Huminstoffbildung während der Kompostierung

Formation of Humic Substances during Composting Wheat Straw During composting straw (with and without N-addition) in a model-compostreactor with continuous progress of rotting it comes to an increase of the fraction of humic acids under simultaneousness decrease of their prestages. The synthesis of humic acids is strongly marked in the thermophilic area. Compared with the untreated variant up to 30% more of the humic acids are formed in the N-treated plots. After the maximum temperature the formation of humic acids break down. A direct relation exists between the microbiological decomposition of the organic matter and the formation of humic acids. IR-spectroscopic measurements show no qualitative differences either between or within the compost variants.     

Untersuchungen über die toxische Wirkung der in Siedlungsabfällen häufigen Schwermetalle auf die Bodenmikroflora

The toxic effects of heavy metals, commonly found in urban wastes on the soil microflora In several series the influence of soluble salts of Cd, Cr, Zn, Cu, Ni and Hg in various concentrations was tested on the development of bacteria and fungi in cultural studies and in soil model systems. In addition the changes in microbial biomass, in the activity of oxidoreductases and hydrolases, and in nitrification were measured in five soils. Comparison of the results of bacteria-plate-counts in the presence of heavy metals in agar-media and in soils demonstrated that all tested elements have a more toxic effect on isolated soil microorganisms under culture conditions than when tested after heavy metal application to soils. Beside Hg, eucaryotic soil fungi proved to be 10 – 50 fold more resistant to heavy metals in vitro as well as in situ. For calculating the effect of heavy metals on soil microbial activity soil enzymatic methods are not reliable and can be used only to some extent, because some cellfree encymes in the soil are activated or inactivated immediately by heavy metals. In long-term experiments, the microbial biomass and nitrification in soil is not significantly influenced by the elements Cd, Cu and Ni in the concentration range of the tolerable limit content. In contrast, Cr, Zn and Hg reduced these microbiological properties more or less distinctly.     

Die Bedeutung des Strohgehaltes für die Erhaltung des Stickstoffs während der Kompostierung von Rindermist

The significance of straw content for the rentention of nitrogen during the composting of cattle manure A mixture of cattle manure (low in straw content) and straw were held at room temperature in perforated cubic containers for a 5 month's composting period. The influence of the availability of carbon on the formation of organically bound nitrogen was examined. For this purpose the added straw was reduced in size to varying degrees. The prepared mixtures all contained the same C/N-ratio. Nutrient losses in liquid form could be avoided by careful addition of water. During the first 6 weeks the content of organically bound nitrogen increased, in the sequence of increasing proportions of milled straw, from 6 to 23 %. This was attributed to the increased availability of carbon. At the end of the experiment the content of organically bound nitrogen, in all mixtures, decreased again to the initial level. This was attributed to an extensive mineralisation into nitrate in the mixtures with straw chaff. It is assumed that the low nitrate content of the variant containing only powdered straw is caused by temporary anaerobic conditions, which may be have induced a denitrification.     

Einfluß von K-Ernährung und Mehltaubefall auf den N-Haushalt von Sommergerste während des Kornwachstums

Influence of K nutrition and mildew attack on N metabolism of spring barley during grain development Spring barley cv Aramir was grown in complete nutrient solutions containing 0,4 (K₁) and 4 me K/l (K₂) respectively. Half of the plants were sprayed regularly with a fungicide, the other half became naturally infected by mildew, Erysiphe graminis. Mildew attack was clearly visible in unsprayed plants, especially at K₁. Accordingly also grain yield was depressed by 18% (K₁) and 15% (K₂) compared to the controls. Better K nutrition reduced symptoms of mildew infection drastically and increased grain yield from 87 g/pot (K₁) to 169 g (K₂). Similar yield increases (106 to 199 g/pot) were obtained in the control plants, revealing that under the experimental conditions better K supply stimulated growth in general rather than inducing specific defense mechanism against the pathogen. The latter was hoped to be detectable by applying ¹⁵N-nitrogen during 3 days at anthesis. Although K₂ plants absorbed more ¹⁵N and incorporated more ¹⁵N into leaf protein, this cannot be considered as a K induced defense reaction. Instead due to lower grain yields in infected plants less proteolysis in the vegetative plant parts occured.     

