scholarly journals Applicability of wetting front advancing method in the sand to silty clay soils

2020 ◽  
Vol 60 (5) ◽  
pp. 1215-1225
Author(s):  
Qiang Liu ◽  
Ping Xi ◽  
Jiali Miao ◽  
Xiaochen Li ◽  
Ke Wang
Keyword(s):  
Clay Soils ◽  
Silty Clay ◽  
Wetting Front

Aggregate slaking during rapid wetting: Hydrophobicity and pore occlusion

2008 ◽  
Vol 88 (1) ◽  
pp. 85-97 ◽  
Author(s):  
Hafida Zaher ◽  
Jean Caron
Keyword(s):  
Organic Matter ◽  
Management Strategies ◽  
Water Entry ◽  
Paper Sludge ◽  
Silty Clay ◽  
Clay Loam ◽  
Wetting Front ◽  
Clay Loam Soil ◽  
Silty Clay Loam ◽  
Loam Soil

The slaking process after rapid wetting is a key factor controlling soil structural stability in dry soil, and an understanding of the relative importance of the different mechanisms involved in slaking may help in the design of management strategies aimed at maintaining a stable surface soil structure. Slaking has been linked to, among other factors, rapid pressure build-up in aggregate, and previous work has emphasized the role of organic matter to hamper that pressure build-up, possibly due to hydrophobicity, reducing rapid water entry within aggregates and hence the build-up. This study emphasizes this latter aspect linked to slaking. The evolution of the intra-aggregate pressure, the matter lost by slaking and the expelled air after rapid wetting of two soils of different textures (clay loam soil and silty-clay loam soil) amended with different types of paper sludge were studied. Hydrophobicity effects were also studied using a tensio-active solution. The results of these experiments showed that when aggregates were submitted to sudden wetting, those treated with paper sludge had an improved resistance to the destructive action of rapid wetting. The lower pressures measured in the aggregates from the amended soils and having less slaking resulted most likely from slow water entry and reduced swelling. Detailed investigation on the link between hydrophobicity and water entry revealed that the true hydrophobic effect (modification of contact angle) was non-existent for the silty-clay loam and minor for the clay loam. This study, rather, suggests that changes in the water potential at the wetting front following organic matter addition and aggregate immersion most likely depend on pore occlusion and on changes in pore surface roughness. Key words: Aggregate stability, organic matter, slaking, pressure, swelling, wettability

scholarly journals Microbial biodiversity as related to crop succession and potato intercropping for management of brown rot disease

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
N. A. S. Messiha ◽  
K. M. A. Elhalag ◽  
N. M. Balabel ◽  
S. M. A. Farag ◽  
H. A. Matar ◽  
...  
Keyword(s):  
Sandy Soils ◽  
Brown Rot ◽  
High Ratio ◽  
Fluorescent Pseudomonads ◽  
Clay Soils ◽  
Silty Clay ◽  
Potato Brown Rot ◽  
Rot Disease ◽  
Bacterial Plant Pathogen ◽  
Crop Succession

AbstractPotato brown rot, caused by Ralstonia solanacearum, ranked globally as the second most important bacterial plant pathogen. In the present study, the influence of different cropping programs in potato brown rot management was investigated in four infected fields in Egypt. Two districts were selected as sandy soils in Giza (Wardan) and Behera (Ganuob El-Tahrir) governorates. The other two were selected as silty clay in Minufyia (Talia) and Beni-Suef (Sids) governorates. The followed crop succession included corn, potato intercropped with cabbage, onion, cowpea, wheat, corn again, and ended by potato. The pathogen was undetectable after corn, onion, and wheat. It decreased in cowpea and cabbage rhizospheres in the clay soils. The pathogen was undetectable at all districts, except at Sids, where the pathogen was significantly decreased but was not eradicated. This was possibly attributed to the high ratio of NO3− and Na+ at this district. Decreased R. solanacearum density after corn coincided with the high ratio of fluorescent pseudomonads, endospores, and actinomycetes, being most clear in the poor soils (Wardan) and less clear under iron excess at Ganoub El-Tahrir as well as the clay soils. Corn rhizosphere supported an array of antagonistic actinomycetes such as strains similar to Streptomyces intermedius, Streptomyces albidoflavus group, Streptomyces argenteolus group, and Streptomyces erythrogriseus. Intercropping potato with cabbage decreased the density of the pathogen in rhizosphere, which is associated with greater antagonistic fluorescent pseudomonads, Bacillus spp. and Serratia spp. Onion soil and rhizosphere associated with abundance of antagonists and fluorescent pseudomonads, followed by S. maltophilia and Bacillus spp. Wheat soil and rhizosphere supported fluorescent pseudomonads and antagonistic Streptomyces spp., especially in sandy soils. The pathogen was undetectable after planting the ending potato in the three districts, Wardan, Ganoub El-Tahrir, and Talia. This was accompanied by a general oligotrophism and increased ratio of fluorescent pseudomonads, endospores bacteria, and actinomycetes along with a diversity of R. solanacearum antagonists such as S. maltophilia, Citrobacter freundii, Acinetobacter sp., Delftia sp., and Serratia marcescens.

