Produced Water Surface Spills and the Risk for BTEX and Naphthalene Groundwater Contamination

The widespread use of unconventional drilling involving hydraulic fracturing (“fracking”) has allowed for increased oil-and-gas extraction, produced water generation, and subsequent spills of produced water in Colorado and elsewhere. Produced water contains BTEX (benzene, toluene, ethylbenzene, xylene) and naphthalene, all of which are known to induce varying levels of toxicity upon exposure. When spilled, these contaminants can migrate through the soil and contaminant groundwater. This research modeled the solute transport of BTEX and naphthalene for a range of spill sizes on contrasting soils overlying groundwater at different depths. The results showed that benzene and toluene were expected to reach human health relevant concentration in groundwater because of their high concentrations in produced water, relatively low solid/liquid partition coefficient and low EPA drinking water limits for these contaminants. Peak groundwater concentrations were higher and were reached more rapidly in coarser textured soil. Risk categories of “low,” “medium,” and “high” were established by dividing the EPA drinking water limit for each contaminant into sequential thirds and modeled scenarios were classified into such categories. A quick reference guide was created that allows the user to input specific variables about an area of interest to evaluate that site’s risk of groundwater contamination in the event of a produced water spill. A large fraction of produced water spills occur at hydraulic-fracturing well pads; thus, the results of this research suggest that the surface area selected for a hydraulic-fracturing site should exclude or require extra precaution when considering areas with shallow aquifers and coarsely textured soils.     

Indexing and display of soil survey data by means of feature-cards and boolean maps

A system is described for indexing information from soil survey by punched feature-cards. Soil and more general site information is recorded in the field, and other information is added to the records from published sources, air photographs and laboratory determinations. The records are numbered systematically by geographic location and stored in numerical sequence. The information on each record is analysed into a number of simple attributes or “features”, which are then used for indexing. For each feature there is a feature-card bearing a matrix of numbered positions corresponding to record numbers in the store. Each card is punched in the positions of all records that possess the feature. To identify and retrieve records, feature-cards are used either singly or superimposed in combination.The system has been applied to grid surveys in which sites at intersections of the National Grid are examined. The feature-card grid is oriented so that it represents to scale the National Grid. Each feature-card thus constitutes a map. By carrying out logical operations using the cards in combination, “Boolean” maps are swiftly derived.The system has been used satisfactorily in the Aberystwyth office of the Soil Survey of England and Wales for 7 years. Ultimately full automation is likely to bring advantages, but a punched feature-card system will be a useful aid for indexing soil survey information in any local soil survey office for some time to come.     

Selenium Associations in Estuarine Sediments: Redox Effects

Selenium (Se) is a contaminant of concern in environments affected by discharges from smelting and coal-burning industries. Experiments hate been performed to investigate the phase associations of selenium in contaminated sediments under a range of controlled redox conditions. In this study, Se sediment associations were examined using the BCR sequential extraction technique after stabilisation at different redox states. It was shown that although most of the sediment-bound Se is associated with the operationally-defined “organic sulfide” fraction, as the measured redox potential of the system is increased. more Se moves into the “exchangeable” and “iron manganese oxy hydroxide” fractions. In these fractions. contaminants can be expected to be more bioavailable. As the mass of Se absorbed to sediments is typically at least an order of magnitude higher than the mass dissolved in porewaters. significant Se exposure may result from oxidative shifts in Se associations.     

Timing,magnitude, and impact of acidic deposition on sensitive forest sites

Adverse effects of acidic deposition on forest health are most likely to occur in forests which develop a thick raw or “mor” humus layer in which the effective cation exchange capacity is highly sensitive to acid input. A study of the trend of exchangeable Ca and Mg ions in sensitive humus layers over the past six decades indicated that a downward shift in equilibrium has occurred that is consistent with theories of ion mobilization and coincident in time with increasing acidic deposition in the mid-1900's. Independent records of a base cation mobilization in wood supports the view of a change in the root zone in sensitive forest sites and in lake water chemistry. Induced nutrient deficiency in declining forest stands was indicated by a high Al∶Ca ratio in fine root tip tissue as a marker of altered uptake efficiency which leads to increased vulnerability to biotic factors and greater sensitivity to abiotic stresses. Evidence indicates that sensitive sites were damaged by acidic deposition 20 to 40 yr ago, long before the problem of “acid rain” was recognized.     

