Soil-water Mixture Research Articles

A New In-Laboratory Method to Make Homogeneous Clayey Samples and their Mechanical Properties

ABSTRACT For the purpose of making reproducible and homogeneous clayey samples, a new method using artificial sedimentation from a diluted soil-water mixture is proposed. The quality of the samples made from the mixtures with widely varying water content was first investigated for sample homogeneity. Then the mechanical characteristics of the samples were investigated for one-dimensional consolidation and undrained triaxial compression tests. The results showed the following: (1) The high degree of homogeneity can successfully be obtained so long as the water content of the dilute mixture is within a certain range, (2) The compressibility and the permeability strongly depend on the mixture’s water content, (3) The triaxial shear behaviour hardly depends on the mixture’s water content except for when it is as low as the mixture is in a plastic state.

Specific energy expenditures for hydraulic transport of highly concentrated soil-water mixture

1. Calculations of the specific energy expenditures for hydraulic transport of soil by the methods of determining the head losses confirm that it is expedient to transport a highly concentrated soil-water mixture. The saving of specific energy expenditures in that case is from 20 to 40% of the existing standards. The greatest saving can be attained in the case of transporting a sand-gravel mix, the concentration of which usually does not exceed 5%. 2. It is economically expedient to deliver a highly concentrated mixture with a smaller flow rate and increased hydraulic gradient of transport than to deliver a mixture with a low concentration at a large flow rate. 3. Designs and equipment have presently been developed for hydraulic transport of thick mixtures.

Development and introduction of the OHTPI-2 optimal hydraulic transport performance indicator

1. The engineering personnel of the trust Gidromekhanizatsiya and experimental industrial enterprise Promgidromekhanizatsiya were able to develop an optimal hydraulic transport performance indicator (OHTPI-2) based on monitoring the soil sediment layer in a pipeline and consistency of the soil—water mixture by the conductometric method. 2. The installation of the OHTPI-2 on a dredge makes it possible to inform the operator about attaining and maintaining optimal saturation of the mixture with soil for the given concrete conditions. An increase of productivity and reduction of energy expenditures by 18% were achieved during the test. For effective use of the indicator it is necessary to instruct the dredge personnel in the rules of operating the device and selecting the dredging regime. 3. By means of the indicator it is possible to check the optimality of the existing parameters of hydraulic transport — head, flow rate, and diameter of the pipeline and their correspondence to the particular soil conditions. 4. The indicator of the soil sediment level in the pipeline can be used for monitoring the soil level and liquid phase in a vessel. 5. It is necessary to continue works on improving the indicator for its combination with other monitoring and calculating instruments.

Nitrate reductase activity of soils

Dissimilatory nitrate reductase in soils is the enzyme that catalyzes the reduction of NO 33 − to NO 2 − under anaerobic conditions. The detection of this enzyme in soils is reported, and a simple, sensitive and precise method to assay its activity is described. The method involves determination of the NO 2 −-N produced when soil. 2,4-dinitrophenol (DNP), and KNO 3 are incubated under waterlogged conditions at 25°C for 24 h. At a certain concentration, depending on the soil type, DNP inhibits nitrite reductase but not nitrate reductase. The DNP concentration required for optimum NO 2 − production in five soils ranged from 5 to 300 μg DNP g −1 soil. The nitrate reductase activity of six soils studied ranged from 18 to 80 μg NO 2 −-N produced g −1 soil 24 h −1. Optimum activity was found at 5 mM KNO 3 and nitrate reductase was inhibited at >5 mM KNO 3. Nitrate reductase activity in soils is inactivated at temperatures above 40°C and is completely destroyed by steam sterilization. The relationship between duration of incubation and the amount of NO 2 −-N produced showed a lag of about 10 h, but in general, thereafter, this relationship was linear for a certain period of incubation, which varied among the soils studied. The duration of the lag was reduced, but not completely eliminated, either by previous incubation for 10 h or by bubbling N 2 gas in the soil-water mixture for 3 min to remove the dissolved O 2 in the soil-water mixture before addition of NO 3 −. The relationship between the amount of soil used and the NO 2 −-N produced was linear unless the substrate concentration was limiting the reaction rate. Application of the Lineweaver-Burk transformation of the Michaelis-Menten equation indicated that the K m values for nitrate reductase in Ames and Okoboji soils were 3.7 and 2.9, respectively, and the V max values were 122 and 126μg NO 2 −-N produced g − soil 24 h −.

The effects of agronomy on C and N distribution in soil organo-mineral fractions

SUMMARYSoils from grass-arable cropping sequences and from an experiment where grassland had been treated with slurry were dispersed by shaking as a soil-water mixture, followed by ultrasonic treatment. Organo-mineral particle size fractions were separated by sieving and by sedimentation.Generally, concentration of C and N in the fractions decreased with increasing particle size. However, when expressed as weight of C per fraction maximum contents were in the 2–10 μm range. With N, maximum contents occurred about 2 μm. Largest differences in C and N contents between soils were found in the 0·2–20 μm size range.Identification of the source of the materials in the various fractions was attempted by interpretation of the C/N ratios, but was generally inconclusive.

Use of specific conductance and contact time relations for separating flow components in storm runoff

The difference between the dissolved‐solids concentration in base flow and in storm flow has often been used as the basis for separating components of flow. However, an analysis that explicitly relates the amount of time that runoff water has been in contact with watershed soils to the resulting dissolved‐solids concentration shows that simple mass balance chemistry methods for hydrograph separation are misleading. Field studies of surface and subsurface storm flow, when coupled with laboratory determination of the relationship between contact time and dissolved solids content of a soil water mixture, suggest that the residence time of infiltrated water is as short as a few hours in the cases studied. In those cases, hydrograph separation methods based on the simple mass balance equation for the dissolved solids will yield considerable overestimates of the base flow component.

