Impact resistance of three soils under varying moisture and subzero temperature conditions

1984 ◽  
Vol 21 (3) ◽  
pp. 449-455 ◽  
Author(s):  
B. J. Zebarth ◽  
D. Lee ◽  
B. D. Kay
Keyword(s):  
Moisture Content ◽  
Impact Resistance ◽  
Particle Diameter ◽  
Soil Surface ◽  
Frozen Soil ◽  
Subzero Temperature ◽  
Simple Method ◽  
Temperature Conditions ◽  
Key Words Density ◽  
Density Dynamic

Impact resistance, the deceleration-time response of a moving body upon impact with a surface, can be used to measure the hardness of a soil surface. A simple method for measuring impact resistance is presented. Impact resistance of three soils (Preston sand, Haldimand clay, and Guelph loam) was measured over a range of moisture and subzero temperature conditions. Impact resistance of frozen soil was found to increase with increasing moisture content, decreasing temperature, and increasing particle diameter. Temperature effects on impact resistance were minimal below −4 °C. Under field conditions, increased impact resistance due to increased particle diameter may be compensated for by reduced moisture content. Key words: density, dynamic loading, grain size, soil strength, sports fields.

A Method for obtaining Samples of the Population of Collembola (Symphypleona) in Pastures

1933 ◽  
Vol 24 (3) ◽  
pp. 351-352 ◽  
Author(s):  
J. Davidson ◽  
D. C. Swan
Keyword(s):  
Moisture Content ◽  
Total Population ◽  
Surface Soil ◽  
Relative Proportion ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Food Plants ◽  
Simple Method ◽  
Factors Affecting

In our investigations on Smynthurus viridis, L., a study has been made of the population of this species, in an area of lucerne, at intervals of three and four days throughout the season.The density of the population of the species in a favourable pasture is markedly affected by the relative abundance of certain food-plants, especially leguminous species and particularly clovers such as subterranean clover (Trifolium subterraneum) and lucerne (Medicago sativa).The activity of the insect is intimately associated with the moisture of its environment, and the moisture content of the surface soil is one of the most important factors affecting the environmental conditions.Considering the habits of the insect, it was felt that the sweeping method would not give a reliable record of the total population in a given area of pasture. A sample obtained by sweeping with a net does not include individuals on or near to the surface of the soil. The relative proportion of individuals situated on or near the soil surface and those situated further up the plants varies considerably from time to time, according to the meteorological conditions, the growth of the herbage and the moisture content of the surface soil. It was necessary therefore to devise a simple method by means of which a more accurate record of the total population in a given area could be obtained.

Hétérogénéité d'une lande haute à Ulex europaeus en relation avec la propagation du feu (Bretagne, France)

1998 ◽  
Vol 76 (5) ◽  
pp. 804-817 ◽  
Author(s):  
Christelle Hely ◽  
Françoise Forgeard
Keyword(s):  
Moisture Content ◽  
Fire Risk ◽  
Soil Surface ◽  
Propagation Models ◽  
Heterogeneous Distribution ◽  
Fuel Distribution ◽  
Ulex Europaeus ◽  
Fire Propagation ◽  
Organic Horizons ◽  
Layered Pattern

This study analyzes plant material in a high Ulex europaeus heath to provide information on the partitioning of this ecosystem for fire propagation models. The aboveground biomass, followed for 15 months, has a spatially heterogeneous distribution that is a result of the layered pattern of the various branches. This pattern creates an internal moisture gradient that decreases from the apex to the base of the plant. This gradient also varies according to the species phenology. New, green branches with a high moisture content are at the top of the plant (upper strata), whereas woody branches with a lower moisture content are found near the ground (lower strata). Dry branches and spines, which produce most of the litter, are homogeneously distributed throughout the plant. Temporally, the layered pattern is homogeneous through the year and thus creates a constant fire risk. Soil organic horizons are temporally, spatially, and compositionally heterogeneous. The L layer is always two to three times thinner and drier than the duff layer (F+H). The total depth, weight, and moisture content of the organic horizons vary considerably across both the plot and square metre scales. The distance from a plant has a significant influence on the depth distribution of the soil organic horizons. Fuel distribution on both the soil surface and the plant must be considered to understand fire behaviour in this ecosystem.Key words: architecture, biomass, fire, fuel, humus, moisture content.

scholarly journals Gold Nanoparticles with Different Particle Sizes for the Quantitative Determination of Chlorpyrifos Residues in Soil by SERS