Studies on growth and distribution of Na+, K+ and Cl− in soybean varieties differing in salt tolerance

Soybean plants, varieties “Lee”, “Jackson” and “Bragg” were grown in solution culture at various salinity levels. A NaCl concentration of 10 mM was already inhibitory to growth of “Jackson”; growth of “Lee”, however, was only reduced at a salt concentration of 50 mM or higher. The moderately salt tolerant variety “Lee” efficiently excluded Cl^? from the leaves up to about 50 mM NaCl in the medium, but showed high Cl^? contents in the root; exclusion of Na⁺ from the leaves was also apparent in this variety. On the other hand, the salt sensitive variety “Jackson” did not have the capacity for exclusion of Cl^? and Na⁺. The physiological behaviour of the variety “Bragg” resembled that of “Jackson”. It is suggested that the exclusion of Cl^? and Na⁺ from the leaves in the soybean variety “Lee” is regulated by the root.     

Hydrogeochemistry and Water Balance in the Coastal Wetland Area of “Biviere di Gela,” Sicily, Italy

In the study area physical and chemical factors control the composition of surface and groundwaters, which in turn determine the water quality of the “Biviere di Gela” lake. These factors combine to create diverse water types which change their compositional character spatially as rainfall infiltrates the soil zone, moves down a topographically defined flow path, and interacts with bedrock minerals. Low-salinity waters, which represent the initial stage of underground circulation, start dissolving calcium carbonate from the local rocks. The progressive increase in salinity, characterized by substantially higher Ca, SO₄, Na and Cl concentrations, suggests that dissolution of CaSO₄ and NaCl is an important process during water–rock interactions. The “Biviere di Gela” lake is often separated into two units (Lago Grande and Lago Piccolo). “Lago Grande” water is generally of Na-SO₄-Cl-type, whereas “Lago Piccolo” water is of Na-Cl-SO₄-type. Their total content of dissolved salts varies with season, the amount of rainfall, and inflow of ground and drainage water. Over time, an increasing trend towards greater salinity and also sudden changes in the relative abundances of Cl and SO₄ have been recorded for the “Lago Grande.” The isotope composition of the lake water appears to be affected by inflow of ground and surface waters and also by evaporative loss. The nitrate content of waters from the recharge basin is of particular concern because it contributes to lake eutrophication. The trace element contents do not evidence the presence of any significant metal contamination of lake waters, although a future potential hazard of metals bioaccumulation by the aquatic biota must be taken into consideration. Finally, a water balance for the basin shows that a drop in precipitation of about 20% might be critical for lake survival.     

三峡库区花岗岩林地土壤特性与“优先路径”的关系

 “优先路径”是指土壤中植物根系穿插而产生的根孔、动物的运动通道和居穴、由于土壤膨胀收缩形成的裂隙,以及因湿润锋不稳定所形成的指状渗透通道等。通过在长江三峡曲溪小流域花岗岩林地坡面开挖土壤剖面,测定了“优先路径”在剖面的分布状况,并采取土壤样品,对土壤的物理特性用筛分法进行了室内测定。结果表明:剖面中距地表以下82～110cm范围内,土壤密度最小,其毛管孔隙度也较小,显示出其土壤中存在有较多非毛管孔隙构成的“优先路径”。“优先路径”在距地表以下80～100cm范围内,分布比较集中。该范围内含有较多粗颗粒物质,有利于“优先路径”的形成。“优先路径”的存在,使该层土壤稳渗速率较其他土层得以大幅度提高,土层内快速运动的水流,又加速了“优先路径”的形成与发展。“优先路径”的存在,影响着土壤物理特性,而土壤物理性质,对“优先路径”的形成与发展,也有较大影响。     

Comparative studies of pyrolysis-mass spectra of melanins,model phenolic polymers,and humic acids

Curie-point pyrolysis in direct combination with a fast-scanning, quadrupole mass-spectrometer was used for the characterization of humic acids from soils, peats, and composted straw, fungal humic acid-type polymers (melanins), model phenolic polymers and lignins. All the humic acids, most of the fungal melanins and the model polymer with linked peptone yielded complex but highly similar spectra. Prominent homologous ion series were: m/e 34, 48 and 62 (“sulfides”); m/e 67, 81 and 95 (“pyrroles”); m/e 78, 92 and 106 (“benzenes”); m/e 94, 108 and 122 (“phenols”); and m/e 117, 131 and 145 (“indoles”). “Humic acid” fractions from fresh straw and straw composted for various periods of time yielded relatively strong but gradually diminishing lignin series peaks at m/e 94, 108, 120 and 122 (phenols); m/e 124, 138, 150 and 164 (methoxyphenols); and at m/e 154 and 168 (dimethoxyphenols). Weak signals for the methoxy and dimethoxyphenol series were also present in the soil humic acid spectra. In addition to the series peaks for the other fungal melanins, the S. chartarum spectrum showed a pronounced ion series at m/e 68, 82, 86 and 96 which is indicative of polysaccharides and at m/e 136, 150 and 164 which suggests the presence of alkylphenols.     

