Bestimmung einiger Parameter des kapillaren Feuchtigkeitstransports in porösen Baustoffen. Teil 2: Untersuchungen an Ziegelstapeln

Determining some parameters of capillary moisture transport in porous building materials. Part 2: Tests on brick stacks Absorption tests on stacks assembled of (three) different types of brick each and assorted according to their apparent density were described. The influence of surface tension on results obtained will be made evident when choosing various aqueous solutions.     

Bestimmung einiger Parameter des kapillaren Feuchtigkeitstransports in porösen Baustoffen. Teil 3: Untersuchungen an Mörteln und Sanden

Determining some parameters of capillary moisture transport in porous building materials. Part 3: Tests on mortars and sands Because a mortar component ultimately belongs to brickwork, the contribution of sand, which serves as an aggregate, to capillary liquid rise was investigated. Since up to now this kind of transport can only be observed with difficulty, as also confirmed by experiment, due to complex interaction of the individual characteristic values, an attempt was made to also enhance present experience on other material than brick.     

Bestimmung der Lagerungsdichte in stark skeletthaltigen Böden

Determination of bulk density in stony soils A new method is represented which makes it possible to measure the bulk density easily even in the case of stony soils. First results demonstrate the reliability of this new method.     

Die analytische Bestimmung der Dehydrogenaseaktivität in Unterwasserböden

The analytical determination of dehydrogenase activity in underwater soils The determination of dehydrogenase activity in recent underwater soils is often troublesome, because of lack of homogeneity of the fresh samples. Mainly the occurrence of very low redox potentials in the lower horizons causes chemical reduction of triphenyl tetrazolium chloride (TTC), which gives misleadingly high dehydrogenase activities. This could be eliminated by a toluene treatment preceding the TTC incubation, by which bacterial dehydrogenase production is inhibited and chemical TTC reduction can be determined. Homogeneity is increased by intensive stirring immediately before weighing the aliquots.     

Die Bestimmung des hydraulischen Gradienten an der Befeuchtungsfront und seine Bedeutung für die Tonablösung im Boden

The determination of the hydraulic gradient of the wetting front and its relevance for clay detachment in soil As a result of some observations and experiments it must be supposed that clay migration does not only depend on the physico-chemical conditions but also on the water regime. Mechanical displacement of clay particles from its carrier can be the result of only rarely occuring high pore water velocities or of intensive changes of moisture suction at the wetting front, which can be quantified with the hydraulic gradient. A method how to determine the hydraulic gradient of the wetting front will be described. The determination and its importance for clay displacement will be explained by results of laboratory-experiments with sandy material packed into columns.     

Vergleich verschiedener Extraktionsmethoden zur Bestimmung der Kaliumverfügbarkeit in Böden

Comparison of different methods for the determination of the potassium availability of soils Extractable K was determined in 148 soil samples by using three different lactate solutions (AL, DL, CAL), 0.1 m HCl and 0.0125 m CaCl₂ as extracting agents. The extractable portion of the total exchangeable K (K(NH₄)) was found to decrease with increasing content of the < 6,3 μm particle size fraction in the samples. Correlation coefficients were calculated for characterizing the relationship between extracted amounts of K (K values) and the ?K numbers”?. The latter serve as a basis for fertilizer recommendations in the Netherlands, where they have been checked in a great number of field trials. The K number depicts the K supplying power of soils as determined by HCl soluble K, content of the < 16 μm size fraction, and pH. The K (CaCl₂) values were found to correlate more closely with the K numbers than the amounts of K extracted with lactate solutions. This is because the influence of particle size on K(CaCl₂) is eliminated as shown by multiple regression analysis. The strength of bonding of the easily exchangeable K is reflected much better by the K(CaCl₂) values than by the lactate values. Improvement of K fertilizer recommendations by taking K(CaCl₂) data as a basis can thus be expected. The different methods of recommendation for K fertilization in the Fed. Republic of Germany and in the Netherlands are illustrated for the soils derived from loess.     

