sand soil, and a mixed soil) used to establish tropical plants in a rainforest exhibition at Fairchild Tropical Garden, Miami, FL. The three areas were excavated to remove native calcareous soil, limestone bedrock, and filled with acidic soils. Various rainforest plants were planted. Soil samples were collected in contiguous 10 cm‐deep segments from the soil surface to the bedrock shortly after deposition of the soils and one year later. Soil pH, EC, particle distribution, buffering capacity were determined. Results showed that both silica sand and mixed soils had been neutralized and the soil pH values had risen over 7 in all soil depths after one year. However, less than 10 cm of the surface and bottom soil layers of red loamy sand had been neutralized and the soil pH in the middle of soil profile remained unchanged due to its higher buffering capacity. A column leaching study showed that the acidity in the red loamy sand soil would be neutralized by irrigation water and by capillary movement of groundwater with a high concentration of calcium bicarbonate. Buffering curves indicate that it is easier to maintain acidity in sandy soil than of loamy sand and mixed soils with acidified irrigation water. Indeed it is difficult to acidify the mixed soils with high organic matter content after these soils have been neutralized.     

土壤质地和灌水器材料对负压灌溉出水流量及土壤水运移的影响

负压灌溉法是一种新近提出的节水灌溉技术，灌溉时供水水头为“负值”，即灌溉水源高程低于灌水器高程。不同材料灌水器和土壤质地是影响灌溉系统出水流量及土壤水运移的重要因素。该文研究了在高程差H为-0.5 m情况下两种灌水器及两种质地土壤对两者的影响。结果表明：灌水器相同时，累计入渗量、水平和垂直最大湿润距离随时间呈幂函数关系变化；在历时相同时黏壤土较砂壤土大；湿润体近似为六分之一的竖直椭球体，但黏壤土水平与垂直最大湿润距离之比大于砂壤土。土壤质地相同时，纤维灌水器较陶土灌水器出水流量高。试验结果进一步证明了负压灌溉的可行性，并为确定负压灌溉系统应用范围及规划设计过程中灌水器选择提供了依据。     

The Impact of Agriculture on Soil Texture Due to Wind Erosion

Wind erosion produces textural changes on topsoil of semiarid and arid environments; however, the selection of particles on different textured soils is unclear. Our objectives were to evaluate textural changes induced by wind erosion on cultivated soils of different granulometry and to asses if textural changes produced by wind erosion are linked to aggregation of granulometric particles into different sizes of aggregates formed in contrasting textured soils. Considering this, we studied the particle size distribution (PSD) with full dispersion (PSD_F) of 14 cultivated (CULT) and uncultivated (UNCULT) paired soils and, on selected sites, the PSD with minimum dispersion (PSD_MIN) and the quotient PSD_MIN/F. Results showed that the content of silt plus clay was lower in CULT than in UNCULT in most of the sites. The highest removal of silt was produced in soils with low sand and high silt content; meanwhile, the highest removal of clay was observed in soils with medium sand content. According to PSD_MIN, particles of 250–2,000 μm predominated in the sandy soil, in the loamy soil particles between 50 and 250 μm and in the silty loam soil particles between 2 and 50 μm. For clay sized particles, PSD_MIN/F was lower than 1 in all soils and managements, but this quotient was higher in CULT compared with UNCULT only in the loamy soil. This means a decrease of clay accumulation in aggregates of larger sizes produced by agriculture, which indicates an increase in the risk of removal of these particles by wind in loamy soils. Copyright © 2014 John Wiley & Sons, Ltd.     

Paleosols buried under kurgans of the Pit-grave culture in the steppe zone of the Cis-Ural region

The analysis of soil chronosequences developed from loamy and loamy sandy substrates and buried under kurgans dating back to the Pit-grave archaeological culture in the steppe zone of the Cis-Ural region demonstrated that it is possible to trace the dynamics of the soil properties and to perform paleoclimatic reconstructions for different intervals within the studied period. The properties of sandy soils changed more rapidly than the properties of loamy soils. For sandy soils, notable changes in their properties were revealed in the soil chronosequences dating back to the particular stages of the Pit-grave culture; for loamy soils, such changes could only be traced for the soils buried under the kurgans dating back to different stages of the Pit-grave culture.     

