Hydroxyl interaction with an alkaline clay soil during column leaching

Soil Research ◽  
1980 ◽  
Vol 18 (2) ◽  
pp. 233 ◽  
Author(s):  
AV Blackmore
Keyword(s):  
Clay Soil ◽  
Salt Content ◽  
Aggregate Size ◽  
Double Layers ◽  
Neutral Salt ◽  
Clay Particles ◽  
Content Change ◽  
Soil Fabric ◽  
Dominant Cation ◽  
Ionic Solutes

A study was made of the diffusion of hydroxide ions, added as leachant, from the inter-aggregate pores of a red-brown earth subsoil into the microporous fabric of the aggregates themselves, and then out again when the columns were leached with water. Electrical conductivity and pH were monitored within the column, in the leachate, and in extracts of the soil. The effects of flow rate, aggregate size, neutral salt content, change of cation, and the state and concentration of the hydroxide were considered. In systems having calcium as the dominant cation, the hydroxyls were able to freely enter the fabric and to react with edges of clay particles. In systems with sodium dominant both of these processes were actively inhibited. Strong anion exclusion, arising in the double layers at clay surfaces, operates in sodium but not in calcium systems. Leaching with water, which by hydrolysis reverses the edge adsorption of hydroxyl, revealed a low reservoir of hydroxide ions in sodium systems but a large one, resulting in strong buffering at high pH, in calcium. It is contended that other anions, although less mobile and less reactive than hydroxyl, will also respond to double layers in their approach and their entry to clay soil fabric. Consequently, any ionic solutes, introduced in the leaching stream or produced by root processes, will sometimes be impeded in penetrating soil fabric, just as such solutes are impeded in leaving it.

The relationship between aggregation and other soil properties in cracking clay soils

Soil Research ◽  
1984 ◽  
Vol 22 (1) ◽  
pp. 59 ◽  
Author(s):  
KJ Coughlan ◽  
RJ Loch
Keyword(s):  
Hydraulic Conductivity ◽  
Salt Content ◽  
Chemical Properties ◽  
Aggregate Size ◽  
Strong Relationship ◽  
Clay Soils ◽  
Coarse Surface ◽  
Seedbed Preparation ◽  
The Relationship ◽  
Dispersion Ratio

This paper explores the processes responsible for clay dispersion, and the formation of large dry aggregates, in cracking clay soils. It also isolates the soil factors causing variations in dry aggregate size using regression analysis. Twelve cracking clay soil samples were selected on visual differences in dry aggregate size distribution following seedbed preparation, and a range of soil structural and chemical properties were measured. The per cent dry aggregates > 5 mm was found to increase with resistance to mechanical abrasion, stability to wet sieving after capillary wetting, and dispersion ratio, indicating that large dry aggregates are formed as a result of binding by dispersed clay. Both raindrop impact and puddling by cultivation may be involved in dispersion. There was a strong relationship between dry aggregate size in the 0-10 cm layer and salt content in the subsurface (60-90 cm) layer. Coarse surface aggregation is explained in terms of limited profile hydraulic conductivity. For the soils studied, the properties of the surface layer appear to be responsible, at least in part, for the limitation in profile hydraulic conductivity. Dry aggregate size in the 0-10 cm layer was not simply correlated with any of the chemical properties of that layer. However, equations containing two (ESP and CEC per gram of clay) or three (ESP, per cent clay and CEC) independent variables were derived to explain variations in dry aggregate size, both for the 12 soils studied and for a wider range of Queensland cracking clay soils.