MEASUREMENT OF FRACTURE MECHANICS PARAMETERS IN SILTY-CLAY SOILS

Soil Science ◽  
1997 ◽  
Vol 162 (5) ◽  
pp. 309-322 ◽  
Author(s):  
J. R. Nichols ◽  
M. E. Grismer
Keyword(s):  
Fracture Mechanics ◽  
Clay Soils ◽  
Silty Clay

SOME OBSERVATIONS ON THE UNDRAINED SHEARING STRENGTH USED TO ANALYZE A FAILURE

1969 ◽  
Vol 6 (2) ◽  
pp. 97-110 ◽  
Author(s):  
F. A. De Lory ◽  
R. J. Salvas
Keyword(s):  
Clay Soils ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Compression Tests ◽  
Foundation Soil ◽  
Shearing Strength

The undrained shearing strength of the foundation soil at the site of a failure of a low embankment was investigated by several methods. It was found that both field vane and laboratory compression tests tended to underestimate the strength required for stability. Further consideration of the test specimens from sample tubes showed the undrained shearing strength varied considerably with the position of the sample in the tube. Specimens from tubes from another site yield the same type of results. The two silty clay soils involved were studied in more detail using CIU and CAU triaxial tests and comparing cu/p′ ratios. It was found that in general they yielded the values usually obtained for lacustrine clays.

Effect of Intermittent Water Application from Trickle Source on The Water Movement and Moisture Distribution in Layered Soil

2020 ◽  
Vol 27 (4) ◽  
pp. 87-97
Author(s):  
haqqi Yasin ◽  
abdul alsattar Al-Dabagh
Keyword(s):  
Sandy Loam ◽  
Soil Depth ◽  
Layered Soil ◽  
Moisture Distribution ◽  
Silty Clay ◽  
Horizontal Distance ◽  
Clay Loam ◽  
Water Application ◽  
Wetting Front ◽  
Silty Clay Loam

The aim of this research is to study the effect of intermittent water application on the wetting pattern and soil moisture distribution for homogeneous and layered soils under trickle source. Thirty experiments were conducted to monitor the advance of the wetting front in the soil profiles. Measurements of soil moisture content were also made at selected locations to evaluate the moisture distribution in soil. Four types of soil profiles were built; the first was sandy loam soil, the second was silty clay loam soil, the third was (silty clay loam/ sandy loam) layered soil, and the fourth was (sandy loam/ silty clay loam) layered soil. Three water application rates were used for each soil profile. Three continuous or intermittent applications were used; continuous applications, equally intermittent applications, and different intermittent applications. In addition, several cylindrical infiltration tests were conducted to describe some characteristics of each soil. Empirical relations to predict each of vertical (under trickle source) and horizontal (at soil surface) wetting front advance were found in this study. Empirical relations to predict the percentage of applied water volume in horizontal strips as a function of soil depth and in vertical strips as a function of horizontal distance from the trickle emitter were also found. The study showed that the wetted soil volume increases as either the water application rate increases, or the intermittent application ratio increases. Also, it showed that the ratio of horizontal advance to vertical advance of wetting front increases as either the water application rate increases, or the intermittent application ratio decreases. The study demonstrated that the accumulated ratio of water application volume at a certain soil depth from trickle source increases as the intermittent application ratio decreases. Also, it demonstrated that the accumulated ratio of water application volume at a certain horizontal distance from trickle source decreases as the intermittent application ratio decreases.

Sorption-desorption and column leaching of strychnine with soil

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 603 ◽  
Author(s):  
H. Ghadiri ◽  
D. Connell ◽  
R. Parker
Keyword(s):  
Pore Volume ◽  
Clay Fraction ◽  
Organic Matter Content ◽  
Clay Content ◽  
Clay Soils ◽  
Silty Clay ◽  
Soil Columns ◽  
High Tendency ◽  
Desorption Process ◽  
Leaching Solution

Sorption–desorption of rodenticide strychnine by soil and its leaching through soil columns were studied on 4 typical soils of south-east Queensland. All 4 soils showed a high tendency to sorb strychnine, with the sorption rate higher for clay soils. The sorption capacities of the 4 soils are in the order Kingsthorpe > Warra > Oakey > Roma, which is also the order of decline in their clay contents. The desorption process also closely followed the clay content of the 4 soils. The 2 clay soils of Kingsthorpe and Warra not only sorbed a higher proportion of the applied strychnine at any application rate, they also showed a greater resistance to releasing their sorbed strychnine compared with the 2 silty clay loam soils. The effects of pH and organic matter content on the sorption–desorption of strychnine were inconclusive due to the dominant influence of clay content and the narrow range of these characteristics provided by the soils under investigation. The 2 clay soils of Kingsthorpe and Warra required a significantly higher number of pore volumes of leaching solution to pass through their respective columns for the concentration of strychnine in the effluent to approach that of the leaching solution, compared with the 2 silty clay soils of Oakey and Roma. The pore volumes of the leaching solution necessary for this point to be reached were not in the order of their clay contents, but when the cumulative volume of solution was used instead of the pore volume, the trend followed the clay content of the soils closely. Pore volume may not be an appropriate characteristic for assessing the leachability of strychnine through soil columns when the soil’s clay fraction is of an expanding type, as it is the case for Kingsthorpe soil. No desorption or leaching of strychnine took place in any of the 4 soils aged with a range of strychnine concentrations.