Effects of Fruit Numbers and Plant Status on Fruit Size in the Strawberry

Abstract

Based on yield and fruit size data from a number of experiments implying effects of nitrogen nutrition, drip-irrigation, plant material and planting times, and including cultivars “Dania”, “Elsanta”, “Bogota” and “Pandora”, distinct negative relationships between fruit size and fruit number per plant or fruit/leaf ratio, were established. Apart from that, fruit size may be affected by plant material and cropping year, the latter probably related to weather conditions. Achene spacing was influenced by year, and increased by irrigation under drought conditions. Relevance of factors influencing fruit size is discussed. It is concluded that an increase in the number of flower meristems (or a more vigorous vegetative growth) might aggravate internal competition, which in turn impairs flower development, resulting in a reduced flower quality and consequently smaller fruits.     

Inhibition of iron-stress reactions in sunflower by bicarbonate

In pot culture experiments using a calcareous soil the growth rate of sunflowers was depressed by latent iron deficiency. Iron-stress reactions, reflected by enhanced uptake rate of Fe-59 after short-term supply of ⁵⁹FeEDDHA were observed under these conditions. These reactions, however, were delayed and much less distinct than those observed under latent iron deficiency in water culture experiments. Addition of MgCO₃ to this soil increased the iron deficiency of the plants and caused chlorosis, but prevented these iron-stress reactions. In contrast to the soil experiments, distinct iron-stress reactions could be observed with latent iron-deficiency in sand culture experiments in which varied amounts of inorganic Fe-III were supplied. These reactions were only observed, however, in absence of bicarbonate. Even 4 meq bicarbonate severely inhibited these iron-stress reactions which were almost totally inhibited at 10 meq bicarbonate. Bicarbonate depressed both short-term uptake of Fe-59 as well as total iron content of the leaves. There was no evidence for an additional “inactivation” of iron within the leaves due to bicarbonate treatment. Bicarbonate also strongly depressed the manganese content of the young leaves. The results demonstrate that the regulatory mechanism of so-called “iron-efficient” plant species like sunflower under iron-stress - increase in H⁺ efflux and reducing capacity of the roots and thus enhanced uptake of iron (and manganese) - is severely inhibited or even blocked by high bicarbonate concentrations. “Lime chlorosis”, caused by high bicarbonate concentrations on calcareous substrates is therefore also widespread in so-called “iron-efficient” species.     

Soil P fractions in a volcanic soil chronosequence of Central Mexico and their relationship to foliar P in pine trees

Phosphorus (P) is a major plant nutrient, however, its availability in volcanic ash soils is presumed to be small, due to its specific sorption on short‐range order minerals. We analyzed distinct P fractions in volcanic ash soils of different age (60 to > 100,000 y BP) under pine forests in Central Mexico to investigate their changes along a chronosequence of Regosols, Andosols, and Lixisols, and to evaluate if P availability limits tree growth at any particular stage. Top soil and subsoil samples were first analyzed by the Tiessen and Moir method, which failed to extract exhaustively “organic” and “occluded P”, and “P associated with apatite”. Therefore, we modified the fractionation scheme by including a “recalcitrant organic P” fraction obtained from the difference between P determined in air‐dried subsamples and subsamples burned at 300°C; P adsorbed to short‐range order minerals was assessed in an extraction with NH₄‐oxalate, and P in primary minerals by subtracting the sum of all other fractions from total P contents determined by XRF. This we did after discovering that primary P occurred in the form of fluorapatite included in plagioclase, volcanic glass or olivine. We also measured P contents in pine needles and related these with the “mobile soil P” fractions. The results show that “organic P” reaches maximum contents in 10,000‐y old soil, as does P associated with short‐range order minerals, while P occluded into crystalline oxides increases constantly over time. After 100,000 y, 31% of total P still remains in the form of primary P in A horizons. “Mobile P” was constant > 40 mg kg^?1 in Regosols and Andosols and related positively with foliar P contents, which were within adequate nutritional ranges. Only in Lixisols small “mobile P” concentrations in soil correspond with inadequate P contents in pine needles.     

