Soil Clods Research Articles

Comparative Field Performance of Rotavator and Rotary Plough

The study was conducted to compare the field performance of rotavator and rotary plough in light, medium and heavy soil taking machine type and soil type as independent parameters and wheel slip (%), fuel consumption (l/h), bulk density of soil (g/cm3, before and after operation of machine), depth of cut (cm), width of cut (cm), field capacity (ha/h) and pulverization index (mm) as dependent parameters. It was found that field capacity of rotary plough was 6.1%, 12.06% and 45.7% lower than the rotavator in light, medium and heavy soil, respectively. The use of rotary plough led to 23.56% and 26.71% higher fuel consumption as compared to commercially available rotavator in light and medium soil, respectively. The pulverization index for rotary plough was 21.3%, 34.85% and 43.46% higher than that of rotavator in light, medium and heavy soil, respectively. Rotavator made smaller size of soil clods as compared to rotary plough, which is favorable for seed germination and crop growth. Tractor wheel slip for rotary plough was positive, whereas, it was negative for rotavator, which revealed that tractor with rotary plough was slipping in the soil while tractor with rotavator was skidding while operation.

Зарубежные технические средства для выкопки посадочного материала с почвенным комом

Зарубежные технические средства для выкопки посадочного материала с почвенным комом

Определение размера почвенного кома деревьев при их выкопке для использования в озеленительных работах

Определение размера почвенного кома деревьев при их выкопке для использования в озеленительных работах

Effects of Road Constructions on Soil Drainage from Paddy Fields

Bad drainage problems from paddy fields adjacent to roads are caused by higher constructed roads which change topography of paddy fields to concave topography and artificial pan to prevent road erosion when road constructions are occurred. This study investigated effects of topography changes on soils by road constructions. Soil samples were investigated by physico-chemical analyses and micromorphology analyses from representative soil profile of Sachon series and soil samples. The characteristics of Sachon series that were adjacent to roads were fewer redoximorphic features (RMF) and increase in grey layers than the original Sachon series. The characteristics of Yecheon Series were shown from Jeollanamdo - Suncheon > Chungchungnamdo - Cheonan > Gangwondo - Wonju. Mosaic speckles were shown from micromorphological analyses because of repeat of shrink and expansion by wetting and drying. The location of graying in soil clods were found from coarse stone blocks to fine stone blocks and color changes of composed particles were also found.

A Study on Soil Characteristics of Paddy Fields with Re-established Soils

Six study sites in Gumi, Goryeong in Gyeongbuk province and Naju in Jeonnam province were selected to investigate soil properties of poorly drained horizons in paddy soils. The horizons were re-established layers which were parent material layers originated from fluvial deposits. Topsoil layers were differentiated from piled parent materials while soil structure of the topsoil layer was massive with striated microstructure. Compaction at soil re-establishment and a lack of structure and aggregate development in these soils may cause the limitation of vertical water movement and result in poorly drained horizons. Soil samples were taken from paddy fields with top soils of sandy loam, silt loam and silty clay loam and re-established soils of coarse and fine texture. The samples were taken from each horizon for the analyses of soil chemical and mineral properties. Soils with re-established soils of coarse texture had greater amounts of sands from top soil texture distributions, while soils with fine texture had greater amounts of silts. Chemical properties of top soils were analyzed from rice cultivated soils at the time of re-establishments and one year after the re-establishments. The coarse texture of the re-established horizons decreased in EC values from 0.23 to 0.11 (dS m -1 ), available phosphate values from 112 to 54 (mg kg -1 ), and exchangeable Ca values from 6.6 to 4.9 (cmolc kg -1 ). On the other hand, soils with fine texture showed decrease only in pH and exchangeable Ca values. Especially, organic matter and available phosphate contents showed heterogeneous distributions from each horizon. This result may be caused by mixture of plough layer and subsurface layer during and consolidation. Hydraulic conductivity values were low at the boundaries of top soil and parent material layers except SL/coarse soil. Soil microstructure was massive structure without soil clods or pores and showed striated structure. Therefore, re-established paddy fields with fluvial deposits as parent material layers showed limited vertical movements of soil water because of occurrence of compacted layers and less-development of soil clods and aggregates.

