Relevant bibliographies by topics / Soil aggregates

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Soil aggregates'

Author: Grafiati
Published: 4 June 2021
Last updated: 25 May 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Soil aggregates.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Soil aggregates"

1

Gijsman, AJ, and RJ Thomas. "Aggregate size distribution and stability of an oxisol under legume-based and pure grass pastures in the eastern Colombian savannas." Soil Research 33, no. 1 (1995): 153. http://dx.doi.org/10.1071/sr9950153.

Full text
Abstract:
This study evaluated soil aggregate size distribution and stability of an Oxisol under improved grass-only or grass-legume pastures, established in previously native savanna. Three grass-legume combinations were included at various stocking rates. In all treatments and soil layers, soils were well aggregated, having more than 90% of their weight in macroaggregates (>250 �m). The addition of legumes to pastures did not affect the soil aggregate size distribution, although aggregates showed somewhat more stability against slaking. An increase in stocking rate negatively affected both average aggregate size and aggregate stability. Aggregates showed little or no dispersion of clay particles in any treatment. A positive correlation was found between wet aggregate stability and hot-water extractable carbohydrate concentration, supporting the hypothesis that these carbohydrates equate with plant-derived or microbial polysaccharides which glue soil aggregates together. It is suggested that determination of hot-water extractable carbohydrates may serve as a useful indicator of small differences in aggregate stability, even when these differences are not evident in the stability measurement itself.
APA, Harvard, Vancouver, ISO, and other styles
2

Ben-Hur, M., G. Yolcu, H. Uysal, M. Lado, and A. Paz. "Soil structure changes: aggregate size and soil texture effects on hydraulic conductivity under different saline and sodic conditions." Soil Research 47, no. 7 (2009): 688. http://dx.doi.org/10.1071/sr09009.

Full text
Abstract:
Hydraulic conductivity of soil is strongly dependent on soil structure, which can be degraded during wetting and leaching. It was hypothesised that this structural degradation is dependent on initial aggregate size distribution and soil texture. The general aim of this study was to investigate the effects of aggregate sizes and soil textures, and their interactions, on the structural degradation and saturated hydraulic conductivity (Ks) of smectitic soils under different saline and sodic conditions. The studied soils were clay and loamy sand soils with low (~4.5) or high (~10) exchangeable sodium percentages (ESP), and with aggregate sizes in the ranges: (i) <1 mm (small aggregates); or (ii) 2–4 mm (large aggregates). The Ks values of the samples in a column after slow or fast pre-wetting were determined by means of a constant head device. Different wetting rates and leaching under various saline and sodic conditions had no effect on the Ks of the loamy sand; however, the Ks values of this soil with large aggregates were an order of magnitude greater than those of the soil with small aggregates. In contrast, in the clay soil with large aggregates, the Ks values after fast pre-wetting were significantly smaller than those after slow pre-wetting, probably because of aggregate slaking. No significant effects of the wetting rates on Ks were found in clay soil with small aggregates. An increase in the ESP in the clay soil decreased the Ks by a factor of 1.5 for the large aggregates and by an order of magnitude for the small aggregates, mainly as a result of increased clay swelling. Leaching the clay soil with deionised water significantly decreased the Ks values, partly because of clay dispersion. Although significant structural degradation of the clay soil occurred during leaching, the Ks values were smaller in the soils with small aggregates than in those with large aggregates, indicating the importance of the initial aggregate size on Ks even in soils that are prone to structural damage.
APA, Harvard, Vancouver, ISO, and other styles
3

Thai, Saven, Tomáš Davídek, and Lenka Pavlů. "Causes clarification of the soil aggregates stability on mulched soil." Soil and Water Research 17, No. 2 (March 4, 2022): 91–99. http://dx.doi.org/10.17221/151/2021-swr.

Full text
Abstract:
Soil aggregates have great effects on soil properties and soil functions. Mulching (organic inputs) has been known as a factor influencing soil aggregate stability. Our study aimed to reveal the causes of the higher stability of soil aggregates under organic mulches. The primary soil characteristics such as organic carbon (Cox), humus quality (E4/E6), potential wettability index (PWI), and aromaticity index (iAR) were determined. The Cox was measured using rapid dichromate oxidation, and E4/E6 was measured using the UV-Vis spectrophotometry. The PWI and iAR were determined according to the intensity of selected bands in diffuse reflectance infrared spectra. Results showed that mulched plots contained higher Cox content in aggregates in comparison with whole soil. This indicates that the carbon was stabilized within the aggregates and sequestrated into the soil. The iAR was significantly higher after using the organic mulches, the aliphatic components of the organic matter thus contribute more to the aggregates stabilization. The PWI of aggregates was found to be higher after applying these mulches than in soil. Organic mulches are therefore able to reduce the wettability of the aggregates and also to protect the aggregate from dispersion with water.
APA, Harvard, Vancouver, ISO, and other styles
4

Hanna Radziuk and Marcin Świtoniak. "Time of aggregate destruction as a parameter of soil water stability within an agricultural hummocky moraine landscape in northern Poland." Bulletin of Geography. Physical Geography Series, no. 23 (December 6, 2022): 49–62. http://dx.doi.org/10.12775/bgeo-2022-0009.

Full text
Abstract:
Slaking is a rapid wetting of soil aggregates that affects their stability in the face of the effects of water. The aggregate’s stability has an indirect influence on soil functioning through its minimising of soil erosion. Testing slaking is very simple, does not need additional complicated equipment and could be done for any point. Testing was performed for natural air-dry aggregates (7–10 mm) sampled from the arable layers of four different types of soils within a young hummocky moraine landscape: Eutric Regosol (Protocalcic), Haplic Luvisol (Protocalcic), Albic Luvisol, Mollic Gleysol. The soil tests were performed on a soil-erosive catena located in Chełmno Lake District (Northern Poland) from the tops of hummocks and from the shoulder to bottom part of depressions. The test results demonstrated a significant decrease in aggregate stability from Mollic Gleysol to Eutric Regosols (Protocalcic) – that is, from colluvial soils at depressions to completely eroded hummock-top soils. However, 75% of all aggregates in Eutric Regosols were unstable when time of aggregate destruction was less than 300 sec. Oppositely to Eutric Regosols laying on hummock tops, 70% of aggregates of Mollic Gleysols in depressions were water stable. The mean time for aggregate destruction for each soil from hummock-top to depression was 209 sec. for Eutric Regosol, 375 sec. for Haplic Luvisol, 616 sec. for Albic Luvisol and 772 sec. for Mollic Gleysol. The main soil properties that affected the time of aggregate destruction are clay content (very strong negative correlation; r=–0.72); soil organic carbon content (strong positive correlation; r=0.69), and content of secondary carbonates (strong negative correlation; r=–0.69).
APA, Harvard, Vancouver, ISO, and other styles
5

Wang, Jingjing, Kunliang Shu, Siyu Wang, Chang Zhang, Yanchun Feng, Ming Gao, Zhonghe Li, and Hongguang Cai. "Soil Enzyme Activities Affect SOC and TN in Aggregate Fractions in Sodic-Alkali Soils, Northeast of China." Agronomy 12, no. 10 (October 18, 2022): 2549. http://dx.doi.org/10.3390/agronomy12102549.

