Physical Properties Of Soil Samples Research Articles

Weak Expansive Soil Physical Properties Modification by Means of a Cement-Jute Fiber

Sixteen groups of comprehensive tests have been conducted to investigate the modifications in the physical properties of a weak expansive soil due to the addition of a cement jute fiber. The tests have been conducted to analyze the liquid plastic limit, the particle distribution and the free expansion rate. The results show that: (1) With an increase in the cement-jute fiber content, the free expansion rate of the modified expansive soil gradually decreases, however, such a rate rebounds when the fiber content exceeds 0.5% and the cement content exceeds 6%. (2) With an increase in the cement percentage, the particle unevenness coefficient (Cu) and curvature coeffi- cient (Cc) of the modified expansive soil tend to grow gradually. The Cc coefficient reaches 1.0 when the cement content is 6%. The unevenness coefficient of 16 soil samples is greater than 5.0, however, the Cu coefficient decreases when the cement content reaches 6%. (3) The plastic limit of soil increases as the cement content is made higher, while the liquid limit and plastic index decrease gradually. When the content of the modified material is 2% + 0.1%~2% + 0.7% (Cement content + jute fiber content), the change of particle size distribution is most obvious. (4) When the contents of cement and jute fiber are is 6% and 0.5%, respectively, the modification induced in the physical properties of soil samples corresponds to the best case.

Estimation of the past and future landslide hazards in the neighboring slopes of the 2016 Aranayake landslide, Sri Lanka

A rapid and long-traveling landslide was triggered by a monsoon rainfall of a total of 446.5 mm for 3 days in the Aranayake area, Sri Lanka. The landslide destroyed 75 houses and killed 127 persons along the course of this landslide. The mechanism of this landslide was investigated by a joint team of the International Consortium on Landslides (ICL) and the National Building Research Organization (NBRO) of the Government of Sri Lanka in 2017 and 2018; the investigation was part of the WCoE and IPL projects. Physical properties of soil samples taken from the source area of the Aranayake landslide were examined through a series of undrained ring-shear tests, and the measured properties were used in a numerical method, LS-RAPID, to simulate initiations and motions of landslides in this area. The authors then tried to first reproduce a landslide, which was considered, from available pieces of evidence, to have most likely happened in the past, then, to assess the risk of a potential future landslide that is expected to occur close to the 2016 Aranayake landslide. Two possible sliding surfaces were assumed to develop through the soil mass, one along the boundary between the weathered surface soil and the jointed bedrock and another along a potential aquiclude inside the soil. This attempt to estimate movements of both past and future landslides based on the numerical reproduction of the 2016 Aranayake landslide hazard will help develop landslide hazard assessment technologies.

Determination of Nutrition Status of Apple Orchards in Doğanşehir, Malatya

In order to determine nutrition status of the apple orchards in Doğanşehir city of Malatya Province, chemical and physical properties of soil samples, and macro and micro nutrient contents of soil and leaf samples collected from the selected orchards from different parts of the city were examined in 2017. Soil samples were collected from two depths of 0-30 cm and 30-60 cm, 1 kg from each depth, in September. Leaf samples, 100 leaves taken from head level of trees representing the related orchard, were collected 11 weeks after full blossom. Results indicated that soil texture, pH and salinity level was appropriate for apple growing, but loam content was generally high and organic matter was poor. Macro and micro nutrients were found adequate in soil samples of most of the orchards, except Mn and Zn. Sampling depth did not affected soil properties in most of the orchards. Almost all of the leaf samples contained adequate amount of N, P, Fe, and Cu, whereas inadequate level of K, Ca, and Zn. N content varied between 0.068% and 0.106% in soil samples, and between 1.78% and 2.68% in leaf samples.

Soil structure quality indicators and their limit values

Abstract Most soil functions, such as food production, carbon and nutrient cycling or water regulation and filtration strongly depend on soil structure quality (SSQ). But SSQ is increasingly threatened by compaction, carbon loss and erosion. SSQ should be protected by environmental regulations, however, reliable and easy methods for SSQ assessment are still missing. The aim of this study was to define a classification scheme and its indicators for soil structure protection regulation. Therefore, the physical properties of soil samples were determined with shrinkage analysis and their structure quality was scored with CoreVESS to provide a classification scheme independent from the indicators. We collected 185 undisturbed samples from the A horizon of Cambi-Luvisols across western Switzerland. CoreVESS score (Sq) 2 was used to identify the target value corresponding to good structure quality. Sq 3 was used to identify the trigger value, i.e. the limit between good and poor SSQ. Sq 4 was used to identify the remediation value. We found that structural porosity and gravimetric air content at −100 hPa (A−100) determined on undisturbed samples equilibrated free to swell in the laboratory were the best suited parameter to assess SSQ. They were correlated to SOC for soils with good SSQ, but not for soils with poor SSQ. As SOC was highly correlated to gravimetric water content at −100 hPa (W−100), it was possible to approximate SOC by W−100 in order to simplify the method for application. A−100 and W−100 are easy and inexpensive to determine and are therefore proposed as indicators. The limit values of A−100 were identified as following: target is 0.023 + 0.288 W−100 cm3g−1, trigger is 0.068 cm3g−1 and remediation is 0.045 cm3g−1. These values were designed to be useful to the Swiss environmental law. They apply to the Cambi-luvisol A horizons, and their applicability to subsoil or other soil types should be further studied.