Alkali investigations in the Sudan

1925 ◽  
Vol 15 (4) ◽  
pp. 407-419 ◽  
Author(s):  
A. F. Joseph
Keyword(s):  
Sodium Carbonate ◽  
Clay Soil ◽  
Salt Content ◽  
Sodium Sulphate ◽  
Water Soluble ◽  
Soluble Salts ◽  
Nile Water ◽  
Heavy Clay ◽  
Alkali Salts ◽  
Very High

(1) The cotton growing area in the Gezira consists of a heavy clay soil, the proportion of clay being about 50–60 per cent. in the upper layers with a maximum at about the 4th foot.(2) The water soluble salts amount to about 0·2 per cent. The proportion is highest at about the 3rd to 5th foot. The alkalinity (pH) is highest at the 2nd foot.(3) In the first 2 feet, the salts consist mainly of sodium carbonate and the third and fourth of sodium sulphate.(4) The irrigation (Blue Nile) water is of excellent quality as judged by its natural chemical composition. The concentrated water, however, contains a very high proportion of alkali salts. It is estimated that a season of normal irrigation would cause an increase of 0·01 per cent. in the alkali content of the first 4 feet of soil.(5) The sodium salts can readily act on the clay and the sodium clay so formed hydrolyses with the formation of sodium carbonate.(6) Samples taken at the same time from good and bad plots in the same area show a strong correlation between salt content and cropyielding power. There is also a correlation between pH and fertility.(7) In the same season and in the same area, virgin (i.e. unirrigated) plots give a higher yield than those which have been previously under the same system of cultivation.

Exchangeable calcium, magnesium and sodium and the dispersion of illites in water. II. Dispersion of illites in water

Soil Research ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 255 ◽  
Author(s):  
WW Emerson ◽  
CL Chi
Keyword(s):  
Water Content ◽  
Particle Aggregation ◽  
The Other ◽  
Clay Particles ◽  
Exchangeable Calcium ◽  
Soil Clays ◽  
Exchangeable Magnesium ◽  
Calcium Magnesium ◽  
Calcium And Magnesium ◽  
Dominant Cation

Samples of illites, two extracted from soils, one from a shale, prepared with a range of exchangeable calcium, magnesium, sodium were immersed dry into water. The extent of dispersion with time was estimated visually and also deduced from the O.D. of the suspensions derived from the dispersed clay. The dispersion of wet calcium and magnesium soil illites sheared at a given water content and then immersed in water was also assessed visually. The dispersion of all three illites was enhanced when magnesium was the dominant cation rather than calcium. For the soil clays a lower ESP was required to initiate dispersion of the dry clay when immersed in water. Both calcium and magnesium forms of the shale illite dispersed partially over a period of several days when immersed dry into water, the magnesium to a greater extent than calcium. The magnesium form of the coarser of the two soil illites also dispersed slowly. By comparing the calcium-magnesium and calcium-sodium forms of the last clay, it was deduced that about 10 times the equivalent concentration of exchangeable magnesium as sodium was needed to cause the same degree of dispersion. For the other soil illite the water content for dispersion of the wet, sheared magnesium clay was found to be less than for the calcium clay. The O.D. of suspensions of the clays was found to decrease with increasing ESP and when magnesium was the dominant cation rather than calcium. This is explained in terms of particle aggregation. The ease of dispersion of the illites was correlated with particle size. Possible reasons for this, and the effect of magnesium, as opposed to calcium, on the forces between the clay particles are discussed.

scholarly journals Groundwater salt content change and its simulation based on machine learning model in hinterlands of Taklimakan Desert

2013 ◽  
Vol 33 (18) ◽  
pp. 5874-5882
Author(s):  
范敬龙 FAN Jinglong ◽  
刘海龙 LIU Hailong ◽  
雷加强 LEI Jiaqiang ◽  
徐新文 XU Xinwen ◽  
王桂芬 WANG Guifen ◽  
...  
Keyword(s):  
Machine Learning ◽  
Salt Content ◽  
Learning Model ◽  
Taklimakan Desert ◽  
Content Change ◽  
Machine Learning Model ◽  
Simulation Based

scholarly journals Timing and conditions modify the effect of structure liming on clay soil