Full text
Abstract:
Soil enzymes strongly affect soil organic carbon (SOC) and nitrogen (TN) storage. However, few studies have focused on their relationships in aggregates, especially in sodic-alkali agricultural fields. In the current study, we hypothesized that the impact of soil enzymes on SOC and TN were different within aggregates for their heterogeneous distribution. Soils collected from the surface (0–20 cm) and subsurface (20–40 cm) layers of sodic-alkali agricultural fields in the northeast of China were separated via the dry sieve method into macro-aggregates (>2000 μm), meso-aggregates (250–2000 μm), and micro-aggregates (<250 μm). SOC, TN, microbial biomass carbon (MBC) and nitrogen (MBN), and C- and N-cycling enzymes, namely amylase (AMY), invertase (INV), β-glucosidase (GLU), catalase (CAT), β-N-acetylglucosaminidase (NAG), and urease (URE) in soil aggregates were tested and analyzed. High content of SOC and TN were observed in macro- and meso-aggregates in both layers, with the largest amount detected in meso-aggregates. The highest values of MBC and MBN were observed in meso-aggregates, followed by micro-aggregates for MBC and macro-aggregates for MBN. Soil enzymes were distributed heterogeneously in soil aggregates, where the activities of AMY, INV, and URE in both layers were in the order of meso-aggregates > macro-aggregates > micro-aggregates. The same trend was followed by NAG of surface soils, while in the subsurface soils, NAG activities increased with the increasing aggregate sizes. NAG activities in both layers decreased with decreasing aggregate sizes. The GLU activity rose with the decreasing aggregate sizes in both layers, contrary to CAT. Enzyme activities affect SOC and TN in soil aggregates, for NAG, INV, GLU, and URE are closely related to SOC and TN across aggregate sizes. The test indices mentioned above in the surface layer were higher than those in the subsurface layer. These results indicate that biophysical processes associated with C- and N-cycling enzymes may be vital to the SOC and TN sequestration within soil aggregates in sodic-alkali agricultural fields.
APA, Harvard, Vancouver, ISO, and other styles
6

Liu, Yufei, Xiaoxu Fan, Tong Zhang, Xin Sui, and Fuqiang Song. "Effects of atrazine application on soil aggregates, soil organic carbon and glomalin-related soil protein." Plant, Soil and Environment 67, No. 3 (March 1, 2021): 173–81. http://dx.doi.org/10.17221/594/2020-pse.

Full text
Abstract:
Atrazine is still widely used in China. Atrazine residue (1.86–1 100 mg/kg) in the soil has exceeded the allowable limit (1.0 mg/kg), affecting soil structure and soil aggregate composition. To understand the long-term application of atrazine on soil aggregates and the binding agent, four treatments were established in cornfield planted since 1998, including without atrazine applied (AT<sub>0</sub>), atrazine applied (28% atrazine, 1 200–1 350 mL/ha/year) once a year from 2012 to 2018 (AT<sub>6</sub>, 167 mg/kg), from 2008 to 2018 (AT<sub>10</sub>, 127.64 mg/kg) as well as from 2002 to 2018 (AT<sub>16</sub>, 102 mg/kg) with three replications. Along with the increase of atrazine application time, the mass fraction of soil aggregates &gt; 5 mm and 2–5 mm decreased significantly while the mass fraction of soil aggregates 0.5–2 mm and &lt; 0.5 mm increased gradually, and the change of aggregate binding agents contents were the same as that of aggregates. The contents of soil organic carbon (SOC) and glomalin-related soil protein (GRSP) in the aggregates &gt; 5 mm and 2–5 mm were significantly negatively correlated with the years of atrazine application. Our results show that although atrazine residue in the soil does not increase with the increased yearly application, its concentration is still markedly higher than the permitted limit value and seriously affected the content of SOC and GRSP of aggregates &gt; 2 mm, which can lead to a decrease of soil aggregate stability and soil quality.
APA, Harvard, Vancouver, ISO, and other styles
7

Liu, Man, Guilin Han, Zichuan Li, Qian Zhang, and Zhaoliang Song. "Soil organic carbon sequestration in soil aggregates in the karst Critical Zone Observatory, Southwest China." Plant, Soil and Environment 65, No. 5 (May 27, 2019): 253–59. http://dx.doi.org/10.17221/602/2018-pse.

Full text
Abstract:
Soil organic carbon (SOC) sequestration in aggregates under land use change have been widely concerned due to intimate impacts on the sink (or source) of atmospheric carbon dioxide (CO<sub>2</sub>). However, the quantitative relationship between soil aggregation and SOC sequestration under land uses change has been poorly studied. Distribution of aggregates, SOC contents in bulk soils and different size aggregates and their contributions to SOC sequestration were determined under different land uses in the Puding Karst Ecosystem Observation and Research Station, karst Critical Zone Observatory (CZO), Southwest China. Soil aggregation and SOC sequestration increased in the processes of farmland abandonment and recovery. SOC contents in micro-aggregates were larger than those in macro-aggregates in restored land soils, while the opposite results in farmland soils were obtained, probably due to the hindrance of the C-enriched SOC transport from macro-aggregate into micro-aggregate by the disturbance of agricultural activities. SOC contents in macro-aggregates exponentially increased with their proportions along successional land uses. Macro-aggregates accounted for over 80% on the SOC sequestration in restored land soils, while they accounted for 31–60% in farmland soils. These results indicated that macro-aggregates have a great potential for SOC sequestration in karst soils.
APA, Harvard, Vancouver, ISO, and other styles
8

Wang, Yunqiu, Muhammad Shahbaz, Mostafa Zhran, Anlei Chen, Zhenke Zhu, Yehia Galal Mohamed Galal, Tida Ge, and Yuhong Li. "Microbial Resource Limitation in Aggregates in Karst and Non-Karst Soils." Agronomy 11, no. 8 (August 10, 2021): 1591. http://dx.doi.org/10.3390/agronomy11081591.