scholarly journals Research of Consolidation of Water-Saturated Silty-Clay Soils with Vertical Drainage

2018 ◽  
Vol 16 (1) ◽  
pp. 76
Author(s):  
A A Kislyakov ◽  
M A Kislyakov ◽  
N K Simakov
Keyword(s):  
Clay Soils ◽  
Silty Clay ◽  
Vertical Drainage ◽  
Water Saturated

В статье рассматриваются вопросы изучения процессов консолидации водонасыщенных пылевато-глинистых грунтов. Перед исследователями ставилась задача оценки эффективности работы ленточных дрен в водонасыщенных пылевато-глинистых грунтах и определения оптимального расстояния между дренами. Методика проведения полевого эксперимента основывалась на положении о необходимости максимально возможного сохранения природной структуры грунта при установке в нем аппаратуры для исследований. Принят бесконтактный способ определения послойных деформаций грунта с помощью глубинных кольцевых марок и методы определения напряжений мессдозами и датчиками порового давления, которые устанавливались в пробуренные в массиве грунта скважины. Оборудование контрольно-измерительной аппаратурой полигонов с разным шагом дрен, а затем проведение наблюдений на них в сочетании с наблюдениями на полигоне без дрен позволяет оценить эффективность работы ленточных дрен в данных грунтах и определить оптимальное расстояние между дренами.

scholarly journals Soil- and land classification in the old coastal plain of Surinam.

1953 ◽  
Vol 1 (4) ◽  
pp. 278-298
Author(s):  
J.J. Van der Eijk ◽  
H.A.J. Hendriks
Keyword(s):  
Coastal Plain ◽  
Tidal Flat ◽  
Aerial Photograph ◽  
Sandy Loam ◽  
Clay Soils ◽  
Silty Clay ◽  
Silt Loam ◽  
Land Classification ◽  
Waterlogged Soils

The old coastal plain consists of isolated, scattered areas of dry or only periodically waterlogged soils. Their total area is 21% of the entire coastal plain. The soils are either sandy loam soils formed on the old offshore bar or silt loam or silty clay soils formed on the old tidal flat. An aerial photograph and a map on a scale of 1: 666, 666 are given and the soils are classified into series. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals The Suitability of Expanded Shale as an Amendment for Clay Soils

2002 ◽  
Vol 12 (4) ◽  
pp. 646-651 ◽  
Author(s):  
John J. Sloan ◽  
Wayne A. Mackay ◽  
Phil Colbaugh ◽  
Steve W. George ◽  
Sam Feagley
Keyword(s):  
Large Diameter ◽  
Small Diameter ◽  
Growing Season ◽  
Plant Performance ◽  
Clay Soils ◽  
First Year ◽  
Silty Clay ◽  
Growing Seasons ◽  
Expanded Shale ◽  
Foliage Quality

Excessive soil moisture in clay soils can cause poor aeration and adversely affect plant growth. Small [1 to 3 mm (0.039 to 0.118 inches)] and large [3 to 6 mm (0.118 to 0.354 inches)] diameter expanded shales (ExSh), quartz sand, sphagnum peatmoss (SPM), and cottonseed hulls (CH) were evaluated as soil amendments for Austin silty clay soil. A 3-inch (7.6-cm) layer of each amendment was incorporated to a depth of 6 inches (15.2 cm), resulting in a 1:1 mixture by volume. Pansies (Viola × wittrockiana `Crown Azure Blue') were grown from December to June, followed by scaevola (Scaevola aemula `New Wonder') from June to November for two growing seasons. Foliage quality and extent of flowering were evaluated biweekly. Pansy root weights and above-ground biomass were quantified at the end of each growing season. None of the amendments significantly affected pansy foliage quality or the number of blooms per plant. Small diameter ExSh and SPM decreased pansy nitrogen content the first year after application, but not the second. During the first growing season, when soils were frequently saturated due to excessive rainfall, pansy root weights were significantly higher in soils amended with the small and large diameter ExSh. Large diameter ExSh treatments significantly increased the survival rate of transplanted scaevola plants and also the quality of foliage and percent blossom coverage during both growing seasons. Cottonseed hulls also increased scaevola survival for both growing seasons, but did not consistently improve scaevola foliage quality or bloom coverage. Of the five amendments tested, large diameter ExSh consistently improved overall plant performance more than the other amendments.

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