Identifying “Free” Full-Text Resources in Agriculture,Food and Life Sciences: A Research Study

Interlibrary loan requests in the fields of agricultural, food, and life sciences were analyzed by material type, department, and levels of users. These data were then used to identify the sources for “free” publications which would have satisfied these requests; to identify whether the “free” full-text found are available as.pdf,.html, or.doc documents, etc.; and to identify the top 30 sources from which the “free” items are available. Twenty-four percent of the requested items were found with full-text via Google Scholar. These came from several sources with ResearchGate, NIH.gov, several publishers, and.edu sites being the top ones.     

How pristine are tropical forests? An ecological perspective on the pre-Columbian human footprint in Amazonia and implications for contemporary conservation

Archeologists, paleoecologists and anthropologists argue that ecologists need to give greater consideration to the pre-historical influence of humans in shaping the current structure and composition of tropical forests. We examine these arguments within the context of Amazonia, and assess the extent to which (i) the concepts of “pristine forests” and “cultural parklands” are mutually exclusive, (ii) the aggregated distribution of some plants necessarily indicates enrichment planting, (iii) pre-Columbian human disturbance has increased forest biodiversity, (iv) pre-Columbian indigenous practices were always sustainable, and (v) if indeed, the ecological impacts of pre-Columbian peoples are relevant for modern biodiversity conservation. Overall, we reject the notion that “the pristine myth has been thoroughly debunked” by archeological evidence, and suggest that the environmental impacts of historical peoples occurred along gradients, with high-impacts in settlements and patches of Amazonian Dark Earth (ADE), lesser impacts where occasional enrichment planting took place in forests surrounding agricultural plots, and a very low influence (in terms of light hunting pressure and other types of resource extraction) across vast areas of Amazonia that may always have been far from permanent settlements and navigable rivers. We suggest that the spatial distribution of pre-Columbian finds is given more attention, and urge caution before case studies are extrapolated to the entire Basin. Above all, we feel that debates over “naturalness” and environmental impacts of pre-Columbian humans are of limited relevance to present and future biodiversity conservation, and can detract from the major challenges facing Amazonia and other tropical forest regions today.     

Spatial heterogeneity effects of Zn/Cd-contaminated soil on the removal efficiency by the hyperaccumulator Sedum alfredii

Purpose

We aimed to examine the effects of spatial heterogeneity on Zn/Cd removal efficiency by the Zn/Cd hyperaccumulator Sedum alfredii grown on agricultural soil contaminated with mine waste.

Materials and methods

Field-collected metal-contaminated agricultural soils were arranged in pots either homogeneously or heterogeneously in “half” or “quarter” patterns. Young shoots of S. alfredii were grown on these substrates in a greenhouse.

Results and discussion

The efficiency of Zn and Cd removal from soil by S. alfredii was highest in the “quarter” pattern heterogeneous treatment, in which the percentages of total soil Zn and Cd extracted were 8.02 and 7.27, respectively. Comparing the two heterogeneous treatments, the amounts of Zn and Cd accumulated in S. alfredii shoots were significantly greater in the “quarter” pattern heterogeneous treatment than in the “half” pattern treatment.

Conclusions

We concluded that the efficiency of Zn/Cd removal increased as the scale of spatial heterogeneity decreased from “half” to “quarter”. These results may have important implications for the efficiency of phytoremediation by hyperaccumulators in the field.     

Influence of Mineral Fertilizer,Farmyard Manure,Natural Zeolite,and their Mixture on Fruit Quality and Leaf Micronutrient Levels of Apple Trees

