Adsorption von Wasser, Äthylenglycolmonoethyläther sowie Stickstoff und ihre Beziehung zu Eigenschaften deutscher und israelischer Bodenproben

Adsorption of Water, Ethylene Glycol Monoethyl Ether as well as Nitrogen and its Relation to Properties of German and Israeli Soil Samples To determine the specific surface area, samples taken from 140 soil horizons were selected and the significant physical and chemical properties were investigated. The specific surface area of the samples was determined by adsorption of H₂O, ethylene glycol monoethyl ether (EGME) and N₂. A comparison of the three methods shows that the specific surface area determined by the adsorption of H₂O and EGME does not differ significantly. However, the specific surface determined by N₂-adsorption differs markedly from the results obtained using the polar substances. As a dependent variable the specific surface area is mainly influenced by the clay content and clay mineral type. Further, the organic substance content as well as the iron- and manganoxide content have a more significant influence on the specific surface area the lower the clay content is, or the content of three layer minerals. As an independent variable, the specific surface area determined by adsorption of EGME, proved to be the characteristic soil factor which reflects the effective cation exchange capacity as well as the hygroscopicity with the highest degree of accuracy.     

Abbau von Huminstoffen durch Bodenmikroorganismen — eine Übersicht

Degradation of humic substances by soil microorganisms — a review Humic substances which represent differently extractable fractions of the soil organic matter exert multifarious effects on soil as a site for plant growth and a part of terrestrial environments. Among them especially humic acids and fulvic acids are subject to degradation and/or transformation by soil microorganisms. Several authors demonstrated the participation of different species of fungi, actinomycetes and also of non-mycelial aerobic or anaerobic bacteria in those processes under laboratory conditions. Indications exist that humic substances irrespective of their structure undergo degradation on cell surfaces due to the activity of exoenzymes. In this respect microbial phenoloxidases play an extraordinarily important role. The degradation rate of humic substances can be followed by optical, gravimetric and chemoanalytical methods as well as using biochemical and microbiological procedures (CO₂ release, microbial growth, biomass formation). An objective evaluation, however, can be hindered by the adsorption of humic substances on microbial biomass and sometimes also by formation of novel humic-like microbial metabolites. Therefore it is necessary to apply a multifactorial approach in the study of the degradation of humic substances which includes both quantitative and qualitative parameters. To better elucidate how these processes may occur under natural conditions, mixed populations of soil microorganisms should be predominantly involved in future studies.     

Einfluß von Bodenreaktion,Redoxbedingungen und organischer Substanz auf die Phosphatgehalte der Bodenlösung

Influence of soil reaction, redox conditions and organic matter on the phosphate content of soil solutions Samples of seven agriculturally used soils of different composition (A_p-horizons), one marine underwater soil and two garbage composts were adjusted in suspensions (soil-water-ratio 1:3) to different pH values between 3 and 8 by additions of NaOH or HCl. By a different degree of aeration the redox potential was kept constant at selected values between +600 and ?300 mV. After an incubation period of 22–24 days under controlled E_h-pH-conditions the content of total phosphate and orthophosphate was measured in the equilibrium solutions. At oxidizing conditions all soil and compost samples show the lowest phosphate content in solution at pH S6. At higher and lower pH values the phosphate content increases. The results indicate that the phosphate concentration is determined by adsorption/desorption processes – mainly connected with iron oxides – and not by dissolution or precipitation of definite phosphorus compounds. Under reducing conditions the phosphate content increases in the equilibrium solutions of all samples. Especially in samples with high content of sulphides a considerable increase of the phosphate concentration could be measured at Eh values below +300 mV at pH 5, +200 mV at pH 6, and ± 0 mV at pH7 and 8. Below these values phosphate containing iron(II1) oxides were reduced and – with further decreasing redox potentials – transformed to iron sulphides. In samples without sulphide formation the phosphate mobilization is much lower. With increasing amount of soluble organic matter the phosphate content of the solutions also increases because of phosphate desorption by organic anions or complexation of aluminium and iron from phosphate adsorbing compounds. But also the content of soluble organically bound phosphate increases and may amount to 70 % of the total phosphate content in solution.     

