Assessment of the effect of the climatic parameters on the distribution of the Al-Fe-humus horizons in the soils of the Russian planes

A comparative-ecological approach for studying the general regularities of soil ecology on the basis of geoinformation systems is suggested. It has been applied to analyze the distribution of Al-Fe-humus horizons. The quantitative climatic parameters of soils with Al-Fe-humus horizons have been estimated, and the relationships between them have been established. The applicability of this approach for assessing the general regularities of soil ecology is shown.     

在伊朗中部源于第三纪沉积物的土壤上影响坡缕石的发生因素研究

Limited information is available on the distribution and origin of palygorskite in soils developed on Tertiary sediments as the major soil parent materials in central Iran and other Middle Eastern countries. The objectives of this study were to determine the distribution and origin of palygorskite in soils developed on Tertiary sediments, and to identify the major soil properties that influence palygorskite distribution in the soils studied. Sixteen soil profiles developed on Paleocene, Eocene, Oligocene, Oligocene-Miocene, Miocene and Pliocene sediments were studied by X-ray diffraction analysis, transmission electron microscope, and scanning electron microscopy. Physicochemical characteristics of the soils and sediments including particle size distribution, pH, electrical conductivity, organic carbon, gypsum, carbonates, and soluble Si, Ca and Mg were determined. The principal component analysis was used to establish the relationships between palygorskite and the physicochemical characteristics of the soils studied. Results showed that clay fraction of all the soils in the study area was dominated by palygorskite. The highest amount of palygorskite was found in horizons where simultaneous accumulation of both carbonates and gypsum occurred. Limited amount of palygorskite was found in salic and calcic horizons. Palygorskite seemed to be of eolian origin in the surface horizon of all the soils. Using principal component analysis, the soluble Mg/Ca ratio, pH, soluble Si and gypsum contents were identified as the most important factors affecting the distribution and genesis of palygorskite in the soils studied. Results might suggest the neoformation of palygorskite by precipitation from solutions in which evaporation fluxes were very high. However, palygorskite in soils developed on Tertiary sediments in central Iran seems to be of both inherited and pedogenic origins.     

Building upon the Conceptual Model for Soil Mercury Flux: Evidence of a Link Between Moisture Evaporation and Hg Evasion

Parameters known to influence mercury (Hg) release from soils include substrate and air Hg concentration, light, atmospheric oxidants, temperature, and soil moisture. However, for low Hg-containing soils, the influence of these parameters has been shown to vary across space and time. Here, we expand upon previous work by investigating whether soil–water evaporative loss, which integrates the influence of multiple parameters, could be applied for predicting Hg flux from soil with low Hg concentrations when bare and planted. To investigate our hypothesis, Hg flux was measured from three soil types (<100 ng Hg g^?1). When these soils were saturated, flux was suppressed. Soil moisture evaporative stage was used to partition the parameters most important for controlling Hg flux as the soils dried. Classification and regression tree (CART) analyses showed that soil moisture was the most important parameter predicting Hg flux. Results also showed an important predictor for Hg flux was whether actual evaporation (E _a) was equal to potential evaporation (E _p) or E _a < E _p. Depending on evaporative stage, the parameters with the next highest correlation to Hg flux were light, temperature, and soil moisture evaporation rate. The presence of vegetation also influenced flux with lower Hg flux when the plants were transpiring. Results indicate for those developing models that estimate Hg flux from low Hg-containing soils, soil moisture and evaporative stage are useful tools for predicting flux.