生物质炭与有机物料配施的土壤培肥效果及对玉米生长的影响

生物质炭作为一种多功能的土壤培肥材料被广泛应用,但其与传统有机物料的对比及配施研究还比较少。通过盆栽试验,研究了生物质炭与秸秆、发酵鸡粪单施及配施对壤质潮土和砂土养分含量、酶活性及玉米生长的影响,并采用主成分分析方法对3种有机物料的培肥效果进行综合评价。试验设6个处理,分别为不添加有机物料(CK)、添加生物质炭(BC)、小麦秸秆(WS)、发酵鸡粪(CM)、秸秆和生物质炭(WS+BC)、鸡粪和生物质炭(CM+BC)。研究结果表明,各处理均增加了砂土玉米生物量和株高,3种有机物料的提升幅度排序为:鸡粪生物质炭秸秆,鸡粪还可增加壤质潮土玉米生物量和株高。添加生物质炭和有机物料还可提高土壤有机质含量,其中生物质炭的提升幅度最大。此外,3种有机物料对土壤养分和酶活性的影响各异,单施鸡粪分别增加壤质潮土和砂土的碱解氮22.08%和26.67%,速效磷91.92%和53.65%,脲酶活性40.54%和36.94%;单施生物质炭分别增加壤质潮土和砂土速效磷83.52%和89.91%,速效钾79.38%和127.02%,过氧化氢酶活性3.41%和11.22%,却降低了土壤碱解氮含量,且与鸡粪配施后会抑制鸡粪中氮的有效性;单施秸秆分别增加壤质潮土和砂土速效钾49.48%和63.02%,β-葡糖苷酶活性51.86%和59.09%;生物质炭与鸡粪或秸秆配施可以更均衡地提升土壤肥力。通过主成分分析和相关分析发现,玉米生物量和株高与土壤氮、磷供应正变化的第2主成分(PC2)得分呈极显著正相关关系。因此,3种有机物料中,鸡粪对土壤氮、磷含量及相关酶活性影响最大;秸秆对土壤钾以及纤维素分解相关酶影响较大,而生物质炭对土壤肥力的提升作用更均衡,且土壤肥力综合得分最高。秸秆或鸡粪配施生物质炭可以更全面地提高土壤肥力。     

Nitrogen availability to grain sorghum from organic and inorganic sources on sandy and clayey soil surfaces in a greenhouse pot study

In a greenhouse pot study, we examined the availability of N to grain sorghum from organic and inorganic N sources. The treatments were¹⁵N-labeled clover residues, wheat residues, and fertilizer placed on a sandy clay loam and loamy sand soil surface for an 8-week period. Soil aggregates formed under each soil texture were measured after 8 weeks for each treatment. Significantly greater ¹⁵N was taken up and recovered by grain sorghum in sandy clay loam pots compared with loamy sand pots. Greater ¹⁵N recovery was consistently observed with the inorganic source than the organic sources regardless of soil texture or time. Microbial biomass C and N were significantly greater for sandy clay loam soil compared with the loamy sand. Microbial biomass ¹⁵N was also significantly greater in the sandy clay loam treatment compared to the loamy sand. The fertilizer treatment initially had the greatest pool of microbial biomass ¹⁵N but decreased with time. The crop residue treatments generally had less microbial biomass ¹⁵N with time. The crop residues and soil texture had a significant effect on the water-stable aggregates formed after 8 weeks of treatments. Significantly greater water-stable aggregates were formed in the sandy clay loam than the loamy sand. Approximately 20% greater water-stable aggregates were formed under the crop residue treatments compared to the fertilizer only treatment. Soil texture seemed to be one of the most important factors affecting the availability of N from organic or inorganic N sources in these soils.Contribution from the MissouriAgricultural Experiment Station, Journal Series No.12131     