Die Persistenz von Chlorcholinchlorid in Weizenpflanzen während der generativen Wachstumsphase und in lagernden Weizenkörnern

The persistance of chlorocholine chloride in wheat plants during the reproductive stage and in the kernels during storage In pot experiments with spring wheat the metabolization of the growth regulator chlorocholine chloride (CCC) has been studied during the reproductive stage. Also the persistance of ¹⁴C labelled CCC in wheat kernels has been examined during a period of one year. The following results were obtained:

• 1 The mobility of CCC in the plant was very low. Even when CCC was applied at a late stage (beginning of ear emergence), 98 to 99% of the applied ¹⁴C activity remained in the shoots and only 1 to 2% were translocated towards the ears. Also when CCC was twice applied the CCC content in the ears amounted only to 1 to 2 ppm.
• 2 Chlorocholine chloride was very stable in the plants and only a small percentage was converted to choline. Thus by far the main proportion of the applied ¹⁴C activity was recovered in the form of CCC and only 2 to 5% were found in the choline fraction. ¹⁴C activity in the other chemical fractions of the plant material was extremely low or zero.
• 3 In the choline fraction of the kernels the ¹⁴C activity amounted to 12% of the total ¹⁴C activity and thus was twice as high as in the straw. This relatively high 14C label in the choline fraction could be related to metabolic processes typical for grain growth. It is also possible that choline synthesized in the leaves is more easily translocated towards the kernels than chlorocholine chloride.
• 4 The mature kernels stored at room temperature did not show any metabolization of CCC during a period of one year. Neither the total ¹⁴C activity nor the content of CCC were altered significantly during this time.

     

Untersuchungen zur Stickstoff-Immobilisation in mineralisch gedüngten Ackerböden aus Löß während der Vegetationszeit von Winter-Weizen

Experiments on nitrogen immobilization in minerally fertilized soils from loess during the growing season of winter wheat The nitrogen regime has been simulated during the growing period of winter wheat 1984/85 on a stagnigleyic cambisol using a simple, functional computer model. The model includes N mineralization from soil organic matter, transport of water and nitrate as well as growth of wheat and N uptake by the crop. Simulation starts at harvest of the previous crop. Simulated and measured N supply (soil mineral nitrogen plus N uptake by the plant) were in good agreement between september and december 1984. On this loess plot as well as on 10 other ones an over-estimation of mineral nitrogen in the soil up to 40 kg/ha was observed with beginning of december/january 1984/85 reflecting a seasonal trend. Experiments with ¹⁵N enriched Ca-nitrate 1984/85 on microplots of the same field point to a non-consideration of nitrogen immobilization. Fertilizer-N-immobilization amounted up to 35 kg/ha in the soil and to further 15 kg/ha in the straw material. The pool of fixed ammonium was of no importance with respect to the mobilization-immobilization-turn-over of fertilizer nitrogen. Experiments 1988/89 on microplots of a colluvial loess soil indicate a change of biomass nitrogen being responsible for the seasonal N-immobilization. An increase of biomass-N of about 30 kg/ha was observed under the growing wheat crop. An additional N-immobilization of nearly 40 kg/ha was observed with straw incorporation. A similar increase of microbial biomass nitrogen under winter wheat has been observed during the growing period 1987/88.     

Veränderungen physikalischer Bodenmerkmale im „Statischen Düngungsversuch”︁ während einer Vegetationsperiode

Temporal variations of physical soil properties in the “Static Fertilization Experiment” The objective of the present paper was to observe short-term changes in physical soil properties of a differently fertilized loess-Chernozem. Samples were taken weekly from the plots with 17.2 g C_org kg^?1 (unfertilized) and 25.0 g C_org kg^?1 (NPK + farmyard manure) of the “Static Fertilization Experiment”, Bad Lauchstädt, and their moisture contents (θ), bulk densities (?_d) and particle densities (?_s) were determined. The soil moisture contents showed very similar variations in the two treatments. Clear differences between the unfertilized (≈ 16 Vol.-%) and the NPK + farmyard manure treatment (≈ 10 Vol.-%) only occurred during summer (means 25th–29th week). The values for ?_d were lower in the NPK + farmyard manure plot (mean: –0.10 g cm^?3). Similar short-term changes in ?_d were found in both treatments and correlated to both, organic matter contents and composition (C_org, N_t, C/N). These data, however, gave no indication of reasons for the short-term changes in particle densities up to 0.09 g cm^?3.     