2021 ◽  
Author(s):  
Jens Erik Blomquist ◽  
Kerstin Berglund
Keyword(s):  
Clay Soil ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Conditions ◽  
Simulated Rainfall ◽  
Rainfall Events ◽  
Inner Diameter ◽  
One Year ◽  
Stability Measurements ◽  
Effect Of Structure

Two dates (early, normal) for application and incorporation of structure lime to clay soil were examined at four field sites, to test whether early liming had more favourable effects on aggregate stability. Aggregate size distribution measurements revealed a finer tilth at the early liming date (20 August) than the normal date (14 September). Aggregate stability estimated one year later, using as a proxy turbidity in leachate from 2–5 mm aggregates subjected to two simulated rainfall events, was significantly improved (11% lower turbidity) with early compared with normal liming date. Three years after structure liming, soil structural stability measurements on lysimeters (15 cm high, inner diameter 18 cm) subjected to repeated simulated rainfall events showed no significant differences in turbidity in leachate between the early and normal liming dates. However, there was a strong interaction between liming date and site indicating different reactions at different sites. Our results suggest that early spreading and incorporation can improve the success of structure liming, but only if soil conditions are favourable.

MONTHLY AND YEARLY CHANGES IN AGGREGATE SIZE OF SURFACE SOILS

1968 ◽  
Vol 48 (2) ◽  
pp. 159-164 ◽  
Author(s):  
Frederick Bisal ◽  
W. S. Ferguson
Keyword(s):  
Wind Erosion ◽  
Clay Soil ◽  
Aggregate Size ◽  
Extended Period ◽  
Soil Types ◽  
Sieve Analysis ◽  
Yearly Variation ◽  
Single Location ◽  
Repeated Sampling ◽  
Erodible Fraction

Repeated sampling at a single location on each of three soil types at irregular intervals during the 12-year period 1955–1967 indicated a highly monthly and yearly variation in the percentage of the total soil in aggregates < 0.84 mm in diameter (the erodible fraction) by dry-sieve analysis. The greatest degree of variation occurred in the clay soil. Increases and decreases in aggregation were correlated among soils.The amount of the erodible fraction determined by dry-sieve analysis is highly dependent on the date of sampling. Consequently, the value of dry sieving as a method of predicting the susceptibility of soils to wind erosion over an extended period of time is limited.

scholarly journals Stabilization soft Clay Soil using Metakaolin based Geopolymer

2021 ◽  
Vol 14 (3) ◽  
pp. 131-140
Author(s):  
Shams Othman ◽  
Jasim M. Abbas
Keyword(s):  
Soil Stabilization ◽  
Clay Soil ◽  
Soft Clay ◽  
Cost Effective ◽  
Alternative Methods ◽  
Chemical Stabilization ◽  
Curing Time ◽  
Clay Particles ◽  
Peak Value ◽  
Properties Of Soil

Chemical stabilization is one of the most alternative methods using on soil stabilization with various materials. In recent decades geopolymer has been attention from engineers and experts geotechnical to use it for improvement of soil, because of considered eco-friendly and cost-effective. This paper aims to investigate the influence of used MK-based Geopolymer in geotechnical engineering and to enhance the properties of soil. Where the MK is considered eco-friendly material and cost-effective compared to other materials. Different percentages of Metakaolin-based Geopolymer were used, which are 8, 10, 12, and 14%. It can be concluded that the peak value of strength illustrated when used MK of 10% with curing time 14 days. In addition, Scanning Electron Microscope (SEM) results show the clay particles covered by cementations compounds due to the reaction of the Geopolymer with clay which led to the production of binder particles.