     

Winter wheat (Triticum aestivum L.) growth potential in the Slovak rural landscape

By the application of geographic information system (GIS) based on existing databases on soil characteristics, it is possible to quantify and assess categories of soil suitability important for crop cultivation. In this article we demonstrate such methods for winter wheat. The objective was to differentiate the Slovak rural landscape with respect to the possibility of effective winter wheat cultivation. The differentiation was based on soil climatic and production economic parameters. For soil categorization, correlation relationships between the site properties (soil and climatic conditions) and crop biological and agro-technical requirements were considered. The prediction was subsequently interpolated into four suitability categories: soils not suitable for wheat cultivation, less suitable soils, suitable soils, and very suitable soils. The database was developed and each area was added to it as well as the particular category of suitability for wheat cultivation. By using the GIS distribution in Slovakia, the maps of soil suitability categories for wheat cultivation were generated. In Slovakia, 29% of farmland was found to be very suitable for wheat cultivation, 25% suitable, 9% less suitable and 37% non-suitable by our calculations. These categories are characterized in detail and specified from the point of view of geographic, soil, climatic, production, economic and energetic parameters.     

Fate of airborne metal pollution in soils as related to agricultural management: 2. Assessing the role of biological activity in micro‐scale Zn and Pb distributions in A,B and C horizons

This work assesses relationships between characteristic aggregate microstructures related to biological activity in soils under different long‐term land use and the distribution and extractability of metal pollutants. We selected two neighbouring soils contaminated with comparable metal loads by past atmospheric deposition. Currently, these soils contain similar stocks, but different distributions of zinc (Zn) and lead (Pb) concentrations with depth. One century of continuous land use as permanent pasture (PP) and conventional arable (CA) land, has led to the development of two soils with different macro‐ and micro‐morphological characteristics. We studied distributions of organic matter, characteristic micro‐structures and earthworm‐worked soil by optical microscopy in thin sections from A, B and C horizons. Concentrations and amounts of total and EDTA‐extractable Zn and Pb were determined on bulk samples from soil horizons and on size‐fractions obtained by physical fractionation in water. Large amounts of Zn and Pb were found in 2–20‐µm fractions, ascribed to stable organo‐mineral micro‐aggregates influenced by root and microbial activity, present in both soils. Unimodal distribution patterns of Zn, Pb and organic C in size‐fractions were found in horizons of the CA soil. In contrast, bimodal patterns were observed in the PP soil, because large amounts of Zn and Pb were also demonstrated in stable larger micro‐aggregates (50–100‐µm fractions). Such differing distribution patterns characterized all those horizons markedly influenced by earthworm activity. Larger earthworm activity coincided with larger metal EDTA‐extractability, particularly of Pb. Hence, land use‐related biological activity leads to specific soil microstructures affecting metal distribution and extractability, both in surface and subsurface horizons.     

红壤性水稻土可溶态稀土分布特征及与酸度调控的关系

测定了具有代表性的4种母质发育、3种水育型的红壤性水稻土及起源土壤的可溶性稀土(REEs)和稀土总丰度(∑REE),分析了REEs的分布特征及与∑REE的相关,研究了经酸碱调节后土壤REEs与pH值的关系,结果表明:(1)不同母质发育的供试土壤REEs平均值依石英闪长岩母质土壤系列、凝灰岩母质土壤系列、黑云母花岗岩母质土壤系列、玄武岩母质土壤系列顺序递减。(2)供试土壤REEs与∑REE的相关不显著。(3)起源土壤剖面中REEs具有明显自上而下增大的趋势,而不同水育型水稻土剖面的REEs分布各有特征,但总的趋势是自上而下减少。(4)经酸度调节后供试土壤的REEs随着土壤pH值的提高而下降,呈显著的幂函数相关。     

The origin of sulfate salts in soils developed on Maikop clays in the North Caucasus region (According to data of the isotope composition of sulfur)

The ratio of ³²S/³⁴S stable isotopes was determined for soils developed on the Maikop clay sediments in the North Caucasus region in order to study the salt geochemistry in the soils. The soil sulfates were proved to be polygenetic. Three groups (generations) of sulfates of different geneses were distinguished according to their isotopic composition (³⁴S). In the underlying deposits and, partially, in the salt-bearing horizons of the soils, secondary sulfates originated from the oxidation of sulfides contained in the marine clay predominate. In the soil profiles, the sulfates inherited from the parent material (marine clay) are mixed with sulfates arriving with the atmospheric precipitation. The portion of the latter reaches about 30% of the total amount of sulfates in the soils. The salt (gypsum)-bearing horizons were formed in the course of the eluvial-illuvial redistribution of salts to the depth of seasonal wetting. The mobilization of sulfate salts from the underlying deposits and their transport to the upper parts of the soil profile with ascending water flows in the course of evaporation from the soil surface did not play a significant role in the accumulation of sulfates in the studied soils.     