Full text
Abstract:
Karst is a widespread ecosystem with properties that affect the microbial activity and storage and cycling of soil organic carbon. The mechanisms underlying microbial resource availability in karst, which limit the microbial growth and activity in soil aggregates, remain largely unknown. We assessed the microbial resource limitations using exoenzymatic stoichiometry and key extracellular enzyme activities in bulk soil and aggregates in karst and non-karst forest soils. Soil organic carbon, total nitrogen, and microbial biomass carbon and nitrogen were significantly higher in bulk soil and the aggregate fractions in karst forests. However, the microbial biomass accumulation was higher in finer aggregates than in macroaggregate fractions. This may be attributed to the surface area of finer aggregates that increase the microbial C accumulation. In karst forests, the activity of extracellular enzymes β-d-glucosidase, β-N-acetylglucosaminidase, α-glucosidase, and α-d-1,4-cellobiosidase was two to three times higher in microaggregates (0.053–0.25 mm) and mineral fractions (<0.053 mm) than in macroaggregates. This coincided with the distribution of microbial biomass carbon and phosphorus in finer aggregate fractions. The microorganisms in bulk soil and aggregates in karst forests were largely co-limited by carbon and phosphorus and rarely by nitrogen and only by phosphorus in non-karst soils. The microbial phosphorus limitation in non-karst soils was alleviated in finer soil aggregates, while these fractions reflected slightly higher. microbial C limitations than bulk and other aggregates in karst forests. The patterns of microbial resource limitations in the bulk and aggregate fractions in karst ecosystems reflected the regulation of enzyme activity and soil organic carbon accumulation in finer aggregate fractions but not in other aggregates.
APA, Harvard, Vancouver, ISO, and other styles
9

Urbanek, Emilia, Rainer Horn, and Alwin J. M. Smucker. "Tensile and erosive strength of soil macro-aggregates from soils under different management system." Journal of Hydrology and Hydromechanics 62, no. 4 (December 1, 2014): 324–33. http://dx.doi.org/10.2478/johh-2014-0034.

Full text
Abstract:
Abstract Reduced soil tillage practices are claimed to improve soil health, fertility and productivity through improved soil structure and higher soil organic matter contents. This study compares soil structure stability of soil aggregates under three different tillage practices: conventional, reduced and no tillage. The erosive strength of soil aggregates has been determined using the abrasion technique with the soil aggregate erosion chambers (SAE). During abrasion soil aggregates have been separated into the exterior, transitional and interior regions. The forces needed to remove the material from the aggregate were calculated as erosive strength and compared with the tensile strength of the aggregates derived from crushing tests. The relationship between aggregate strength and other soil properties such as organic carbon and hydrophobic groups’ content has also been identified. The results show that erosive and tensile strength of soil aggregates is very low in topsoil under conventional and reduced tillage comparing with the subsoil horizons. Negative correlation was found between the content of organic carbon, hydrophobic compounds and erosive aggregate strength which suggests that the stabilising effect of soils organic carbon may be lost with drying. The positive relationship between the tensile strength and erosive strength for aggregates of 8-5 mm size suggests that the total strength of these aggregates is controlled by the sum of strength of all concentric layers
APA, Harvard, Vancouver, ISO, and other styles
10

Eynard, Anna, Thomas E. Schumacher, Michael J. Lindstrom, Douglas D. Malo, and Robert A. Kohl. "Wettability of soil aggregates from cultivated and uncultivated Ustolls and Usterts." Soil Research 42, no. 2 (2004): 163. http://dx.doi.org/10.1071/sr03029.

Full text
Abstract:
Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowed rapid water entry. Differences of wettability between management systems at 300 mm tension (in Ustolls, grasslands had greater wettability than cultivated soils, 0.24 v. 0.17 g water/h.g dry soil) and between soil orders (Usterts had longer WDPT than Ustolls, 2.9 v. 1.7 s) were explained by both clay and organic C contents. Simple measurements of aggregate wettability may be effectively used for soil quality characterisation. Aggregate wettability is a desirable property for agricultural soils when it is related to stable porosity, as may be found in high organic matter soils (e.g. grasslands). Wettability is excessive when fast aggregate wetting results in aggregate destruction as observed in low organic matter cultivated soils.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Soil aggregates"

1

Carminati, Andrea. "Unsaturated water flow through soil aggregates /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17011.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Walworth, James. "Using Gypsum in Southwestern Soils." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2006. http://hdl.handle.net/10150/144801.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Walworth, James. "Using Gypsum and Other Calcium Amendments in Southwestern Soils." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2012. http://hdl.handle.net/10150/246053.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Liang, Yun [Verfasser]. "Emerging threats to the stability of soil aggregates / Yun Liang." Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1234451573/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Okunlola, A. "Mechanics of breakdown of soil aggregates under static loading and impact." Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373750.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Cincotta, Malayika. "Soil Aggregates: The mechanistic link to increased dissolved organic carbon in surface waters?" ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/961.

Full text
Abstract:
Dissolved organic carbon (DOC) plays an important role in the global carbon (C) cycle because increases in aqueous C potentially contribute to rising atmospheric CO2 levels. Over the past few decades, headwater streams of the northern hemisphere have shown increased amounts of DOC coinciding with decreased acid deposition. Although the issue is widely discussed in the literature, a mechanistic link between precipitation composition and stream water DOC has not yet been proposed. In this study, the breakup of soil aggregates is hypothesized as the mechanistic link between reduced acid deposition and DOC increases in surface waters. Specific hypotheses state that soil aggregate dispersion (and the ensuing release of DOC from these aggregates) is driven by a decrease in soil solution ionic strength (IS, decreasing the tendency of flocculation) as well as a shift from divalent to monovalent cations (reducing the propensity for cation bridging) in soil solution. These hypotheses were tested on soil samples collected from several riparian zone and hillslope positions along three flagged transects in the acid-impacted Sleepers River Research Watershed in northeastern Vermont. To determine soil C content by landscape position, samples from transects spanning hilltop to hillslope and riparian area, as well as replicated hillslope and riparian samples (n=40) were analyzed. Aqueous soil extracts simulate the flushing of soils during hydrologic events (e.g. rain or snowmelt) and were used to test the effect of soil solution chemistry on DOC release. Extracts were prepared with solutions of varying IS (0-0.005M) and composition (CaCl2 and NaCl) on replicated soil samples (n=54) and changes in DOC release and aggregate size were monitored. As IS of the extraction solution increased, the amount of DOC in solution decreased, and aggregate size increased. This was presumably due to cations bridging and diffuse double layer effects. This effect was reversed in low ionic strength solutions where DOC release was significantly higher and average aggregate size was smaller. While extraction solution controlled the amount of C liberated, landscape position impacted the quality, but not quantity, of released DOC. This study is the first to propose a mechanistic link observed changes in DOC in surface waters and recovery from acidification and provides initial experimental evidence that soil aggregates indeed play a role in the generation of DOC.
APA, Harvard, Vancouver, ISO, and other styles
7

Chacón, Montes de Oca Paula. "Effect of Land Use, Climate and Soil Structure on Soil Organic Carbon in Costa Rican Ecoregions." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1252995403.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Nebo, Godwin Iloabuchi. "Soil aggregates characteristics and interrill erosion in some weakly weathered coarse textured ecotopes in Eastern Cape Province, South Africa." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1004351.