Soil permeability in relation to sodicity and salinity

1986 ◽  
Vol 316 (1537) ◽  
pp. 297-317 ◽  
Keyword(s):  
Irrigation Water ◽  
Soil Structure ◽  
Particle Interaction ◽  
Threshold Concentration ◽  
Double Layers ◽  
Soil Permeability ◽  
Clay Particles ◽  
Irrigation Practice ◽  
Repulsive Forces ◽  
Soil Colloids

Difficulties encountered in the irrigation of sodium-affected soils or in the reclamation of sodic—saline soils can be circumvented by controlling the electrolyte level in the irrigation water, which prevents deterioration of the soil structure. The threshold concentration concept simply expresses the minimum level of electrolyte required to maintain the soil in a permeable condition for a given degree of sodium saturation of the soil colloids. It is shown that decreases in permeability at concentrations below the threshold concentration are occasioned by increased clay-particle interaction owing to the extensive development of diffuse double layers which give rise to enhanced swelling. Mechanical failure is associated with this swelling and deflocculation of clay particles. This behaviour of sodium-affected soils is considered in relation to the operation of van der Waals forces, hydration forces and osmotic repulsive forces arising from the development of diffuse double layers on particle surfaces. Considerations of ion-exchange equilibria between particle surfaces and the soil solution (irrigation water) are discussed in relation to the threshold concentration concept, and the application of the concept in irrigation practice is illustrated by reference to several case histories.

The availability of nitrogen in liquid sewage sludges applied to grassland

1984 ◽  
Vol 102 (3) ◽  
pp. 703-709 ◽  
Author(s):  
N. J. Hutchings
Keyword(s):  
Organic Matter ◽  
Sandy Soil ◽  
Field Trial ◽  
Ammonia Volatilization ◽  
Clay Soil ◽  
Digested Sludge ◽  
Clay Particles ◽  
Anaerobically Digested Sludge ◽  
The Mean ◽  
Aerobic Sludge

SummaryThe availability to grass of the nitrogen in liquid anaerobically digested sludge (LDS) and liquid aerobic sludge (LAS) was investigated in a 2-year field trial. The mean availability of the nitrogen in the LDS over the 2 years was 44% on a freely drained sandy soil and 34% on a poorly drained clay soil. The corresponding values for the LAS were 56 and 44%. A greater inhibition or organic-matter decomposition by clay particles or a greater loss of nitrogen by either ammonia volatilization or denitrification were all possible reasons for the lower availability of the sludges on the clay soil. Investigation of the magnitude of gaseous losses of nitrogen from sludge-amended grassland under U.K. conditions is required. Current models of the availability of the nitrogen in liquid sludges may not be realistic if these losses are significant.

scholarly journals Determination of Particles and Minerals Content in Soft Clay Soil of the Mekong Delta Coastal Provinces, Southern Vietnam for Inorganic Adhesives Stabilization

2020 ◽  
pp. 791-804
Author(s):  
Nguyễn Thị Nụ ◽  
Do Minh Toan ◽  
Hong Thinh Phi ◽  
Bui Truong Son
Keyword(s):  
Clay Soil ◽  
Ph Value ◽  
Saline Soil ◽  
Soft Clay ◽  
Salt Content ◽  
Mekong Delta ◽  
Acid Sulfate Soil ◽  
Acid Sulfate ◽  
Soil C ◽  
Southern Vietnam

The paper aims at investigating the content of particles and minerals of soft clay soil in the Mekong Delta coastal provinces, southern Vietnam, as well as improving soil stability using inorganic adhesives, i.e.lime and cement-based stabilization. To study the composition of soft clay soil, a series of different laboratory methods were carried out and revealed various characteristics related to mineral composition, pH value, soluble salt content, and grain particle composition of soft clay soils. The results demonstrated five soil subtypes, namely high – saline soil (S2), low-saline soil (S1), acid sulfate soil (A), acid sulfate - saline soil (S-A), soil without salt andacid sulfate content (S0- A0). The soft clay soil (C) included 5 subtypes, which were C-S2, C-S1, C-A, C-AS, and C-S0-A0, whereas the soft sandy clay soil (SC) included three subtypes, namely SC-S2, SC- S1, and SC-S0-A0. Analysis of the above results showed that the high - saline soil, acid sulfate soil, and acid sulfate - saline soil are not suitable for lime and cement stabilization. This observation was illustrated by the initial experiment of cement – soil mixture properties. 

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