Bestimmung der Dichte von Boden-Aggregaten durch Messung des Auftriebs

Apparent Density Determination of Soil Aggregates by a Submergence Method A submergence method using water and a water protective spray adherent for mantling the aggregates is presented as a method for the rapid determination of apparent density of soil aggregates but also of larger samples of soil fabrics. An electronic scale accelerates repeated determinations. By this method also the increase of volume by swelling can be measured.     

Die Messung des Benetzungswinkels von Bodenfilmen nach einem Plattenkontaktverfahren

Measurement of wetting angles of soils using films grown on glas plates Glas plates (microscope mounts) were bedded into 5 soils (A_h-horizons) and incubated for 3 months. Wetting angles against water were measured with a special microscope on the films that developed on the mounts. Results showed higher values than those, obtained on films that were prepared by drying water- or NaOH-extracts on the mounts. Values were considerably lower however than those obtained at earlier measurements or reported by other investigators using indirect methods. The reason for this difference might be inadequacy of the indirect methods, different angle conditions (wetting or transient state) or low age of incubation films.     

Die Messung der Katalaseaktivität von Böden

The determination of Catalase Activity in Soils by Dr. Beck 1. The elaboration of a method for the determination of the activity of catalase in soils is described. The method envolves the gasvolumetric determination of oxygen released by decomposition of a H₂O₂-solution by soils, suspended in buffers in the presence and absence of the catalase inhibitor NaN₃. 2. The influences of the following factors on catalase activity were studied: Methods for the determination of developed oxygen, enzyme- and substrate concentration, inhibition of catalase by NaN₃, pH- and temperature-optima of catalase and the presence of plant residues in soils. 3. It was found, that there was only a little decrease in catalase activity when fresh or dried samples of soils were stored over a periode of 4 months under laboratory conditions. The catalase activity of different soils showed very good correspondence to the dehydrogenase activity of the soils and less correspondence to the amount of soil respiration and the amylase activity. No relation could be found to the number of microorganisms in soil.     

Zum Einsatz von TRIME-TDR zur Messung der Bodenfeuchte auf leichten Sandböden

Using TRIME-TDR for the determination of soil water dynamics on sandy soils In this study the suitability of the TRIME-TDR system for the determination of soil water content was analysed. For this purpose a period of three years with continuous data of soil water contents, measured by TRIME-TDR, and soil water suction measured by tensiometer were available. Additionally soil samples at different times were taken for gravimetric moisture analysis. The determinations of soil moisture with the TRIME-TDR is based on a new measuring technique. The soil water contents measured by TRIME-TDR were analysed by comparison with corresponding soil moisture values from gravimetric measurements of soil samples. The soil water contents determined by TRIME-TDR in comparison with gravimetric soil moisture values show an absolute mean error of 7.9 Vol%. In most cases the soil water contents measured by TRIME-TDR were distinctly higher than the corresponding soil moisture values from gravimetric measurements. After correcting the TRIME-TDR the absolute mean error was reduced to 2.5 Vol%. Due to the results of this study soil water contents measured by TRIME-TDR-technique cannot be used in hydrological or ecological studies without a check based on the comparison with gravimetric soil moisture values.     

Ein Verfahren zur Messung der Verlagerungsrichtung von gelösten Pflanzenschutzmitteln im bewachsenen Boden

A procedure to measure the direction of translocation of solved pesticides in planted soil In an experimental pot, which permits the airtight isolation of the root region, the rooted and non-rooted soil compartment are separated by stainless steel wire nets. The translocation and mineralisation of a pesticide can be studied by alternative application of radioactive labelled compounds to either one of the compartments. As an example results with ¹⁴C-atrazine are discussed.     

Automatische Registrierung der Feuchtdichte und der Wassergehaltsänderung eines Bodens durch Messung der Absorption von Gammastrahlen (Geländemessung)

Determination of the moisture density and the water content variation of a soil by measuring the absorption of gamma rays A method is described with which above all the density and its changing (water content) can be measured automatically. A collimated gamma ray (137-Cs) is measured according to the absorption principle. Two tubes are inserted into the soil as parallel as possible about 50 cm apart. In the one tube a gamma ray source, in the other one a detector simultaneously moves step by step in a homogeneous manner up and down. The density and the changing of the water content is calculated from the measured counting rate. The measuring time for each step is variable, but usually about 5–10 minutes are chosen. The difference in depth between the stations can also be varied. The accuracy of the instrument in field use amounts to:

• 1 Water content changing: ± 0.0015 g/cm³
• 2 Soil density: ± 0.003 g/cm³

The solution power is such that horizontal layers of about 10 mm thickness can be distinguished in respect to the water content changing.     