Organische Bodensubstanz und Bodenzönose — Qualitäten,Korrelationen und Wechselbeziehungen — Einführung in das Symposium

Dead organic matter and soil biota — qualities, correlations and interrelationships At the biannual meeting of the German Soil Science Society at Konstanz, September 7 to 12, 1997, a symposium was held to summarize actual research on the quality of soil dead organic matter and its interrelations with the soil biota. This introduction outlines the frame and reports on lectures by O. Dilly and J. C. Munch, L. Beyer and U. Irmler, by W. Foissner and also by U. Graefe not included in the following papers.     

Ein Vergleich und eine Bewertung von Dränformeln für die Drändistanz von geschichteten Grund- und Stauwasserböden

A comparison and an evaluation of drain spacing equations for layered soils Drain spacings, calculated with different steady-state tile drainage formulas for layered soils, were compared. The formulas under consideration were those of Ernst, van Beers and of Toksöz and Kirkham. It was found that, for certain ranges of the drainage parameters, the drain spacings compare well. For other conditions, differences of over 100 percent did occur. Especially, results obtained with the Ernst equation may deviate considerably from those of the other authors. However, also drain spacings calculated with the van Beers equation do occasionally differ from those of Toksöz and Kirkham. For practical use the equation of Toksöz and Kirkham is recommended.     

Abbau von Isoproturon in Regenwurm‐Makroporen und in der Unterbodenmatrix – Eine Feldstudie

Degradation of isoproturon in earthworm macropores and subsoil matrix—a field study The objective is to compare the time scale of microbial degradation of the herbicide Isoproturon at the end of earthworm burrows with the time scale of microbial degradation in the surrounding soil matrix. To this end, we developed a method which allows the observation of microbial degradation on Isoproturon in macropores under field conditions. Study area was the well‐investigated Weiherbach catchment (Kraichgau, SW Germany). The topsoil of a 12 m² large plot parcel was removed, the parcel was covered with a tent and instrumented with TDR and temperature sensors at two depths. After preliminary investigations to optimize application and sampling techniques, the bottom of 55 earthworm burrows, located at a depth of 80–100 cm, was inoculated with Isoproturon. Within an interval of 8 d, soil material from the bottom of 5–6 earthworm burrows was taken into the laboratory and analyzed for the Isoproturon concentration for investigation of the degradation kinetics. Furthermore, the degradation of Isoproturon in the soil matrix, that surrounded the macropores at the field plot, was observed in the laboratory. Microbial degradation of Isoproturon at the bottom of the earthworm burrows was with a DT‐50‐value of 15.6 d almost as fast as in the topsoil. In the soil matrix that closely surrounded the center of the earthworm burrows, no measurable degradation was observed within 30 d. The clearly slower degradation in the soil matrix may be likely explained by a lower microbial activity that was observed in the surrounding soil matrix. The results give evidence that deterministic modeling of the fate of pesticides once transported into heterogeneous subsoils by preferential flow requires an accuracy of a few centimeters in terms of predicting spatial locations: time scales of microbial degradation in the subsoil drop almost one order of magnitude, in case the herbicides dislocates from the bottom of an earthworm burrow a few centimeter into the surrounding soil matrix. If at all, predictions of such an accuracy can only be achieved at locations at sites where the soil hydraulic properties and the macropore system are known at a very high spatial resolution.     

Die Stabilität von Sandböden in Abhängigkeit vom Gehalt an organischer Substanz und deren Humifizierungsgrad

The Stability of Sandy Soils and its Dependence on Humification Degree and Content of Organic Matter The influence of organic matter on the strength parameters cohesion and friction angle was investigated with mixtures of a fine sand and 0-8% peat of different humification degrees - determined by using a thermobalance - and under different soil water suction. The results show that the strength parameters cohesion and friction angle increase with increasing organic matter content, but the increase is greater with lower humification degree. Especially if the organic matter content is lower than 5%, cohesion and friction angle depend on soil water suction and have a maximum in the range of about 50 hPa soil water suction. A simplified model based on the capillary theory for the calculation of cohesion was proposed to explain the influence of content and humification degree of organic matter on cohesion. One possible reason for the lower cohesion with higher humification degree is its lower wettability. The dependence of friction angle on soil water suction and humification degree of organic matter needs further examinations.     

