Bilanzierung der Tonbildung und -verlagerung sowie der Tonmineralumwandlung in Löß-Parabraunerden

Balances of alteration and migration of clay fractions and clay minerals in Gray Brown Podzolic Soils from Loess Balances of alteration and migration of clay fractions, clay minerals, K, Mg and Fe bound in clay silicates were calculated for Gray Brown Podzolic Soils (Parabraunerden) derived from Young Pleistocene Loess below arable and forest land in the district south of Würzburg. The extent of clay formation lies between 63 and 98 kg/m², of which 60–80 % belong to the fraction <0.1 μm. The clay migration varies between 35 and 51 kg/m², the fractions < 0.2 μm (especially the fraction <0.1 μm) predominating, the coarse clay being involved only to a smaller extent. During Holocene soil formation 121 kg illite, 16 kg vermiculite and 11 kg kaolinite per m² are formed in the clay fraction (< 2 pm). The loss of smectite amounts to 68 kg/m². The biggest alterations of the clay mineral quantities occur in the fraction <0.1 pm; they indicate a smectite-illite transformation. Illite, at 23 kg/m², accounts for half of the clay migration, followed by smectite and vermiculite each at 9 kg/m² and kaolinite at 5 kg/m². When comparing the migrated with the present amounts no preference of certain clay minerals during clay migration can be determined. In the clay fractions the gained Fe (3.07?4.32 kg/m²) and K (2.75?3.84 kg/m²) predominate over Mg (0.57?1.15 kg/m²). The three elements accumulate to the greatest extent in the fine clay fraction. The element migration parallels the gain. The balances of the elements are discussed in connection with pedogenic illite formation as well as biotite and vermiculite disintegration.     

Löslichkeit des anorganischen Bodenphosphors und Phosphatdüngung

Solubility of the inorganic soil phosphorus and fertilizer phosphate The solubility of the inorganic soil phosphate of different soils was determined in up to 40 consecutive extractions with water and lactate solutions. The graphs showing the relationship between total extracted P, and P concentration in the extract ants (Fig. 1 and 3) were of an exponential type, independent of chemical bonding of the soil phosphorus, and independent of other soil properties. P contents in the first extractions were closely correlated with the sum of the P contents of all extractions with a solubility > 100 μg P/1 (fig. 2). All of the soil phosphate capable of diffusion is plant available. Therefore all phosphate in the soil which originated from fertilizer phosphate will be utilized. This follows from the data of solubility of the soil phosphorus (20–140 μg P/1) after repeated water and lactate (CAL) extractions. The slow adjustment of equilibrium, which is common with phosphate adsorption experiments is due to the influence of diffusion. The relationships between P fertilization, solubility of soil phosphate, and the recommended soil P content for economical P utilization with optimum plant growth (e.g. Tab. 2) is shown.     

Einfluß der Löslichkeit verschiedener Phosphatdüngemittel auf die Phosphataufnahme und den Ertrag von Sommerweizen

Solubility of various phosphate fertilizers in a brown podzolic soil and their effect on phosphate uptake and yield of spring wheat. The solubility of various phosphate fertilizers (Superphosphate, Rhenaniaphosphate, Novaphos, Carolonphosphate and Hyperphosphate) was studied in an incubation experiment, and P uptake and yield effect of these fertilizers were investigated in a pot experiment. The soil used was a carbonate free brown podzolic earth (C horizon) with a neutral pH and low in available phosphate and humus. The quantities of P extracted from the soil by the EUF technique were the lower, the higher the amount of non processed phosphate of the incubated P fertilizers. This clear differentiation in the solubility of the various P-fertilizers was not obtained by the DL extraction. The P uptake of plants was highly correlated with the P quantities extracted by EUF (r = 0,95***), while the correlation between P uptake and the P of the DL extract was less narrow (r = 0,64*). The yield, particularly the grain yield, decreased with an increase of the non processed P in the fertilizers tested. Grain yield and EUF extractable P were highly correlated (r = 0,86***); while the relationship between grain yield and the DL extractable P was poorer (r = 0.62*). The experiments have shown that mainly the easily soluble phosphate is of decisive importance for the yield formation.     