Messung und Simulation der anisothermen Feuchtebewegung in benetzungsgehemmten Mineralböden

Measurement and simulation of nonisothermal moisture movement in water-repellent mineral soils Water repellency often occurs in surface soil horizons, where the temperature may have a significant effect on water movement. Relatively few studies have been conducted to measure the effect of temperature gradients on hydraulic processes in water-repellent soils. The objective of this paper is to analyze the simultaneous impact of hydraulic and thermal gradients on water movement in unsaturated soils. Four sandy soils with organic matter contents between 1.0 and 2.4 percent were used in a laboratory column experiment. The soils had similar particle size distribution and contact angles between 25 and 111 degrees. The water repellency was measured with the “sessile drop method”. The experiments were conducted with open laboratory soil columns. A ceramic plate was placed at the upper end of the soil column to allow water movement from a reservoir, the lower end was closed. The matric potential of ?175 hPa at the upper part of the column was held constant. Simultaneously a constant temperature gradient of approximatly 1.1 °C/cm was applied during the nonisothermal runs. Hydraulic properties of the four soils were determined sequentially at different temperatures (5, 20 and 38°C). The time dependent volumetric water content, matric potential and temperature were measured at five positions in the column. It was found that after steady state was established the water content and matric potential profiles of the four soils differed considerably. A computer code based on the theory of Philip and De Vries (1957) was developed to simulate water and heat transport. For three soils with contact angles of 25–35, 93–108 and 109–111 degrees, respectively, the model performed well when the theoretically calculated thermal vapor difivisivity, D_TV, was multiplied by a factor between two and three. For the slightly water repellent soil with a contact angle between 45 and 83 degrees, however, this factor was about seven to eight. This factor could be the result of a combined impact of the moderate water repellency and the micromorphology of the humic substance.     

Messung einer Bodenbelastung durch radioaktive Immissionen mit dem Bergerhoff-Sammelgefäß

Monitoring of atmospheric soil contamination by Cs-134, Cs-137 and Ru-103 with Bergerhoff-collection vessels At 131 locations all over Bavaria it was possible to compare the radioactivity of Cs-134, Cs-137 and Ru-103 in atmospheric precipitates with that of neighbouring soil samples in 0–3 and 0–30 cm depth. 85% of duplications from two Bergerhoff-vessels per location indicate a CV of < 20% and a correlation with 0–3 and 0–30 cm soil depth of r = 0,63*** and r = 0,89***, respectively.     

Ein Elektrodensystem zur Messung des Redoxpotentials im Kontaktbereich Boden/Wurzel

An electrode matrix for Eh measurements in the root/soil interface For redox potential measurements in the rhizosphere an electrode matrix was constructed from a teflon disc, in which 37 short Pt wires were placed with a 3.5 mm distance between two electrodes. The potentials of these electrodes were recorded periodically by a data logger and were stored on punched tape. With this arrangement, redox potential patterns for the rhizosphere of single roots could be recorded and plotted by a small computer.     

Langstreckentransport von Calcium in Stolonen von Kartoffelpflanzen

Long-distance transport of calcium in stolons in potato plants In potato plants grown in water culture the influence of the tuber growth rate and the Ca supply to the tubers as well as the effect of the relative humidity around the stolons and tubers on the ⁴⁵Ca translocation in the stolon was investigated. If the stolon tip or the tuber were supplied with additional exogenous Ca and the relative humidity around the stolon or tuber was very high then ⁴⁵Ca applied to the roots was translocated in a negligible amount into the stolon or tuber. Even when the supply of exogenous Ca to the tubers was low, the tubers exerted no “sink”-effect on the ⁴⁵Ca translocation within the stolon. Under conditions of high relative humidity around the stolon ⁴⁵Ca applied to the stolon surface was nearly exclusively translocated in direction of the shoot. In contrast, under low relative humidity around the stolon or tuber ⁴⁵Ca applied to the stolon surface or to the root system was translocated into the stolon tip and into the tuber. The results indicate that within the stolon Ca is exclusively translocated in the xylem. A “sink”-effect of the tuber on the Ca translocation into the stolon as well as within the stolon was not been observed.     

Eine Infiltrationsmethode zur Messung der hydraulischen Leitfähigkeit im Felde

An infiltration method for measuring the saturated hydraulic conductivity under field conditions A new field method to measure the hydraulic conductivity under field conditions, developed by Reynolds and Elrick (1985), is presented and compared with a laboratory method using 100 cm³ cylinder cores.     

Ein Verfahren zur Messung der ungesättigten Wasserleitfähigkeit

Course of cellulose decomposition in a brown earth under a Trisetum flavescens – meadow after different fertilization The cellulose decomposition in the soil of a Trisetum flavescens-meadow untreated and treated with NPK. and PK fertilizer was determined by means of burial of pieces of cellophane. The rate of decomposition of the cellulose film was chosen as a measure of cellulolytic activity in soil. The cellulolytic activity had its maximum in the summer months and near the surface. The decrease with increasing depth was more obvious in the untreated lot than in the lot treated with NPK fertilizer. Under field conditions the influence of fertilization on the cellulolytic activity was low. In the laboratory there was a slight effect of the addition of soil from the NPK-lot on the decomposition of filter paper only with a slightly alkaline nutritive solution. The determination of soil cellulose content and mineralization of soil cellulose showed no differences between fertilized and untreated soil.     