Adequate soil conditions and fertilization as a cultural practice are the basis of fruit crops production. This study was conducted in 2011 and 2012 to determine impact of soil application of complex nitrogen, phosphorus, and potassium (NPK) mineral fertilizer alone and its mixture with cattle manure (M) and natural zeolite (A) on yield, fruit physico-chemical traits and leaf micronutrient amounts at 120 days after full bloom (DAFB) in “Idared” and “Melrose apples grown on heavy and acidic soil under Serbian conditions. Results showed that NPK increased yield in “Idared” and both NPK+A and NPK+M in “Melrose.” Fertilizer applications were not influenced by fruit physico-chemical attributes, but differences between cultivars were significant. Fertilizers induced changes of leaf micronutrients amount, but effect was not consistent. In “Idared,” NPK+A and NPK+M mixtures improved amounts of the most micronutrients, whereas in “Melrose,” NPK and mixture NPK+A+M increased leaf micronutrients in more cases. According to deviation from optimum percentage (DOP and ΣDOP indexes), excessive leaf iron (Fe) and zinc (Zn) was found and deficiency of manganese (Mn), copper (Cu), and boron (B). “Melrose” exhibited much better balanced nutritional values for nutrients as compared to “Idared,” whereas NPK+M in “Idared” and NPK alone in “Melrose” promoted better balanced nutritional values. Since the impact of nutrients on the studied features is not consistent, more research will need to be conducted to investigate the long-term effect of NPK alone or in mixture with natural zeolite and manure fertilization on apples.     

Potassium uptake efficiency of two pear cultivars and leaf concentration at deficiency symptoms appears

Two pear cultivars (Meski Ahrech and Alexandrine) grown in pot culture under normal daylight conditions in a greenhouse were submitted to potassium deficiency treatments. The potassium-free treatment decreased leaf K concentration, relative water content, SPAD, and gas exchange comparatively to the control. “Alexandrine” appeared more sensitive to potassium deficiency due to the main decrease in stomatal conductance (gs), photosynthesis (A) and transpiration (E) compared to “Meski Ahrech” that reduced only carbon assimilation (A). After 42 days of treatments, leaf K concentration in “Alexandrine” was 0.75% DM compared to 1.15% DM in “Meski Ahrech”, which appeared to be more efficient in potassium uptake.     

Aegilops tauschii Coss.: allelic variation of enzyme-encoding genes and ecological differentiation of the species

Three hundred and seven accessions of Aegilops tauschii Coss., including 160 of subsp. tauschii and 147 of subsp. strangulata, representing all the species range—from Turkey to Kirgizstan, were analyzed electrophoretically. Twenty polymorphic enzyme-encoding loci were studied, 10 of which were essentially polymorphic in Ae. tauschii. Climatic data for each of the 307 Ae. tauschii habitats were taken from WORLDCLIM database of computer system ArcGIS. Forty-nine climatic parameters were considered: precipitation, minimum, mean and maximum temperatures for each month, and also the total annual level of precipitation. The data were analyzed with multivariate statistical methods, such as Principal Components Analysis (PCA), Multiple Correspondence Analysis (MCA) and Two-Block Partial Least Squares. Variability of climatic conditions among Ae. tauschii habitats is reflected by the two approximately orthogonal “vectors”. The “first vector” is mostly determined by negative impact of precipitation and minimum temperatures during winter. The “second vector” is mostly determined by negative impact of maximum temperatures during summer, and positive impact of precipitation during late spring and summer. Aegilops tauschii is essentially variable along the “second vector”, and especially high level of variation is characteristic for subsp. tauschii. This variation reflects that Ae. tauschii is very tolerable to the climatic variation during summer season. Aegilops tauschii subsp. strangulata is also characterized by the high level of variation along the “first vector”. Moreover, all the habitats of subsp. strangulata fall into the two distinct separate clusters: the habitats in Precaspian Iran, which have the highest minimum temperatures in winter,—and all the other habitats. In the plot of the first two factors of PCA, the “cluster of Precaspian Iran” can be further divided into “Western Precaspian Iran (WPI)”, having relatively higher level of annual rainfall, and relatively dryer “Eastern Precaspian Iran (EPI)”. This three groups of subsp. strangulata accessions, from WPI, EPI and other areas, are also distinctly differed in enzyme-encoding genes allelic variation, as revealed on the plot of the first two axes of MCA. In contrast to subsp. strangulata, the level of variation of subsp. tauschii along the “first vector” is rather low. It was pointed out that variation along “the first vector” reflects adaptive intraspecies divergence of Ae. tauschii: its subspecies strangulata “prefers” the habitats of seaside climate, with warm and moist winter; while subsp. tauschii mostly occupies the habitats with rather continental climate, with relatively cold and dry winter. Allelic variation of enzyme-encoding genes Acph1, Ak, Est2, Est5, Got1, Got2, and Got3 correlate with climate along “the first vector”. Apparently, polymorphism of these loci were involved into the process of Ae. tauschii intraspecies adaptive divergence. Allelic variation of Cat2 and Fdp loci correspond to climatic variation along “the second vector” in subsp. tauschii. Therefore Cat2 and Fdp are likely to be among the genes which polymorphism “helped” subsp. tauschii to succeed in vast geographical expansion far to the east from Caspian Sea.     