Aluminiumkonzentrationen und -bindungsformen von Bachwässern und wässrigen Bodenextrakten in den Hochlagen des Inneren Bayerischen Waldes

Aluminium concentrations and -species in streamwaters and water extracts at high elevations of the Inner Bavarian Forest During summer half-years 1986–1988 Al concentrations and Al species were recorded periodically for streamwaters of the Inner Bavarian Forest. Furthermore these analyses were carried out once with water extracts of 5 typical high elevation pedons. Total Al of streamwaters is strongly influenced by the hydrological situation. Highest Al concentrations (up to 1,5 mg/l Al) were found during subsurface flow (interflow) events, when inorganic Al species (Allabil) were predominant. In interflow and water extracts of high elevation sites the average molar ratio of Ca/Al_labil is ≧ 0,5 and the average Mg/Al_labil ratio ≧ 0,4. After Ulrich et al. (1984) and Jorns et al. (1985) these values are above the level of serious Al toxicity and thus they might not be the reason of the widespread Mg-deficiency in high elevation stands of Norway spruce. Water extracts of the examined soils have pK values similar to the mineral Jurbanit (AlOH₂SO₄). Thus in these soils a considerable part of Al should exist in this phase. The differing situation in interflow waters can be explained by an incomplete chemical equilibrium.     

Anionenbestimmung in natürlichen wässrigen Lösungen: ein Methodenvergleich von ionenchromatographischen und Continuous-Flow-Verfahren

Analysis of anions in natural waters: a comparison of methods including ionchromatography and continuous-flow-technics Using waters from different compartments of forest ecosystems, standard solutions, moreover samples containing known internal standards, several analytical methods were tested for the comparability of nitrate, sulfate and chloride results in an inter-laboratory study. The analytical instruments were ion chromatographs with and without suppression as well as continuous-flow-analyzers. A cluster analysis showed a strong correlation between the obtained data and the analytical method used for nitrate, and a poorer relation for sulfate. Concerning nitrate-analysis, the IC-systems showed a better detection limit and a higher recovery of standards. Mean standard deviation among all tested analytical methods was calculated to be 15% for nitrate, 10% for sulfate and 14% for chloride. These results represent deviations as they may occur during laboratory routine analyses with a high amount of samples and the need for simultaneous determination of several anions. For the examined anions no significant correlation was obtained between the variation of the analytical results and the dissolved organic carbon concentrations of the samples.     

Stickstoffernährung und Al-Toxizität bei Buchenjungpflanzen. I: Entwicklung von Buchenjungpflanzen in Abhängigkeit von der Form der Stickstoffernährung und dem Aluminiumgehalt der Nährlösung

Nitrogen nutrition and Al toxicity with young beech plants. I: Development of young beech plants in relation to the source of nitrogen and the Al content of the nutrient solution Young beech plants were grown in aerated nutrient solutions with different Al concentrations over a period of 14 weeks. Nitrogen was supplied in either NO₃- or NH₄-form. pH-changes of the solutions were either corrected to the initial pH of 4 after two days, or not corrected over a period of two weeks. Root growth of the beech seedlings was inhibited by Al. Reduction of root length and dry matter production was more severe if the plants were fed with ammonium nitrogen compared to nitrate nitrogen. Detrimental effect of Al on root growth was also influenced by the pH of the solution. NH₄-N-nutrition led to pH decrease and therefore to increased solubility and toxicity of aluminium. On the contrary, NO₃-N-nutrition weakened Al toxicity because of pH increase at the root surface and in the AFS. This led to an inactivation of Al in the form of insoluble hydroxy aluminium polymers. Compared to NO₃-N-nutrition NH₄-N promoted shoot growth. During 14 weeks no detrimental effect of Al on shoot growth was observed.     

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.     