喷灌强度对滨海盐碱地土壤水盐运移特征的影响

为研究一维条件下喷灌强度对滨海盐碱地土壤湿润峰运移、水分再分布特征及盐分淋洗的影响,选用滨海盐碱地黏质重度盐碱土和砂质重度盐碱土2种土壤,设置5个喷灌强度(分别是1.72、3.13、5.27、8.75、10.11mm/h),进行室内喷灌条件下土柱模拟试验。结果表明,喷灌强度与土壤黏粒含量显著影响湿润锋运移。湿润锋推进速度随着喷灌强度增加而增大,而湿润深度随之减小,且土壤黏粒含量越高,越不利于湿润锋运移;随着土壤水分再分布过程的推进,黏质重度盐碱土在3.13mm/h喷灌强度下同一深度体积含水率较其他处理大,砂质重度盐碱土在1.72mm/h喷灌强度条件下土柱具有较高的保水性;采用喷灌淋洗,可使上层土壤脱盐,盐分均累积至下层土壤,并使其急剧增加且达到最大值。对于黏质重度盐碱土,3.13mm/h喷灌强度下,盐分淋洗效果较好,而对于砂质重度盐碱土,8.75mm/h喷灌强度淋洗效果优于其他处理。该研究可为喷灌技术合理和可持续开发利用滨海盐碱地提供参考。     

Salinization,alkalinization and sodification in Punjab (Pakistan): characterization of the geochemical and physical processes of degradation

Evidence of soil degradation impeding soil tillage and irrigation in cultivated soils in Pakistan is identified, described and represented in a general process of degradation. Based on a chemical analysis of soil characteristics, it is shown that a more general geochemical degradation process may occur in these soils. Two paths of salinization, i.e. neutral salinization and alkalinization inducing a process of sodification, are identified. The wide range of chemical properties of soils and corresponding geochemical processes can be explained by the great diversity of quality in irrigation water that is taken either from the canal or from the groundwater. The basic module of a geochemical model AQUA (Vallès and DeCockborne, 1992) is calibrated with the help of a study of the soil geochemical properties (identification of minerals, characterization of exchanges) and then used to assess the effect of four different water qualities on sandy and loamy soils. Based on these scenarios, the salinity, alkalinity and sodicity hazard of irrigation water is assessed by taking into account simultaneously the electrical conductivity and the residual alkalinity (calcite-residual alkalinity, residual sodium carbonates) or irrigation water and the soil cation exchange capacity: these three indicators appear the most relevant in the context of the study. Copyright © 1999 John Wiley & Sons, Ltd.     

生物炭对东北黑土持水特性的影响

为探究生物炭对东北黑土持水特性的影响,系统研究3种添加比例(2%、5%、10%)、3种粒径(0.25、0.5、1 mm)的杨木炭和竹炭对3种质地东北黑土(壤土、砂壤土、砂土)田间持水量和含水率的影响规律,构建添加生物炭黑土的水分特征曲线,并采用Van-Genuchten和Broods-Corey模型进行拟合。结果表明:生物炭能显著提高不同质地东北黑土的持水能力,黑土的田间持水量与生物炭的添加比例呈显著正相关,而与生物炭的粒径呈负相关,0.5 mm和1 mm粒径的生物炭对黑土田间持水量的影响差异不显著,杨木炭显著优于竹炭,0.25 mm、10%添加比例的杨木炭对东北黑土持水能力的提高效果最优,壤土、砂壤土、砂土3种质地黑土的田间持水量和饱和含水率分别可提高64.97%、66.42%、69.39%和47.60%、38.93%、31.18%;Van-Genuchten模型能更精确的模拟添加生物炭黑土的水分特征曲线,最佳离心时间为100 min,三次函数曲线能够较好的拟合添加生物炭黑土的体积含水率与离心吸力之间的多元动态关系,为生物炭对各种质地东北黑土水分运动规律的深入研究提供理论依据。     

