Bildung und Eigenschaften amorpher Tonbestandteile in Böden des gemäßigt-humiden Klimabereichs

Formation and properties of amorphous clay constituents in soils of the temperate-humid climate region A review of literature and of some own work was given on formation and properties of amorphous clay constituents which occur along with crystalline clay minerals in soils. By that the importance of soil amorphous material with respect to pedologic-agricultural and social-environmental problems was tried to emphasize. At the beginning some clarification of the different terms used for inorganic amorphous clay constituents and a sort of difinition of the different kinds of amorphous materials seemed to be evident. Then, the occurence and the formation of amorphous material in soils of the temperate-humid climate region was commentated. As a result of this it was stated that amorphous clay constituents occur mainly as coatings on negatively charged surfaces of crystalline layer silicates. From the grouping of amorphous substances around negatively charged cores (layer silicates or Al^IV-cores in allophanic soils, respectively) it was deduced that the organisation of amorphous clay constituents and allophanes as well as synthetic aluminosilicates might be due to an unique structural principle, which was tried to explain more detailed. The methods used for determination of amorphous materials, especially allophanes, were discussed. Since the determination of amorphous clay constituents by chemical dissolution techniques is ambiguous with respect to soils containing different weathering stages of crystalline layer silicates as well, some suggestions were made for characterizing amorphous substances in soils by cation exchange and anion adsorption properties. Finally the importance of exchange-reactions caused by specific adsorption of ions and molecules (e.g. nutrients and pesticides) was indicated. Furthermore, the possibility was mentioned that harmful environmental substances might be bound (neutralized) and waste nutrients might be recycled by specific adsorption on amorphous soil constituents.     

Eine Methode zur Bestimmung austauschbarer Kationen in Waldböden

A Method for the Determination of Exchangeable Cations in Forest Soils A simple extraction method with NH₄Cl was developed for determining exchangeable cations in forest soils. The influence of selected parameters (reaction time, concentration of NH₄Cl, filter medium etc.) affecting the amount of extractable cations was tested and a standardisation was done. The cation exchange was completed in less than 4 h. For a quantitative extraction of K, Mg, Ca, and Mn a concentration of 0.05 M NH₄Cl was sufficient. The extractable amount of these cations was always clearly defined. However, extracted Al and Fe increased with the NH₄Cl-concentration. Depending on the soil samples, the exchange is not quantitative even when using a saturated solution. The extractable H⁺ is nearly independent of the NH₄Cl-concentration. Probably considerable amounts are dissociated from organic acids. The optimized method is feasible and can be used for K, Mg, Ca, and Mn as an alternative to percolation methods.     

Zur Bestimmung austauschbarer Kationen in sauren Waldböden

On the determination of exchangeable cations in acid forest soils Different samples from acid forest soils were percolated with large amounts of H₂O. Significant amounts of anions, especially sulfate, were found in the percolates mainly accompanied by Na. K, Ca and Mg (M_b-cations). The dissolution of Al-Sulfates and subsequent exchange of M_b-cations by Al as dominant mechanism is proposed. Thus the common method for determination of the cation exchange capacity (CEC) of acid forest soils, the percolation with NH₄Cl may overestimate the CEC. The overestimation may be related to the sulfate content of the soil and also influences the calculation of relative CEC proportions of individual cations.     

Über die Humusdynamik in vier österreichischen Waldböden

Humus dynamics in four Austrian forest soils The humus of four Austrian forest soils was characterized by means of a chromatographic and a mass spectrometric (δ¹³C, δ¹⁵N) method. With this combination it was possible to explain changes in the humic acid systems within the profiles. The leaching of humic acids in a Spodo-Dystric Cambisol and therefore the beginning of podsolization could be deduced. In a Stagno-Dystric Gleysol processes of dehumification were determined. The value of non humic substances was enhanced within the profile of a Fluvi-Calcaric Fluvisol. The δ¹⁵N-values increased in the four profiles much more with depth than the δ¹³C-values. This indicated the rapid mineralization of organic nitrogen.     

Schwermetallverteilung und -bilanzen typischer Waldböden aus nordischem Geschiebemergel

Heavy metal distribution and balances of typical forest soils out of German and Danish till The total contents of Cd, Cu, Fe, Mn, Pb and Zn were determined in different horizons as well as in clay coatings, mottles and concretions from 4 Orthic and Gleyic Luvisols around the Baltic Sea. Profile balances resulted in very small losses of Fe, small losses of Cu, Pb and Zn but higher losses of Cd and Mn. All elements were translocated by clay migration but corresponding enrichments in the B-horizons were covered by translocations in soluble form. Only Fe and Mn had been enriched in mottles of the water logged soils.     

