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Alvenäs, Gunnel. "Evaporation, soil moisture and soil temperature of bare and cropped soils /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5714-9.pdf.
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Franks, Carol Dawn. "Temperature, moisture and albedo properties of Arizona soils." Thesis, The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_263_sip1_w.pdf&type=application/pdf.
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Chang, Chao-Ting. "Soil water availability regulates soil respiration temperature dependence in Mediterranean forests." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/406082.
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The variations of ecosystem and soil respiration are mainly driven by temperature and precipitation, but the importance of temperature and precipitation could vary across temporal and spatial. At diurnal to annual temporal scales, ecosystem and soil respiration generally increase with average annual temperature, but very low or very high soil moisture has been shown to diminish the temperature response of respiration. Therefore, in water-limited ecosystem, such as the Mediterranean region where the seasonal pattern is characterized with significant summer drought, precipitation patterns are likely to play a particularly important role in regulating ecosystem and soil respiration inter annual whereas temperature may be much less factor. In this dissertation, I try to reduce the uncertainties of terrestrial net ecosystem exchange in Mediterranean region by measuring the interaction between environmental factors and soil respiration at short (i.e., diurnal) and medium (i.e., seasonal-years) temporal scales. Three in situ experiments were employed to investigate how soil respiration responds to environmental variations and management. Together, these three studies gave a consistent picture on how soil moisture strongly affects the dynamic and magnitude of soil respiration in Mediterranean forests. Results elucidated a clear soil moisture threshold; when soil moisture is above this threshold, soil temperature is the main driver of soil respiration, meanwhile, when soil moisture is below this threshold, soil respiration decoupled from soil temperature and is controlled by soil moisture. This suggests that soil moisture modified, at least in Mediterranean ecosystems, the temperature sensitivity of respiration through threshold-like response.Las variaciones de la respiración del ecosistema y del suelo son principalmente impulsadas por la temperatura y la precipitación, pero la importancia de la temperatura y la precipitación puede variar a lo largo del tiempo y el espacio. En las escalas temporales diurnas a anuales, la respiración del ecosistema y del suelo generalmente aumenta con la temperatura media anual, pero se ha demostrado que la humedad del suelo muy baja o muy alta disminuye la respuesta a la temperatura de la respiración. Por lo tanto, en ecosistemas con escasez de agua, como la región mediterránea, donde el patrón estacional se caracteriza por sequías significativas en verano, es probable que los patrones de precipitación jueguen un papel particularmente importante en la regulación de la respiración del ecosistema y del suelo. En esta tesis, intento reducir las incertidumbres del intercambio de ecosistemas netos terrestres en la región mediterránea midiendo la interacción entre los factores ambientales y la respiración del suelo a escalas temporales cortas (diurnas) y medias (estacionales). Se utilizaron tres experimentos in situ para investigar cómo la respiración del suelo responde a las variaciones y manejo del ambiente. En conjunto, estos tres estudios dieron una imagen consistente de cómo la humedad del suelo afecta fuertemente la dinámica y la magnitud de la respiración del suelo en los bosques mediterráneos. Los resultados dilucidaron un umbral claro de humedad del suelo; Cuando la humedad del suelo está por encima de este umbral, la temperatura del suelo es el principal impulsor de la respiración del suelo, mientras que la humedad del suelo está por debajo de este umbral, la respiración del suelo está desacoplada de la temperatura del suelo y controlada por la humedad del suelo. Esto sugiere que la humedad del suelo modificó, al menos en los ecosistemas mediterráneos, la sensibilidad a la temperatura de la respiración a través de la respuesta tipo umbral.
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Burns, Nancy Rosalind. "Soil organic matter stability and the temperature sensitivity of soil respiration." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/9922.
