Fly ash influence on near-surface temperature of a clay loam soil

1998 ◽  
Vol 78 (2) ◽  
pp. 345-350 ◽  
Author(s):  
A. M Hammermeister ◽  
D. S. Chanasyk ◽  
M. A. Naeth
Keyword(s):  
Particle Size ◽  
Heat Capacity ◽  
Fly Ash ◽  
Particle Size Distribution ◽  
Soil Temperature ◽  
Water Content ◽  
Bulk Density ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Loam Soil

It has been suggested that fly ash, when applied as a soil amendment, would increase soil temperature. However, no quantitative data have been provided to support this hypothesis. This hypothesis was tested on four fly ash treatments (0, 100, 200, and 400 t ha−1) applied to clay loam soil in a randomized block design. Bi-hourly soil temperatures were measured on 3 summer days over 2 yr, and afternoon temperatures were measured on randomly selected spring days at 5-, 10-, and 20-cm depths in the four fly ash treatments. Temperatures were measured in conjunction with surface bulk density, water content, and particle size distribution which were also used to calculate thermal heat capacity. Fly ash decreased percent clay, soil water content, and soil heat capacity. Contrary to previously expected trends, fly ash amendment did not significantly increase mean daily soil temperature under dry conditions. Generalizations in the literature regarding the influence of fly ash on soil temperature, bulk density, and water-holding capacity must be considered carefully since they generally relate only to coarse to medium textured soils. Key words: Soil amendments, bulk density, reclamation, heat capacity, thermal diffusivity, thermal conductivity, volumetric water content, particle size distribution

Freeze-drying processes and wind erodibility of a clay loam soil in southern Alberta

1999 ◽  
Vol 79 (1) ◽  
pp. 127-135 ◽  
Author(s):  
Murray S. Bullock ◽  
Francis J. Larney ◽  
Sean M. McGinn ◽  
R. César Izaurralde
Keyword(s):  
Water Content ◽  
Vapour Pressure ◽  
Wind Erosion ◽  
Freeze Drying ◽  
Northern Great Plains ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Canadian Prairie ◽  
Loam Soil ◽  
Erodible Fraction

Freeze-drying has been implicated as a factor causing soil aggregate breakdown on the Canadian Prairies and northern Great Plains. Aggregates of a Dark Brown Chernozemic clay loam soil sampled in October 1993 and January and April 1994 were subjected to repeated cycles of wetting (to 0.1, 0.2 and 0.3 kg kg−1 water contents) freezing, and freeze-drying under laboratory conditions. The October 1993 samples showed less disruption when initially exposed to freeze-drying cycles compared to samples taken in January and April 1994. Using regression analysis, we predicted that 31 freeze-dry cycles were required for the 0.1 kg kg−1 water content aggregates to reach 60% erodible fraction (EF, % aggregates <0.86 mm), 9 cycles for the 0.2 kg kg−1 aggregates and 2 for 0.3 kg kg−1 aggregates. In a field study, conducted over the 1994–1995 winter on a similar clay loam soil, we estimated the number of freeze-drying cycles using large vapour pressure (VPL) and small vapour pressure (VPS) gradients between the soil surface (which had a mean winter water content of ~0.1 kg kg−1) and the atmosphere. With solar energy adjustments, we predicted that the number of freeze-dry cycles required for the soil to reach 60% EF was 60 for VPL and 37 for VPS conditions. The latter number was similar to the 31 cycles predicted in the laboratory study of aggregates at 0.1 water content. Our results demonstrate that freeze-drying is an important overwinter process in the breakdown of soil aggregates and hence wind erosion risk in the Canadian prairie region. Key words: Freeze-drying, wind erosion, erodible fraction

scholarly journals Influence of the Spacing of Steam-Injecting Pipes on the Energy Consumption and Soil Temperature Field for Clay-Loam Disinfection

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3209 ◽  
Author(s):  
Zhenjie Yang ◽  
Xiaochan Wang ◽  
Muhammad Ameen
Keyword(s):  
Heat Transfer ◽  
Energy Consumption ◽  
High Temperature ◽  
Soil Temperature ◽  
Relative Energy ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Loam Soil ◽  
Steam Pipe ◽  
Steam Heat

Soil steam disinfection (SSD) technology is one of the effective means to eliminate soil-borne diseases, especially under the condition of clay-loam soil cultivation for facility agriculture in Yangtze River delta (China). With the fine particles, small pores and high density of the soil, the way of steam transport and heat transfer are quite different from those of other cultivation mediums, and when using SSD injection method, the diffusion of steam between pipes will be affected, inhibiting the heat transfer in the dense soil. Therefore, it is necessary to explore the influence of steam pipe spacing (SPS) on the energy consumption and soil temperature (ST) for clay-loam disinfection. The best results are to find a suitable SPS that satisfies the inter-tube steam that can be gathered together evenly without being lost to the air under limited boiler heating capacity. To this purpose, we first used a computational fluid dynamics model to calculate the effective SPS to inject steam into deep soil. Second, the ST, ST rise rate, ST coefficient of variation, and soil water content variation among different treatments (12, 18, 24, or 30 cm pipe spacing) were analysed. Finally, the heating efficiency of all treatments depending on the disinfection time ratio and relative energy consumption was evaluated. The result shows that in the clay-loam unique to Southern China, the elliptical shape of the high-temperature region obtained from the numerical simulation was basically consistent with the experiment results, and the ratios of short diameter to long diameter were 0.65 and 0.63, respectively. In the SPS = 12 and 18 cm treatments, the steam completely diffused at a 0–20 cm soil layer depth, and the heat transfer was convective. However, at an SPS = 12 cm, steam accumulation occurred at the steam pipe holes, causing excessive accumulation of steam heat. The relative energy consumptions for SPS = 30, 24, and 12 cm were above 2.18 kJ/(kg·°C), and the disinfection time ratio was below 0.8. Thus, under a two-pipe flow rate = 4–8 kg/h, the inter-tube steam was found to be completely concentrated with a uniform continuous high temperature distribution within the soil for an appropriate SPS = 18–22 cm, avoiding the unnecessary loss of steam heat, and this method can be considered for static and moving disinfection operations in the cultivated layer (−20–0 cm) of clay loam soil. However, for soil with higher clay contents, the SPS can be appropriately reduced to less than 18 cm. For soil with lower clay contents and higher sand contents, the SPS can be increased to more than 22 cm.