Schwermetallgehalte in Waldböden Nordrhein-Westfalens -Klassifizierung und kartographische Auswertung

Heavy metal contents in forest soils of North Rhine-Westphalia - classification and cartographic evaluation Many forest areas in North Rhine-Westphalia (Germany) are contaminated with heavy metals. To evaluate this pollution of forest soils and its geographical distribution all available literature data on total heavy metal contents in forest soils of North Rhine-Westphalia were included in this study. The results show that an accumulation of heavy metals, especially of Pb, occurred in the litter layer and in the litter layer and in the topsoil. The highest values were measured in the vicinity of industrial areas and at elevated locations such as Egge Mountains and Teutoburger Forest. About 50 % of the samples from the litter layer and the topsoil have pH values below 3. 4. Since the translocation of heavy metals in the soil profile at this low pH increases, potential risk from the mobilization of high stores in the litter layer was estimated for several locations of North Rhine-Westphalia.     

Schwefelformen in Waldböden SO2-belasteter Standorte des Fichtelgebirges

Sulfur fractions in forest soils of the SO₂-polluted Fichtelgebirge The sulfur status of a soil sequence (two Dystric Cambisols, Haplic Podzol, Eutric Cambisol) in SO₂-polluted coniferous and hardwood forests of the Fichtelgebirge (North-East Bavaria) is investigated. In the mineral soil layers S_t fluctuates between 37 to 943 ppm; 11–84% of S_t is S_p. Layers rich in clay contain up to 79%-S_E, whereas in sandy to silty substrates organic bound C?S-S dominates. The organic surface layers show 1.0–2.9‰ S_t, maximum in the Oh. 69–90% of S_t are C?S-S. S_p is low with a maximum in the L-horizons (9–19% of S_t). S_E is vice versa, because values increase from L (0–8% of S_t) to Oh (7–22% of S_t). The characterization of the sulfur status in a forest ecosystem by investigation of organic layers presumably is more reliable than the results of needle and mineral soil analyses.     

Bestimmung der Lagerungsdichte in stark skeletthaltigen Böden

Determination of bulk density in stony soils A new method is represented which makes it possible to measure the bulk density easily even in the case of stony soils. First results demonstrate the reliability of this new method.     

Das Verhalten des Herbizids 2.4.5-T in deutschen Acker- und Waldböden

The behavior of the herbicide 2.4.5-T in german soils under arable land and forest Sorption, degradation and movement of trichlorphenoxy acetic acid (2.4.5-T) were investigated in 10 german soils with very different climatic and edaphic conditions in field and laboratory experiments. Under field conditions 50% of the applied herbicide were liminated in 8 to 46 days during summer time (13-18°C mean temperature), but in 40 to 220 days during (and after) winter time (4-7°C in the first weeks). Beside microbial decomposition losses due to volatility were observed. Uptake by plants (Lolium perenne) was lower than 1%. Sometimes 10% of 2.4.5-T moved downward more then 30cm during summer time but more then 50cm during winter time. Translocation in the profile was reduced by high contents of organic matter in the A horizon but not by high clay contents. Correlations between behaviour in the field and laboratory experiments were found so that the first could be predicted by the latter.     

Al-Spezies im Sickerwasser saurer Waldböden - Einfluß von Wasserbewegung und Löslichkeitsgleichgewichten