Floristic Composition and Carbon Sequestration of "Indikada Mukalana" Forest Reserve, Waga; A Lowland Wet Evergreen Forest in Sri Lanka

Tropical lowland wet zone forests hold the greatest plant diversity, promise high plant carbon stocks. This study examined plant and soil carbon stocks of Forest reserve, Waga, Sri Lanka. Five representative sampling sites (20x20 m) in the forest were used for floristic survey and soil core sampling. Chemical and physical properties of soil samples were analysed for five years during 2011 and during 2014 to 2017. Vegetation survey documented 17 common tree species belonging to 15 genera and 12 families. Of the recorded species, 10 were endemics and 7 were native species. There were two species belonging to Dipterocarpaceae (Diptrocarpus zeylanica and Hopea juncunda). The mean total % C showed a negative correlation (R2=0.42) ranges in value between 2.84% in 2011 and 2.16% in 2017. The soil C fractions were determined by Loss on Ignition (LOI) method and predominated by the fulvic fractions (68.88%) followed by the humic fractions (18.36%) and the free soil litter fractions (12.76%). The total ecosystem carbon in the Indikada Mukalana lowland wet zone forest was 625t C/ha (i.e. biomass C 573.57 tC/ha and soil C 51.68 tC/ha), which was comparatively higher than our previous studies conducted in a highland wet zone forest (361 tC/ha at Udawattakele forest reserve) and a dry zone forest (176 tC/ha at Sigiriya forest sanctuary). The above ground biomass carbon for the forest was 477.98 t C/ha and the below ground biomass was 95.6t tC /ha. The mean total N % showed a positive correlation (R2=0.84) ranges in value between 0.14% in 2011 and 0.18% in 2017. Soil pH in Waga forest was acidic (<5) over the five-year period due to accumulation of more organic acids due to decomposed litter. In conclusion, we recommend this study to further extend towards other land-use classes to understand carbon sequestration in associated land-use classes for providing carbon benefits through carbon conservation via sustainable land management practices. Keywords: Floristics, Carbon sequestration, Waga forest, Soil organic carbon

English

The system of intercropping maize with other plant species has been a common practice for several years, but its use has been increasingly mainly to improve the quality of soil physical properties of no-tillage system. The objective of this study was to investigate the effect of intercropping using different cover plants on the physical properties of soil and the productivity of maize. Field experiments were conducted on the property of Mr. Arno Paulo Deimling, located in Linha S&atilde;o Jo&atilde;o, in the municipality of Quatro Pontes-PR. The experiment was carried out using a randomized complete block design, with four treatments and five repetitions. The treatments were winter maize intercropped with Urochloa brizantha, Urochloa ruziziensis or black oats (Avena strigosa), and maize sown in monoculture. In winter period, the production of maize used for silage and the production of dry matter from cover crops were assessed. The physical properties of soil samples were also investigated. Cover crops did not influence the productivity of winter maize used for silage, but it promoted improvements in soil macroporosity. The cover crops promoted improvements in the macroporosity of the soil and reduction at soil penetration resistance, particularly in the area planted with U. brisantha, demonstrating its potential in improving water infiltration and soil aeration. &nbsp; Key words: Direct seeding system, green manures, macroporosity, soil penetration resistance, conservationist system.

Evaluation of soil liquefaction potential index based on SPT data in the Erzincan, Eastern Turkey

This study includes determination of liquefaction potential in Erzincan Province. Erzincan Province, the study area, is located in a deep alluvial basin in a mountainous region of eastern Turkey that is a few kilometers from the highly active North Anatolian Fault Zone (NAFZ). North Anatolian Fault Zone is located approximately 7.7 km from Erzincan city center. In a probable earthquake, Erzincan Province is thought to be affected. On 13 March 1992, an earthquake having a surface wave magnitude of 6.8 struck Erzincan, giving rise to peak horizontal accelerations in the center of the city of 0.501g in the east–west direction and 0.398g in the north–south direction. Liquefaction potential for peak horizontal accelerations (0.501g and 0.398g) was determined. Liquefaction potential was investigated using Standard Penetration Test (SPT). Liquefaction potential analyses are determined in two steps: geotechnical investigations and calculations. In the first steps, boreholes were drilled to obtain disturbed and undisturbed soil samples and SPT values were obtained. Laboratory tests were made to identify physical properties of soil samples. In the second step, Liquefaction potential analyses were examined by a Seed and Idriss (1971) method (simplified method) based on Standard Penetration Test (SPT). In order to liquefaction analysis complete within a short time, MATLAB program were prepared. Following the analyses, liquefaction potential is investigated and by Sonmez and Gokceoglu (2005) method. At the final stage of this study, liquefaction potential maps and liquefaction potential index maps were prepared for different earthquake magnitudes and different depths.