Some Factors Which Influence the Toxicity of UHF Energy to Weed Seeds

Weed Science ◽  
1977 ◽  
Vol 25 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Robert P. Rice ◽  
Alan R. Putnam
Keyword(s):  
Soil Temperature ◽  
Loamy Sand ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Sand Soil ◽  
Loamy Sand Soil ◽  
Controlled Conditions ◽  
Weed Seeds ◽  
Loam Soil ◽  
Soil Mixtures

UHF energy (2450 MHz) was applied to seeds and seed-soil mixtures with a waveguide under controlled conditions. After treatment, seeds were germinated at 27 C to determine viability. Seeds were either killed or seedlings grew normally with no intermediate levels of inhibition typical of that produced with sub-lethal dosages of herbicides. The energy required to kill several species of dry seeds ranged from 88 to 183 J/cm2and could be reduced 12 to 42% by a 24-hr imbibition period prior to treatment. When several seed-soil mixtures were treated, the greatest toxicity occurred in a moist muck and clay loam soil, with the least toxicity on a dry loamy sand soil. Although attenuation of activity occurred in dry soils of three types, less energy was required to kill seeds in moist soils than was required in the absence of soil. Increasing the power levels reduced the time of exposure necessary to kill barnyardgrass [Echinochloa crus-galli(L.) Beauv.] seeds. Less energy was required to kill seeds as the soil temperature was increased from −20 to +18 C.

scholarly journals Field evaluation of a vibrating dual bent-share cultivator

2020 ◽  
Vol 66 (No. 4) ◽  
pp. 123-130
Author(s):  
Ali Esehaghbeygi ◽  
Milad Abedi ◽  
Jalil Razavi ◽  
Abbass Hemmat
Keyword(s):  
Water Content ◽  
Vibration Frequency ◽  
Field Performance ◽  
Field Evaluation ◽  
Coefficient Of Determination ◽  
Clay Loam ◽  
Plastic Limit ◽  
Clay Loam Soil ◽  
Efficient Energy ◽  
Loam Soil

In this research, the suitability of a vibrating dual bent-share cultivator was studied. Therefore, an eccentric pin-slider mechanism was designed to vibrate the two shanks laterally, using a tractor power take-off. The present study investigates the field performance of the vibrating dual bent-share cultivator with three different vibration frequencies (0, 0.88, and 2 Hz) in a clay loam soil at two working depths (100 and 200 mm) and having a water content of a 0.7 or 0.9 plastic limit. The lowest values of the draught, specific draught, and MWD were recorded at a vibration frequency of 2 Hz and a working depth of 100 mm. The draught force, specific draught, and MWD of the non-vibration implement were reduced by using a vibration frequency of 2 Hz. The coefficient of determination and F-values proved that the vibration frequency was more effective than the soil water content and the working depth on the draught, specific draught, and MWD. Although a dual bent-share cultivator needs low energy compared with a mould-board plough, the vibration of the dual bent-share cultivator may be recommended as an efficient energy-demanding implement in the soil manipulation process.

Influence of soil matric potential on 14C exudation from fungal propagules

1987 ◽  
Vol 65 (10) ◽  
pp. 2084-2089 ◽  
Author(s):  
A. B. Filonow ◽  
D. K. Arora
Keyword(s):  
Water Content ◽  
Sandy Loam ◽  
Macrophomina Phaseolina ◽  
Sandy Loam Soil ◽  
Soil Matric Potential ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Matric Potential ◽  
Fungal Propagules ◽  
Loam Soil

The influence of soil matric potential (ψm) on 14C exudation from labeled fungal propagules incubated in two soils over 5 days was determined, using tensiometers set at 0, −50, −100, and −200 mbar ψm (1 bar = 100 kPa). In general, 14C exudation to soil (as a percent of initial label) tended to be greatest at 0 mbar and decreasing ψm. In a sandy loam soil, the range of 14C exudation from conidia of Bipolaris victoriae or sclerotia of Macrophomina phaseolina was 18.4–20.9 or 4.4–5.5% at 0 mbar. At −200 mbar, it was 5.5–6.0 or 1.2–1.7%, respectively. In a clay loam soil at 0 mbar, conidia of B. victoriae or B. sorokiniana lost 17.6–19.9 or 7.3–9.2%, respectively, of total 14C label as exudate. At −200 mbar 14.6 or 5.9–7.2% was lost, respectively. Sclerotia of M. phaseolina lost 5.1–5.7% 14C-labeled exudate to the clay loam soil at 0 mbar and 4.3–4.6% at −200 mbar. 14C exudation at ψm less than saturation was about 2–3 times greater in the clay loam soil than in the sandy loam soil. Calculated ratios of evolved 14CO2/total 14C-labeled exudate were lowest at 0 mbar and increased as ψm decreased, suggesting that oxygen availability and soil water content as regulated by ψm were related to soil respiratory utilization of exudate.

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