Aqueous Aluminum Species in Acidic Forest Soils - Influence of Water Pathways and Solubility Equilibria In the seepage of three typical Black Forest soils (Haplic Podzol, Dystric Cambisol, Dystric Planosol) the fractions ‘Labile-Monomeric Al’, ‘Stabile-Monomeric Al’ and ‘Acid-soluble Al’ were analyzed. Activities of aqueous Al species and saturation indices (SI) with respect to various Al-bearing minerals were calculated from ‘Labile-Monomeric Al’, using the computer program WATEQF. Al-mobilization/immobilization processes were evaluated by means of AI/CI molar ratios. With 1.5 mg/L in average, the Al_total concentrations are relatively low in all studied soils. In the O-horizon leachates, 70 to 80% of aqueous Al occur as ‘Stabile-Monomeric’ and ‘Acid-soluble’ forms mainly consisting of organo-complexes. This portion decreases in the mineral soil to 35% in the podzol and the planosol as well as to 10% in the Cambisol. Simultaneously, Al³⁺ increases to 40% (planosol), 50 (podzol), and 70% (cambisol). In all horizons, 5 to 15% of Al_total are covered by Al-fluoride-complexes, whereas Al-sulfate-complexes are insignificant. With 5 to 10% monomeric Al-OH-ions play a role only in the subsoil. Aluminum is strongly mobilized in the upper mineral horizons of all studied soils. In the planosol and the cambisol, Al is immobilized in the subsoil. In the subsoil of the podzol, in contrast, Al reveals further mobilization due to a distinct internal production of HNO₃ and H₂SO₄ as a consequence of mineralization of organic matter. In the podzol, rapid percolation in macropores is crucial for Al dynamics, whereas in the planosol the temporal variation of the perched water table. Leachates from all O-horizons and upper mineral horizons as well as from the planosol subsoil are undersaturated with respect to the solubility of all mineral phases considered. With SI > O imogolite appears to be a permanently stable mineral in the subsoils of both podzol and cambisol. There is evidence for the Al(OH)₃ interlayer of Al-chlorites controlling Al dynamics in the subsoil of the podzol. Al(OH)SO₄ type minerals are not likely to regulate aqueous Al activities in any of the studied soils.     

Über die Sorptionseigenschaften von Waldböden bezüglich gelöster organischer Substanzen

About the sorption of dissolved organic matter to forest soils This investigation characterizes the major forest soils of the temperate climatic zones (leptosols, vertisols, cambisols, luvisols, podzols, stagnosols, gleysols) as sorbents for dissolved organic matter (DOM). Sorption isotherms were obtained for 135 soil horizons from 36 profiles. When solutions containing no DOC were added, the release of dissolved organic carbon (DOC) was highest for horizons rich in organic C (A and Bh horizons). In subsoil horizons DOC release was much lower. Most of the investigated top soils (A and E horizons) and Bh, Bg, and C horizons showed a weak DOC sorption. This was caused by low contents of sorbents (clay and sesquioxides) and/or high contents of organic C. Organic C seems to reduce the DOC sorption by occupying binding sites. Subsoils rich in clay and sesquioxides like Bs, Bt, and Bw horizons showed a strong retention of DOC. Under the aerobic conditions of the experiments, some of the subsoils of stagnosols and gleysols also showed a strong sorption of DOC. However, in sorption experiments conducted after an anaerobic incubation, the DOC sorption decreased significantly.     

Die Bedeutung amorpher AI-Verbindungen für Al-Freisetzungsraten in carbonatfreien,sandigen Böden

The importance of amorphous Al-compounds regarding Al-release rates in carbonate-free, sandy soils In a preceding investigation the kinetics of proton consumption and the release of elements in carbonate-free, sandy forest soil horizons was analyzed by pH-stat-titrations. The soil matrix should reveal losses of Al and DOC equivalent to the amounts mobilized, and several extraction procedures (wet combustion: C_org; Pyrophosphateextraction: Al_p, C_org-p; Oxalate-extraction: Al_o) were applied in order to distinguish between different pools. In eight of the ten horizons investigated the dissolution of Al resulted in equivalent decreases of organically bound Al (Al_p), four of them also exhibited reductions of C_org-p?levels equal to the release of DOC. For the other two horizons, Al mobilization could be attributed to the dissolution of organic and inorganic amorphous Al-compounds, each fraction contributing about half of the total. Like the release of Al and DOC, the losses of Al_p, Al_o and inorganically bound Al (Al_o?Al_p) could be well described as 1st order reactions, the constants of dissolution [h^?1] of Al_p (0.027), Al_o (0.023) and C_org-p (0.026) being in accordance with those of Al-(0.027) and DOC- (0.024) release, respectively. For the dissolution of inorganic Al-compounds the reaction constants (0.066 and 0.052) were calculated to be nearly double.     

Einfluß der Probenvorbereitung auf die Adsorption von Cd und Cu in sauren Waldböden

Influence of Soil Sample Preparation on Cd and Cu Adsorption in Acid Forest Soils The influence of soil sample preparation on Cd and Cu adsorption was investigated using six acid forest soil samples and comparing adsorption isotherms for fresh and air-dried samples. While no influence of sample preparation on Cd adsorption capacity was found, air-drying resulted in a significant decrease in Cu adsorption density in all six soil samples under investigation at ecotoxicologically relevant concentrations in the soil solution.     