Verteilung und Löslichkeit von Bor in Helianthus annuus in Abhängigkeit vom Bor-Angebot

Distribution and Solubility of Boron in Different Organs of Sunflower Plants in Relation to the Boron Concentration of the Nutrient Solution The distribution of boron in different plant organs and its solubility in various extractants was investigated in sunflowers supplied with different concentrations of boron in the nutrient solution. 1. The distribution of boron within the plant differs depending on boron supply. Under deficiency conditions the boron content of younger tissues is decreased (compared with older tissues) while under conditions of boron toxicity an accumulation in the older leaves results. 2. A cell in need of B takes the B from the solutions continuum of its surroundings. Under conditions of poor B supply almost all the B is converted to a form which is not soluble in water. A large part of this B is soluble in chloroform; a similar amount is chloroform-extractable from chloroplasts. The remainder is neither soluble in chloroform nor in inorganic extractants. 3. Surplus boron is not accumulated in all cells. It remains in the solutions-continuum until it is deposited at the end of the transpiration stream. Here it remains soluble in water or unspecifically occluded and is soluble in soda or acids. The distribution of surplus boron follows the pattern of a toxification. 4. In a plant adequately supplied with B only the boron in the transport pathways seems to be soluble in water.     

Einflußgrößen der Schwermetallöslichkeit und -bindung in Böden

Solubility and retention of heavy metals in soils Model experiments were carried out under oxidizing conditions with soil samples from surface and subsurface horizons of different composition in order to investigate the solubility and retention of Cu, Zn, Cd, and Pb in soils. The solubility of heavy metals is mainly determined by ad- and desorption processes and complexation reactions of organic and inorganic ligands. Precipitation and dissolution of definite heavy metal compounds do not seem to govern the solution concentration in soils. An exception may probably be the formation of lead phosphate and zinc silicate under specific reaction conditions. The main factors which determine solubility and retention of heavy metals are total amount (except the proportion incorporated in the silicate structure) of the different metals, soil reaction, content of mobilizing and immobilizing organic substances, content of pedogenic oxides and clay minerals, and kind and concentration of salts and inorganic ligands. The results of the model experiments are used together with the results of other authors and general physico-chemical data to give an interpretation of the solubility behaviour of heavy metals in soils. The relations between heavy metal solubility, availability and mobility and possible procedures for melioration of soils contaminated with heavy metals are discussed.     

Zum Einfluß von pH und organischem Kohlenstoffgehalt auf die Löslichkeit von Eisen,Blei, Mangan und Zink in Waldböden

Influence of pH and organic carbon content on the solubility of iron, lead, manganese and zinc in forest soils Several soil factors determine the solubility of heavy metals in soils. The contents of exchangeable and in consequence potentially plant available heavy metals are mainly influenced by the pH and the content of organic carbon. Samples of the A_h-horizon from the stemflow area and from soil not influenced by stemflow water were investigated in beech forests. The solubility or iron, lead, manganese and zinc is described in relation to the pH and the content of organic carbon. Exchangeable iron and lead appear in significant amounts at pH below 3.5 and 4.5, respectively, regardless to the content of organic carbon. Manganese and zinc are exchangeable at pH below 5.0 and are leached for about 90% from the A_h-horizon at pH values below 3.0. The effects of higher soluble iron and lead contents on the distribution of herbaceous plants are discussed.     

Ordination von Waldökosystemen nach Stoffkonzentrationen der Lösungsphase und bodenchemischen Tiefengradienten

Ordination of forest ecosystems using element concentrations of the solution phase and soil chemical depth gradients Using data sets from 16 forest ecosystems the possibilities of an ordination procedure with respect to matter budget parameters are demonstrated. Principal component analysis was selected as method of ordination. Ordinations were carried out separately for (i) depth gradients of base saturation, for (ii) average element concentrations in the soil solution at two different depths, and (iii) for element concentrations in the bulk deposition and the throughfall. In the majority of cases the procedure yields plausible and interpretable arrangements of the ecosystems along the first and the second principal component axes. These two components contain over 80 percent of the total variance in the datasets. Compared to other methods of ecosystem characterization the ordination procedure is advantageous concerning practicability and objectivity. It is suggested to apply the method to a larger set of forest ecosystems with the aim of grouping the systems according to their individual states. An additional application is the analysis of temporal changes as attempted in ecosystem monitoring.     