Soil and Soil Science Education in the Primary School Through Appearance of "흙[heuk], Soil" in the Korean Reading Textbook

Public education on soil and soil science in Korea was reviewed through textbooks written in Korean which were used in the primary schools since 1950s. Numbers of words 흙[heuk], the Korean native word meaning soil, and 토양[土壤, toyang], originated from Chinese characters, were counted, and compared with the textbooks published in 1950s, 1970s, and 1990s, 2010s. The Korean native word “heuk” was used 20 times in 1950s, and increased to 55 times in 1970s. In 1990s version, it was decreased to 31 times and to 20 times in the 2010s version. The first appearance in the 1950s version was in the 3rd grade book, but was in the 1 st grade books in both 1990s and 2010s. In this recent version, the primary school students met this word on the poet, “Toad, Toad build a house”, and “Sprout come out through soil clod”. The word, “토양, toyang”, originated from Chinese characters, 土壤, appears only 2 times in the 6 th grade in 2010s version. Authors conclusively recommend children should learn meaning of soil at early stage of primary school easily with positive image.

Effect of water salinity on Atterberg limits of El-Hodna sabkha soil

Sabkha soils are recent saline sediments widely distributed in Algeria and other countries. As they are characterised by low strength and high compressibility, they are considered to be difficult foundation soils that pose special problems for design and construction engineering. This study deals with the effect of salts on the determination of the water content and Atterberg limits of sabkha soils. The tests were performed using distilled water, natural sabkha brine and saline solutions with different salt concentrations. The results indicate that the liquid and plastic limits decrease with pore fluid salinity when the conventional water content procedure is used, but increase when the fluid content method is used. Also, the results revealed that the oven-drying time of saline soils is highly affected by the size of soil clods and surface salt precipitation.

Influence of clod size and water content on gas permeability of a compacted loess

The northwestern region of China is mainly semi-arid to arid and loess is ubiquitous. This natural resource has considerable potential to be transformed into earthen final covers for local landfills, but first its suitability must be ascertained through extensive tests. In this study, a device was developed to measure the gas permeability of unsaturated compacted loess specimens. Experiments were carried out to investigate the influence of clod size, compaction water content, and post-compaction water content on the gas permeability of the compacted loess. To maintain an identical soil structure, the post-compaction water content was changed using the osmotic technique. It was found that the compaction water content and resultant soil clod size exerted a combined effect on the gas permeability such that, at low water contents, the gas permeability remained fairly constant, but at high water contents the clods became relatively large, and the effect of the clod size dominated the water blockage effect from increasing water content. For specimens with identical soil structure, the gas permeability decreased with the increasing post-compaction degree of saturation at an accelerated rate. A power function is proposed to predict the relationship between the gas permeability normalized by the porosity function of the Kozeny–Carmen model and the post-compaction degree of saturation. Analysis of the experimental data indicates that the parameters for the power function still depend on the porosity of the compacted loess, particularly at high degrees of saturation.

The Role of Water Content in Electrical Resistivity Tomography of a Vertisol

Electrical resistivity tomography (ERT) has been suggested as a noninvasive approach for measuring cracks in Vertisols; however, its use has been limited, in part due to a lack of knowledge of the interactions between soil water content and electrical resistivity in cracking soils. In this study, we examined the relationship between soil water content and electrical resistivity for a Vertisol under cracked and noncracked conditions. Electrical resistivity was measured on soil clods, where desiccation does not result in cracking. Results showed that soil matrix electrical resistivity could be predicted from soil water content using an empirical model (RMSE = 8.3 Ωm andr2= 0.84). On a 4.5‐ by 5‐m area of a Vertisol, in situ measurements of bulk soil electrical resistivity and soil water content were made using three‐dimensional ERT and neutron soil moisture meter, respectively. Using the empirical model from soil clod measurements and field measured soil water content, we predicted the electrical resistivity of the in situ soil. When cracks were absent, measured soil electrical resistivity fell within the prediction intervals of the empirical model. When cracks were present, average measured electrical resistivity between the 0.2‐ and 0.8‐m depth exceeded predicted electrical resistivity by 15,200 Ωm. The increased electrical resistivity measured on cracked soil cannot solely be attributed to lower soil water content. We, therefore, concluded that cracking directly increased the bulk soil electrical resistivity. Additionally, these data showed that for soils with and without cracks, in situ measurements of soil electrical resistivity could not predict soil water content within the accuracy of the neutron soil moisture meter. Observed differences between in situ electrical resistivity of the soil matrix and bulk soil indicate that ERT might be utilized to nondestructively map soil cracking.