Full text
Abstract:
Aggregate stability and aggregate size distribution on soil surface that is impacted by rain drops affect soil erosion yet little is known about less weathered coarse textured soils. The objectives of the current study were to determine (i) the aggregate stability and associated aggregate fraction size distribution and (ii) the impact of the initial aggregate size on the aggregate stability and the resulting sediment fraction size distribution following rain drop impact in some quartz dominated coarse textured soils in the Eastern Cape Province. Soil samples for this experiment were collected from 14 ecotopes on the surface with a natural slope between 7.5 to 11% and at the depth between 0 to 0.2 m in the Eastern Cape Province. In each ecotope, twenty-five different spots were sampled using a spade at depth 0 to 0.2 m in other to eradicate biasness and ensure homogeneity. Thereafter, the soil samples were mixed to make a composite sample. The composited soil samples were then placed in rigid containers and taken to the soil science laboratory of the University of Fort Hare, Alice Campus where analyses were carried out. The soil properties were determined by passing the < 5 mm soil sample through a 2 mm sieve. The total Na, Ca and Mg contents in the soil samples were also determined using the wet digestion with sulphuric acid method. The total Soil organic matter content (SOM) was determined by the process known as weight loss on ignition. Thereafter, the fraction size distribution and aggregate stability was done by passing < 5 mm soil samples through a 3 mm sieve. The obtained calibrated aggregates between 3 and 5 mm were oven dried at 40o C. Thereafter, five gram (5g) of oven dried calibrated aggregates was immersed in a 50 mL deionized water in a 250 mL beaker for 10 minutes. The soil material left was transferred to a 0.053 mm sieve already immersed in ethanol and moved five times in the ethanol to separate < 0.053 mm from > 0.053 mm fragments. The remaining > 0.053 mm was re-immersed in ethanol and further oven dried at 40o C for 5 minutes. Thereafter, the > 0.053 mm fraction was transferred from 0.053 mm sieve, oven dried at 40o C, dry sieved using Digital Electromagnetic Shaker on a six column of sieves: 2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.106 mm, and 0.053 mm. The aggregate stability was determined using the resulting size distribution in seven classes by calculating the mean weight diameter (MWD, mm). The soils were very stable, moderately stable or unstable. The presence of smectite and cultivation as opposed to pasture lowered aggregate stability. The studied soils showed three different aggregate size distributions. Unstable soils were dominated by 0.106 – 0.25 mm aggregate size and showed a positively skewed aggregate fraction size distribution. Aggregates finer than 0.106 mm were limited because of the coarse nature of the soil texture. Moderately stable soils broke down to both micro aggregates, 0.106 – 0.25 mm and macro aggregates, 2 – 5 mm giving a bimodal distribution. The aggregate size distribution in the very stable soils was dominated by the aggregate fraction size 2 – 5 mm and a negatively skewed aggregate fraction size distribution. The smaller the initial aggregate size the higher was the aggregate stability but the reverse was true for splash erosion. It was thought that the short 5 minutes duration of the rainfall might not have been enough to cause a total breakdown of the aggregates. Alternatively, ecotopes that were dominated by primary soil minerals such as quartz showed different breakdown behaviour compared to those containing secondary minerals such as kaolinite or smectite.
APA, Harvard, Vancouver, ISO, and other styles
9

Gumbert, Amanda A. "INFLUENCE OF RIPARIAN BUFFER MANAGEMENT STRATEGIES ON SOIL PROPERTIES." UKnowledge, 2013. http://uknowledge.uky.edu/pss_etds/27.

Full text
Abstract:
The Kentucky Division of Water indicates that agriculture is responsible for 55% of the Commonwealth’s assessed streams not supporting their designated uses. Riparian buffers reduce nonpoint source pollution in agroecosystems by storing and cycling nutrients, stabilizing streambanks, increasing infiltration, and storing water. Specific information regarding riparian buffer management is needed for land managers to maximize buffer effectiveness at reducing agricultural contaminants impairing water quality. Baseline soil properties (texture, pH, C and nutrients) of the riparian buffer surrounding a tributary of Cane Run Creek in Fayette County, KY were characterized prior to imposing three mowing regimes (intense, moderate, and no mow treatments) and one native grass regime. Measurements were made along parallel transects located 2-m and 8-m distances from the stream. Root biomass, aggregate distribution, and saturated hydraulic conductivity were measured along the 2-m transect in two consecutive years following treatment establishment. The 2-m transect soils had the highest C, pH, Ca, Zn, and sand content. The 8-m transect had the highest P, K, Mg, and clay content. Semivariogram analysis of C content indicated slight to moderate spatial dependency along the 2m transect and moderate to strong spatial dependency along the 8m transect. Root biomass increased with decreased mowing frequency at the surface depth after one year; the native grass treatment had significantly less root biomass in both years compared to mowing treatments. There was no significant treatment effect on aggregate size distribution at the surface depth in either year. Mean weight diameter and large macroaggregates decreased from 2011 to 2012. Vegetation treatment had no statistically significant effect on water stable aggregates or saturated hydraulic conductivity. Experimental semivariograms provided evidence of spatial structure at multiple scales in root biomass, aggregates, and soil C. Spatial variability occurred over a shorter lag distance in 2012 than 2011, suggesting an effect of imposed treatments slowly developing over time. This study provides important insights on riparian buffer soil properties, soil sampling strategies to detect spatial variability in riparian buffers, and length of time needed to assess effects of vegetation management regimes on riparian root biomass, soil aggregates, and hydraulic conductivity.
APA, Harvard, Vancouver, ISO, and other styles
10

Asmus, Chad Donald. "Soil aggregation and carbon sequestration following a single tillage event in no-till soils in a semi-arid environment." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1405.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Soil aggregates"