Some relationships between quality of irrigation waters and chemical characteristics of irrigated soils of the Nagaur district,Rajasthan

Studies were conducted on the effects of waters of different quality on the chemical characteristics of 74 surface and subsurface soils of the Nagaur district, Rajasthan. The electrical conductivity (EC) of the saturation extract of these sandy and loamy sand soils were found to be less than that of the irrigation water. Correlations were observed between EC and the constituent ions (Na⁺, Ca²⁺ and Mg²⁺ of the irrigation water and of the saturation extract of the soil samples. The pH values of the irrigation water and soil suspensions also showed a positive correlation. The carbonate and bicarbonate ion concentrations in both the irrigation water and the saturation extract of the soils correlated with their respective pH values. EC of both the irrigation water and the saturation extract from surface and subsurface soil layers correlated with total cations. Correlations between the chemical characteristics of the irrigation water and the saturation extract of the soils are of limited value for prediction purposes, due to other factors operating under field conditions.     

Biochemical properties of forest soils as affected by a fire retardant

Synthetic polymers are currently being used as water additives to control wildfires and prescribed burns. This laboratory study examines the effects of one of these acrylic-based polymers (Firesorb) on some biochemical properties (microbial biomass C, hydrolysis of FDA, #-glucosidase, urease and N mineralization) of two coarse textured soils (loamy sand and sandy loam) under pinewood located at Galicia (NW Spain). Firesorb was added to unheated and heated soil samples at two levels of application (1 and 3 times the recommended dose) and measurements were made after 6 and 12 weeks of aerobic incubation. The results obtained for both soils at different incubation times were found to be comparable. Except for N mineralization, which was reduced by Firesorb addition, in both unheated and heated soils, the Firesorb-treated samples showed similar or significantly higher values for the biochemical parameters analyzed than those in the untreated control soils. This finding suggests that under these assay conditions the synthetic polymer used as a fire-fighting chemical had no adverse effects on soil microbial communities.     

Contact angle of soils as affected by depth, texture, and land management

Water repellency can be a significant factor in soil physical behaviour, but little is known about the depth dependence of the contact angle of field soils. We investigated contact angles and wetting properties as a function of depth for a wide range of agricultural and forest soils in Germany. The agricultural soils ranged from silty to sandy texture (six profiles), and the forest soils ranged from sandy to loamy texture (eight profiles). Contact angles (CA) were measured with the Wilhelmy plate method (WPM). In most of the soils, advancing WPM contact angles were considerably greater than 0° and they varied irregularly with depth. In general, sandy soils had larger WPM contact angles than silty soils. From the relation of the contact angle with texture and pH the quality of soil organic matter (SOM) was considered as more important for the wetting properties than the total amount of soil organic carbon (SOC). Finally, it was found that for soils with intermediate sand contents either under agricultural or forest use, the kind of land use seemed not to influence CA. Coarse‐textured sandy soils that were used only as forest sites were more hydrophobic than silty soils which were exclusively used as agricultural soils. We conclude that a coarse texture favours, in combination with other factors (mainly pH), hydrophobic SOM.     