Explanation of Phenomenological Characteristics in Seepage Force Concept System

Soil mechanics has been developed for a long time and its concept system is basically complete. But there are still some concepts not being defined clearly. The unclear concepts of seepage force are stated from three phenomenological characteristics aspects in this paper. The difference between loaded object and calculated range is cleared. The contact rule of solid phase and liquid phase is illustrated. The mathematical meaning of seepage force is clarified. Though judging the critical hydraulic gradient of soil flow on surface of cohesionless soil, the difference and correlation of the soil particle and clod analysis based on the phenomenological characteristics will be illustrated.

Porosity distribution by computed tomography and its importance to characterize soil clod samples

Gamma-ray computed tomography (CT) was employed to study the soil quality of clod samples used to investigate porosity (ϕ). Samples with volumes varying from 50 to 100cm3 were collected from the soil surface. 2D CT images were obtained with millimetric resolution. Porosity distribution analyses were carried out to infer the soil clod structure. Results obtained provided a new insight on the variability of internal clod structure due to the large amount of data analyzed, information that is not provided by traditional methods used in physics applied to soil.

Aqueous and non-aqueous soil processes on the northern plains of Mars: Insights from the distribution of perchlorate salts at the Phoenix landing site and in Earth analog environments

In 2008, the Phoenix lander returned chemical evidence of perchlorate salts in the soils at its landing site on the northern plains of Mars. Subsequent spectral mapping of the perchlorate using Phoenix׳s multispectral Surface Stereo Imager (SSI) showed that concentrated patches of the salt exist in the subsurface. Because atmospheric formation of Martian perchlorate should form a highly-concentrated layer of salt on the surface, subsurface concentrated patches have been interpreted as evidence that Phoenix soils experienced minor amounts of aqueous reworking after perchlorate formation. Here, we present results from a wide-scale mapping of the Phoenix landing site using SSI multispectral data. We report that, contrary to preliminary case studies, limited occurrences of rocks and soil clods with perchlorate coatings are also found on the undisturbed surface. The discovery of these patches on undisturbed surfaces points to more complex processes operating on modern-day polar soils, perhaps including a combination of aqueous and mechanical processes, such as cryoturbation. Finally, we combine results from this study with an analysis of perchlorate redistribution mechanisms on Earth to illustrate the mechanisms likely responsible for modern processing of soils on the northern plains of Mars.

Representative Elementary Length to Measure Soil Mass Attenuation Coefficient

With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (μ s) is an important parameter for CT and GAT analysis. When experimentally determined (μ es), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils for μ es measurements. Two radioactive sources were employed (241Am and 137Cs), three collimators (2–4 mm diameters), and 14 thickness (x) samples (2–15 cm). Results indicated ideal thickness intervals of 12–15 and 2–4 cm for the sources 137Cs and 241Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated that μ es average values obtained for x > 4 cm and source 241Am might induce to the use of samples which are not large enough for soil bulk density evaluations (ρ s). As a consequence, ρ s might be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study.

The effects of soil freeze—thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review

Edwards, L. M. 2013. The effects of soil freeze-thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review. Can. J. Soil Sci. 93: 459-472. The importance of aggregate size and integrity in soil productivity and crop production is paramount, and aggregate size reduction or increase invariably becomes a primary concern in such soil management practices as tillage and organic matter manipulation. In this regard, therefore, the present review looks particularly at the consequence of freeze-thaw cycling (FTC) on agricultural lands in Prince Edward Island (PEI) where an annual average of 40 cycles induce measurable aggregate breakdown with mixed consequences. On the one extreme, the consequences are manifest in increased soil erosion. On the other extreme, reduced (or reversed) soil compaction and improved seedbed conditions are welcomed consequences where temperature alternation breaks up hard pans or soil clods, or where the predominance of smaller aggregates can be an as...