Assessment of liquefaction potential of Erzincan Province and its vicinity, Turkey

One of the most important causes of damages after the earthquakes is the soil liquefaction. Liquefaction can be defined as temporary loss in strength of saturated sandy and silty deposits under transient and cyclic loadings due to excess pore water pressure. This study includes determination of liquefaction potential in Erzincan city center and its vicinity. Due to the proximity of the North Anatolian Fault Zone, in a probable earthquake, Erzincan Province is thought to be affected. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes was determined. These earthquake magnitudes were selected as 6.0, 6.5, 7.0, 7.5, respectively. Liquefaction potential was investigated using standard penetration test (SPT) data. The first stage of the study, 63 boreholes in different locations was drilled and SPT was performed. Disturbed and undisturbed soil samples were taken from these boreholes. Laboratory testing was performed to determine physical properties of soil samples, and liquefaction potential analyses were examined using three methods, namely Seed and Idriss (J Soil Mech Found Div ASCE 97(9):1249–1273, 1971), Tokimatsu and Yoshimi (Soil Found 23(4):56–74, 1983), Iwasaki et al. (Soil liquefaction potential evaluation with use of the simplified procedure. International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, pp 209–214, 1981). In order to complete liquefaction analysis within a short time, MATLAB program was prepared. Liquefaction potential analyses were carried out with the MATLAB program. At the final stage of this study, liquefaction potential maps were prepared for different earthquake magnitudes. The expected results will be shared with the local authorities and important engineering remedial measurements will be proposed to prevent further life losses and to mitigate property losses.

Assessment of wheel traffic effect on soil compaction using a soil core sampler

This study was conducted to evaluate the relative physical properties of soil samples collected with a manual sampling method and a tractor‐mounted portable soil core sampler under uncompacted and compacted soil conditions, and to determine the compaction depth resulting from successive passes of a tractor wheel. The compaction of soils was induced by one, three and five successive passes of the tractor wheel. The physical properties of soil samples obtained by both methods were similar at 10–15 cm soil depth. However, the methods produced significantly different results (P < 0.01) at 30–35 cm soil depth. Traffic applications resulted in a significant effect on both soil bulk density and hydraulic conductivity at both depths. The increasing number of passes resulted in increasing penetration resistance values at the depth of ploughing. In contrast, below the 25 cm depth, passes did not affect soil compaction compared to that at shallow depths. The results revealed that the portable sampler device could safely be used to collect soil cores. However, in clay soils having a high potential for compaction, the device needs to be supplemented by extra weight.

INFLUENCE OF SOIL AND TOPOGRAPHY ON THE COMPOSITION OF A TREE COMMUNITY IN A CENTRAL BRAZILIAN VALLEY FOREST

The purpose of the present study was to investigate the correlations between environmental variables related to the substrate (soil and topography) and the distribution of tree species in a valley forest in the Chapada dos Guimarães National Park, Mato Grosso State, Brazil. The forest lies in the Cerrado Domain of Central Brazil where the dominant vegetation cover is cerrado (woody savanna). A survey of the tree community registered all live individuals with circumference at breast height (cbh)≥15cm found in eighteen 600m2 plots (total area 1.08ha). The substrate variables used in the gradient analyses were obtained from a topographic survey and from analyses of the chemical and physical properties of soil samples. A principal components analysis of soil and topography variables and a canonical correspondence analysis of the species–environment relationships produced similar results, separating both the substrate variables and the tree species abundances, mainly according to the two types of bedrock, sandstone or slate, underlying their soils, and secondly to the three topographic sectors recognized: Streamside, Mid Slope and Upper Slope. The differences in soil fertility and texture (related to the bedrocks) and the soil water regime (related to both soil texture and topography) were probably the chief factors determining the distribution of tree species in the forest.

Numerical Analysis of a Chronosequence, Including the Development of a Chronofunction

AbstractMultivariate techniques were applied to 11 chemical and physical properties of soil samples collected along a prograded beach chronosequence, located on the west coast of Vancouver Island, British Columbia. The samples were taken from three horizons at each of seven sites. The 21 samples were considered as independent observations. Application of principal component analysis with a normal varimax rotation gave highly interpretable results. The first component was readily identified with podzolic pedogenic processes, whereas the second component appeared to relate closely to sea spray input. A nonlinear optimization procedure was used to fit the first principal component to an empirical equation incorporating a logistic term for time and an exponential term for depth. A correlation coefficient value of 0.99 was obtained. The notion of a pedogenic damping depth analagous to a thermal damping depth is suggested.