Die Beeinflussung der Bodenlösung durch Saugkerzen aus Ni-Sintermetall und Keramik

Influencing soil solution by suction cup material (Ni, ceramics) The influence of suction cup material (ceramics, Ni) on the chemical composition of the soil solution was tested in the laboratory by percolating soil solutions of different concentration (pH ～ 4.0). Ceramic cups of P 80 material can be used for the collection of soil solution and its determination for the concentrations of H, Na, K, NH₄, Ca, Mg, Mn, Al, S, Cl and NO₃. They can't be used to determine P-concentrations. The cups must be prepared and preconditioned by leaching large amounts of equilibrium soil solution which should not be oversaturated with respect to the solubility product of AlOHSO₄. The changes in the concentration of extracted soil solution when it passes through the cups depend upon the extracted volume. The lower the volume, the greater are the changes. Sintered Ni-cups show many severe disadvantages (decreasing permeability, insufficient resistence against acid solutions, large variability among single cups), and can only be used for cases where Na, Ca, K, and S are to be determined. Ceramic cups of the type ‘Czeratzki’ are comparable with those of P 80. However, they can only be used, when the concentrations don't vary too much and large amounts of water can be extracted.     

Veränderungen der Blattspreiten und des Chlorophyllgehaltes der Fahnenblätter von Winterweizen durch Wachstumsregulatoren

Changes of leaf-blades and chlorophyll content of flag leaves from winter wheat due to growth regulator application In pot experiments with winter wheat at two N-levels the effect of CCC and Ancymidol on the morphology, the chlorophyll content and the slope of the chorophyll degradation after anthesis were studied. The area of the blades and the number of flag leaves per pot were increased by the higher N-supply and by the growth regulators as well, resulting in a larger leaf area of flag leaf-blades per pot. In all cases the mixture of CCC + Ancymidol at the higher N-level reached the maximum values. The late intermediate harvesting showed distinct differences in the chlorophyll concentration of the flag leaf-blades and the total amount of chlorophyll of all flag leaf-blades per pot, whereby a delay of senescence in the growth regulator trials compared with the control could be proved.     

Bestimmung der Dichte kleiner Einzelaggregate durch Tauchwägung nach Paraffin-Tränkung

Determination of the bulk density of small single aggregates by submersed weighing following paraffining The bulk density of 105°C-dry aggregates ≧ 3 mm was determined by soaking these in paraffin at 100°C, 170°C, 70°C, and 180°C and, after cooling, weighing each single aggregate under ethanol as the submersion liquid. The average standard deviation when using 8–10 aggregates is 0.035 g/cm³ for numerous different samples. It is therefore possible to evaluate both the effect of different land use or fertilization and the influence of depth and parent material on the density of aggregates. Greater standard deviations indicate, among others, aggregates of different density within the same size fraction of aggregates of a soil.     

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.     

Abschätzung der organischen Kohlenstoffeinträge in Waldökosysteme durch Messung der UV-Absorption (254 nm) im Niederschlagswasser

Estimation of organic carbon deposition into forest ecosystems by determination of the spectral absorption of rainwater in range of ultraviolet radiation (SAC₂₅₄) Organic compounds are mostly neglected within deposition measurement programs because their determination is expensive and complicated. A very simple and rapid estimation of total organic carbon (TOC) is possible by determination of the spectral absorption coefficient in the range of ultraviolet radiation at 254 nm wave-length (SAC₂₅₄): TOC (mg/1) = 0,5 SAC₂₅₄ (m^?1) - 0,15     

Erfassung der Mineralstoffverteilung in Wurzelnähe durch getrennte Analyse von Rhizo- und Restboden

Estimation of the nutrient distribution around plant roots by separate analysis of rhizo and bulk soil A procedure is described to separate rhizo soil from bulk soil. For this purpose the living plant roots along with the strongly adhering soil are taken out of the surrounding soil. After a short period of drying, roots are separated from rhizo soil by gently sifting. Chemical analysis of the samples has shown that the nutrient content of rhizo soil usually differs markedly from bulk soil. Phosphate and potassium content of the rhizo soil of wheat and maize is lower than in bulk soil. Percentagewise, these differences are higher by using water as an extractant when compared to the slightly acid lactate or formate solutions. The water soluble calcium content of several wheat fields was in most cases higher in the rhizo than in the bulk soil. In sandy soil the depletion zone of phosphate does not exceed the length of the root hairs markedly whereas in the case of potassium it does. This is concluded from data showing that the potassium content, but not the phosphate content, was decreased in the bulk soil if compared to the uncropped soil. In heavier loess soils the nutrient concentrations of rhizo and bulk soil were not always found to be markedly different. It is assumed that the depletion zones are smaller than in sandy soils. In addition, because of aggregation, rhizo soil cannot be separated from bulk soil as neatly as in sandy soils. Therefore, in heavier soils the method does not yield satisfactory results.     

Ein Versuch zur Beeinflussung der F2-Spaltungen von Bastarden aus der GattungAntirrhinum durch Pfropfung von F1-Bastarden auf ihre Ausgangseltern

Ohne Zusammenfassung     

Verringerung der Phosphatsorption durch Zusatz organischer Verbindungen zu Böden in Abhängigkeit vom pH-Wert

Reduction of Phosphate sorption in soils by some organic compounds as dependent on pH 3 soils of pH 4.1, 5.9, and 7.1 were treated with aqueous solutions (at 3 concentrations) of 37 organic compounds (organic acids, phenolics, uronic acids, sugars); following an equilibration with ³²P-diammonium phosphate the recovery of ³²P was measured in the soil extract. All tested compounds did not show any effects at a concentration of 0.1 mg/g soil. Sugars, uronic acids, 2-keto-D-gluconic acid and most amino acids (with the exception of Glu, Asp, Cys, Phe which raised the recovery of ³²P by 2 to 3%) were ineffective even at the highest rate (10 mg/g soil). Aromatic acids and phenolics increased the recovery to a greater extent (highest increases with gallic acid: 8 to 11% depending on the soil). Effects were greatest with aliphatic acids like citric acid (45 to 48%), isocitric acid (8 to 64%), malic acid (12 to 57%), and malonic acid (8 to 38%). Only these four acids as well as ascorbic and isoascorbic acid markedly increased the recovery of ³²P even at a concentration of 1 mg/g soil. The effects of these acids (with the exception of malonic acid) decreased with increasing soil pH. By adding HCl to the soil in controls, it could be shown that the increased recovery rates of ³²P were not caused by the decrease in pH.     

Zur Auswirkung organischer Substanz verschiedener Humifizierungsgrade auf die Aggregatstabilität durch Reduzierung der Benetzbarkeit

Effect of differently humified organic matter on aggregate stability by reducing aggregate wettability The subject of this study was to examine the significance of the contribution of organic matter to the aggregate stability against slaking by reducing aggregate wettability. Artificial spherical aggregates were formed from about 50 g paste each of a loessial (B_t-horizon) and of a clayey soil (P-horizon), which were then coated with ground peat moss (strongly and slightly humified). The slaking behavior of the air-dry aggregates was determined by measuring the water infiltration rate and the aggregate breakdown as a function of time. The results show, not only the water infiltration rate but also the aggregate breakdown were slowed down in presence of the organic coating. This effect of organic matter increased with increasing huminification. The fragments derived from aggregates with organic coating were significantly larger than those from aggregates without organic coating. The main reason for this difference is the reduced water infiltration rate into aggregates, so that the aggregates break down rather slowly and progressively than explosively. It plays an important role, that because of the wetting inhibition at the beginning the distance is longer and/or the resistance is greater for the further water infiltration into the aggregates with organic coating than those into the aggregates without organic coating. The organic matter would possibly also be transported into the inside of the aggregates by water flux.     

Bestimmung des Wasserentzuges aus dem Boden durch die Pflanzenwurzeln im Gelände als Funktion der Tiefe und der Zeit

Field determination of water withdrawal from soil by plant roots as a function of depth and time . The water flow through roots as a function of depth and time can be determined in homogeneously rooted, level soils with closed plant canopies, provided the total vertical water flow and the capillary water flow are known for the soil profile. Theory, measuring methods and some results on water withdrawal of wheat (fig. 2–4) and sugar-beet (fig. 5) roots on a loess grey-brown podsolic soil profile underlain by gravelly sand (fig. 1) are described. The time averaged rates (2–7 day periods) for water extraction by roots are up till about 12 × 10^?3 \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm cm}^3 {\rm water}}}{{{\rm cm}^3 {\rm soil} \cdot {\rm day}}} $\end{document} During the growth period variations of the depth of the effective root zone and of the extraction rate in distinct layers were found (fig. 6 + 7). A capillary rise from the subsoil into the effective root zone exists for some time (fig. 3); seepage water within the lower root zone causes a strong increase of extraction rates in these depths (fig. 4). The relative water extraction rate at the depths of 15 and 25 cm decreases with increasing soil water suction in the range between 150 and 10⁴ cm (fig. 8).     

Förderung des Wachstums und der Nährstoffaufnahme bei kruziferen Ölund Zwischenfrüchten durch inokulierte Rhizosphärenmikroorganismen

Promotion of plant growth and nutrient uptake of cruciferous oil- and intercrops by inoculated rhizosphere microorganisms The vegetative growth of rape, oil radish and mustard was repeatedly stimulated by isolates of Pseudomonas fluorescens (PsIA12), P. putida (A1 A2), Stenotrophomonas maltophilia (PsIB2, Psl2), Agrobacterium rhizogenes (A1A4) and Rhizobium trifolii (R39) by improved root development and nutrient uptake (N. P. K. Mg) in pot and field experiments on loamy sand and sandy loam at different yield levels. The seed yield of rape could be increased only by 2 isolates (PsIA12, PsIB2). The growth stimulating bacteria produced phytohormones (auxins and partly cytokinins). No direct relations between plant growth stimulation and the potential microbial metabolic activities nitrogenase, nitrate reductase, P-mobilization, pectinase, cellulase could be found. Effective bacteria are in close association with the plants and can survive in the rhizosphere.     

Bestimmung der Benetzungseigenschaften von Moorbodenlösungen durch Kontaktwinkelmessung

Determination of the wetting characteristics of peat soil extracts by contact angle measurements A simple method for determination of contact angles of soil extracts and of coats of dried extracts is described. Results of the wetting characteristics of the single horizons of a high bog, an acid and a calcareous low bog are given. Influences of pH, salt content, degree of soil dryness and of degree of decomposition are existing.