Schwermetall- und Nährelementgehalte von Pflanzen und Bodenproben schwermetallhaltiger Halden im Raum Bleiberg in Kärnten (Österreich) I. krautige Pflanzen

Heavy metal- and nutrient contents of plants and soil samples from metal liferous waste dumps in Bleiberg (Carinthia, Austria). I. herbaceous plants Lead and zinc concentration in the fine fraction (< 0,2 mm) of mine dump material were twice as high as in coarser fraction (2–0,2 mm) (table 1). Due to high metal levels in roots of several mine dump plants (table 3) interactions between plants and soil-microorganisms are assumed. Furthermore root originating exsudates (organic acids) are probably responsible for an increase in heavy metal availability in soil in spite of a general high pH of soil solution. The low mobility of lead within intact plants is caused by a selective affinity of this metal to cell wall pectines. On the other hand a physiological barrier (endodermis/pericycel) in primary roots of these plants is assumed, which partly prevents lead from upward transport into the shoots. Heavy metal compartmentation may be part of a tolerance mechanism diminishing a surplus of toxic metals within plant metabolism.     

Schwermetall- und Nährelementgehalte von Pflanzen und Bodenproben schwermetallhaltiger Halden im Raum Bleiberg in Kärnten (Österreich). II. Holzpflanzen

Heavy metal- and nutrient contents of plants and soil samples from metalliferous waste dumps in Bleiberg (Carinthia, Austria). II. Woody plants Needles, stem- and root-samples from coniferous trees (Norway spruce and Scots pine), taken from a waste dump habitat and an offmine-site in Bleiberg (Carinthia) were analysed on their macronutrient-and heavy metal-contents. No significant age dependent differences in N-and P-content of the two species were observed. The highest potassium levels occured in the youngest needle age group. The needles of the trees from the mining dump site show increasing Ca- and Fe- concentrations with increasing needle age. The Mn-contents of needles collected in offmine-sites were higher than those from the waste dump. The Mg-levels in the needles from both sites are remarkably low, a symptom of undersupplement. High Pb- and Zn-concentrations were determined in older needles of waste-dump-trees. Because of rather high Pb- and Zn-levels in the roots of the trees from this site a physiological transport barrier is assumed, which partly inhibits the upward lead transport; on the other hand lead is partly deposited in stem-wood of the two species. The heavy metal contents of roots from mining dump site are interpreted as an effect of high metal stress in the fine fraction of soil material.     

Cu‐, Zn‐ und Cd‐Aneignungsvermögen von zwei Spinatgenotypen in Abhängigkeit von der P‐Versorgung und Wurzelexsudation

Cu, Zn, and Cd acquisition by two spinach cultivars depending on P nutrition and root exudation Within a spectrum of 11 spinach cultivars (cvs) differences in the Cu, Zn, and Cd contents of shoots had been noticed. The aim of this study was therefore to analyze in more detail the acquisition of Cu, Zn, and Cd by the most differing cultivars (Tabu and Monnopa) in dependence on P nutrition. The plants were grown in a low phosphorus Luvisol (pH 6.3; total contents Cu: 89, Zn: 297, Cd: 2.4 mg kg^—1) with two phosphorus levels in pots under natural conditions. For the determination of inflow, root length/shoot weight ratio and of the Cu, Zn, and Cd concentration in the soil solution (rhizosphere) plants were harvested 26 and 40 days after sowing. Root exudation of organic acids of the two cvs was measured 35 days after growing in quartz sand with different P supply. Both cultivars responded to P fertilizer by doubling their shoot weight. With increased P supply (0.68—0.77% P in shoot‐DM) both cultivars showed similar heavy metal contents in the shoot resulting from similar root length/shoot weight ratios (RSR) and net uptake rates of the three elements as well as the same element concentrations in the rhizosphere soil solution. Under P deficiency, however, cv. Tabu (0.52% P in shoot‐DM) showed in comparison with cv. Monnopa (0.48% P) higher Cu, Zn, and Cd contents of shoots although its RSR was smaller than that of cv. Monnopa. However, the inflow for Cu was higher and for Zn and Cd significantly higher compared with cv. Monnopa. This result of cv. Tabu corresponded with higher concentrations of Cu, Zn, and Cd of its rhizosphere soil solution, and its higher exudation rates of oxalate, citrate, and malate (3.9; 1.0; 0.7 nmol cm^—1 h^—1). The corresponding values for cv. Monnopa were: 1.7; 0.3; 0.4 nmol cm^—1 h^—1. The mobilization of Cu, Zn, and Cd by the excreted organic acids seems to be responsible for the higher Cu, Zn, and Cd inflow of cv. Tabu.     