Stickstoffverbindungen in Böden und ihre Beziehung zur Humusdynamik. 2. Mitteilung: Zur Bestimmung und Zuordnung des Amidstickstoffs

Nitrogen compounds in soils and their relation to humus dynamics. 2. Communication: On the determination and attachment of amide-nitrogen The amide-nitrogen fraction in soils – so far very insufficiently defined – has been determined in the hydrolysates of 12 different soil samples. The proposed procedure allows to split this amide-nitrogen fraction into two better befined N-fractions, namely: real amide-N (EAN) and pseudo-amide-N (PAN). This splitting is based on. 1.) a detailed N-fractionation, especially a quantitation of aspartic acid + glutamic acid (AG) and ammonia in the hydrolysate, 2.) on the fact, that pure proteins and ?soil proteins”? do not significantly differ in terms of their amino acid composition (average basis per mol protein) and deductive hereupon 3.) on the assumption, that the calculated NH₄/AG- ratio of 0,5 from pure proteins can be transferred to ?soil proteins”?. Methodically the real amide-N (EAN) and the pseudo-amide-N (PAN) are determined as follows: After quantitation of aspartic acid + glutamic acid (AG) in the soil hydrolysate EAN can be calculated by the equation: EAN = (AG) X 0,5. PAN amounts to the difference between Ammonia of the hydrolysate and EAN. For the 12 soil samples the PAN/EAN-ratios are in the range 1,5–11,7.     

Bestimmung der Harnstoffabbaurate in Land- und Unterwasserböden nach verschiedenen Methoden

Determination of urease activity by two different methods in some soils and underwater soils Two methods differing in microbial activity during incubation with urea were used for the determination of urease activity. The results obtained showed a better relationship with natural conditions such as pH, organic substance-, or clay content, if the microbial activity was not inhibited during incubation. This effect was found to be particularly pronounced in underwater soils, where addition of a bacteriostatic substance (toluene) resulted in practically uniform values that reflected neither bacterial nor nutrient status.     

Ertragssimulation mit “Ceres Wheat” an Grundwasserböden gemäßigter Klimazonen. Teil 1: Anwendungsgrenzen des Originalmodelles und Modelländerungen

Calibration of the simulation model “Ceres Wheat” under conditions of soils with shallow watertable and temperate climate. Part 1: Limitations in the applicability of the original model and necessary modifications To apply the yield simulation model “Ceres Wheat” under the specific climate conditions of Schleswig Holstein, the following modifications were necessary:

• Wheat development is strongly influenced by climatic conditions. Therefore the model has been adjusted to the temperate climate of Schleswig Holstein.
• The soil water balance routine of the model was originally designed for soils without oxygen deficiencies due to water logging. Routines for shallow water tables and artificial drainage were formulated.
• Due to modifications of the soil water balance routine, the associated nitrogen routine, especially the leaching of nitrate, has been changed.
• The simulation of yield depressions due to excessive water required the introduction of a trafficability delay function and an additional reduction factor for crop development.

All routines concerning the water and nitrogen balances and the quality of simulations have been tested under conditions of coastal marsh soils in Schleswig Holstein.     

Eine optimierte Methode zur Bestimmung der Proteaseaktivität in Sauren Waldböden

An optimized method for the determination of protease activity in acid forest soils A method for the determination of protease activity was tested for its applicability to acid forest soils (O-horizon and mineral soil). The influences of the following parameters on the protease activity and its determination were investigated: incubation time, substrate concentration. pH-value of the incubation solution, buffer solution, sample matrix and storage of soil samples. In consequence of the results an optimized method is proposed. The application of this modified method to two forest sites with contrasting N-transformation indicates, that also in acid forest soils the determination of protease activity allows significant differentiations.     

Eine verbesserte Methode zur Bestimmung der Anzahl von Endospermzellen in Weizenkörnern

An improved method for the determination of the number of endosperm cells in wheat grains A method is described, which allows a clear and quantitative determination of endosperm cells in wheat grains even during the late stages of grain filling. After treatment with pectinase the tissue of the endosperm disintegrates in single cells, in the same step the starch in the endosperm cells is dissolved. The nuclei of the endosperm cells are stained with hematoxylin, drawn by vacuum on to a millipore filter, and counted in the still recognizable cell structures under a microscope. This is advantageous for exact counting of all the endosperm cells.     

