Die N-Mineralisierung von Böden im Laborbrutversuch

N mineralization in soils under laboratory incubation conditions The potential rate of release of nitrogen by the organic matter in agriculturally used soils was determined under laboratory conditions by means of incubation. Mineralization of the more resistant soil organic matter proceeded linearly with time during an incubation period of 2–3 weeks, when field-moist and air-dried samples were used and at the beginning of the incubation experiment sufficient water was added to bring them to saturation. Mineralization was taking an exponential course in soils with additions of easily decomposable organic matter or in soils with a higher proportion of organic residues from crops. For the 14 investigated arable and grassland soils great variations in the average daily rate of mineralization were found ranging from 5–60 μg N_min/10 g DM. The data correlated very well with the biomass (r = 0.96) and the cell-free protease activity (r = 0.98) of the soils. Different measures of soil management (preceding crops, application of sewage sludge, addition of heavy metals) had a more or less pronounced influence on the rate of mineralization. The optimum temperature was 50°C for N mineralization and 26°C for nitrification. Contrary to nitrification, the soil reaction had only little influence on mineralization and proved also independent of the N_min content of soils. The results indicate that ammonification of organic N compounds may largely proceed via the microbial biomass.     

Die Adsorption von HCB und DDD in Böden

The Adsorption of HCB and DDD by soils A method for studying the adsorption of substances with low water solubility by soils has been set up. The method has been verified by two chemicals (HCB, DDD) and a number of different soils. The results have shown a significant correlation between the distribution ratio and the content of organic carbon.     

Die Verwendung von Antimon-Elektroden zur pH-Messung in Böden

The application of antimony electrodes for soil pH measurements Glass electrodes are unsuitable for long-term, micro-volume pH measurements in soils because of their form, size and drying of the glass membrane. Sb-electrodes are suited for pH measurements in soils whose oxygen saturation does not vary excessively. pH values determined with Sb electrodes decrease with increasing water tension or decreasing moisture. Colour changes of pH indicators confirm this trend.     

Protonenpuffersubstanzen in Böden

Proton buffer compounds in soils A classification of solid soil buffer substances according to the type of proton accepting sites, viz. carbonate buffer, variable charge buffer, silicate buffer and hydroxide buffer is proposed. The buffer reactions are discussed in some detail and so are formation and transformation processes of buffer. An association of pH-ranges to various buffer compounds is hampered by an insufficient knowledge of the acid strength of the different functional groups.     

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.     

Anthropogener Asbest in Böden

Anthropogenic Asbestos in Soils Fibers of different asbestos types as well as other fibrous minerals, e.g. zeolites, have been found as natural contamination of soils or quarries in numerous countries and regions. Epidemiological studies have shown that inhabitants of these regions have high incidence of calcified pleural plaques and malignant pleural mesotheliomas. Anthropogenic contamination of soils by asbestos as well as asbestos contamination of the soil-near air layer were measured in this study. Soils were contaminated with chrysotile and amphibole asbestos during and after industrial asbestos processing. Asbestos fiber contaminations in the range of 10⁶ to 10¹¹ fibers/g soil and fiber concentrations as high as 5 × 10⁵ fiber/m³ air were measured. Soil contamination by anthropogenic asbestos can produce high or very high contamination of water and of ambient air by very fine fibers and entail carcinogenic risk for the general population, mainly for the inhabitants in the neighbourhood.     

Die Ermittlung von langfristigem O2-Mangel (Stickigkeit) in Böden aus Nährstoffanalysen

The evaluation of long lasting O₂-deficiency in soils from nutrient analyses The relation between soil reserve (b) related plant contents (p) of nutrients, which are taken up preferentially under good (Y, e.g. N, K) or poor (X, e.g. Mn, Na) aeration (Y_p: Y_b): (X_p : X_b) decreases with increasing oxygen deficiency, therefore it is a suitable measure for the stifling during the growth season. In four very different landscapes N and Mn turned out to be the most useful indicators. Thus, appropriately combined analyses of plant and soil samples from the rooting zone taken once can replace chronosequent measurements of the E_H and ODR or indirect determinations of air volume, no matter, whether single plant species or the same plant communities are investigated. This method could be applied generally, with threshold values, if the same plants and in a given landscape adequate soil extractants were used.     