Einfluß von Sorte und Phosphordüngung auf den Phosphorgehalt und die Aktivität der sauren Phosphatasen von Weizen und Gerste. — Ein Beitrag zur Diagnose der P-Versorgung von Pflanzen —

Influence of cultivar and phosphorus application on P concentration and acid phosphatase activity in wheat and barley. — A contribution to the diagnosis of P supply of plants — Acid phosphatase activity compared to total P concentration was studied as a diagnostic criterion of the phosphorus nutritional status of wheat and barley. In a field experiment with wheat cv ‘Sperber’ the influence of P level on P_ase activity and P concentration was monitored at four developmental stages. Significant correlations with grain yield were found for P_ase activity at all four stages whereas P concentration was significantly correlated with grain yield in the early stage (DC 26–27) only. Genetic variability and influence of P supply on P_ase activity and P concentration was studied at low and at high P supply with 9 wheat and 23 barley cultivars grown for 4 and 5 weeks in pot experiments. The variability of P_ase activity caused by cultivars was higher than that caused by P supply. It is, therefore, concluded that the acid phosphatase activity is not suitable as a generally applicable tool for diagnosing P supply. In comparison, total P concentration of the plants was influenced to a higher degree by P supply than by cultivars. Total P is, therefore, more suitable as a criterion for diagnosing P supply of plants than P_ase activity. The samples, though, have to be collected in stages before DC 27.     

Nitrat‐Austräge auf intensiv und extensiv beweidetem Grünland,erfasst mittels Saugkerzen‐ und Nmin‐Beprobung II Variabilität der NO3‐ und NH4‐Werte und Aussagegenauigkeit der Messmethoden

Nitrate leaching from intensively and extensively grazed grassland measured with suction cup samplers and sampling of soil mineral‐N II Variability of NO₃ and NH₄ values and degree of accuracy of the measurement methods Data from a grazing experiment — comparison of mean values, see Anger et al. (2002) — were used to estimate within‐field variability to asses the accuracy of two frequently used methods of estimating NO₃ leaching on pastures: (1) the ceramic suction cup sampling (with 34 cups ha^—1 minimum, calculated climatic water balance, 4 leaching periods) and (2) using the soil mineral‐N method (vertical soil NO₃ and NH₄ content in 0—0.9 m (N_min) measured at the beginning and end of two winters on a minimum of 10 different areas of 50 m² each with a minimum of 7 different sample cores). These methods were used on two permanent pastures with high mean stocking density of cattle of 4.9 LU ha^—1 on 1.3 ha with N‐fertilization of 250 kg N ha^—1 (= intensive [I]) and 2.9 LU without N fertilization on a 2.2 ha pasture (= extensive [E]). The results show that NO₃ leaching on pastures was largely due to few selectively extremely high NO₃ amounts under a few excrement spots — mainly urine spots — which would not be sampled representatively with an acceptable effort in a conventional grazing experiment. In both grazing treatments, very large spatial variation occurred. This was greater between the different suction cups than between the compound mineral N samples of each area. Therefore, a marked skewness and kurtosis demonstrated a non‐normal distribution of samples from suction cups, while mineral N values did not show this effect consistently. Sampling selected mostly spots without noticeable influence of excrement, but a few samples with very high values identified evidently urine spots from summer or autumn grazing. The differences in mean coefficient of variation (CV) between the grazing treatments and estimation methods were mainly based on the stocking rate and the density of excrement spots. CV values were 131 % [I] / 242 % [E] for NO₃ leaching measured with suction cup samplers and of 71 % [I] / 116 % [E] for soil NO₃ values and 24 % [I] / 34 % [E] for soil NH₄ values in 0—0.9 m according N_min‐method. Results of the N_min method are obviously inaccurate even with a sampling intensity much greater than 70 cores ha^—1; and so making an estimation of NO₃ leaching by this method is unsatisfactory for pastures. Compared to this, the results of suction cup sampling are more convincing; but even with a tolerated deviation of ± 20 % from the empirically estimated average and with a 95 %‐confidence interval, the calculated mean minimum number of samples in our experiment should be increased to 146 and 265 suction cups ha^—1 for the intensively and extensively grazed treatments, respectively. This requirement would be prohibitive for many field experiments.     