The effects of soil freeze–thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review

Edwards, L. M. 2013. The effects of soil freeze–thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review. Can. J. Soil Sci. 93: 459–472. The importance of aggregate size and integrity in soil productivity and crop production is paramount, and aggregate size reduction or increase invariably becomes a primary concern in such soil management practices as tillage and organic matter manipulation. In this regard, therefore, the present review looks particularly at the consequence of freeze–thaw cycling (FTC) on agricultural lands in Prince Edward Island (PEI) where an annual average of 40 cycles induce measurable aggregate breakdown with mixed consequences. On the one extreme, the consequences are manifest in increased soil erosion. On the other extreme, reduced (or reversed) soil compaction and improved seedbed conditions are welcomed consequences where temperature alternation breaks up hard pans or soil clods, or where the predominance of smaller aggregates can be an asset in seedbed environments, favouring improved crop emergence and early-spring establishment. In the PEI soils studied, the greatest changes in aggregate size distribution with FTC occurred in the largest and smallest size fractions wherein fractions <0.5 mm showed a 33% average increase while, simultaneously, the 4.75–9.5 mm fractions showed a 28% average decrease. This breakdown is reflected most contrastingly where FTCs to maximum (asymptotic) breakdown averaged up to 3.5 times for a loam as it did for a sandy loam or a fine sandy loam soil. This review also examines FTC in a broader agricultural and environmental context where it can potentially impact agro-sustainability. Where FTC effects on a fine sandy loam were measured in terms of erosion, there was a sediment mass increase of about 90% in interrill flow and about 25% in rill flow. Further, this review emphasizes methodology that has proven to be workable under the circumstances of PEI's dominant agricultural soils and the FTC research objectives that they helped to shape. It was considered important in this review, also, to highlight the need for expanded research (commencing with regional cooperation), particularly on frost depth, to feed into moisture-availability modelling towards improved clarity for end-user benefit.

Experimental subsoiling by in-line shallow and deep tines

Conventional soil ripping has high fuel consumption because it involves high draft force and may produce large soil clods. This experiment compares the use of shallow leading tines ahead of the main tine with use of a conventional single-tine ripper. The study showed that attaching a single, shallow leading tine ahead of, and in line with, the main tine and 25–40% shallower in depth gave the greatest significant decrease in specific draft force. This led to a fuel reduction from 13.6 to 11.5 L/ha, or a saving of 15% when ripping a moist loamy sand soil to 330 mm depth. Attaching more than one shallow lead tine ahead of the ripper did not significantly affect specific draft forces, whether the shallow lead tines were in line or offset. Other advantages of using the shallow leading tine ripper over the conventional ripper are: improved soil tilth by significantly decreasing soil clod size; potentially a wider moisture range for ripping the soil (as soil clods are smaller and drier soil increases clod size) thus increasing the time available for the operation; and decreased depreciation of ripping components.

Aggregate and Soil Clod Volume Measurement: A Method Comparison

Reference volume for soil physical and chemical characteristics of soil samples is often based on soil core extraction. At the aggregate level, however, volume determination is more difficult and fraught with greater uncertainty due to irregular shapes. Our objective was to identify a method that best described relevant variables in aggregates. For this purpose, we compared four methods to determine the possibilities and limitations in acquiring those variables: paraffin coating and submerging, automated pycnometer, three‐dimensional laser scanner, and x‐ray microcomputed tomography. All methods gave reliable results for aggregate volume, but the pycnometer and three‐dimensional laser scanner slightly overestimated the volume. The key benefits of the three‐dimensional laser scanner and x‐ray microtomography are the gain of additional parameters such as surface roughness, axial ratios, and interaggregate pore volumes. These characteristics may be of interest for further questions such as aggregate stability or accessibility of sorption surfaces.

Analysis of Three-dimensional Geometrical Pore Parameters From Rock Weathering

Weathering produces porosity that influences rocks’ hydrologic properties and thus affects ecosystem processes. The objective of this research was to quantify three-dimensional geometrical pore parameters and characterize microstructure differences as rock weathers. Three granodiorite rock fragments (clasts) and two soil clods sampled from a moraine chronosequence in the eastern Sierra Nevada, California, were evaluated. Surface ages of the parent moraines, ranging from 78 to 120 ka, were used to approximate clast weathering. Samples were scanned at a volume element (voxel) size of 6.9 × 104 μm3 at the High-Resolution X-ray computed tomography (CT) facility at the University of Texas, Austin. Images were analyzed with the Three-dimensional Medial Axis Rock (3DMA) software (CT-3DMA). Porosity estimated by bulk density and CT methods indicated excellent agreement between the two methods. Characteristic coordination numbers increased with weathering, and the soil had the highest value; means for 78-ka rock and 100-ka rock and soil were 2.49, 2.68, and 4.32. The difference between rock treatments was not significant, but tended to increase with age. The difference between soil and rock was significant. The characteristic path length varied between 1.20 and 1.46 but was not different among rock age. The mean value for the soil was 0.86, and the difference between rock and soil was significant. Pore path tortuosity ranged from a high of 1.35 in the 78-ka rock to a low of 1.31 in the soil, with significant differences between rock and soil. Results suggest that rocks imaged with X-ray CT and analyzed in 3DMA will help quantify microstructural differences in pore geometry related to rock weathering.