Phytolith transport in soil: a laboratory study on intact soil cores

Column experiments on phytolith transport were conducted to assess the partial contributions of water percolation and earthworm activity to phytolith transport in loamy and sandy soils. Six intact cores of a loamy sandy Haplic Cambisol and nine cores of a silty loamy Stagnic Luvisol were excavated. With the Luvisol, three treatments were perfomed: a percolation treatment with periodic irrigation, but without earthworms, a percolation and earthworm treatment with periodic irrigation and earthworms (Aporrectodea caliginosa) and a control. The Cambisol cores did not contain earthworms and hence only percolation and control treatments were tested. The phytoliths of common reed (Phragmites australis) were labelled with the fluorescent dye fluorescein isothiocyanate and applied to the soil surface of each core. Except for the control treatment, 3600 mm of water was applied over 6 months. In the Cambisol, the weighted mean transport distance of phytoliths was significantly greater with percolation (2.2 ± 0.1 cm) than in the control (0.9 ± 0.3 cm), indicating that water percolation is a driving mechanism of phytolith transport. In the Luvisol, the difference in mean transport depth between control and percolation treatments (1.0 ± 0.2 and 1.5 ± 0.3 cm) was not significant. The earthworms did not affect the mean transport distance of phytoliths in the Luvisol, but the phytolith concentrations in the leachates were significantly greater and their size distribution did not change with soil depth as observed in the percolation treatment without earthworms. Further studies are required to quantify the effect of earthworms on phytolith transport.     

DMPP硝化抑制效果受其浓度、施用方式及土壤基质势的影响

The efficacy of nitrification inhibitors depends on soil properties and environmental conditions. The nitrification inhibitor 3.4-dimethylpyrazole phosphate （DMPP） was investigated in a sandy loam and a loamy soil to study its effectiveness as influenced by inhibitor concentration, application form, and soil matric potential. DMPP was applied with concentrations up to 34.6 mg DMPP kg^-1 soil as solution or as ammonium-sulfate/ammonium-nitrate granules formulated with DMPP. DMPP inhibited the oxidation of ammonium in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. When applied as solution, increasing DMPP concentrations up to 7 mg DMPP kg^-1 soil had no influence on the inhibition. The effectiveness of DMPP formulated as fertilizer granules was superior to the liquid application of DMPP and NH4^＋, particularly in the loamy soil. Without DMPP, a decline in soil matric potential down to -600 kPa decreased nitrification in both soils, but this effect was more pronounced in the sandy loam than in the loamy soil. DMPP was most effective in the sandy loam particularly under conditions of higher soil moisture, i.e., under conditions favorable for nitrate leaching.     

Studies of 65Zn movement in soil columns under laboratory conditions

Zinc movement was studied in relation to moisture regime, element source, and method of application in soil columns constructed from samples of surface layers of Begu loamy sand and Gurgaon sandy loam. Maximum movement was only 10 mm laterally and 40 mm downward. The amount of zinc and the distance moved were greatest under the wettest regime. Movement was also greater in loamy sand than sandy loam columns, with Zn-EDTA rather than sulphate as the source, and when the amount of zinc was greater for a given volume of soil material.The effect of urea, monocalcium phosphate, calcium carbonate, and farmyard manure on the movement of zinc was determined at one moisture level in columns constructed from samples of surface layers of Begu loamy sand and Thana loam. The movement of zinc within the soil columns was reduced by all four treatments.     

Mobility of heavy metals in polluted soils near zinc smelters

The distribution and the availability of Cd, Zn, Cu, and Pb along the entire profile of two highly polluted soils located near Zn smelters have been related to the chemical and mineralogical composition of the soil. Lead and Cu deposits always remain in the surface layers and their availability measured by neutral ammonium acetate extraction was very weak. The behavior of Cd and Zn appears different in sandy acidic podzolic soils and in neutral loamy soils. These metals are associated with the organic matter migration in podzolic soils, while they remain in the upper layers in loamy soils provided that the pH is higher than 6. When the pH drops below 6, the mobility of Cd increases while that of Zn increases only below pH 5. The availability of heavy metals is lower in neutral loamy soils than in sandy acidic soils due to precipitation of carbonates and phosphates. With increasing depth, Cd and Zn are more available if the soil is acid; but, if the soil is neutral and loamy the availability is kept low by adsorption on clays and free oxides. The results of the complex trace metals interactions with the soil components show a higher accumulation capacity for loamy soils than for sandy soils notwithstanding the fact that their CEC is similar.