Wirkungen organischer Substanzen auf Boden- und Düngerphosphat Teil 1: Einfluß von Stroh- und Maiswurzelextrakten auf die Löslichkeit von Boden-und Dünger-P

Effects of organic substances on soil- and fertilizer phosphate Part 1: Influence of straw or maize-root extracts on the solubility of soil and fertilizer P The effects of straw and maize-root extracts on the solubility of soil and fertilizer phosphate were tested in incubation trials. The following results were obtained. 1. Addition of an extract of unrotted straw (10 g straw/100 g soil) to incubate a brown-earth soil, (high or low in P) for 1–14 days did not have any significant effects on the H₂O and CAL P-fraction as compared to a KH₂PO₄ control, but markedly increased transformation of ‘easily soluble’Fe- and Al-phosphates (?15 to ?40 ppm) into ‘less soluble’forms (+15 to +20 ppm). Addition of an extract of rotted straw decreased the amounts of water extractable P and ‘easily soluble’Fe- and Al-phosphates but CAL-extractable P and ‘less soluble’Fe- and Al-phosphates were increased. 2. Incubation of the same soil (P-enriched) with an extract of maize roots (roots: soil = 1:3) for 1 day resulted in a reduction in the fixation of fertilizer phosphate (34 as compared to 42%) and in a decrease of fertilizer P recovered as ‘less soluble’Fe- and Al-P (from 31 to 11%); however, fixation was markedly increased after 14 days.     

Ermittlung wirtschaftlich optimaler Phosphatgaben auf Löß- und Geschiebelehmböden auf Basis der CAL-Methode

Determination of Economical Optimum of Phosphate Fertilization on Loess and Loamy Soils 82 field trials with phosphate fertilizers on loess and loamy soils were evaluated to find out the economical optimum of fertilization. The evaluation in each trial was done by using the exponential function according to Mitscherlich with respect of profits and costs for yields and fertilizers. The result of this evaluation was, applied to the named soils, that the yield level has essential influence on the economical optimum of fertilization. Likewise the optimal P₂O₅ (CAL)-value in the soil is dependent on the yield level (CAL-value of group C), (Tab. 7). Accumulation of phosphate in soil caused by semi-liqued manure, magnesium content in soil, pH-value, and rainfall have a significant influence on the effect of mineral phosphate fertilization and on the reliability of prediction as well. Optimising resp. considering these factors and others are of supposition for exact evaluation of trials, for reasonable recommendation of both fertilization and threshold P₂O₅ (CAL)-value, and for critical examination of methods of soil analysis.     

Bodennutzung und Nitrat-Stickstoff in der Dränzone von Lößdecken der südlichen Niederrheinischen Bucht

Land use and nitrate-nitrogen in the vadose zone of loess deposits in the southern part of the Lower Rhenish Embayment Mean annual nitrogen-leaching was studied at seven experimental sites with grain-sugar beet crop rotation. Soil water simulation models and determination of the nitrogen content in the vadose zone below the rooting zone were combined to quantify the annual leaching rates. Leaching amounts to 11–18 kg NO₃^? N/ha · a at sites where only mineral fertilizer was applied, whereas sites with additional organic fertilizers show higher leaching rates of 30–36 kg NO₃^? N/ha · a.     

Quantitative Mineralbestimmung in der Schlufffraktion von Böden auf der Grundlage der chemischen Analyse und unter Anwendung der Karl-Fischer-Titration. II. Ergebnisse bei Böden aus Geschiebedecksand,Geschiebemergel und Löß

Quantitative estimation of the mineralogical composition from silt-fractions of soils on the basis of the chemical analysis and by application of the Karl-Fischer-titration. II. Results obtained with soils from glacial sand, boulder marl and loess The contents of micas and feldspars were quantified in the silt-fractions from horizons of a podsolic brown earth developed on glacial sand and of lessives on loess as well as on boulder marl by using a method that has been described in detail in part I. Three components each of micas and of feldspars, namely muscovite (Ms), phlogopite (Phl), annite (Ann), orthoclase (Or), albite (Ab) and anorthite (An) were determined. The silt fractions of the three investigated soils are similar in their mineralogical composition. Feldspars are composed of equally high amounts of Or and Ab. Micas are dominated by the Ms-component. Apparently the mica content of the silt fractions is reduced during soil development, whereas no significant changes can be found for feldspars. The loss of micas is responsible for the decreasing potassium content of the silt fractions.     

Die Bedeutung der Umsetzung von Weizenstroh im Hinblick auf den C- und N-Haushalt von Löß-Ackerböden

The significance of wheat straw decomposition with regard to the C- and N-cycle of a cultivated loess soil In 1984/85, a microplot experiment with ¹⁵N-enriched fertilizer was carried out on a field of the Calenberg loess area near Hannover (surface area of the plots: 1 ± 2 m; experimental soil: stagnigleyic cambisol from loess). On the one hand, the extent of immobilization as well as remobilization of native soil- and fertilizer-N associated with straw incorporation (± 8 t/ha) was quantified. On the other hand, the turnover as well as the alteration of C- and N-masses in the decomposing straw material was studied. About 70% of the initial dry organic matter of straw was mineralized within one year. An enrichment of fertilizer-N as well as native soil-N in the residues of up to 20 kg/ha was observed as compared to the initial N-mass. On a microplot cropped with winter-wheat, microbial N-immobilization of about 30–40 kg/ha (native soil-N and fertilizer-N) occured in the soil after straw incorporation. The immobilization extended to march 1985. Subsequent, associated with a C/N-ratio in the straw of 43, N-remineralization as well as -extramineralization was observed with 40 kg/ha at maximum in december 1985.     