Climate and soil salinity in the deserts of Central Asia

A comparative analysis of climatic and soil salinity characteristics of the deserts of Central Asia, including deserts of the Turan Depression, the Gobi Desert, and deserts of the Dzungar and Tarim depressions was performed. The climatic characteristics—the degree of aridity, the degree of continentality, and the amount and regime of precipitation—are different in these deserts. No direct relationships between the areas occupied by the automorphic salt-affected soils and the aridity of the climate are observed in the studied regions. In the automorphic landscapes of Asian deserts, the degree and chemistry of the soil salinization and the distribution of salt-affected soils are controlled by the history of the particular territories rather than by their modern climatic conditions. The presence and properties of the salt-bearing rocks and the eolian migration of salts play the most significant role. The deficit of moisture in the modern climate favors the preservation of salt accumulations in places of their origin. The specific features of the climate, including the regime of precipitation, affect the redistribution of salts in the profiles of automorphic salt-affected soils. An increase in the degree of climatic continentality is accompanied by the decrease in the intensity of weathering and initial accumulation of salts. A different situation is observed in the soils of hydromorphic desert landscapes, in which the degree of salinity of the surface horizons and the area occupied by salt-affected soils are directly influenced by the modern climatic conditions.     

Mercury in soils of the agro-industrial zone of Zima city (Irkutsk oblast)

Data on mercury concentrations in soils of the agro-industrial zone of Zima city in Irkutsk oblast are discussed. It is shown that mercury concentrations in the plow horizon of studied soils exceed background values. The distribution pattern of mercury in soils of the investigated area is characterized. The revealed mercury anomalies are allocated to the industrial zone of the Sayanskkhimprom plant. The combined analysis of data on mercury concentrations in the plow and subplow horizons and on the chemical composition of snow indicates that mercury enters the soil mainly with atmospheric precipitation and is present there in the adsorbed form. The correlation analysis indicates that the local thermal power station plays a significant role as the source of mercury emission to the atmosphere. Close relationships between mercury concentrations and concentrations of mobile forms of elements attest to the presence of mobile organomineral mercury compounds in the studied soils.     

Field measurements of the water content in the top soil using a new capacitance sensor with a flat sensitive volume

Water content directly near the soil surface plays an essential role for degradation of natural organic material and agrochemicals by soil microbes. Furthermore, the water losses by evaporation depend sensitively on the top‐soil water content. Rain, irrigation, evaporation, and the water flow between the soil horizons together with the natural inhomogeneity of soils cause a high spatial gradient and a pronounced time dependence of the water content in the top soil. To understand processes in top soil such as redox gradients, the knowledge on ecological conditions in the top soil, which is subject to rapid changes, is essential. In order to meet the requirements for such field measurements, a capacitance sensor with a depth resolution of 1 cm and an active area of 7.5 cm × 14 cm was constructed and operated by a special electronic circuit. Field measurements using these sensors at 1 cm depth showed the high dynamics when measurements were carried out every 10 min. As simultaneous measurements of the soil temperature at 1 cm depth exhibit large temperature variations during the day, its influence on the measurements must be compensated for. As the data, measured during drying periods, allow the assessment of the temperature coefficient, the water content at a reference temperature can be calculated. The course of the water content reflects precipitation events and quantifies the drying of the soil, providing these parameters for process evaluation. Furthermore, the diurnal variation exhibits the drying during the day and the possible rewetting from deeper horizons during the night.     