1

NATO, Advanced Research Workshop on Soil Colloids and Their Associations in Aggregates (1984 Ghent Belgium). Soil colloids and their associations in aggregates. New York: Plenum Press, 1990.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

Sivakugan, N. Laboratory testing of soils, rocks, and aggregates. Ft. Lauderdale, FL: J. Ross, 2011.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

De Boodt, Marcel F., Michael H. B. Hayes, Adrien Herbillon, Eric B. A. De Strooper, and Jonathan J. Tuck, eds. Soil Colloids and Their Associations in Aggregates. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4899-2611-1.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Ruenkrairergsa, Teeracharti. Proposed specifications of soil aggregates for low volume roads. Bangkok, Thailand: Dept. of Highways, Ministry of Communications, 1988.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

McHattie, Robert L. Evaluating a simplified method to estimate compaction of soils & aggregates. Juneau, AK: Alaska Department of Transportation [and Public Facilities], Statewide Research Office, 2007.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Soil and rock construction materials. London: E & FN Spon, 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

McNally, G. H. Soil and Rock Construction Materials. London: Taylor & Francis Inc, 2002.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

Soil and rock construction materials. London: E & FN Spon, 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

McNally, G. H. Soil and Rock Construction Materials. London: Taylor & Francis Group Plc, 2004.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

National Research Council (U.S.). Transportation Research Board., ed. Geoenvironmental and engineering properties of rock, soil, and aggregate. Washington, D.C: Transportation Research Board, National Research Council, 1992.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Soil aggregates"

1

Papadopoulos, Apostolos. "Soil Aggregates, Structure, and Stability." In Encyclopedia of Agrophysics, 736–40. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-3585-1_142.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Emerson, W. W., and D. J. Greenland. "Soil Aggregates — Formation and Stability." In NATO ASI Series, 485–511. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4899-2611-1_18.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Oades, J. M. "Associations of Colloids in Soil Aggregates." In NATO ASI Series, 463–83. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4899-2611-1_17.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Torri, Dino, Rossano Ciampalini, and Pietro Accolti Gil. "The Role of Soil Aggregates in Soil Erosion Processes." In Modelling Soil Erosion by Water, 247–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-58913-3_19.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Yost, Jenifer L., Corey E. Palmer, and Louise M. Egerton-Warburton. "The Contribution of Soil Aggregates to Carbon Sequestration in Restored Urban Grasslands." In Soil Carbon, 147–54. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04084-4_15.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Chevallier, Tiphaine. "Physical Protection of Organic Carbon in Soil Aggregates." In Encyclopedia of Agrophysics, 592–95. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-3585-1_197.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Clothier, B. E., I. Vogeler, S. R. Green, and D. R. Scotter. "Transport in Unsaturated Soil: Aggregates, Macropores, and Exchange." In Physical Nonequilibrium in Soils Modeling and Application, 273–95. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003076094-10.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Chen, Can, Wolfgang O. Eisenhut, and Thanh Ngo. "Examination of the Ignition Oven Method Correction Factor for Hot Mix Asphalt with Granite Aggregates." In New Developments in Soil Characterization and Soil Stability, 109–20. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95756-2_11.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Gonet, S. S., H. Czachor, and M. Markiewicz. "Organic Carbon and Humic Substances Fractions in Soil Aggregates." In Functions of Natural Organic Matter in Changing Environment, 385–89. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-5634-2_70.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Karimov, Akmal, A. Noble, R. Kurbantoev, and N. Salieva. "Determining Degraded Soils of Southern Kazakhstan Through Assessing Stability of Soil Aggregates." In Developments in Soil Classification, Land Use Planning and Policy Implications, 731–49. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-5332-7_42.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Soil aggregates"

1

Chandrasiri, Janith, and Janaka Perera. "The Properties of Lime/Soil Concrete." In The SLIIT International Conference on Engineering and Technology 2022. Faculty of Engineering, SLIIT, 2022. http://dx.doi.org/10.54389/bjwt7503.

Full text
Abstract:
The investigation of materials for replacing cement in concrete manufacturing has garnered steady interest from experts in recent years. However, the majority of past researches have only focused on the use of lime as a cement substitute in producing Lime Concrete. The reason for this is that lime concrete can be made easily and cheaply while still providing a durable material that can minimize negative environmental impacts. Even though lime is used as an alternative material the integration of a new material as a replacement for conventional aggregates has been limited. As a result, this study will attempt to examine the various compositions of hydraulic lime as a partial replacement of cement while completely replacing the coarse and fine aggregate with a soil to find the influence on the physical characteristics of Lime/Soil concrete. This will also help in decreasing the ecological imbalance caused due to the excess use of conventional aggregates. Locally available reddish-brown laterite soil was used in this study without any modifications. C30 concrete mixes containing 0%, 10%, 15% of hydraulic lime replaced with OPC and complete replacement of aggregate with laterite soil were casted before subjected to water curing. Workability, compressive strength, splitting tensile strength and water absorption test were conducted in accordance with the existing standard. Based on the results obtained from the study it has shown that even with complete replacement of aggregate with laterite soil it was able to produce workable concrete with satisfactory strength that can be employed for ground improvements in pavement design and to manufacture economical non-load bearing concrete blocks. The targeted strength still can be achieved with replacement of 15% hydraulic lime for a lower cost. With the accomplishment from the composition, future studies will be able to better assess the long-term effects of construction operations on the environment. KEYWORDS: Compressive strength, lime concrete, physical properties, hydraulic lime, laterite soil.
APA, Harvard, Vancouver, ISO, and other styles
2

Bartlova, Jaroslava. "INFLUENCE OF SOIL ORGANIC MATTER ON ITS WATER STABILITY OF SOIL AGGREGATES." In 17th International Multidisciplinary Scientific GeoConference SGEM2017. Stef92 Technology, 2017. http://dx.doi.org/10.5593/sgem2017/32/s13.043.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Huo, Li-Li, Han-Yu Huang, and Yi An. "Effect of Wetland Reclamation on Soil Aggregates Content and Soil Organic Carbon Distribution of Aggregates in Peat Mire Soil around Xingkai Lake in Northeast China." In 3rd 2017 International Conference on Sustainable Development (ICSD 2017). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/icsd-17.2017.16.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Suleymanov, Ruslan, and S. Zaykin. "THE INFLUENCE OF NO-TILL MANAGEMENT SYSTEM ON AGROPHYSICAL PROPERTIES OF AGROCHERNOZEMS IN THE TRANS-URAL STEPPE ZONE OF RISKY AGRICULTURE (REPUBLIC OF BASHKORTOSTAN)." In Land Degradation and Desertification: Problems of Sustainable Land Management and Adaptation. LLC MAKS Press, 2020. http://dx.doi.org/10.29003/m1710.978-5-317-06490-7/208-212.