Wasseraufnahme und Wasserverbrauch von Ackerbohne und Hafer auf einer Löß-Parabraunerde

Water uptake and water use of field beans and oats grown on a loess-derived grey-brown podzolic soil (Eutroboralf) The terms of the water-balance equation were determined, when field beans (Vicia faba L.) and oats (Avena sativa L.) were grown on a loess-derived soil during two seasons (1982 and 1983). A specific objective of this investigation was to quantify the water uptake from different layers and the total transpiration of both crops, as field beans are known to be susceptible to water shortage. Beside soil physical measurements climatological data for calculation of potential evapotranspiration were recorded. Plants were analyzed due to leaf area and root length density once a week. Actual evapotranspiration including interception, as determined by the soil physical approach, was split up by calculation procedures into actual evaporation, interception and actual transpiration. Total root length and root length density of field beans were much smaller and the rooting system was shallower as compared with oats. Development of leaf area and of roots was slower with beans than oats and was retarted by 2 to 3 weeks. Accordingly the time of maximum transpiration was found begin of June with oats and at begin of July with field beans. Despite reduced root growth Vicia faba transpired 250 mm in total, that is 86 % of what was found for the cereal crop (290 mm). Water uptake field beans however, was restricted to the upper 80-cm profile with 90 % of total uptake. The water uptake per unit length of root was substantial higher with beans than with oats. Due to the delayed development of the bean crop the losses by evaporation and seepage exceeded those from the soil grown to oats by 40mm (64 %). These investigations support the conclusion that yield stability of field beans may be substantially improved by selection of new varieties with increased rooting depth.     

Initiale Bodenentwicklung in aufgespültem Löß und Hafenschlick

Initial soil development in loess and harbourbasin mud reclaimed by slurry poldering In the Rhenish Brown Coal Strip Mining Area initial soil development was investigated for 6–15 and 15–25 years old loamy-silty loess soils reclaimed by slurry poldering. In the Emden environs the same analyses were applied to 6, 17, and 28 years old silty-clayey harbour-mud soils, also reclaimed by slurry application. The most prominent results when comparing these two types of soil are as follows: The mud soils show higher contents of clay and organic matter. Therefore they reveal more favourable characteristics concerning cation-exchange capacity, soil physical and soil biological properties in comparison to those of the loess soils. In both types of soils cation-exchange-capacity and soil biological activity increase in the Ap-horizon over time. The soil physical characteristics of the mud soils markedly improve in the run of the development, whereas those of the loess soils hardly improve. It remains a subject of discussion, since what stage of development mud soils should be classified as sea-marshes/“Kleimarschen” and loess soils as rendzinas.     

Die Bedeutung der K-Ca-Austauschisotherme für eine Beurteilung der K-Versorgung der Pflanzen bei Lößböden

K-Ca-exchange isothermes of soils from loess and the potassium supply of plants From 80 Ap-horizons of Luvisols and Phaeozems on loess from south of Hannover K-Ca-exchange isotherms and cation concentrations in saturation extracts were investigated. Though not K deficient these soils show a very wide range of available K. From the very high K-concentrations in the saturation extracts (up to 3 meq/1) of part of the soils it was concluded, that mass flow should be sufficient for plant needs of K. The only soil property varying the exchange isotherms seems to be the clay content (Fig. 4). In order to calculate available K from the exchange isotherms in the same way as available water from pF characteristics the isotherms were extended down to activity ratios, according to literature, marginal for plant uptake of K (Fig. 6). The estimated soil K content, sufficient for plant in loess soils, amounts to about half that considered marginal by the regional extension service. With the assumption that so called non exchangeable, but plant available K is essentially very slowly exchangeable, an experiment was performed at 80°C to accelerate the exchange and to establish a true equilibrium. The comparison between the new exchange curve and the 25°C curve (Fig. 8) seems to reveal additional 180–450 kg/ha · 30 cm bound with equal free energy of exchange as easily exchangeable K.