Schwermetallanreicherung in den Böden des Abwasserbehandlungsgebietes Braunschweig

The accumulation of heavy metals in the soils of the Braunschweig wastewater irrigation area The concentration of lead, zink and cadmium in the Ap-horizons and subsoils of sandy Podzols and Cambisols were investigated. As compared with same soils outside the irrigation area an accumulation of the heavy metals in the Ap-horizons of the older sprinkler irrigation plots was found. On the rill irrigation area the heavy metals also were concentrated in the subsoils.     

Kurzfristige pH-Pufferung von Böden

Short-time pH buffering of soils Changes in pH of 60 soils after HCl addition were related to reaction time and soil characteristis. Between 80 and 100% of the added protons were taken up by the soils within a few seconds, resulting in the release of exchangeable Ca, Mg and Al in strongly acid soils. The decrease of proton activity between 0.25 and 30-70 h can be formally described as a diffusion process. pH buffering depended on soil pH and organic C content but not on clay content. Buffering decreased from pH 3.5 to about 6 and increased again up to pH 7. Increase of C_org increased buffering mainly from pH 6-7.     

Phosphatsorption einiger Böden in Bayern

Phosphate adsorption of some Bavarian soils . Phosphate adsorption isotherms were established in buffered (pH 4.6, 5.5, 7.0) and some in unbuffered (0.01 M CaCl₂) systems for 9 soil profiles, 6 of which represent loess soils in various stages of development. In the P-equilibrium concentration range of 0–10^?4 mole/l two to three ranges can be identified, each of which obeys the Langmuir equation. In the lowest concentration range (0–0.2·10^?4 mole/l) adsorption is linearly related to equilibrium concentration. For the different Langmuir ranges the adsorption maxima (b) increase and the adsorption coefficients (k) decrease with increasing equilibrium concentration. The maxima depend on buffer-pH in the order 5.5<4.6<7.0. A single point method similar to the one recently proposed by Bache and Williams (1971) was succesfully applied to obtain b from a single measurement using a significant correlation between b from complete isotherms and the ratio of P adsorbed to that in solution after the addition of a fixed amount of P (0.8–1,6 mg P/g of soil). The b-values in the equilibrium concentration range of 1–20·10^?4 mole/l depend mainly on soil pH (negative) and clay (positive) (multiple correlation coefficient r = 0.858). The common reason for this appears to be the amount of exchangeable Al which is also significantly correlated with b. During soil development the depth function of b changes due to decalcification, drop of pH and migration of clay and iron oxides.     

Die Böden von Wallhecken in Schleswig-Holstein I. Klassifikation und Genese

Soils of Mound Hedges in Schleswig-Holstein I. Classification and Genesis In typical landscapes of Schleswig-Holstein soils of mound hedges were investigated (FAO (1989): Cumulic Anthrosol). New soils have been developed from the deposit of the mound hedge in less than 250 years. A classification with regard to the German classification of natural soils is suggested. The soil genesis from sandy deposits has reached the step of Dystric Regosols, groundwater has induced gleyic features. Soil genesis could be described chronologically, if time of deposition of these mound hedges is known. Some of the natural soils are conserved below the deposit. Pedogenesis in an area, changed by man, could be reconstructed. This is why systematic, scientific soil investigations of mound hedges may be very interesting.     

Schwermetallverteilung und Tongehalte in Böden

Heavy metal distribution and clay contents in soils . In soil profiles differing considerably in horizon pattern and parent material the contents of Mn, Zn, Cu and Co were correlated with those of clay (and CEC), of total Fe (and dithionite soluble Fe) and - after relation to clay - with C. The correlations with clay, CEC, Fe_t and Fe_d were in all cases positive and highly significant, though differing between the different metals and between the references. Deviations for all elements are due to lithogenic differences in soils from mesozoic sediments and for Mn also due to its lower pedogenic stability. The correlations with C were not significant, since O horizons were not yet investigated. The ‘mobility’ of the heavy metals ( = EDTA + NH₄O Ac-extractable in relation to total amount) in topsoils could be more correlated (negative) with the reserves than with other soil features. Relating the ‘immobile’ heavy metal contents to the other soil features considerably improved the correlations.     

Nitratumverteilung in Böden durch Trocknung

Redistribution of nitrate in soil samples due to drying Soil core samples of 500 cm³ volume were dried at 105°C and divided into 0-1 to 1.0 cm thick layers. The nitrate content of layers from the evaporating upper and lower surface greatly increased as compared with the central parts of the core. This process may take place on drying soil samples in general and may create problems of homogenisation when dried soil samples are analysed on their nitrate content.