Die Bedeutung von hohen Aluminiumgehalten für die Humusanreicherung in sauren Waldböden

The role of aluminium on humus accumulation in acid forest soils The impact of soil-borne aluminum on humus accumulation was investigated in a forest soil of the chestnut zone (Castanea sativa) in southern Switzerland (Ticino). Soil samples of two soils formed on bedrocks which differ mainly in their aluminum content were extracted with HNO₃, NH₄Ac.-EDTA, NH₄Cl, KCl, and NH₄F-HCl and analyzed for the most abundant elements. On gneiss which contains up to about 10% of total aluminum the common soil type in this area is a Cryptopodzol. This soil is similar to the nonallophanic Udands. It is rich in wellhumified organic matter and shows dark-colored A_h-, A(E)- and B_h-horizons. The soil samples of these horizons are extremely rich in nonexchangeable aluminum which is, however, extractable with NH₄Ac.-EDTA. It is assumed that this Al is intimately bound to the organic matter. The soil samples of these horizons contain large amounts of HNO₃-extractable phosphorus. Up to 90% of this P appears in the organic fraction. The content of NH₄F-HCl-extractable P is only 0.7 to 3.4 mg/kg. It is concluded that due to excessive Al in the organic matter the humus mineralization is inhibited compared to the Haplumbrepts of the region.     

Eine optimierte Methode zur Bestimmung der Proteaseaktivität in Sauren Waldböden

An optimized method for the determination of protease activity in acid forest soils A method for the determination of protease activity was tested for its applicability to acid forest soils (O-horizon and mineral soil). The influences of the following parameters on the protease activity and its determination were investigated: incubation time, substrate concentration. pH-value of the incubation solution, buffer solution, sample matrix and storage of soil samples. In consequence of the results an optimized method is proposed. The application of this modified method to two forest sites with contrasting N-transformation indicates, that also in acid forest soils the determination of protease activity allows significant differentiations.     

Schwefelausstattung ausgewählter europäischer Waldböden in Abhängigkeit vom atmogenen S-Eintrag

Sulfur status of selected European forest soils as dependent on the atmospheric S deposition Along a transect from the Pyrenees (SP), over the Vosges Mountains (FR), the Black Forest and the Bavarian Forest (D). and the eastern Ore Mountains to the Iser-Mountains (CR) 10 representative forest soil forms derived from granite regolith and 1 developed from gneiss debris (Dystric Cambisols, Leptic and Ferro-Humic Podzols) at montane and high-montane elevation were analyzed for their concentrations and amounts of total sulfur and various S fractions in order to study the impact of the atmospheric sulfur input, increasing from SW to NE, on the soil sulfur characteristics. Soils receiving low S inputs are generally characterized by low amounts of inorganic (especially water soluble) sulfate. Most of their total S amount consists of organic sulfur. With increasing S deposition, the concentrations of total S and C-S and the ratios S_t/C_org, C-S/C_org and SO₄?S_tor/C_org in the L-. Of- and Oh-horizons increase. The Aeh- and Ah-horizons of Cambisols and Podzols under different sulfur load do not differ with regard to the S parameters. The B horizons of the northeastern soils affected by high sulfur deposition, however, are markedly enriched with adsorbed and water-soluble sulfate and show comparably high ratios of sulfate S versus dithionite-extractable iron.     

Chemische Eigenschaften von Waldböden im Nordwestdeutschen Pleistocän und deren Gruppierungen nach Pufferbereichen

Chemical properties of forest soils in the pleistocene of Northwest Germany and their classification based on soil buffering systems In order to characterize the chemical characteristics of forest soils of Hamburg, 800 soil samples and 400 root samples from 172 sites were used to obtain suitable soil chemical and ecochemical parameters. A strong and deep reaching soil acidification was observed on all sites with exception of those on till. The sulfate concentration in the equilibrium soil solution allows the conclusion that deposition of acid plays a significant role in this acidification. Classification of sites based on edaphic factors did not provide useful information on the chemical status of soils. However, grouping of soil horizons using pH measured in 0.01 M CaCl₂ lead to a stratification according to the soil buffering systems. Distinction between the exchanger and the aluminium buffer ranges was, however, not quite satisfactory.