Eine Kombination der Thermogravimetrie mit der 15N-Tracertechnik zur Untersuchung von Huminsäurepräparaten

A combination of thermal analyses and ¹⁵N tracer technique for investigation of humic acids Differences in humic acids of two extreme variants of three long-term trials due to a three years intensive fertilization in a pot experiment are also to be found by means of thermogravimetry. Additionally the ¹⁵N contents of humic acids were investigated at certain temperatures according to the peaks given by thermogravimetric study. The ¹⁵N isotope is also incorporated in higher molecular compounds. The ¹⁵N content varies due to differences in humus content and composition of the soils used.     

Zur Abhängigkeit des Bodenwasserpotentials von der Temperatur

Soil-water-potentials depending on temperature The soil-water-potential · of different soils has been measured in dependence of temperature. Between about — 0.2 · 10⁶ and — 0.7 · 10⁶ erg cm^?3 (corresponding to a pressure head of 2 resp. 7 m water) all soils show a significant dependence of the soil-water-potential on temperature always in connection with hysteresis phenomena. With soils rich in clay or sand the dependence is most pronounced. At very high suction values (< — 0.7 · 10⁶ erg cm^?3) the dependence becomes small. Thus the measurements agree well with psychrometric evaluations of Campbell and Gardner (1971) on the no-temperature-dependence of the soil-water-potential in the range of about — 3 ·10⁶ to — 20 ± 10⁶ erg cm^?3.     

pH-Änderungen in der Rhizosphäre von Mais- und Erdnußwurzeln

pH changes in the rhizosphere of peanut and maize roots pH changes in soil near growing peanuts and maize seedlings were measured using antimony microelectrodes. The roots of each plant actively altered pH, both at the root tip and root hair zone (maize) and immediately behind the root elongation zone (peanut). Along the root elongation zone and at distances greater than 10-15 cm from the root tip, pH moved towards the value in the soil outside of the rhizosphere. Peanut seedlings grown in unfertilized and NO₃-fertilized soil (initial pH 5.5) lowered soil pH by 1.5 and by 0.7 units, respectively; whereas maize seedlings caused pH increases of 1.0 and 1.5 units, respectively. In NH₄-fertilized soil, both seedlings caused soil pH to fall by 2-3 units. In an acid soil, pH changes occurred at distances of up to approximately 2.5 mm from root surfaces.     

Die Bestimmung der effektiven Kationenaustauschkapazität von Gesteinen

The determination of the effective cation exchange capacity of rocks The extractable cations (1 N NH₄Cl) of broken, mortared, and ground rocks (Sandstone, Clay schist, Diabase, Alkali-Olivinbasalt) were determined using vibration extraction and percolation. These methods were evaluated by re-exchange experiments. In addition mineralogical components, specific surface and effective porosity of the rocks were determined. Al-silicates which are cation exchangers like Illite and Zeolite minerals were found in these rocks. Mortaring and grinding increased the specific surface and the exchange capacity of the rocks which have a low porosity (Clay schist and Basalt). For example, the CEC of broken Clay schist was 27 μmol_c g^?1 and increased to ≈ 40 μmol_c g^?1 after mortaring. The CEC of the rocks with a high porosity (Diabase and Sandstone) did not depend on the particle size. Therefore we assume, that inner parts of the broken rocks were reached by extraction. The CEC amounts to ≈ 50–80% of the sum of the cations, which could be extracted with NH₄Cl. This difference is probably due to the dissolution of salts. Mortaring and grinding increased the amount of cations derived from dissolving of salts. The results show, that rocks are of signficance not only for silicate weathering, but also for the cation exchange.     

Bewertung von Pedotransferfunktionen zur Schätzung der Wasserspannungskurve

Evaluation of Pedotransfer Functions for Estimating the Water Retention Curve On the basis of 1693 data records of the laboratory database of the Lower Saxony Soil Information System (NIBIS), six pedotransfer functions for estimating the water retention curve were tested and their usefulness was evaluated. Among the three methods used to calculate water content for individual matrix potentials on the basis of linear regression analysis, the equations of Renger (1971) stand out because they yield the least deviation between the estimated and measured values. The algorithm of Vereecken et al. (1989) is the better of the two methods for estimating the parameter values of the equation of van Genuchten, describing the water retention curve by a continuous function. The methods examined here show no distinction with respect to which type of substrate they are best suited. The results allow a target-oriented selection of methods for the method database of a Soil Information System.     

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.