2019 ◽  
Vol 20 (11) ◽  
pp. 2817 ◽  
Author(s):  
Yong He ◽  
Shupei Xiao ◽  
Tao Dong ◽  
Pengcheng Nie
Keyword(s):  
Gold Nanoparticles ◽  
Limit Of Detection ◽  
Soil Surface ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Substrate ◽  
Least Squares Regression ◽  
Simple Method ◽  
Good Linear ◽  
Relative Standard

Chlorpyrifos (CPF) is widely used in the prevention and control of crop pests and diseases in agriculture. However, the irrational utilization of pesticides not only causes environmental pollution but also threatens human health. Compared with the conventional techniques for the determination of pesticides in soil, surface-enhanced Raman spectroscopy (SERS) has shown great potential in ultrasensitive and chemical analysis. Therefore, this paper reported a simple method for synthesizing gold nanoparticles (AuNPs) with different sizes used as a SERS substrate for the determination of CPF residues in soil for the first time. The results showed that there was a good linear correlation between the SERS characteristic peak intensity of CPF and particle size of the AuNPs with an R2 of 0.9973. Moreover, the prepared AuNPs performed great ultrasensitivity, reproducibility and chemical stability, and the limit of detection (LOD) of the CPF was found to be as low as 10 μg/L. Furthermore, the concentrations ranging from 0.01 to 10 mg/L were easily observed by SERS with the prepared AuNPs and the SERS intensity showed a good linear relationship with an R2 of 0.985. The determination coefficient (Rp2) reached 0.977 for CPF prediction using the partial least squares regression (PLSR) model and the LOD of CPF residues in soil was found to be as low as 0.025 mg/kg. The relative standard deviation (RSD) was less than 3.69% and the recovery ranged from 97.5 to 103.3%. In summary, this simple method for AuNPs fabrication with ultrasensitivity and reproducibility confirms that the SERS is highly promising for the determination of soil pesticide residues.

Evaluation of the magnetite as a magnetic tracer of eroded sediment from ephemeral gullies: conditioning factors of magnetic susceptibility

2020 ◽  
Author(s):  
Elena Zubieta ◽  
Juan Larrasoaña ◽  
Rafael Giménez ◽  
Alaitz Aldaz ◽  
Javier Casalí
Keyword(s):  
Magnetic Susceptibility ◽  
Soil Moisture ◽  
Moisture Content ◽  
Soil Surface ◽  
Field Capacity ◽  
Field Studies ◽  
Silty Clay ◽  
Magnetic Signal ◽  
Conditioning Factors ◽  
Detection Depth

<p>In gully erosion, the soil detached by the action of the erosive flow can be transported over long distances along the drainage network of the watershed. In this long way, the eroded material can be redistributed and/or deposited on the soil surface, and then eventually buried by eroded material from subsequent erosion events. Likewise, the variability of the soil (i.e., in texture and moisture content) over which this material moves can be considerable. The presence of the eroded material could be detected through magnetic tracers attached/mixed with the eroded soil. In this experiment, the degree to which the magnetic signal of the magnetite is conditioned by (i) the burying tracer depth, (ii) the texture and moisture content of the soil covering the tracer and (iii) the tracer concentration was evaluated.</p><p>The study was carried out in the lab in different containers (0.5 x 0.5 x 0.3 m<sup>3</sup>). Each container was filled with a given soil. In the filling process, a 0.5-cm layer of a soil-magnetite mixture of a certain concentration was interspersed in the soil profile at a certain depth. Overall, 3 different soil:tracer concentrations (1000:1, 200:1, 100:1), 4 tracer burying depths (0 cm, 3 cm, 5 cm and 10 cm from soil surface), and  2 contrasting soils (silty clay and sandy clay loam) were used. In each case, the magnetic susceptibility was measured with a magnetometer (MS3 by Bartington Instruments). Experiments were repeated with different soil moisture contents (from field capacity to dry soil).</p><p>If the tracer is located under the soil surface a minimum soil:tracer concentration of 200:1 is required for its correct  detection from the surface using a magnetometer. The intensity of the magnetic signal decreases dramatically with the vertical distance  of the tracer from the soil  surface (burying depth). The maximum detection depth of the tracer magnetic signal is strongly dependent on the natural magnetic susceptibility of the soil which hides the own tracer signal. Variation in soil moisture content does not significantly affect the magnetic signal. For extensive field studies the soil-tracer volume to be handled would be very high. Therefore, it is necessary to explore new tracer application techniques.</p>

Heat-Transfer in the Soil During Very Low-Intensity Experimental Fires - the Role of Duff and Soil-Moisture Content