Eine Anordnung zur Messung kleiner Sauerstoffaustauschraten photosynthetisierender Algen bei geringen Lichtintensitäten

Zusammenfassung Es wird eine Meßanordnung zur amperometrischen Registrierung der relativen Nettosauerstoffaustauschrate mittels einer membrangeschützten Platinelektrode beschrieben, die besonders für die Verwendung kleiner Versuchsobjekte (einzelliger Algen und isolierter Chloroplasten) geeignet ist. Die hohe Empfindlichkeit ermöglicht die Analyse von Sauer-stoffaustauschraten unter Verwendung monochromatischen Lichtes relativ hoher spektraler Reinheit. Die gute Stabilität des Elektrodenpotentials läßt eine große Verstärkung des Meßwertes und eine direkte Registrierung des Anstiegs der relativen Sauerstoffaustauschrate zu.

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Summary An amperometric device is described for the registration of relative oxygen exchange rates of small particles such as algae or isolated chloroplasts. The high sensitivity of the electrode according to the Clark-type make possible the application of monochromatic light with small half band wides for examination of photosynthetic reactions. The employed Ag/AgO-reference electrode has a very stable potential and allows a high amplification necessary for direct registration of the oxygen exchange rate derivatives. Some examples are given for registrated exchange rates.

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Erfassung von Humusprofilmerkmalen mit Hilfe von Anschliffen

Evaluation of humus profile parameters with the aid of polished blocks On polished blocks, humus profile parameters can be isolated optically and estimated quantitativly by stereological methods. The parameters are, above all, shoot residues, roots and root residues, droppings of enchytraeids and earth-worms, lobular pore edges, pores. By the estimation of those parameters, investigations of polished blocks can contribute to problems of ecology of humus profiles and sites as well as problems of humus systematics.     

Langstreckentransport von Natrium in Bohnenpflanzen

Long distance transport of sodium in bean plants In 8–10 days old bean plants Na⁺ (²²Na) has been applied to either a certain root zone, the stem, or the base and tip respectively of a primary leaf and the long distance transport of Na⁺ was studied in the following 12–48 h. The long distance transport of Na⁺ applied to the root zone 9–12 cm behind the tip was strongly restricted towards the shoot and hardly detectable towards the root tip (phloem transport). Presence of K⁺ in the surrounding solution strongly increased the Na⁺ efflux from the roots. After leaf application within 48 h 30–40% of the absorbed Na⁺ had been translocated out of the leaf in direction of the root where, from the basal root zones, intensive Na⁺ efflux took place. This Na⁺ efflux was hardly affected by presence of K⁺ in the external medium and was usually more than 10% of the Na⁺ taken up by the leaves. From the Na⁺ taken up by the hypocotyl within 12 h more than 25% had been released from the basal root zones into the nutrient solution. Less than 1% of the Na⁺ applied either to the leaf or the stem was translocated towards the shoot apex. Separation of the hypocotyl into cortex and stele at the end of the experiment demonstrated the high capacity of the stele for Na⁺ accumulation. Within the hypocotyl the transfer of Na⁺ from the stele to the cortex and the phloem seems to be a rapid process whereas the release of Na⁺ from the phloem into the stele is obviously very restricted. The long distance transport of Na⁺ within the phloem of the shoot is strictly basipetal and very efficient. Low Na⁺ contents of bean leaves are therefore the result of several regulating mechanisms: K⁺ stimulated Na⁺ efflux in the roots, restricted long distance transport in the xylem due to high Na⁺ accumulation in the stele, Na⁺ pumps at the phloem in stem and leaves for phloem loading of Na⁺, and finally strictly basipetal retranslocation of Na⁺ in the phloem into the roots and efflux into the solution from basal root zones.     

Lignin in Wurzeln von Triticum

Lignin in roots of Triticum Lignin isolated from roots of T. vulgare was on the whole quite similar to that from straw. From all analytical methods used the fluorescence spectroscopy shows the greatest differences between the two lignins. But also the u. v.-spectra differentiated regarding the oxygen substituted benzene rings and the higher degree of condensation of root lignin. The latter had also ～ 25 % less conjugated aldehyde groups and between 1720–1620, about 1365 and from 720–630 cm^?1 slight modifications in the region of infrared absorption. The free radicals of the lignin and their oxidation in NaOH had only insignificant deviations. The content of lignin in roots was ～ 22 % and in straw ～ 25 %.