Full text
Abstract:
The article presents the results of the evaluation agrophysical properties of agrochernozems under influence of No-Till management system. The research was conducted in the Trans-Ural Plain-Steppe Zone of the Republic of Bashkortostan (Russia). The territory is located in the zone of risky agriculture and is arid. The territory characterized by a high level of agricultural use. Various degradation processes are observed in the soil cover. Such parameters as bulk density, soil-hydrological constants, structural-aggregate composition and water resistance of aggregates are studied.
APA, Harvard, Vancouver, ISO, and other styles
5

Arie Kremen, Uri Shavit, Jacob Bear, and Avi Shaviv. "A Model for Nitrogen Transformations in Effluent Irrigated Soil Aggregates." In 2002 Chicago, IL July 28-31, 2002. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2002. http://dx.doi.org/10.13031/2013.11232.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Peth, Stephan, Rainer Horn, Felix Beckmann, Tilman Donath, and Alvin J. M. Smucker. "The interior of soil aggregates investigated by synchrotron-radiation-based microtomography." In Optical Engineering + Applications, edited by Stuart R. Stock. SPIE, 2008. http://dx.doi.org/10.1117/12.794647.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Tukhtabayev, M. A., and B. F. Valiyev. "Applying for wide coverage machine-tractor aggregates in reducing soil compaction." In CONTEMPORARY INNOVATIONS IN ENGINEERING AND MANAGEMENT. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0158537.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Kim, YoungSeok, and Sewon Kim. "Evaluation of the Frozen Ground for Developing Construction Technology of Pipelines in Cold Regions." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18632.

Full text
Abstract:
Abstract Cold regions, such as Alaska, Russia and Canada, get attention from many countries due to the tremendous amount of natural resources which are buried there. An accurate evaluation of the frozen ground is very important because the behavior of the active layer is greatly affected by the soil characteristics and water content in the active layer. It is necessary for developing a construction technology for pipelines in cold regions. This study has two objectives: 1) First one is to evaluate the characteristics of a newly-produced insulated aggregate and 2) the other one is to check the applicability of insulated aggregate. A series of laboratory experiments (specific gravity test, sieve analysis test, direct shear test, test for abrasion of coarse and aggregates by use of the Los Angeles machine) were performed to estimate the characteristics of the newly-produced insulated aggregate. In addition, the laboratory chamber tests were carried out to evaluate the applicability of frozen soil behavior using the newly-produced insulated aggregate. The chamber tests were conducted to check the laboratory model surrounded by soil mixing the insulated aggregate and ordinary soil in order to prevent the damage of structures such as pipelines due to the ground being frozen. For the laboratory chamber tests, the extreme cold engineering laboratory was built within the Yeon Cheon SOC Demonstration Research Center, of the Korea Institute of Construction Technology. The performance of the frozen ground which was installed with the insulated aggregate using vinyl was evaluated through monitoring the time-dependent distribution of temperature and earth-pressure.
APA, Harvard, Vancouver, ISO, and other styles
9

Jin, Lixia, Peggy O'Day, and Asmeret Asefaw Berhe. "Role of Iron Oxides on Physical Protection of Soil Organic Matter Inside Aggregates." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1207.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Kintl, Antonin, Igor Hunady, Jaroslav lang, Martin Brtnicky, and Jakub Elbl. "EFFECT OF GROWING CLOVERS AS INTERMEDIATE CROPS ON THE STABILITY OF SOIL AGGREGATES." In 21st SGEM International Multidisciplinary Scientific GeoConference Proceedings 2021. STEF92 Technology, 2021. http://dx.doi.org/10.5593/sgem2021/3.1/s13.57.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Soil aggregates"

1

Snyder, Victor A., Dani Or, Amos Hadas, and S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580670.bard.

Full text
Abstract:
Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.
APA, Harvard, Vancouver, ISO, and other styles
2

Fuchs, Marcel, Jerry Hatfield, Amos Hadas, and Rami Keren. Reducing Evaporation from Cultivated Soils by Mulching with Crop Residues and Stabilized Soil Aggregates. United States Department of Agriculture, 1993. http://dx.doi.org/10.32747/1993.7568086.bard.

Full text
Abstract:
Field and laboratory studies of insulating properties of mulches show that the changes they produce on the heat balance and the evaporation depend not only on the intrinsic characteristics of the material but also on the structure of air flow in boundary layer. Field measurements of the radiation balance of corn residue showed a decrease of reflectivity from 0.2 to 0.17 from fall to spring. The aerodynamic properties of the atmospheric surface layer were turbulent, with typical roughness length of 12 to 24 mm. Evaporation from corn residue covered soils in climate chambers simulating the diurnal course of temperature in the field were up to 60% less than bare soil. Wind tunnel studies showed that turbulence in the atmospheric boundary layer added a convective component to the transport of water vapor and heat through the mulches. The decreasing the porosity of the mulch diminished this effect. Factors increasing the resistance to vapor flow lowering the effect of wind. The behavior of wheat straw and stabilized soil aggregates mulches were similar, but the resistance to water of soil aggregate layer with diameter less than 2 mm were very large, close to the values expected from molecular diffusion.
APA, Harvard, Vancouver, ISO, and other styles
3

Bradford, Joe, Itzhak Shainberg, and Lloyd Norton. Effect of Soil Properties and Water Quality on Concentrated Flow Erosion (Rills, Ephermal Gullies and Pipes). United States Department of Agriculture, November 1996. http://dx.doi.org/10.32747/1996.7613040.bard.