An Image-Based Method for Determining Bulk Density and the Soil Shrinkage Curve

12 Current laboratory methods for determining volume and bulk density of soil clods include 13 dipping saran-coated clods in water (a destructive process due to the permanent coating), 14 performing physical measurements on samples with well-defined geometries, or using expensive 15 equipment and proprietary software (such as laser scanners). We propose an alternative method 16 for determining the volume and bulk density of a soil clod, which is non-destructive, low-cost 17 and utilizes free and open-source software. This method (the clodometer method) uses a standard 18 digital camera to image a rotating clod, which allows for reconstruction of its three-dimensional 19 surface and subsequent calculation of its volume. We validated the method through comparison 20 to the standard displacement method, and then used the method to create a soil shrinkage curve 21 for the Waldo silty clay loam soil. The method had acceptable precision (relative standard errors 22 of the mean between 0.4 – 1.6%), which may be further improved through future software 23 development. 24 25 Abbreviations: coefficient of linear extensibility (COLE); soil shrinkage curve (SSC) 26

CARBON SEQUESTRATION: ESTIMATION OF CARBON STOCK IN TEAK (Tectona grandis Linn. f.) ECOSYSTEM

Carbon management in forest plantations will probably be the single most important agenda of the first half of the 21st century in India in the context of the greenhouse effect and mitigation of global climatic changes. Today teak (Tectona grandis) is widely planted in south-east Asia and in Africa, South and Central America as an exotic species. This teak based global sink would certainly increase because during the past 20 years most supplies of teak wood from natural forests have dwindled and increased interest has developed in the establishment of teak forest plantations.Unlike in developed countries, developing countries do not have carbon inventories and data bank to monitor and enhance carbon sequestration potential of different plantations. In India attempts were made to assess carbon sequestration studies at macro level, mostly with the available data. No attempt has been made so far to assess the biomass and soil carbon sequestration at micro level. Therefore, a pilot study was taken up to estimate the carbon stock available in teak ecosystem. The study was conducted in a 12 year old teak planta tion planted at 2 m x 2 m spacing. Timber volume of about 100 trees was worked out by using height and gbh. Finally, the total biomass in the 1 ha area of teak plantation was estimated. Carbon estimation from the biomass was calculated based on the methodology described by Koch (1989) and the minimum value of 49.1 was adopted as the conversion factor.Soil samples were collected at the surface (0-30 cm) and sub-surface (0-60 cm) layers. The collected soil samples were air dried in shade, broken the clods with wooden mallet and passed through 2 mm sieve, labeled and stored in cloth bags. The per cent of coarse fraction (> 2.0 mm size) for each layer was estimated. Undis turbed soil clods were collected from each layer and preserved for determination of bulk density. The deter mined bulk density was corrected for per cent coarse fractions. The corrected bulk density (Mg m-3) was used for the estimation of SOC density (Mg ha-1) and SOC stock.The total biomass carbon of teak plantation was 5.52 t C /ha and total SOC was 6.71 t C /ha. The ratio between SOC and biomass carbon was 1.22. Post et al. (1990) reported that the ratio between SOC and biomass carbon is 2.5 to 3.0 times in the terrestrial ecosystem.The present study indicates that the SOC is higher than that of biomass carbon but not 2.5 to 3.0 times of biomass carbon as recorded in well-managed terrestrial ecosystem. However, in the tropical forest, the carbon in the soil is roughly equivalent or lesser than the above ground biomass due to degradation. Hence, data bank on carbon stock will certainly help the foresters to enhance the soil carbon for sustainable management of forest plantations in the context of mitigating climate changes.