1994 ◽  
Vol 4 (4) ◽  
pp. 225 ◽  
Author(s):  
JC Valette ◽  
V Gomendy ◽  
J Marechal ◽  
C Houssard ◽  
D Gillon
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Temperature Rise ◽  
Soil Moisture Content ◽  
Soil Surface ◽  
Dry Weight ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Lethal Temperatures ◽  
Maximum Temperatures

The aim of this study was to analyse the effects of duff thickness and moisture content, and of soil moisture content on the transfer of heat in the soil. The experimental design used intact soil blocks with their duff layer, subjected to controlled fires of variable very low intensities of up to 100 kW m-1. The fuel on the surface was composed of needles and twigs of Pinus pinaster. The maximum temperatures measured within the fuel were of the order of 650 degrees C and were independent of the fireline intensities. For fires with fireline intensity of the order of 30 kW m-1, the presence of the duff layer reduced from 330 degrees C the temperature rise at the soil surface. Duff thickness played only a secondary role, but increasing moisture content reinforced its insulating effect, so that the temperature rise was 2.5 times less at 1 cm depth in the duff when the moisture content exceeded 70% dry weight, than when the moisture content was less than 30%. For more intense fires (> 50 kW m-1) that produced longer-lasting surface heating, duff thickness and moisture content played an important role in significantly reducing the temperature rise at the soil surface (range 140 degrees C to 28 degrees C). Because of low soil thermal conductivity, temperature attenuation with increasing depth was noticed. In the case of low intensity fires (< 30 kW m-1) in the absence of a duff layer, the maximum temperatures were reduced from 350 degrees C at the surface to 7 degrees C at 3.5 cm. The temperature rise in the soil decreased with depth according to a negative exponential relation. The rate constant of this relation was greater when the initial surface temperature and the soil moisture content were higher. For the soil studied, and under the moisture conditions encountered (between 7 and 19% of dry weight), the rate constant could be predicted with acceptable precision (r2 = 0.67), if the surface soil temperature rise and the soil moisture content were known. In these experimental fires, which were carried out when the air temperature did not exceed 20 degrees C, lethal temperatures (> 60 degrees C) were measured in the upper few centimetres of the duff layer in very low-intensity fires, and in the upper few centimetres of the soil (where nutrients are most concentrated and biological activity most intense) in the slightly more intense fires. The fire intensities were always very moderate, and of the order of magnitude df those encountered in the prescribed burns conducted on fuel-breaks of the french Mediterranean area. Their impact on the surface of the forest soil, in terms of lethal temperatures transmitted to the horizon rich in organic matter, are not negligible. In contrast, below 3 to 5 cm depth, prescribed burns, conducted under the conditions of the experiments, would not lead to significant change to nutrients or microfaunal or microfloral activity; in particular, root tips would not be subjected to heat stress sufficient to kill them.

scholarly journals A simple approach to recycle broiler litter as animal feed

2012 ◽  
Vol 12 (55) ◽  
pp. 6963-6975
Author(s):  
OA Makinde ◽  
Keyword(s):  
Moisture Content ◽  
Soybean Meal ◽  
Broiler Chickens ◽  
Crude Protein ◽  
Dry Matter ◽  
Animal Feed ◽  
Protein Digestibility ◽  
Simple Method ◽  
Broiler Litter ◽  
Cattle Blood

Broiler litter (BL) is a major waste from poultry production that constitutes serious disposal and environmental pollution problems globally despite its potential as animal feed. Therefore, the objective of this study was to develop a simple procedure for converting broiler litter into animal feed using wheat offal (WO) and cattle blood (B) as absorbent and nutrient booster, respectively. Initially, broiler litter was mixed with increasing concentrations (w/w) of blood at 1:1 or 1:2 or 1:3, and then each to WO at 1:1 or 1:2 or 1:3, making nine different ratios/blends before sun drying for 4 h. Finally, three blends (BL:B - 1:1 or 1:2 or 1:3 each mixed to WO at 1:1) were selected for nutrient evaluation based on economic considerations and capacity to dry to ≤10% moisture content in 4 h. The blends and feces were analyzed for proximate composition. Birds were tube-fed respective blends, feces collected after 48 h and dried for 48 h at 60oC. Dry matter, apparent and true crude protein digestibilities were determined. Soybean meal, considered as the standard protein, analyzed for dry matter, apparent and true crude protein digestibility was compared to the blends. The results showed that all the nine different blends dried to ≤ 10% moisture content in 4 h (range, 6 – 9%) and the blends with the highest WO content had the lowest (P<0.01) moisture contents. The three blends had crude protein and crude fiber ranging from about 19 – 28% and 8 - 12%, respectively. The blend with the highest blood concentration BL:B [1:3] to WO at 1:1) was superior (P<0.01) to soybean meal in dry matter, apparent and true crude protein digestibility by broiler chickens. A simple method was developed to recycle broiler litter as animal feed in combination with wheat offal and cattle blood. The resulting product showed good potential as feedstuff for broiler chickens.