A quaternary soil sequence in the Kennet Valley,central southern England

The field characteristics, texture, mineralogy and micromorphology of the soils of four chronologically separate river terraces of the River Kennet are described. The soils on the three uppermost terraces have illuvial (palaeoargillic) horizons, which have been intensely disturbed by periglacial activity. These horizons are overlain by similarly disrupted eluvial horizons mixed with aeolian silts derived from outside the Kennet catchment. The illuvial horizons most probably result from interglacial pedogenesis under climatic conditions warmer and wetter than at present, whilst the aeolian material was probably added to the soils during the last glacial period (Devensian). The lowest and youngest terrace is characterised by an undisturbed (normal argillic) soil developed in loams derived predominantly from the aeolian silts. Consequently, it is postulated that the soils of the lowest terrace owe their characteristics to a phase of postglacial pedogenesis.The results illustrate that several phases of pedogenesis can be recognised, which provide important information on the Quaternary development of the area. This is especially significant where floral, faunal, or archaeological evidence of environmental changes is unavailable.     

The effects of agricultural use on the structure and physical properties of three soil types

This investigation was carried out to determine the influence of the use of soils on their morphological structure and properties. Three soil types (i.e. Haplic Phaeozem derived from loess, Orthic Luvisol derived from loess and Orthic Luvisol derived from sandy loam) were involved. In each soil unit, profiles lying at a small distance from one another were taken for detailed examination. The main difference between the soils within each unit was the use to which they were put. The following soils were selected for evaluation: (A) soil from natural forest habitat; (B) soil cultivated in farms with a very low level of mechanisation; (C) soil cultivated in farms which had been completely mechanised for many years; (D) soil used for many years in a vegetable garden, similar to hortisol.

In the selected profiles the morphological features, soil structure in all genetic horizons, granulometric composition, humus content, pH, density, air and water capacity and air permeability were analysed.

It was found that the transition from forest soil management to agricultural use leads not only to the formation of an arable-humus horizon and to changes in structure but also to changes of the physico-chemical properties of soils. Soils under agricultural use manifest a lower level of acidification than forest soils, as well as a different distribution of organic matter. In all agricultural soils, increased compaction of humus horizons was observed, compared with the corresponding horizons of forest soils, as well as changes in other physical features. The use of heavy machines over many years in field operations results in increased density of the soil and deterioration of soil structure. This effect is greater in soils with low colloids and organic matter contents.     

试论潮土基层分类

潮土是直接发育在河流沉积物上,受地下水活动影响,经不断耕种熟化而成的一类土壤.国际上通常称为冲积土或河积土.根据成土母质特性及时间因素所反映的成土过程及其属性,分别进行土纲、土类和亚类等高级分类单元的划分,至于基层分类的各级单元尚缺乏系统研究资料以供参考.     

Etude de la nutrition potassique du sorgho II‐ incidence du remplacement du potassium par le sodium sur la teneur en acides organiques des feuilles

Abstract

An Investigation was conducted to determine the content and distribution of total and DTPA‐extractable Zn in the genetic horizons of 72 agriculturally important soils from the six major mineral soil areas in Louisiana.

The concentration of total Zn appeared to vary more with the clay constituents of the soils and the amount of the element in the parent materials than with soil depth. The majority of the soils had the largest amounts of total Zn in the subsurface horizons. The range in total Zn for all soils and horizons was from 7.0 to 150.0 ppm.

The DTPA‐extractable Zn in all of the soils and horizons ranged from 0.08 to 4.22 ppm. In the majority of the soil profiles the highest concentration of extractable Zn was in the surface horizons. There was a decrease in the extractable Zn with increasing soil depth. The alluvial soils along the Ouachita and Mississippi Rivers, and the Mississippi Terrace soil areas contained relatively large amounts of DTPA‐extractable Zn.

In some soils the extractable Zn significantly correlated with total Zn. There was also a close relationship between extractable Zn and organic matter content, especially in the Ap horizons.     