Classification des sols bruns ocreux et cryptopodzoliques par analyse des extraits tetraborates tamponnes a ph 9,5

The Fe/Al ratio from pH 9.5 buffered tetraborate extract is proposed as a test to classify the “sols bruns ocreux” and “sols cryptopodzoliques”, which are hard to classify in situ according to morphological characteristics. Determined from AB or AB_h horizons, the Fe/Al ratio is significantly less than 1 in “sols bruns ocreux” and more than 1 in “sols cryptopodzoliques”.     

Determination of “normal” levels and upper limit values of trace elements in soils

To determine “normal” levels of trace elements in soils, soil samples taken all over Belgium were analysed. The selection of the sampling places was based on the geological substrata, from which the soils originate and on the texture class to which they belong. The elements As, B, Be, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Ti, V and Zn were determined using an extraction method with strong acids. The found concentrations were called “total acid extraction concentrations”, although this extraction does not extract all the elements which are incorporated into the minerals. This has been done, however, by arc emission spectrography which was applied to determine the elements Ag, B, Co, Cr, Ga, Mo, Ni, Sn, Sr and V. The greatest difference between the “overall total” concentrations and the “total extractable concentrations” were found for chromium. Based on the obtained results, an upper limit for normal levels of trace elements was fixed. For Ag, Cd, Hg, Pb and Sb, this upper limit value is almost the same for all the investigated soils irrelevant of their texture. The same conclusion could not be made for the other elements. For these elements, the soil texture and also the geological parent material, on which the soil was formed, have an influence on the upper limit value.     

Chemisch-mineralogische und mikromorphologische untersuchung einer eutrophen (Ramann-) braunerde des Budapester Hügellandes

In spite of the fact that Ramann's concept of Braunerde was extensively used throughout the world, some pedogenic processes and soil properties which are important for the formation and existence of Brown Forest Soils (eutrophic brown earths) are still not well known. Hence, a soil was investigated which was classified as a “Braunerde” by Ramann in 1909. The main question was, whether there might be soil constituents such as inorganic amorphous substances (allophanes) which are able to stabilize the brown-earth fabric, or to inhibit clay migration. From chemical data as well as from the magnitude of the pH-dependent CEC, it was deduced that there are no appreciable amounts of allophanes within the soil. The fabric, however, seems to be stabilized by colloid-chemical flocculation of the clay particles caused by large amounts of carbonates and silicates deposited with the parent material (loess). The decalcified solum is still rich in silicates, especially sand and coarse-silt-sized micas and feldspars (60–200 and 20–60 μm fractions, respectively). Since - in comparison - loesses and loess-derived soils of the Central German mountain region contain less silicates, mainly in fine and medium silt fractions (2–6 and 6–20 μm diameter, respectively), the coarser-grained silicates were assumed to be important for maintaining the Ca²⁺ and Mg²⁺ saturation of the soil by continuous weathering and thus stabilizing the brown-earth fabric.Although the soil is saturated predominantly with Ca²⁺ and Mg²⁺ ions, clay migration proceeds within the upper horizons. This was shown by calculation of the amounts of clay formed by breakdown of micas originally present in the parent material (“clay formation balance”), as well as by micromorphological studies. Furthermore, micromorphological studies and x-ray diffraction data gave some evidence for the migration of preferably finest grained montmorillonitic clays (smectites) penetrated by organic substances (humus). This kind of “selective clay migration” was assumed to be caused by high Ca²⁺ (or Mg²⁺) concentrations in soil solution required for flocculation of humus-penetrated (humus-coated) smectites. From the occurrence of these “humus-smectites” the possibility was assumed that the soil studied has been developed from a former Chernozem type.Quantitatively, clay migration does not reach the amounts of clay formation (breakdown of micas) accompanied by precipitation of iron oxides on mineral surfaces (“Verbraunung”). Thus, the soil profile visually and macromorphologically clearly exhibits the features of brown earths. On the other hand, however, some clay migration was observed. Hence, the soil was classified as a “brown earth with some clay migration” (“schwach durchschlämmte Braunerde”).Judging from the results of the “clay formation balance” an appreciable pedogenic (autigenic) clay formation from weathering products of feldspars was excluded for the soil studied.