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. 相似文献
Intersite estimation of biological activity of soils by determination respiration and cellulolytical activity in the field A temperature differentiated scale of estimation is presented, which is derived from long-term investigations of respiration and cellulolytic activity. This is suitable for intersite comparison of different soil-ecosystems. Investigations in spring are representative and could be done during mapping the soil-ecosystems. It exists a strong correlation to the quality of the humus body and to the available nutrients. 相似文献
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 相似文献
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. 相似文献
Remarks on the determination of the unsaturated hydraulic conductivity based on field measurements In a previous paper hydraulic conductivity — moisture tension functions have been evaluated by a field method for various layers of a fallow loess soil (grey brown podzolic soil). The aim of the paper presented here, is to demonstrate the magnitude of error when the hydraulic functions are calculated in the presence of transpiring plants, as it was done elsewhere. The error arises, because the water uptake rates of roots are added to the capillary water flux through the soil matrix. From the present investigation it becomes clear that with advancing growing stages of winter wheat and the increasing water extraction ability the error becomes more and more pronounced. The conductivity values may then be overestimated by a factor of half the power of ten as compared to the results computed from the fallow soil. 相似文献
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. 相似文献
Course of cellulose decomposition in a brown earth under a Trisetum flavescens – meadow after different fertilization The cellulose decomposition in the soil of a Trisetum flavescens-meadow untreated and treated with NPK. and PK fertilizer was determined by means of burial of pieces of cellophane. The rate of decomposition of the cellulose film was chosen as a measure of cellulolytic activity in soil. The cellulolytic activity had its maximum in the summer months and near the surface. The decrease with increasing depth was more obvious in the untreated lot than in the lot treated with NPK fertilizer. Under field conditions the influence of fertilization on the cellulolytic activity was low. In the laboratory there was a slight effect of the addition of soil from the NPK-lot on the decomposition of filter paper only with a slightly alkaline nutritive solution. The determination of soil cellulose content and mineralization of soil cellulose showed no differences between fertilized and untreated soil. 相似文献
A Spatially Differenciating Method for Computing High Resolution Maps of Soil Loss by Rain Wash - Fundamental Principles of the dUSLE The theoretical basis of a procedure to compute maps of the soil loss is presented. This procedure allows to estimate soil loss on a large scale (1:5000) for planning specific protection measures. The procedure uses the Universal Soil Loss Equation combined with a digital terrain model that consists of a triangulated, irregular network. In this way not only slope but also the influence of increasing soil loss down slope and the slope morphology are taken into account. Also, slope morphology is considered along the slope as well as across the slope. Therefore the procedure is called differentiating Universal Soil Loss Equation dUSLE. With the dUSLE it is possible to combine high resolution with high automatisation and reasonable computation time. The application of the USLE has the advantage of easy use and availability of data. Furthermore, most parts of the USLE have been adapted to and verified for German conditions in recent years. In part 2 the integration of the equations presented in the digital terrain model will be described. In a third part the application of the dUSLE in land reconsolidation and farmers extension service will be presented. 相似文献
Presentation of the SrCl2-method after Bach for the determination of the effective cation exchange capacity and comparison with the NH4Cl-method The SrCl2-method for the determination of the effective cation exchange capacity CECeff has been developed by Dr. H. Bach, a former geochemist of the “Geologisches Landesamt Schleswig-Holstein”. Exchangeable metallic cations in soils are displaced by a 0, 1 M SrCl2-solution and analyzed from the percolate. Reexchange of strontium by a 0, 1 M MgCl2-solution allows to determine the CECeff by analyzing for strontium in the second percolate. In comparison with the customary application of NH4Cl, SrCl2 shows the following advantages:
1 The nearly unbuffered SrCl2-solution adopts instantly the pH of the soil.
2 In contrast to the weakly acid NH4Cl-solution, no H3O+-cations compete with the exchange cation. Furthermore, partial dissolution of clay minerals is prevented because of the near-neutral character of the SrCl2-solution.