Full text
Abstract:
Concentrated flow erosion in rills, pipes, ephermal gullies, and gullies is a major contributor of downstream sedimentation. When rill or gullies form in a landscape, a 3- to 5-fold increase in soil loss commonly occurs. The balance between the erosive power of the flow and the erosion resistance of the bed material determines the rate of concentrated flow erosion. The resistance of the bed material to detachment depends primarily on the magnitude of the interparticle forces or cohesion holding the particles and aggregates together. The effect of soil properties on bed material resistance and concentrated flow erosion was evaluated both in the laboratory and field. Both rill erodibility and critical hydraulic shear were greater when measured in 9.0 m long rills under field conditions compared with laboratory mini-flumes. A greater hydraulic shear was required to initiate erosion in the field compared to the mini-flume because of the greater aggregate and clod size and stability. Once erosion was initiated, however, the rate of erosion as a function of hydraulic shear was greater under field conditions because of the greater potential for slaking upon wetting and the greater soil surface area exposed to hydraulic shear. Erosion tests under controlled laboratory conditions with the mini-flume allowed individual soil variables to be studied. Attempts to relate rill erosion to a group soil properties had limited success. When individual soil properties were isolated and studied separately or grouped separately, some trends were identified. For example, the effect of organic carbon on rill erodibility was high in kaolinitic soils, low in smectitic soils, and intermediate in the soils dominated by illite. Slow prewetting and aging increased the cohesion forces between soil particles and decreased rill erodibility. Quick prewetting increased aggregate slaking and increased erodibility. The magnitude of the effect of aging depended upon soil type. The effect of clay mineralogy was evaluated on sand/clay mixtures with montmorillonite (M), Illite (I), and kaolinite (K) clays. Montmorillonite/sand mixtures were much less erodible than either illite or kaolonite sand mixtures. Na-I and Na-K sand mixtures were more erodible than Ca-I and Ca-K due to increased strength from ionic bonding and suppression of repulsive charges by Ca. Na-M was less erodiblethan Ca-M due to increased surface resulting from the accessibility of internal surfaces due to Na saturation. Erodibility decreased when salt concentration was high enough to cause flocculation. This occurred between 0.001 mole L-1 and 0.01 mole L-1. Measuring rill erodibility in mini-flumes enables the measurement of cohesive forces between particles and enhances our ability to learn more about cohesive forces resisting soil detachment under concentrated water flow.
APA, Harvard, Vancouver, ISO, and other styles
4

Rahman, Shahedur, Rodrigo Salgado, Monica Prezzi, and Peter J. Becker. Improvement of Stiffness and Strength of Backfill Soils Through Optimization of Compaction Procedures and Specifications. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317134.

Full text
Abstract:
Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials commonly used by INDOT (No. 4 natural sand, No. 24 stone sand, and No. 5, No. 8, No. 43 aggregates) were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table when both tools were used at the highest amplitude and frequency of vibration available. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. The more angular the particles, the greater the shear resistance measured in the direct shear tests. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.
APA, Harvard, Vancouver, ISO, and other styles
5

Walker, David, Craig Baker-Austin, Andy Smith, Karen Thorpe, Adil Bakir, Tamara Galloway, Sharron Ganther, et al. A critical review of microbiological colonisation of nano- and microplastics (NMP) and their significance to the food chain. Food Standards Agency, April 2022. http://dx.doi.org/10.46756/sci.fsa.xdx112.

Full text
Abstract:
Microplastics are extremely small mixed shaped plastic debris in the environment. These plastics are manufactured (primary microplastics) or formed from the breakdown of larger plastics once they enter the terrestrial, freshwater and marine environments (secondary microplastics). Over time, a combination of physical, photochemical and biological processes can reduce the structural integrity of plastic debris to produce microplastics and even further to produce nanoplastics. NMPs have been detected in both the aquatic and terrestrial environments and can be easily spread by water, soil and air and can be ingested by a wide range of organisms. For example, NMPs have been found in the guts of fish and bivalve shellfish. Microplastics have also been detected in food and in human faeces. Therefore, NMPs are not only found in the environment, but they may contaminate the food supply chain and be ingested by consumers. There is evidence suggesting that microorganisms are able to colonise the surfaces of microplastics and aggregates of nanoplastics. However, the risk to consumers posed by NMPs colonised with microorganisms (including those that are AMR) which enter the food supply chain is currently unknown.
APA, Harvard, Vancouver, ISO, and other styles
6

Litaor, Iggy, James Ippolito, Iris Zohar, and Michael Massey. Phosphorus capture recycling and utilization for sustainable agriculture using Al/organic composite water treatment residuals. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600037.bard.

Full text
Abstract:
Objectives: 1) develop a thorough understanding of the sorption mechanisms of Pi and Po onto the Al/O- WTR; 2) determine the breakthrough range of the composite Al/O-WTR during P capturing from agro- wastewaters; and 3) critically evaluate the performance of the composite Al/O-WTR as a fertilizer using selected plants grown in lysimeters and test-field studies. Instead of lysimeters we used pots (Israel) and one- liter cone-tainers (USA). We conducted one field study but in spite of major pretreatments the soils still exhibited high enough P from previous experiments so no differences between control and P additions were noticeable. Due to time constrains the field study was discontinued. Background: Phosphorous, a non-renewable resource, has been applied extensively in fields to increase crop yield, yet consequently has increased the potential of waterway eutrophication. Our proposal impetus is the need to develop an innovative method of P capturing, recycling and reuse that will sustain agricultural productivity while concurrently reducing the level of P discharge from and to agricultural settings. Major Conclusions & Achievements: An innovative approach was developed for P removal from soil leachate, dairy wastewater (Israel), and swine effluents (USA) using Al-based water treatment residuals (Al- WTR) to create an organic-Al-WTR composite (Al/O-WTR), potentially capable of serving as a P fertilizer source. The Al-WTR removed 95% inorganic-P, 80% to 99.9% organic P, and over 60% dissolved organic carbon from the agro-industrial waste streams. Organic C accumulation on particles surfaces possibly enhanced weak P bonding and facilitated P desorption. Analysis by scanning electron microscope (SEM- EDS), indicated that P was sparsely sorbed on both calcic and Al (hydr)oxide surfaces. Sorption of P onto WW-Al/O-WTR was reversible due to weak Ca-P and Al-P bonds induced by the slight alkaline nature and in the presence of organic moieties. Synchrotron-based microfocused X-ray fluorescence (micro-XRF) spectrometry, bulk P K-edge X-ray absorption near edge structure spectroscopy (XANES), and P K-edge micro-XANES spectroscopy indicated that adsorption was the primary P retention mechanism in the Al- WTR materials. However, distinct apatite- or octocalciumphosphatelike P grains were also observed. Synchrotron micro-XRF mapping further suggested that exposure of the aggregate exteriors to wastewater caused P to diffuse into the porous Al-WTR aggregates. Organic P species were not explicitly identified via P K-edge XANES despite high organic matter content, suggesting that organic P may have been predominantly associated with mineral surfaces. In screen houses experiments (Israel) we showed that the highest additions of Al/O-WTR (5 and 7 g kg⁻¹) produced the highest lettuce (Lactuca sativa L. var. longifolial) yield. Lettuce yield and P concentration were similar across treatments, indicating that Al/O- WTR can provide sufficient P to perform similarly to common fertilizers. A greenhouse study (USA) was utilized to compare increasing rates of swine wastewater derived Al/O-WTR and inorganic P fertilizer (both applied at 33.6, 67.3, and 134.5 kg P₂O₅ ha⁻¹) to supply plant-available P to spring wheat (TriticumaestivumL.) in either sandy loam or sandy clay loam soil. Spring wheat straw and grain P uptake were comparable across all treatments in the sandy loam, while Al/O-WTR application to the sandy clay loam reduced straw and grain P uptake. The Al/O-WTR did not affect soil organic P concentrations, but did increase phosphatase activity in both soils; this suggests that Al/O-WTR application stimulated microorganisms and enhance the extent to which microbial communities can mineralize Al/O-WTR-bound organic P. Implications: Overall, results suggest that creating a new P fertilizer from Al-WTR and agro-industrial waste sources may be a feasible alternative to mining inorganic P fertilizer sources, while protecting the environment from unnecessary waste disposal.
APA, Harvard, Vancouver, ISO, and other styles
7