Einfluß von Makrobicyclus „Kryptofix 222”︁ auf die Calcium- und Strontium-Aufnahme von Buschbohnen-Keimpflanzen

Influence of macrobicycle ?Kryptofix 222”? on calcium- and strontium-uptake of bush bean seedlings Macrobicycle ?Kryptofix 222”? (4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo-8,8,8-hexacosane) is the only known organic compound which chelates Sr (pK = 8.0) stronger than Ca (pK = 4.4). Therefore it was proved in experiments with 10 days old seedlings of bush beans, whether Kryptofix enables plants to discriminate between the physiological important Ca and the undesired Sr in favour of Ca. The following results were obtained: 1. At a constant (equimolar) supply of CaCl2 + SrCl₂ (50 μM/l each) increasing levels of Kryptofix raised the Ca/Sr-ratio of the seedlings from 0.8 (without Kryptofix) to 2.7 (with 150 μM Kryptofix/l) by reducing their Sr-content and increasing their Ca-content correspondingly. 2. Despite of reduced Sr-uptake the translocation of Sr to the primary leaves was promoted by Kryptofix (presumably via preventation of Sr fixation by the xylem vessels and in the surrounding tissue), whereas no influence exists on the movement of Ca. 3. At low CaCl₂ + SrCl₂ supply (5 μM/l each) the bean seedlings showed similar Ca and Sr-contents (Ca/Sr-ratio about 1.07), both in the presence or absence of equimolar Kryptofix concentrations. 4. With increasing CaCl₂ + SrCl₂ supplies (25–125 μM/l each), bean seedlings without Kryptofix increasingly favours Sr- against Ca- uptake (reaching a Ca/Sr-ratio of 0.49). On the contrary, in the presence of equimolar concentrations of Kryptofix (50–250 μM/l) there is an increasing preference of Ca versus Sr-uptake (Ca/Sr = 1.89).     

Pilotstudie zur Gleichwertigkeit oder Vergleichbarkeit der Korngrößenbestimmung von Bodenproben nach E DIN ISO 11277:06.94 (Pipettmethode) und mit dem Sedigraphen

Pilot study to test the equivalence or comparability of soil‐particle‐size analysis according to E DIN ISO 11277:06.94 (pipette method) and by the use of the sedigraph According to Federal Soil Protection Ordinance (BBodschV), the recommended technique for the determination of particle size is the Köhn method (E DIN ISO 11277:06.94, 1994), a technique that is relatively time consuming and laborious. The BBodSchV, however, allows the application of alternative analytical methods provided the equivalence or comparability to the legally required method is proven. We tested the less laborious sedigraph method to determine the <63 μm fractions of soil particles (coarse (gU), medium (mU), fine silt (fU), and clay (T)) at 30 soil samples from Bavaria. The equivalence of results for the fractions (gU, mU, fU, and T) as derived from the Köhn and sedigraph methods was tested according to the guidelines of E DIN 38402–71:10.01 (2001). Following these guidelines, equivalence exists for none of the fractions gU, mU, fU, and T. The comparability of results for each fraction could nevertheless be established by means of a highly significant linear‐regression model (gU: r² = 0.89; mU: r² = 0.93; fU: r² = 0.84; T: r² = 0.97). An extensive validation of the achieved statistical regressions based on independent samples is planned in a subsequent study. The application of the sedigraph will speed up analyses by approximately 30% as compared to the conventional Köhn method.     