Einfluß der Kaliumdüngung auf die Verfügbarkeit des Kaliums in K-fixierenden Böden im Verlaufe der Vegetationszeit

Effect of potassium fertilization on K-availability in potassium fixing soils over the vegetative period The effect of potassium fertilization on the K-availability over the course of the vegetative period was tested on nine potassium fixing soils over two years. The availability of potassium fertilized at the beginning of vegetative period falls (on a soil with 50% clay) to half of the original amount within one month. The availability decreases especially during the time without vegetation. Only after fertilization with 1200 kg K₂O/ha are substantial amounts of potassium available for the plants until the end of the vegetative period (determined by electroultrafiltration). An annual application of 300 kg K₂O/ha only slightly increased the CAL-K and exchangeable K in comparison with the unfertilized plots, although the plants showed marked yield responses. A significant improvement in potassium supply was not obtained with less than 600 kg K₂O/ha. The potassium wet fixation values are relatively constant on the plots without or with low K-fertilization: after high potassium application they show considerable fluctuation. The fixation potential is considerably reduced with an annual application of 1800 kg K₂O/ha, but is not completely removed. Potassium can be removed by repeated extraction with a dilute CaCl₂-solution but the rate at which it is released into the soil solution is too slow compared to the needs of rapidly growing crop plants. The rise in the level of available potassium by fertilization is reverse to the clay content. There was considerable variation between the different available potassium forms over the vegetative period on the highly fertilized plots; consequently a soil test made annually can only give a rough idea of the K-level in potassium fixing soils.     

Über die Magnesiumverarmung der Böden in den Hochlagen des Inneren Bayerischen Waldes

On the depletion of magnesium in soils of high altitudes of the Inner Bavarian Forest A widespread magnesium deficiency in stands of Norway spruce, growing at high altitudes of the Bavarian Forest, was the reason for an extensive soil survey and for hydrological-hydrochemical studies of these areas. The prevailing soils are Fragiorthods and Fragiumbrepts (great soil groups after US Soil Taxonomy). Total element contents of soils show clear relation to the respective parent rock. These relations are missing for exchange capacity (CEC_e) and exchangeable elements. This fact can be explained by a consolidated layer in the upper soil and high annual precipitations, which favor episodic interflow with low pH (about 4,0) and high SO₄- respectively NO₃-concentrations. Water of the deeper ground (baseflow) however, shows high pH-values (about 6,5) and low SO₄-concentrations. Increased concentrations of SO₄ and NO₃ in seepage water (interflow) show relation to considerable atmospheric S- and N-input. Furthermore the qualitative evaluation of the nutrient balance in these forest ecosystems revealed a release of SO₄ and NO₃ in soils of the high elevations, which must be followed by an equivalent removal of cations. The balance of element translocations in soil profiles shows, that magnesium is mostly affected by these depletion processes.     

Raten der Deposition,der internen Produktion und des Umsatzes von Protonen in zwei Waldökosystemen

Rates of deposition, of soil internal production and of turnover of protons in two forest ecosystems The rates of deposition, of turnover and of soil internal production of protons are calculated from the flux balance of chemical elements within two forest ecosystems (Dystic Cambisols from loess/sandstone with beech or spruce). The rates of interception deposition vary significantly throughout the season and determine the rates of total deposition to a large extent. The comparison of the actual rates of proton load with the buffer rates possible in the soils leads to the conclusion that soil acidification up to the level of the Al-buffer range is unavoidable in most forest soils in Middle Europe. The behaviour of the incoming S in the soil is related to the dissolution and precipitation of Al-hydroxo-sulfate. The accumulation of S within the soil of the spruce stand was found to be reversible and was followed by a phase of strong leaching of S and Al from the soil. The processes that account for the rates of soil internal proton-net-production are quantified. More than 70% of the total proton load results from the deposition of air pollutants while only less than 30% is of soil internal origin.