scholarly journals Strength characteristics of artificial organic soils stabilized with copolymer stabilizer

2018 ◽  
Vol 169 ◽  
pp. 01010 ◽  
Author(s):  
Chia-Wen Law ◽  
Felix Ngee-Leh Ling ◽  
Boon-Khiang Ng
Keyword(s):  
Organic Matter ◽  
Organic Soil ◽  
Organic Soils ◽  
Chemical Stabilization ◽  
Test Device ◽  
Compressive Test ◽  
Acid Ratio ◽  
Strength Material ◽  
Strength Increment ◽  
Effective Stabilization

Organic soil is known as low strength material, and chemical stabilization is widely used to increase its bearing capacity. However, the use of traditional stabilizer has some limitations. Therefore, stabilization was carried out by using non-traditional stabilizer - Vinyl acetate-ethylene (VAE) copolymer emulsion in this study with the aim to determine its suitability to stabilize soil mixed with organic matter. Two types of artificial organic soil with kaolin: organic acid ratio of 5:5 (K5HA5) and 7:3 (K7HA3) were utilized. Control specimens were tested using pure kaolin. Different percentages of VAE (5%, 7.5%, 10%) were added in order to determine the minimum amount of stabilizer required to achieve a minimum strength increment of a 345 kPa. The strength of samples was determined with automated unconfined compressive test device. Specimens were air cured for 7 days prior to testing. Both K7HA3 with 7.5% VAE and K5HA5 with 10% VAE had achieved the minimum strength increment to be considered as effective stabilization. The strength of the artificial organic soil was found to be increasing with the increment of percentages of VAE used. Hence, it can be concluded that stabilizing mechanism of the artificial organic soils with VAE is not affected by organic matter.

HUMIC-FULVIC ACID RELATIONSHIPS IN ORGANIC SOILS AND HUMIFICATION OF THE ORGANIC MATTER IN THESE SOILS

1967 ◽  
Vol 47 (3) ◽  
pp. 245-250 ◽  
Author(s):  
M. Schnitzer
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acid ◽  
Fulvic Acid ◽  
Oxidative Degradation ◽  
Fulvic Acids ◽  
Organic Soil ◽  
Organic Soils ◽  
Salting Out ◽  
Naoh Solution

Twenty organic-soil samples of widely differing degrees of decomposition were extracted with 0.5 N NaOH solution under N2. Amounts of humic and of fulvic acids in the acidified extracts did not correlate significantly with pyrophosphate solubilities. This was thought to be due to interference in the separation scheme by relatively large amounts of ash constituents in the extracts. Since the "classical" fractionation of soil organic matter appears to involve essentially the "salting out" of higher molecular-weight humic from lower molecular-weight fulvic acids, an excessively high salt concentration during the separation should be avoided.To lower the concentration of inorganic constituents in the extracts, the samples were first pretreated with dilute HCl–HF solution and then extracted with 0.1 N NaOH rather than with 0.5 N NaOH. Under these conditions, amounts of fulvic acids in the acidified extracts showed a significant positive correlation (r = 0.52) with pyrophosphate solubilities of untreated extracts, whereas amounts of humic acids in the extracts exhibited a highly negative correlation (r = −0.57) with pyrophosphate solubilities. In the soils examined, increased humification was associated with increases in fulvic-acid but decreases in humic-acid concentrations.From the results of this and of earlier investigations done in this laboratory it appeared that the main mechanism governing humification in these soils was oxidative degradation, resulting ultimately in the formation of fulvic from humic acid.

scholarly journals Organic Matter Causes Chemical Pollutant Dissipation Along With Adsorption and Microbial Degradation

2021 ◽  
Vol 9 ◽  
Author(s):  
A. Vilhelmiina Harju ◽  
Ilkka Närhi ◽  
Marja Mattsson ◽  
Kaisa Kerminen ◽  
Merja H. Kontro
Keyword(s):  
Organic Matter ◽  
Microbial Degradation ◽  
Mineral Soil ◽  
Organic Soil ◽  
Organic Soils ◽  
First Response ◽  
Chemical Pollutant ◽  
Mineral Soils ◽  
Soil And Sediment

Views on the entry of organic pollutants into the organic matter (OM) decaying process are divergent, and in part poorly understood. To clarify these interactions, pesticide dissipation was monitored in organic and mineral soils not adapted to contaminants for 241 days; in groundwater sediment slurries adapted to pesticides for 399 days; and in their sterilized counterparts with and without peat (5%) or compost-peat-sand (CPS, 15%) mixture addition. The results showed that simazine, atrazine and terbuthylazine (not sediment slurries) were chemically dissipated in the organic soil, and peat or CPS-amended soils and sediment slurries, but not in the mineral soil or sediment slurries. Hexazinone was chemically dissipated best in the peat amended mineral soil and sediment slurries. In contrast, dichlobenil chemically dissipated in the mineral soil and sediment slurries. The dissipation product 2,6-dichlorobenzamide (BAM) concentrations were lowest in the mineral soil, while dissipation was generally poor regardless of plant-derived OM, only algal agar enhanced its chemical dissipation. Based on sterilized counterparts, only terbutryn appeared to be microbially degraded in the organic soil, i.e., chemical dissipation of pesticides would appear to be utmost important, and could be the first response in the natural cleansing capacity of the environment, during which microbial degradation evolves. Consistent with compound-specific dissipation in the mineral or organic environments, long-term concentrations of pentachloroaniline and hexachlorobenzene were lowest in the mineral-rich soils, while concentrations of dichlorodiphenyltrichloroethane (DTT) and metabolites were lowest in the organic soils of old market gardens. OM amendments changed pesticide dissipation in the mineral soil towards that observed in the organic soil; that is OM accelerated, slowed down or stopped dissipation.

Evaluation of Contributing Factors on Strength Development of Lime Stabilized Artificial Organic Soils Using Statistical Design of Experiment Approach

2014 ◽  
Vol 905 ◽  
pp. 362-368 ◽  
Author(s):  
Felix N.L. Ling ◽  
Khairul Anuar Kassim ◽  
Ahmad Tarmizi Abdul Karim ◽  
S.C. Ho
Keyword(s):  
Organic Matter ◽  
Statistical Design ◽  
Organic Soil ◽  
Curing Temperature ◽  
Organic Soils ◽  
Strength Development ◽  
Test Results ◽  
Contributing Factors ◽  
Strength Enhancement ◽  
Factor Interactions

Lime is widely used as chemical stabilizer in soft soil stabilization. However, lime is reported to be less effective when dealing with organic soil. It is believed that the organic matter in the soil will retard the pozzolanic reaction which is responsible for strength enhancement. The heterogeneity nature of the organic matter in the soil makes the study complicated and reduced the repeatability of the test results. Hence, artificial organic soil with known organic matter and content are preferred by researchers when repeatability of the test results are required in determining the influential effect of each contribution factor. Various factors such as additive contents, effect of aging (curing periods), curing temperature, density of materials and moisture content are reported by previous researchers as the potential contributing factors towards the strength development. It is believed that the interaction of the factors also will contribute to the strength enhancement. Hence, this study is carried out to evaluate the contributing factors and its interactions on strength development of artificial organic soils with known type and contents of organic matter. Statistical design of experiment (DOE) approach was utilized to evaluate the factors and its interaction on the strength development of lime stabilized artificial organic soils by using commercial statistics package. Three main factors were investigated: effect of organic content, effect of curing periods, and effect of additive, while other factors namely curing temperature, molding water content, types of compaction and compactive effort were keep constant through controlled experiments. Processed kaolin (inorganic material) is mixed with humic acid (organic matter) to simulate the organic soil which comprised of inorganic soil and organic matter. The density of the soil specimen and its moisture content were recorded before and after the curing process. General Linear Model (GLM) was utilized to determine the significance of the main factors, two-factor interactions, and three factor interactions. The significance factors and interactions were utilized in multiple regression analysis to develop the strength prediction model which can be utilized to predict the strength of stabilized materials within the inference space defined by the experiment.

Challenges of using microbial explicit models for evaluating organic matter decomposition in predominantly organic soils 

2021 ◽  
Author(s):  
Debjani Sihi ◽  
Stefan Gerber
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Organic Soil ◽  
Organic Soils ◽  
Mineral Matter ◽  
Carbon Limitation ◽  
Classical Models ◽  
Mineral Soils ◽  
Set Up ◽  
Som Decomposition

<p class="rolelistitem">Models of soil organic matter (SOM) decomposition are critical for predicting the fate of soil carbon (and nutrient) under changing climate. Traditionally, models have used a simple set-up where the substrate is divided into conceptual pools to represent their resistance to microbial degradation, and decomposition rates are often proportional to the amount of substrate in each pool. Emerging models now consider explicit microbial dynamics and show that SOM loss under warming may be fundamentally different from the classical models. Microbial explicit models use reaction kinetics, represented on a concentration basis. However, when the substrate makes up most of the volume of soils (e.g., the organic horizon in forest soils or peat), an increase or decrease in SOM does not, or only very little, affect concentrations of microbes and substrate. Consequently, reduction in SOM does not reduce the amount of substrate the microbial biomass encounters. This problem does not occur in classical models like CENTURY. We incorporated the effect of organic matter on soil volume in several microbial models. If microbes are solely limited by enzymes, organic soils or peats are decomposed very quickly as there is no mechanism that stops the positive feedback between microbial growth and SOM concentration until the substrate is gone. Alternative formulations that account for carbon limitation or microbial ‘cannibalism’ display a sweet spot of soil carbon concentration. Interestingly, a response to warming will depend on the amount of organic vs. mineral materials. Apparent Q<sub>10</sub> was higher in fully organic soil than in mineral soils, which was pronounced when small to moderate amounts of the mineral matter was present that diluted the substrate for microbes. We suggest that model formulations need to be clear about the assumption in key processes, as each of the steps in the cascade of biogeochemical reaction can produce surprising results.</p>

scholarly journals Solutions for subsidence in the California Delta, USA, an extreme example of organic-soil drainage gone awry

2020 ◽  
Vol 382 ◽  
pp. 837-842
Author(s):  
Steven J. Deverel ◽  
Sabina Dore ◽  
Curtis Schmutte
Keyword(s):  
Organic Matter ◽  
Water Supply ◽  
Greenhouse Gas ◽  
Greenhouse Gas Emission ◽  
Animal Feed ◽  
Organic Matter Content ◽  
Organic Soil ◽  
Organic Soils ◽  
Human Consumption ◽  
Land Uses

Abstract. The Sacramento-San Joaquin Delta is at the heart of California's water supply system that provides water for irrigation and human consumption. It is also home to subsiding organic soils, decreasing native aquatic species populations, water quality degradation, vulnerable levees (levees are equivalent to dikes) and decreasing agricultural viability. There has been substantial progress in the interdisciplinary understanding and quantification of the nature and effects of subsidence and its mitigation. Because of the need for a drained rootzone, farming of crops such as vegetables, trees, vines, corn and alfalfa, results in an ongoing unsustainable cycle of continuing peat oxidation and deepening of drainage ditches to compensate for elevation loss. Despite substantial evidence for the increasing risks to the State's economy and water supply, the unsustainability of the status quo, and evidence for the benefits of alternatives, there has been limited progress in converting to land uses that can reduce, stop and reverse subsidence. Our overall approach has been to measure land-surface elevation changes; understand, quantify and model subsidence and greenhouse gas emissions from drained organic soil, and evaluate alternate land uses. Subsidence rates vary from less than 0.5 to over 2 cm yr−1, depending primarily on depth to groundwater and soil organic matter content. The primary cause of subsidence is the oxidation of organic matter, which has resulted in elevations of −3 to −9 m on about 100 000 ha. Using the results from micrometeorological measurements and modelling, we estimate that organic-matter oxidation causes an annual emission of over 2×106 t of CO2-equivalent which represents about 21 % of the State's plant-based agricultural emissions. Rewetting of the peat soils is emerging as a viable solution. Rice and wetlands stop and (in the case of wetlands) reverse the effects of subsidence and result in a net greenhouse-gas emission reduction benefit. Wetlands accrete about 3 cm of soil per year, can break the unsustainable subsidence/drainage cycle, reverse the trajectory of increasing hydraulic pressures on levees, reduce the probability of levee failure and seepage onto islands (islands are equivalent to polders), and may provide material for biofuels and animal feed. The recent implementation of a methodology for quantification of the GHG benefit is facilitating land use conversion and participation in the carbon market.

Stabilization of Artificial Organic Soil at Room Temperature Using Blended Lime Zeolite

2013 ◽  
Vol 723 ◽  
pp. 985-992 ◽  
Author(s):  
Felix Ngee Leh Ling ◽  
Khairul Anuar Kassim ◽  
Ahmad Tarmizi Abdul Karim ◽  
Tze Wei Chan
Keyword(s):  
Room Temperature ◽  
Organic Soil ◽  
Pozzolanic Reaction ◽  
Organic Content ◽  
Organic Soils ◽  
Zeolite A ◽  
Reaction Products ◽  
Lime Stabilization ◽  
Curing Period ◽  
Strength Increment

Organic content in soil is believed to inhibit formation of reaction products in lime stabilization which resulted in low gain of strength when dealing with organic soils. Zeolite, a kind of pozzolan with high CEC capacity is proposed to be use in this study in order to improve lime stabilization of organic soil. The effectiveness of blended lime zeolite in stabilization of organic soils was investigated by using two types of artificial organic soils with predetermined organic contents. Artificial organic soils were formed by mixing inorganic soil (commercial kaolin) with organic matter (commercial humic acid) at specific ratio. Initial consumption of lime for organic soils was determined in order to determine the minimum percentage of stabilizer required for each soil. Potential influencing factors that might affect the strength such as organic contents, contents of stabilizer, and curing periods were studied. The findings of the study showed that high organic contents and low lime contents resulted in lower gain of strength. However, it is found that slight replacement of lime with zeolite works well with low organic soil at long curing period which resulted in highest strength among all the mixes. Overall, longer curing periods will increase the strength of the soil in the order of 56 days > 28 days > 7 days. Nevertheless, the percentage of strength increment over curing periods is linear with the lime contents, which proved that lime is required for pozzolanic reaction.

scholarly journals Phosphorus Behaviour and Its Basic Indices under Organic Matter Transformation in Variable Moisture Conditions: A Case Study of Fen Organic Soils in the Odra River Valley, Poland

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1997
Author(s):  
Magdalena Debicka ◽  
Adam Bogacz ◽  
Karolina Kowalczyk
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Soil Degradation ◽  
Organic Soil ◽  
River Valley ◽  
Organic Soils ◽  
Groundwater Levels ◽  
Odra River ◽  
P Transformations ◽  
Moisture Conditions

Lowering of groundwater levels caused by anthropogenic changes in the environment gives rise to global problems, most of which relate to soil degradation such as land desertification or organic soil degradation. The transformation of drainage-sensitive organic soils causes many irreversible changes during organic matter (OM) transformation. Phosphorous (P) behaviour is one of the aspects of OM transformation that requires further investigation, due to the P transformations’ complex dependency on many environmental factors. Our study aimed to characterise behaviour of P and find indices reflecting P changes under the influence of OM transformation in drained organic soils in the Odra river valley. The studies were carried out on soils representing different stages of soil degradation in which basic soil properties, including different P forms, were determined with commonly used methods. The results showed significantly higher content of soluble P forms (Pw, PCaCl2, PM3), particularly in the most drained postmurshic soil (P1). The indices used in this study—Ip, PSD, C:Pt, N:Pt—reflected well the P and OM transformations in organic soils degraded by drainage. This was indicated by numerous statistically significant relationships between the indices and basic soil properties (e.g., Ash, C, N), as well as different P forms (Pt, Pmin, Pox, Porg, Pw, PCaCl2, PM3). The PSD and Ip values increased and the C:Pt and N:Pt ratios decreased with the degree of OM mineralisation and the degree of site drainage (P3 < P2 < P1).