A simple ion-exchange resin procedure for extracting plant-available elements from soil

A simplified procedure for extracting ions from soil with ion-exchange resins is reported. The resin, placed in nylon-netting bags, were immersed in soil suspensions and shaken. Compared to the conventional procedure, where the resin beads are freely suspended in the soil-water mixture, this bag-procedure allowed quicker separation of resin from the soil suspensions. Furthermore, the severe soil grinding as done in the conventional procedure was eliminated. Phosphate was extracted from 4 Danish soils using both procedures. The bag-procedure resulted in slightly higher values than did the conventional procedure. re]19760408

A Procedure for Extraction of Molybdenum from Soil with Anion-Exchange Resin

A revised procedure for extracting Mo from soil with an anion-exchange resin and a method for eliminating colorimetric interferences of soluble organic matter from the extracts are reported in this study. Brass screen cups were used to contain the resin while the cups were immersed in a soil-water mixture. The extraction of Mo from soil suspensions using brass screen cups allowed rapid separation of resin from the suspensions and eliminated a filtration step from the normal procedure. Interference due to dissolved organic matter was eliminated by oxidation with acidic hydrogen peroxide. The interference ranged from 21 to 99% for 8 samples tested.

High dielectric constant microwave probes for sensing soil moisture

Implantable soil moisture sensors suitable for long-term monitoring of moisture in highway subgrades and for similar applications are needed. Two candidate designs of microwave sensors (operating range 4 to 6 GHz) have been investigated for such applications. One design uses the fringing field of a low-loss dielectric slab waveguide (relative dielectric constant of 25) to obtain good resolution for finely divided soil such as bentonite clay with moisture ranging from 10 to 50 percent by dry weight for effective sample volumes of 20 to 40 cm2. The response of the dielectric waveguide sensor has been calculated in terms of the effective dielectric constant of the soil-water mixture. A model based on index of refraction yields an effective dielectric constant in reasonable agreement with experiment when effects of ionic conduction are accounted for. Another sensor design, better adapted for coarse materials, such as crushed limestone aggregate, uses waves launched from a tapered dielectric slab. By using either frequency or spatial averaging methods, the launched wave sensor accommodated aggregate particles passed by a 0.63-cm mesh sieve, and was found to have satisfactory resolution for the range of 0- to 10-percent moisture by dry weight.

Hydraulic filling of dams constructed of silty soils, using a flattened profile

1. Construction experience and experimental investigations established that it is advantageous to use silty soils for the construction of dams with a flattened profile, consisting of a downstream impervious shoulder (hydraulic fill) and upstream wave-resistant ramp (dumped material). This design eliminates the construction of massive shoulders of gravel-pebble material which are needed in hydraulic filling of compressed dams of disperse soils. 2. Flattened dams, depending on the content of sand particles in the disperse soils, are constructed by unilateral hydraulic filling with limitation of the upstream slope or by unilateral hydraulic filling with bypass of the soil-water mixture into settling pools arranged on the section of the upstream ramp. With both methods the stability of the dam is provided during construction by layerwise consolidation of the soil. The wave-resistant ramp, constructed beforehand by dumping soil, eliminates the need of an upstream slope revetment and provides stepwise filling of the reservoir. 3. In the case of unilateral hydraulic filling with bypass of the soil-water mixture into settling pools the quality of the soil placed in the impervious shoulder improves. In this case the carry-off of soil with the drain water does not exceed 5%, whereas with hydraulic filling by the old technology carry-off averaged 25% 4. The cost of constructing a flattened dam for a height up to 15 m is about 3% less than the cost of a compressed dam with gravel shoulders, and with consideration of the reduction of soil carry-off the construction cost is reduced additionally by 10–15% in the case of hydraulic filling by the recommended technology with placement of settling pools on the section of the upstream ramp. 5. In hydraulic filling of dams by the recommended technology labor productivity increases 19% owing to the reduction of soil losses and decrease of manpower. 6. When planning construction operations, it is necessary to take into account the basic parameters characterizing the technological process: rate of hydraulic filling designated so as to provide layerwise consolidation of the soil and calculated by Eq. (1) and the optimal layers of hydraulic fill and dumped soil in the settling pools, determined by Eqs. (5) and (6).

Computation of some soil-water mixture parameters involved in the immersion of a suction tube into soil

Computation of some soil-water mixture parameters involved in the immersion of a suction tube into soil

A Comparison of Glass and Quinhydrone Electrodes for Determining the pH of some IOWA Soils: III. The Change in pH of the Soil‐Water Mixture with Time1

Agronomy JournalVolume 27, Issue 8 p. 585-595 Article A Comparison of Glass and Quinhydrone Electrodes for Determining the pH of some IOWA Soils: III. The Change in pH of the Soil-Water Mixture with Time1 Harold L. Dean, Harold L. DeanSearch for more papers by this authorR. H. Walker, R. H. Walker Research Fellow and Research Associate Professor of Soils, respectively. The authors are indebted to Dr. P. E. Brown for the suggestions and criticisms offered in the course of this work and in the preparation of the manuscript.Search for more papers by this author Harold L. Dean, Harold L. DeanSearch for more papers by this authorR. H. Walker, R. H. Walker Research Fellow and Research Associate Professor of Soils, respectively. The authors are indebted to Dr. P. E. Brown for the suggestions and criticisms offered in the course of this work and in the preparation of the manuscript.Search for more papers by this author First published: 01 August 1935 https://doi.org/10.2134/agronj1935.00021962002700080001x 1 Journal Paper No. J 253 of the Iowa Agricultural Experiment Station, Ames, Iowa. Project No. 229. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume27, Issue8August 1935Pages 585-595 RelatedInformation