Wells, Aaron, Tracy Christopherson, Gerald Frost, Matthew Macander, Susan Ives, Robert McNown, and Erin Johnson. Ecological land survey and soils inventory for Katmai National Park and Preserve, 2016–2017. National Park Service, September 2021. http://dx.doi.org/10.36967/nrr-2287466.

Full text
Abstract:
This study was conducted to inventory, classify, and map soils and vegetation within the ecosystems of Katmai National Park and Preserve (KATM) using an ecological land survey (ELS) approach. The ecosystem classes identified in the ELS effort were mapped across the park, using an archive of Geo-graphic Information System (GIS) and Remote Sensing (RS) datasets pertaining to land cover, topography, surficial geology, and glacial history. The description and mapping of the landform-vegetation-soil relationships identified in the ELS work provides tools to support the design and implementation of future field- and RS-based studies, facilitates further analysis and contextualization of existing data, and will help inform natural resource management decisions. We collected information on the geomorphic, topographic, hydrologic, pedologic, and vegetation characteristics of ecosystems using a dataset of 724 field plots, of which 407 were sampled by ABR, Inc.—Environmental Research and Services (ABR) staff in 2016–2017, and 317 were from existing, ancillary datasets. ABR field plots were located along transects that were selected using a gradient-direct sampling scheme (Austin and Heligers 1989) to collect data for the range of ecological conditions present within KATM, and to provide the data needed to interpret ecosystem and soils development. The field plot dataset encompassed all of the major environmental gradients and landscape histories present in KATM. Individual state-factors (e.g., soil pH, slope aspect) and other ecosystem components (e.g., geomorphic unit, vegetation species composition and structure) were measured or categorized using standard classification systems developed for Alaska. We described and analyzed the hierarchical relationships among the ecosystem components to classify 92 Plot Ecotypes (local-scale ecosystems) that best partitioned the variation in soils, vegetation, and disturbance properties observed at the field plots. From the 92 Plot Ecotypes, we developed classifications of Map Ecotypes and Disturbance Landscapes that could be mapped across the park. Additionally, using an existing surficial geology map for KATM, we developed a map of Generalized Soil Texture by aggregating similar surficial geology classes into a reduced set of classes representing the predominant soil textures in each. We then intersected the Ecotype map with the General-ized Soil Texture Map in a GIS and aggregated combinations of Map Ecotypes with similar soils to derive and map Soil Landscapes and Soil Great Groups. The classification of Great Groups captures information on the soil as a whole, as opposed to the subgroup classification which focuses on the properties of specific horizons (Soil Survey Staff 1999). Of the 724 plots included in the Ecotype analysis, sufficient soils data for classifying soil subgroups was available for 467 plots. Soils from 8 orders of soil taxonomy were encountered during the field sampling: Alfisols (<1% of the mapped area), Andisols (3%), Entisols (45%), Gelisols (<1%), Histosols (12%), Inceptisols (22%), Mollisols (<1%), and Spodosols (16%). Within these 8 Soil Orders, field plots corresponded to a total of 74 Soil Subgroups, the most common of which were Typic Cryaquents, Typic Cryorthents, Histic Cryaquepts, Vitrandic Cryorthents, and Typic Cryofluvents.
APA, Harvard, Vancouver, ISO, and other styles
8

Gibbs, Holly, Sahoko Yui, and Richard Plevin. New Estimates of Soil and Biomass Carbon Stocks for Global Economic Models. GTAP Technical Paper, March 2014. http://dx.doi.org/10.21642/gtap.tp33.

Full text
Abstract:
We synthesized a range of geographically-explicit forest, grassland and cropland biomass and soil carbon input data sources and used geographic information systems (GIS) software to calculate new estimates of soil and biomass carbon stocks for use with global economic models, particularly for the Global Trade and Analysis Project (GTAP). Our results quantify the average amount of carbon stored in soil and biomass in each of the 246 countries, stratified by agro-ecological zones (available in the accompanying spreadsheet). We also provide the data aggregated to the 134 regions defined for the GTAP 8.1 database both in spreadsheet form and in GTAP’s native binary file format. Finally, we provide an add-on to FlexAgg2 program to further aggregate the 134 regions as desired. Our analysis makes substantial refinements to the estimates of carbon stocks used for modeling carbon emissions from indirect land use change. The spatial detail of our analysis is a major advantage over previous databases because it provides estimates tailored to the regions of interest and better accounts for the variation of carbon stocks across the landscape, and between wetland and non-wetland regions.
APA, Harvard, Vancouver, ISO, and other styles
9

Pinney, D. S., and E. S. Duenwald. Directory of aggregate, rock, and soil producers in Alaska (updated 2001). Alaska Division of Geological & Geophysical Surveys, October 2001. http://dx.doi.org/10.14509/2772.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Behnood, Ali, and Jan Olek. Development of Subgrade Stabilization and Slab Undersealing Solutions for PCC Pavements Restoration and Repairs. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317128.

Full text
Abstract:
The loss of functionality and the development of distress in concrete pavements is often attributable to the poor subbase and subgrade conditions and/or loss of support due to the development of the voids underneath the slab. Subgrade soil stabilization can be used as an effective approach to restore the functionality of the subgrades in patching projects. This research had two main objectives: (1) identifying the best practices for soil stabilization of the existing subgrade during pavement patching operations and (2) identifying and developing new, modified grouting materials for slab stabilization and undersealing. Various stabilization scenarios were tested and showed improved performance of the subgrade layer. The use of geotextile along with aggregate course was found to significantly reduce the settlement. Non-removable flowable fill was also found to significantly reduce the subgrade settlement. Cement-treated aggregate and lean concrete provided the best performance, as they prevented formation of any noticeable settlement in the underlying subgrade.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Soil aggregates' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography