Veränderung des Scher- und Kompressionsverhaltens von Ap-Horizont-Material aus Löß-Parabraunerden durch Kalkung

Change of shear resistance and compressibility of Ap-horizon material from loess-derived Parabraunerde Standardized artificial bodies prepared from soil material of a loessderived parabraunerde-Ap-horizon were tested with respect to their shear resistance and compressibility. The noncalcareous material was enriched with lime (2 stepts), soil humidity changed (3 steps) and the normal pressure increased (4 steps). Liming generally caused an increased initial shear resistance and led to a lowering of compressibility. The effect of lime is interpreted as an result of flocculation of the clay particles at the points of contact between silt grains in the soil matrix. The problems of transferring those results to the field are discussed.     

Abbau und Umwandlung von Pflanzenrückständen und ihren Inhaltsstoffen durch die Mikroflora des Bodens

Degradation and transformation of plant residues and their components by the microflora of the soil This review describes recent results of publications in this area. It condsiders the dynamics of degradation under field and laboratory conditions and indicates some of the problems of simulation models. The preponderant part of transformation processes apparently takes place in a relatively small fraction of soil organic matter which also includes the biomass. Methods for the quantitative measurements of the biomass have been considerably improved. The turnover rates of plant residues are effectively influenced by their chemical composition, for instance by their C/N ratio and their content of lignin or polysaccharides. C/N ratios also seem to influence the socalled priming effect and the transformation of increasing amounts of plant residues added to the soil. Some progress has been also made in the transformation of plant, residues under different climatic conditions. Experiments with polysaccharides and glucose have indicated that a major portion of the residual carbon residues in soil are contained in the biomass or N-containing microbial metabolites. A small part is also present in the phenolic constituents of humic compounds. Root excretions also contribute carbohydrates. Recent experiments indicated the transportation of a considerable amount of photosynthetic products from sprouts through roots into the soil. They cause intensive microbial turnover processes in the root zone. N-containing compounds are stabilized in the soil biomass. Proteins and aminopolysaccharides are furthermore stabilized by sorption on humic compounds or clay particles. They are even more effectively stabilized by linkage into humic compounds. Plant residues contain appreciable amounts of free and polymerized phenols which are degraded by microorganisms or incorporated into humic compounds. Easily oxidisable phenols are more slowly degraded in soil than the more stable ones. This is especially true for low concentrations of phenols added to the soil. The pH-values of the soil and its content of humic compounds influence essentially the degradation rate. Lignins belong to the most important natural biopolymers. Methods for their specific labelling with 14°C have essentially promoted studies about their degradation and transformation in soil and have enlarged the knowledge about lignin degrading organisms. Beside lignins and other plant polyphenols, melanins may play an important role in the formation of humic compounds. These melanins are synthesized form carbohydrates by some microscopic fungi through secondary metabolic reactions. They are formed from phenols, quinones, polyenes, aminoacid and aminosugar derivatives. Similar to humic acids they are relatively stabile against rapid microbial degradation. Analytical methods developed in the last years indicate that both groups of polymers contain similar building blocks.     

Einfluß von Stickstoffdüngung auf die Umwandlung von Monolinuron-[Phenyl-14C] im Boden und seine Aufnahme durch höhere Pflanzen unter Freilandbedingungen

Effects of nitrogen fertilizer on the fate of monolinuron in the soil-plant-system Quantitative changes in the fate of monolinuron in soil and crops (potatoes, barley) produced by nitrogen fertilization were investigated in a lysimeter-type set-up. Since crop yields were increased by the fertilizer, lower concentrations of residues were found as expected compared to the blank experiment. The total quantity of residues, however, in plants and soil was increased during the first vegetation period by the fertilizer. The major portion of residues was found at the site of application (upper soil layer). Following TLC analysis of soil extracts, no difference in the chemical structures of the residues was found between fertilized and non fertilized lysimeters.     

Aufnahme und Umwandlung von 1-14C-Glycin und35S-Methionin sowie ihr Einbau in das Protein durch isolierte Erbsenwurzeln bei Kultur in vitro

Zusammenfassung Erbsenwurzeln wurden in Nährlösungen nach Bonner und Addicott mit Zusatz von 1-¹⁴C-Glycin oder³⁵S-Methionin kultiviert. Es wurde die Abnahme der Radioaktivität in der Nährlösung, die Radioaktivität der ausgeschiedenen CO₂-Menge, diejenige im pool der alkohollöslichen Substanzen und im Protein an aufeinanderfolgenden Kulturtagen bestimmt. 1-¹⁴C-Glycin beeinträchtigte in der beim Versuch benutzten Substanzmenge und der in ihr enthaltenen Radioaktivität das Wurzelwachstum nicht; jedoch wurde es durch die-Strahlung von³⁵S-Methionin bei einer Substanzmenge, die in inaktiver Form keine erkennbare Wachstumshemmung verursacht, gehemmt. Der CO₂-Partialdruck in den Kulturgefäßen beeinträchtigt das Wurzelwachstum nicht. Die Wurzeln nehmen beide Aminosäuren schnell aus den Lösungen auf, und zwar Glycin schneller als Methionin. Einen großen Teil der¹⁴C-Glycin-Radioaktivität scheiden die Wurzeln als¹⁴CO₂ wieder aus. Die Intensität der¹⁴CO₂-Bildung an aufeinanderfolgenden Tagen ändert sich in gleicher Weise wie die Radioaktivität des pool der löslichen Substanzen. Erbsenwurzeln bilden wie viele andere pflanzliche Gewebe aus 1-¹⁴C-Glycin hauptsächlich¹⁴C-Serin. Daneben wurde ein Teil der Radioaktivität aus dem 1-¹⁴C-Glycin auch in anderen Substanzen vorgefunden.³⁵S-Methionin oxydieren die Wurzeln, vielleicht durch physiologische Vorgänge, zu Methioninsulfon und Methioninsulfoxid. Aus den täglichen Änderungen der gemessenen Radioaktivität und der spezifischen Aktivität im pool der löslichen Substanzen und im Protein kann geschlossen werden, daß die Änderungen der Wachstumsintensität, welche die Wurzeln in den ersten Tagen nach der Isolierung vom Keimling erfahren, von Veränderungen der Intensität der Protein-Bildung oder des Protein-Stoffwechsels begleitet sind.

---

Uptake and metabolism of 1-¹⁴C-glycine and³⁵S-methionine and their incorporation into protein by excised pea roots cultivated in vitro

Summary Excised roots of pea seedlings were cultivated in nutrient solution according to Bonner and Addicott additionally containing 1-¹⁴C-glycine or³⁵S-methionine, respectively. The diminution of radioactivity in the culture medium, the radioactivity of CO₂-output, that of the pool of ethanol-soluble substances and that of protein were estimated during subsequent days of culture. The growth of pea roots is not diminished by amount and radioactivity involved of glycine used in experiments. But it was inhibited by-radiation of such concentrations of³⁵S-methionine which does not markedly influence root growth in unlabelled state. Root growth is not affected by CO₂ partial pressure present in the culture flasks. Roots take up both amino acids rapidly, glycine more quickly than methionine. A great part of the¹⁴C-radioactivity of glycine roots do put out as¹⁴CO₂. The intensity of this output shows variations during subsequent days in the same manner as the radioactivity of the pool of soluble substances. From 1-¹⁴C-glycine pea roots synthesize mainly¹⁴C-serine as known from many other plant tissues. Besides some radioactivity originating from 1-¹⁴C-glycine is also found in other substances. Perhaps by physiological pathway pea roots oxidize methionine to methioninesulfone and methionine-sulfoxide. The daily variation of radioactivity and specific activity of the pool of soluble substances and of protein allow the conclusion that changes in growth intensity, which occur during the first days after isolation of roots from seedling, are accompanied by variations of intensity of protein synthesis or protein metabolism.

---

1-¹⁴- ³⁵S- in vitro

1-¹⁴- ³⁵S-. : , CO₂, . ; , -, , . CO₂, , . , , . ¹⁴CO₂. ¹⁴CO₂ , . , , 1-¹⁴- ¹⁴-. . , , . , , , , .

     

Aufnahme von sorbiertem Monolinuron durch Haferpflanzen

Uptake of adsorbed monolinuron by oat plants The uptake of soil adsorbed ¹⁴C-ureido-labelled herbicide monolinuron by oat plants was investigated. After a growing period of 9 weeks 35 to 57 % of the initial ¹⁴C-radioactivity was found in the shoots. An incubation period of 16 weeks of soil and monolinuron reduced the uptake by plants in contrast to either short term adsorption or the addition of monolinuron in solution. Changes in the herbicide soil ratio had no influence on the plant availability of freshly adsorbed monolinuron or monolinuron added in solution. However, after 16 weeks of incubation the availability of monolinuron was reduced by a narrow herbicide soil ratio. Monolinuron was identified in the soil solution by mass-spectrometry. As much as between one half and two third of the total monolinuron was taken up by the plants in the first 3 weeks. ¹⁴C-radioactivity was also found in the roots as well as in shoots of untreated control plants. The amount of ¹⁴C-activity adsorbed on soil after harvest was calculated.     

Bestand,Umwandlung und Neubildung von Tonmineralen in küstennahen Sedimenten der Nordsee

Content, Transformation and Neoformation of Clay Minerals in near shore Sediments of the North Sea From literature and our own results, approximate quantitative values are given on the mineral content of clay and silt fractions of marine sediments from the Wadden Sea. Besides this, the extent of clay mineral transformation and neoformation in a marine environment is discussed. According to our knowledge, the extent of clay mineral transformation and neoformation must be unimportant because the sea water and pore solution of the sediments seems to be - with the exception of a small Mg-surplus — something like an equilibrium solution for three-and fourlayer minerals, which neither favors a considerable base fixation nor base release. Therefore illite neoformation during halmyrolysis or early diagenesis seems to be impossible because of unfavourable relations of potassium to all other cations in the sea water. Obviously the neoformation of illite is connected with later diagenesis. The processes of clay mineral neoformation in a marine evironment are probably restricted to the formation of amorphous (Mg-) Fe-Si-particles, which may be first steps in the formation of chamosites, chlorites or smectites.     

Quantitative und qualitative Veränderungen im A-Horizont von Sandböden nach Umwandlung von Dauergrünland in Ackerland

Quantitative and qualitative changes in soil properties of A- horizons of sandy soils caused by conversion of grassland to arable land Changes in physical soil properties and in soil organic matter of the A-horizons due to the conversion of permanent grassland to arable land are quantified and described as a function of time for sandy soils. The study was carried out in an area northeast of Hannover. A decrease of about 100 t/ha C_org (- 57%), 5 – 6 t/ha N_org (- 58%) and 1 t/ha S_t (- 58%) was measured for a period of 2 – 4 years after grassland conversion. Thereby the quality of the soil organic matter remains unchanged (no changes of the C/N ratio and of the distribution of N_org in 5 N-fractions). However, an increase of soil bulk density from 1.0 to 1.3 g/cm³ and a decrease of total pore volume from 0.59 to 0.47 were observed. The fast mineralization of soil organic matter in the A-horizon following the conversion of grassland soils results in a temporary heavily increased nitrate input into the groundwater. Furthermore mineralization and leaching of nitrate and sulfate induces an acidification push in the soil by a proton release in the order of 350 keq/ha during a 2 – 4 years period. However, this proton production is compensated quantitatively by several applications of lime or marl by farmers and by the buffering of bases cations released from mineralized soil organic matter.     

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.     

Ausfilterung von Schwefelverbindungen aus der Luft durch einen Buchenbestand

Filtering of Sulfur compounds from air by beech forest In a mature beech (Fagus silvatica) forest the amounts of sulfate-S per ha and year in open land precipitation, throughfall, stem flow and seepage in 100 cm soil depth have been measured from 1969 to 1976. From the fluxes measured quantitative data on plant leaching and dry deposition in the form of plant filtering are derived. Dry deposition amounts to 26kg S · ha^?1 · y^?1 and is of the same size as wet deposition (24 kg). The leaching of sulfate takes place only in autumn and amounts to ca. 3 kg S. The acid soil in the range of Al-buffering increases its sulfate storage annually by ca. 17 kg S/ha.     

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.     

Veränderung und Fixierung von Lignin durch Ca-Bentonit

Modification and fixation of lignin by Ca-bentonite Under the influence of Ca-bentonite natural and heavy decomposable lignin was modified to an oily product not easily to dry. A distinct part of lignin is fixed by Ca-bentonite as shown by uv., ir. spectra, carbon content and loss of ignition. These results suggest that clay-lignin complexes may be found mild conditions similar to natural conditions. The altered lignin is probably fixed on the edges of the clay mineral.     

Umwandlung und Verfügbarkeit von Rohphosphat (Hyperphos) verglichen mit aufgeschlossenen Phosphaten unter kontrollierten Temperatur- und Feuchtebedingungen

Transformation and availability of rock phosphate (Hyperphos) compared with other fertilizer phosphates under controlled temperature and moisture conditions . In order to characterize the efficient portion of a fertilizer after transformation in soil, in samples of typical soils of Schleswig-Holstein the easily mobilizable and the mobile P-content were investigated with specific extractants. The transformation under controlled varied temperature and moisture conditions results first (besides in mobile phosphates) in easily mobilizable Ca-phosphate. In acid soils this changes gradually into Al- and Fe-phosphate the content of which decreases due to ageing (transformation into hardly mobilizable forms). The pH is the most important factor influencing the kind of transformation whereas high temperature and moisture content mainly increase speed and extent (high temperature accelerating especially the ageing process). The water soluble phosphate is less influenced by temperatur and moisture. The best efficiency of rock phosphates results from rapid transformation (promoted by low pH) into easily mobilizable soil phosphate followed by an ageing-retarding constellation of factors such as low temperature and moisture.