3 The SrCl2-method can be applied on all types of soils including carbonate- and salt-bearing soils.
4 The amount of free (dissolved) cations can be approximated.
An autoregressive procedure to predict the hydraulic conductivity — Comparison of measured and predicted results An instantaneous profile method was used to measure the unsaturated hydraulic conductivity. Relatively new techniques involving undisturbed soil samples instrumented with minitensio-meters and Time-Domain-Reflectometry (TDR) mini-probes were used for the experiments. The laboratory method allows a high spatial and temporal resolution. Laboratory measurements were carried out for 40 soil horizons with a wide spectrum of texture and bulk density. In addition, retention curves were measured using the standard pressure plate apparatus. Using this homogeneous set of data, an autoregressive model was developed which allows a stepwise calculation of the hydraulic conductivity for a water potential range of —30 up to —600 hPa. This model was developed for loamy sands, sandy, silty and clayey soils in conjunction with data from the retention curves. The calculation procedure starts with the determination of an initial unsaturated conductivity (k) close to field capacity, i.e., for water potential from —60 hPa up to —100 hPa. This first value is then used to predict other conductivity values using appropriate changes in soil water content corresponding to a defined range of the soil water potential. Subsequently, the hydraulic conductivities for higher and lower potentials were estimated considering the k value of the previous step in combination with the data of the retention curve of the next water potential range. The advantage of this empirical model is the indirect consideration of soil structure, in contrast to the closed-form van Genuchten-Mualem (vGM) model. To demonstrate these effects on different fitting procedures, the vGM model was also used to describe soil hydraulic functions. The accuracy of both, the vGM model and the autoregressive one, were compared for various fitting procedures and soils. 相似文献
Some remarks concerning the determination of the hydraulic conductivity with the auger hole method Values of hydraulic conductivity, achieved with the auger hole method, may depend on the calculation procedure that is used. In this paper, values obtained with the method of Ernst (1950) are compared with such of Boast and Kirkham (1971). It is found, that differences of 25 percent and more may occur. It is concluded that care should be taken when conductivities are calculated from auger hole measurements. The method of Boast and Kirkham (1971) appears to be superior. 相似文献
The improvement of Chromium determination in soil extracts by means of atomic absorption spectroscopy (flame technique) In order to achieve an improvement in the determination of chromium in soil extracts by means of atomic absorption spectroscopy, the influence of elements (Hg, Cd, Pb, Cu, Ni, Zn, Fe, Al, Mg, K, Na, Ca, P) which could possibly disturb the measurements of the chromium absorption using different flames (air/acetylene and laughing gas/acetylene), flame characteristics and measuring wavelengths (357,9 nm and 359,4 nm) was investigated. In this connection disturbances occurred which both raised or lowered the signal level. For nearly interference-free determination of chromium in the field of soil analysis we recommend the measuring wavelength 359,4 nm and the blue air/acetylene flame which has a low fuel gas content or the laughing gas/acetylene flame (approx. 5 cm high inner reduction zone). 相似文献
Land use and nitrate-nitrogen in the vadose zone of loess deposits in the southern part of the Lower Rhenish Embayment Mean annual nitrogen-leaching was studied at seven experimental sites with grain-sugar beet crop rotation. Soil water simulation models and determination of the nitrogen content in the vadose zone below the rooting zone were combined to quantify the annual leaching rates. Leaching amounts to 11–18 kg NO3? N/ha · a at sites where only mineral fertilizer was applied, whereas sites with additional organic fertilizers show higher leaching rates of 30–36 kg NO3? N/ha · a. 相似文献
Estimating soil water and air capacity from physical properties in anthropogenic substrate horizons Up to now there is no appropriate method available to estimate soil water and air capacity in anthropogenic substrate horizons. The “Bodenkundliche Kartieranleitung” (German soil classification key) was developed for natural soils and can be applied to anthropogenic soils only with limited validity. For developing an estimation system, a data base of 197 anthropogenic substrate horizons was established, consisting of soil characterizations gained from own investigations and from literature. By using multiple linear regression analysis, estimating models were developed to calculate soil water and air capacity derived from values of soil bulk density, texture, amount of skeleton and content of organic matter. Though every regression model proved to be highly significant, some gained coefficients of determination less than 50%. Absolute mean standard errors of estimate vary between 3.4 and 9.1 Vol%. 相似文献
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. 相似文献
A method for bulk density determination of gravel rich or thin soil horizons A limitation of bulk density determinations using the core sample method is that soil horizons must be thick enough for coring and nearly free of rock material. The significance of the proposed method lies in the fact that it is applicable also to soil samples rich in rock fragments and/or thin horizons. The samples are impregnated in the laboratory using an epoxy resin. Bulk density (ρb) is determined after hardening according to the following equation: ρf = density of soil material Bulk densities determined by the new method were found to agree well with such resulting from the core sample method. 相似文献
Nitrogen nutrition and Al toxicity with young beech plants. II: Mineral contents 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 4,0 after two days, or not corrected over a period of two weeks. The cation contents of the roots and shoots were greater if the nitrogen was supplied in NO3-form. Increasing Al concentrations in the nutrient solutions led to an increase in Al contents and a decrease in Ca- and Mg-contents in roots and shoots. 相似文献
The determination of aggregate stability - a comparison of methods The mechanical load bearing capacity and strength of aggregates against external forces can be described and quantified by indirect test (wet sieving method) and direct tests (e.g. crushing test, direct shear test). With the mean of the crushing test and the direct shear test in the shear box it is possible to achieve definite stresses, with which the influence of pore water pressure on soil stability can be explained by the occurence of water menisci forces. It is also possible to proof the pore water pressure dependent increase of strain by the particle reorientation during the process of aggregation. By the method of wet sieving, however, the summarized effect of hydraulic and mechanical processes can be described qualitatively only. A definite relation to single processes is therefore not possible. 相似文献
A Methodical Study on Soil Moisture Determination by the Neutron Scattering Method The use of the neutron scattering probe for the determination of soil moisture content in 60 plots in Dikopshof fertilisation experimental station for two years had required the study of some methodical aspects. One of the points is to get the standard curve. It was found that the standard curves taken from the model and from the field were nearly identical. Although regression analysis of the standard curve yield linear shapes, significance for non linear curves, was also obtained. The centre of sensitivity was more easily obtained by lowering the probe between two water filled containers than by the usual method. 相似文献