Influence of chemical characteristics in the development of soil colour

Factors responsible for the development of colour in reddish-brown basaltic soils of Malwa Plateau, India, were studied with the aid of multiple regression correlation analysis between the soil Munsell colour parameters and the chemical characteristics. Titanium and ferrous iron for soil “hue”, clay and organic matter for soil “value” were found to influence the development of colour in these soils. Partial regression analysis was carried out to assess the relative importance of individual factors in soil colour.     

Correlations between different acidity forms in amorphous loamy soils of the tundra and taiga zones

Pair correlation coefficients (r) between the acidity parameters for the main genetic horizons of soddy-podzolic soils (SPSs), typical podzolic soils (TPSs), gley-podzolic soils (GPSs), and tundra surfacegley soils (TSGSs) have been calculated on the basis of a previously developed database. A significant direct linear correlation has been revealed between the pH_water and pH_KCl values in the organic and eluvial horizons of each soil, but the degree of correlation decreased when going from the less acidic SPSs to the more acidic soils of other taxons. This could be related to the fact that, under strongly acid conditions, extra Al³⁺ was dissolved in the KCl solutions from complex compounds in the organic horizons and from Al hydroxide interlayers in the soil chlorites. No significant linear correlation has been found between the exchangeable acidity (H _exch) and the activity of the [H]⁺ ions in the KCl extract (a(H⁺)_KCl) calculated per unit of mass in the organic horizons of the SPSs, but it has been revealed in the organic horizons of the other soils because of the presence of the strongest organic acids in their KCl extracts. The high r values between the H _exch and a(H⁺)_KCl in all the soils of the taiga zones have been related to the common source and composition of the acidic components. The correlation between the exchangeable and total (H _tot) acidities in the organic horizons of the podzolic soils has been characterized by high r values because of the common source of the acidity: H⁺ and probably Al³⁺ ions located on the functional groups of organic acids. High r values between the H _exch and a(H⁺)_KCl have been observed in the mineral horizons of all the soils, because the Al³⁺ hydroxo complexes occurring on the surface and in the interlayer spaces of the clay minerals were sources of both acidity forms.     

Soils with complex organic profiles on the Vasyugan Plain

Soils with intricate patterns of their humus profiles developing in the neutral-calcium landscapes of the southern taiga of Western Siberia under highly dynamic paleogeographic, climatic, and weather conditions are characterized. The specific features of these soils comprise the diverse modern humus horizons along with the relic ones of different preservation rates, shallow leaching of carbonates, and a weak development of the middle-profile soil horizons. Specifying these organo-accumulative soils is substantiated by their high humus content against the geochemical background of the clayey calcareous parent rocks. The conjugated series of soils reflect different stages of the soil evolution (the humus profile degradation, the development of eluvial process, and the increase of contrasts in the acid-base conditions) and the hydromorphic transformation accompanied by the formation of organic horizons making the humus profile more complicated. In accordance with the diagnostic horizons, the position of the soils studied was determined in the Classification and Diagnostics of Soils of Russia. The relic enrichment of the humus horizon is proposed to be used as a specific feature of these soils.     

Vertical distribution of low molecular weight aliphatic carboxylic acids in some forest soils of Japan

Low molecular weight organic acids are widespread and reactive in soils, but their distribution among mineral horizons is uncertain. We investigated the distribution of low molecular weight aliphatic carboxylic acids (LACAs) in three Japanese forest soils, two Acid Brown Forest soils and one Podzolic soil. The total LACAs ranged from 207.3 to 411.8 μmol kg^–1 and were abundant in the lower horizons as well as in the surface horizons of these soils. The illuvial horizons of the Podzolic soil were rich in adsorbed oxalic acid and citric acid. Total LACAs were similar in the two subtypes of Brown Forest soils derived from different parent materials but formed under similar vegetation and climate, and were larger than that in the Podzolic soil. Among the volatile LACAs, formic acid and acetic acid dominated the moist horizons containing much organic material, whereas the non-volatile LACAs, the most abundant being oxalic acid and citric acid, increased in the subsurface horizons. The distribution of water-soluble LACAs in the Brown Forest soil profiles was closely correlated with soil acidity.