Einfluss von klima und textur auf die biologische aktivität beim umsatz der organischen bodensubstanz

Der Umsatz organischer Bodensubstanzen läßt sich durch Kinetiken 1. Ordnung beschreiben. Die Reaktionskoeffizienten sind von der Bodentemperatur und ‐feuchte sowie den Aerationsverhältnissen im Boden abhängig. Unter Verwendung des Quasistationaritätsprinzips können die Umsatzprozesse in einer biologischen Zeitbasis, der wirksamen Mineralisierungszeit (WMZ), auf einfache und überschaubare Art und Weise beschrieben werden. Die standortspezifischen Werte der WMZ müssen in der Regel durch zeitaufwendige Simulationsrechnungen über verschiedene Fruchtfolgen ermittelt werden. Zur Vereinfachung wurde eine Regressionsgleichung entwickelt, mit deren Hilfe eine Abschätzung der standorttypischen Jahressumme der WMZ bei Kenntnis des Jahresmittels der Lufttemperatur, des Niederschlags sowie des Feinanteilgehaltes im Boden möglich ist.     

Magnesium- und Calcium-Ernährung von Hochlagenfichten —Vergilbungszustand und Reaktion auf unterschiedliche Düngung

Magnesium and calcium nutrition of spruce on high altitude sites — yellowing status and effects of fertilizer application On the ARINUS experimental sites in the Schwarzwald (SW Germany) since 1987 the mineral nutrition of Norway spruce was investigated using various experimental fertilizer treatments. The studies were focused on the nutrient Mg as acute Mg deficiency symptoms were observed at the beginning of the experiments. Treatments with ammonium sulfate, kieserite and dolomitic limestone were carried out to achieve an experimental modification of the Mg supply. In this paper, results on yellowing status, long-term foliar analysis, and data on the binding forms of Mg and Ca in the needles are presented. By application of Mg containing fertilizers the Mg nutrition of the trees could be markedly improved. Thus, deficiency symptoms disappeared. Kieserite application resulted in the fastest response of foliar Mg concentrations. In contrast to Mg, Ca deficiency could not be observed. The results of the (NH₄)₂SO₄ application show that high N input in ecosystems can amplify latent deficiency of mineral elements. Recently on many sites the risk of nutrient imbalances has developed as a consequence of improved N supply due to deposition. Thus, nutritional and site specific aspects should be payed more attention when liming and fertilization measures are planned. A higher percentage of deep rooting tree species as beech and fir could be useful for stabilizing mineral nutrition of forest canopies.     

Einfluss Kombinierter organischer und mineralischer Düngung auf den Ertrag und Rohproteingehalt von Winterweizen und Wintergerste sowie die Rübenqualität im IOSDV Speyer

Im IOSDV‐Speyer wird die Wechselwirkung der organischen und mineralischen Düngung in der Fruchtfolge Zuckerrüben—Winterweizen—Wintergerste geprüft. Der seit 1984 laufende Versuch wurde nach fünf Rotationen (15 Jahren) ausgewertet. Der mit organischen Düngern ausgebrachte Stickstoff wird ertragswirksam und kann teilweise bei der Düngeplanung berücksichtigt werden. Er wirkt sich insbesondere im Ertragsoptimum positiv auf die Rohproteingehalte im Korn von Weizen und Gerste aus. Vom mit der Rübenblattdüngung ausgebrachten Stickstoff werden ca. 25% bei der Folgekultur Winterweizen überwiegend zur Kornbildung wirksam und können angerechnet werden. Die Stallmist—Nachwirkung ist bei Weizen vorwiegend durch Ertragssteigerung sichtbar und führte zu einer höheren N‐Aufhahme von ca. 15 kg/ha. Bei Wintergerste wirkt die Strohdüngung leicht positiv auf den Ertrag und den Rohproteingehalt. Eine N‐Ausgleichsdüngung zum Stroh ist langfristig nicht erforderlich. Die Stallmist—Nachwirkung zeigt sich auch noch bei Wintergerste und war ertragswirksam wie 25 kg N‐Mineraldünger, sie führte in den niedrigen N‐Stufen über den Mehrertrag zu einer um 5–10 kg/ha höheren N‐Aufhahme. Bei Zuckerrüben verläuft die Ertragskurve des bereinigten Zuckerertrages relativ flach, deshalb kommt der Berücksichtigung der Stickstoffnachlieferung aus der organischen Düngung bei der Düngebedarfsermittlung eine besondere Bedeutung zu.