scholarly journals Effect of various soil cultivation methods on some microbial soil properties

2020 ◽  
Vol 1 (1) ◽  
pp. 14-20 ◽  
Author(s):  
Sándor Zsolt ◽  
Magdolna Tállai ◽  
Ida Kincses ◽  
Zoltán László ◽  
János Kátai ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Moisture Content ◽  
Dehydrogenase Activity ◽  
Microbial Biomass Carbon ◽  
Soil Layer ◽  
Soil Surface ◽  
Favorable Effect ◽  
Biomass Carbon ◽  
Positive Effects ◽  
Cultivation Methods

Cultivating the top 0-25 cm soil layer by ploughing cultivating method requires considerable energy, labor, and additional costs. Also, the larger soil surface caused by cultivation, the moisture content of soil can be lost easier. Therefore, in recent years soil loosening cultivation has become gained popularity, particularly to protect the moisture content of soil and reduce the risk of desertification. At the Experimental Station of Debrecen University, known as Látókép (a name, which corresponds approximately to visual image), two cultivation methods have been applied for research: (i) conventional ploughing and (ii) strip and streaked loosening cultivation methods (and variation of this method applying satellite determination of position, RTK system). In this paper, total number of bacteria, soil respiration, biomass carbon and nitrogen, net nitrification, and dehydrogenase activity were measured under irrigated and non-irrigated conditions. The aim of the research was to evaluate the effects of the various cultivation methods. Soil samples were collected in spring (May) and autumn (September). Microbiological effects on the soil resulted from various cultivation methods were compared. Results demonstrate that the loosening cultivation method (strip tillage with loosening) exerts a more favorable effect on the parameters of soil biological activity than the conventional ploughing system. The most significant effect of loosening cultivation system was experienced in the increase of microbial biomass carbon (MBC) and nitrogen (MBN) by over 80%, along with an intensified dehydrogenase activity. Loosening system yielded positive effects on the other examined biological parameters, except for the total bacteria number and soil respiration.

scholarly journals Experimental Study on the Effect of Freezing and Thawing on the Shear Strength of the Frozen Soil in Qinghai-Tibet Railway Embankment

2022 ◽  
Vol 2022 ◽  
pp. 1-12
Author(s):  
B. Wang ◽  
J. H. Gao ◽  
Y. Q. Wang ◽  
X. J. Quan ◽  
Y. W. Gong ◽  
...  
Keyword(s):  
Growth Rate ◽  
Internal Friction ◽  
Moisture Content ◽  
Initial Moisture Content ◽  
Friction Angle ◽  
Frozen Soil ◽  
Internal Friction Angle ◽  
Freezing Process ◽  
Dry Density ◽  
Freezing And Thawing

The direct shear tests of different dry density and moisture content samples at different temperatures of the frozen soil in the Qinghai-Tibet Railway embankment between Tanggula South and Anduo section were carried out to analyze the influence rules of each experimental factor on the mechanical properties of frozen soil during the freeze-thaw process. The results show the following. (1) When the frozen soil temperature is below 0°C and continues to drop during the freezing and thawing process, each sample shows the law of a significant increase in cohesion and a slight decrease in the internal friction angle. In the meantime, the cohesion obtained during the thawing process of the sample at the same temperature point is higher than that obtained during the freezing process. In contrast, the internal friction angles exhibit an opposite law, where the internal friction angle during the melting process is lower than the internal friction angle during the freezing process. After freezing-thawing action, it deserves to be mentioned that the cohesion increases slightly while the internal friction angles present a slight decrease trend compared to the initial state. (2) With the decrease in temperature and the gradual increase in cohesion, the temperature curve can be divided into a fast-growing section from 0 to −2°C, a slow-growing section from −2 to −8°C, and a second fast-growing section from −8 to −10°C owing to the combined effect of the pressure-thawing action and ice-water phase change. In addition, the rate of decrease in the internal friction angle also shows a similar pattern. (3) The cohesion and the internal friction angle of samples both tend to increase first and then decrease with the rise of the initial moisture content, and the critical initial moisture content is near the optimal moisture content of 15%. (4) Both the cohesion and the internal friction angle of the samples increase with dry density growth. The growth rate of cohesion will gradually increase as the temperature decreases. Moreover, the growth rate of cohesion of low dry density samples is more susceptible to temperature, while the internal friction angle growth rate is not affected by temperature.

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