scholarly journals 529 Relationship of Soil Temperature, pH, and Organic Carbon Content to Nitrogen Release in Cranberry Soils

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 537A-537
Author(s):  
Joan R. Davenport ◽  
Carolyn DeMoranville
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Temperature ◽  
Carbon Content ◽  
Organic Soil ◽  
Organic Soils ◽  
Organic Carbon Content ◽  
Key Factors ◽  
Wide Range ◽  
N Release

Soluble nitrogen (ammonium and nitrate) is released when soil organic matter is mineralized. The amount of N released by this process depends on the amount of organic matter present and soil temperature. Cranberry (Vaccinium macrocarpon Ait.) grows in acidic soils with a wide range in organic matter content. To evaluate how soil N release is affected by soil temperature, intact soil cores were collected from sites that had received no fertilizer and placed in PVC columns. Four different soil types, representing the range of cranberry soils (sand, sanded organic soil, peat, and muck), were used. Each column was incubated sequentially at six different temperatures from 10 to 24 °C (2.8 °C temperature intervals) for 3 weeks at each temperature, with the soils leached twice weekly to determine the amount of N release. The total amount of N in leachate was highest in organic soils, intermediate in the sanded organic soil, and lowest in the sands. The degree of decomposition in the organic soils was important in determining which form of N predominated. In the more highly decomposed organic soil (muck), most of the N was converted to nitrate. The data from this study resulted in the development of two models—one predicting the N mineralization and the other predicting the proportion of N in each of the two forms. Key factors for N release rate were soil temperature, percentage of clay, and organic carbon content. For predicting the proportion of N as ammonium vs. nitrate, key factors were soil temperature, soil pH, and the distribution of mineral matter in the silt and sand fractions.

RELATIONSHIPS BETWEEN SOME PROPERTIES OF ORGANIC SOILS FROM THE SOUTHERN CANADIAN SHIELD

1990 ◽  
Vol 70 (3) ◽  
pp. 363-377 ◽  
Author(s):  
D. ANN BROWN ◽  
S. P. MATHUR ◽  
ANTON BROWN ◽  
D. J. KUSHNER
Keyword(s):  
Principal Component Analysis ◽  
Acid Leaching ◽  
Principal Component ◽  
Organic Soil ◽  
Component Analysis ◽  
Soil Types ◽  
Organic Soils ◽  
Mining Districts ◽  
Two Populations ◽  
Inorganic Components

Different numerical methods used to distinguish between organic soil types are evaluated. The research was initiated by the suggestion that acid leaching from mining wastes could be prevented by capping the tailings with a self-renewing methane-producing muskeg bog, in order to prevent the penetration of oxygen to the wastes. Thirty organic soils from bogs in the mining districts of Elliot Lake, Sudbury, and Timmins, Ontario, and Noranda, Quebec, were sampled and 28 soil characteristics were measured. These characteristics, whose values are normally or lognormally distributed, were analyzed by several different statistical methods. Some characteristics indicate the existence of two populations, and others are bivariantly correlated. Canonical discriminant analysis was more successful than cluster analysis in separating the bogs into well-defined geographical groups. However, principal component analysis proved best at grouping the organic soils according to their organic and inorganic components, and we suggest that this is a suitable method for the general discrimination of organic soil types. Methane was present in all the 17 bogs tested for it, and in two very wet bogs more than 2 mmol of methane per liter were extracted. Key words: Muskeg bog, organic soils, soil characterization, principal component analysis

Studying Organic Matter Molecular Assemblage within a Whole Organic Soil by Nuclear Magnetic Resonance

2008 ◽  
Vol 37 (4) ◽  
pp. 1501-1509 ◽  
Author(s):  
Charisma Lattao ◽  
Justin Birdwell ◽  
Jim J. Wang ◽  
Robert L. Cook
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Organic Matter ◽  
Magnetic Resonance ◽  
Organic Soil ◽  
Nuclear Magnetic
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