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Soil respiration is an important source of atmospheric CO2, with the potential for large positive feedbacks with global warming. The size of these feedbacks will depend on the relative sensitivity to temperature of very large global pools of highly stable soil organic matter (SOM), with residence times of centuries or longer. Conflicting evidence exists as to the relationships between temperature sensitivity of respiration and stability of SOM, as well as the temperature sensitivity of individual stabilisation mechanisms. This PhD considers the relationship between different stabilisation mechanisms and the temperature sensitivity of SOM decomposition. I used physical fractionation to isolate SOM pools with a variety of turnover rates, from decadal to centennially cycling SOM, in a peaty gley topsoil from Harwood Forest. Mean residence times of SOM as determined by 14C dating was most strongly affected by depth, providing stability on a millienial scale, while OM-mineral associations and physical protection of aggregates provided stability to around 500 years. Chemical characteristics of organic material in these fractions and whole soils (13C CP-MAS NMR spectroscopy, mass spectrometry, FTIR spectroscopy, thermogravimetric analysis, ICP-OES) indicated the relative contribution of different stabilisation mechanisms to the longevity of each of these fractions. Two long-term incubations of isolated physical fractions and soil horizons at different temperatures provided information about the actual resistance to decomposition in each SOM pool, as well as the temperature sensitivity of respiration from different pools. Naturally 13C-labelled labile substrate additions to the mineral and organic horizons compared the resistance to priming by labile and recalcitrant substrates. Manipulation of soil pore water was investigated as a method for isolating the respiration of SOM from physically occluded positions within the soil architecture. Contadictory lines of evidence emerged on the relative stability of different SOM pools from 14C dating, incubation experiments and chemical characterisation of indicators of stability. This led to the interpretation that physical aggregate protection primarily controls SOM stability within topsoils, while mineral and Fe oxide stability provides more lasting stability in the mineral horizon. Less humified and younger SOM was found to have a higher sensitivity to temperature than respiration from well-humified pools, in contrast to predictions from thermodynamics.
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Hartley, Iain P. "The response of soil respiration to temperature." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434021.
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Attalla, Daniela, and Wu Jennifer Tannfelt. "Automated Greenhouse : Temperature and soil moisture control." Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-184599.
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In this thesis an automated greenhouse was built with the purpose of investigating the watering system’s reliability and if a desired range of temperatures can be maintained. The microcontroller used to create the automated greenhouse was an Arduino UNO. This project utilizes two different sensors, a soil moisture sensor and a temperature sensor. The sensors are controlling the two actuators which are a heating fan and a pump. The heating fan is used to change the temperature and the pump is used to water the plant. The watering system and the temperature control system was tested both separately and together. The result showed that the temperature could be maintained in the desired range. Results from the soil moisture sensor were uneven and therefore interpret as unreliable.I denna tes byggdes ett automatiserat växthus med syftet att undersöka dess bevattningssystems pålitlighet samt om ett önskat temperaturspann kan bibehållas. Microkontrollern för att bygga detta automatiserade växthus var en Arduino UNO. Detta projekt använder sig av två olika sensorer, en jordfuktsensor och en temperatursensor. Sensorerna kontrollerar en värmefläkt och en pump. Värmefläkten används för att ändra temperaturen och pumpen för att vattna plantan. Bevattningssystemet och temperaturstyrningen har testats både separat och tillsammans. Resultatet visar att temperaturen kan bibehållas inom det önskade spannet. Resultaten från jordfuktsensorn var ojämna och därför tolkats som opålitliga.
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Al-Ali, Abdullah Mubarak Abdulmohsen. "Temperature effects on fine-grained soil erodibility." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32514.
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Master of ScienceCivil Engineering
Stacey Tucker
Recent climate changes may affect the stability of our infrastructure in many ways. This study investigated the effects of fine-grained soil temperature on erosion rate. If climate change is shown to affect the erodibility of soils the impacts must be identified to monitor the stability of existing infrastructure, improve design of levees and structures founded in erosive environments, and to prevent sediment loss and stream meanders. Fine-grained soil erosion is complicated by the dynamic linkage of multiple parameters, including physical, biological and geochemical properties. This study held constant all parameters that influence fine-grained soil erodibility while only varying soil temperature in order to study the effects it has on erodibility. This study also confirmed previous findings that water temperature affects soil erodibility. The main objective of this study was to investigate the effects of fine-grained soil temperature on erosion rate. This study also instrumented a turbidity sensor to reliably map soil erosion. Based on this research, the conclusion was made that an increase in soil temperature increases soil erosion rate. The turbidity sensor was a valuable tool for comparing soil erosion. Future studies should investigate the effects soil temperatures below room temperature, the magnitude of temperature increase or decrease, and the effects of cyclic heating and cooling on fine grained soil erodibility.
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Mampana, Reedah Makgwadi. "Cropping system effects on soil water, soil temperature and dryland maize productivity." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/43165.
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Improved soil water conservation has become an important subject in semi-arid areas due to low and erratic rainfall which is often combined with higher temperatures to provide unsuitable conditions for successful crop productivity. Dryland agriculture remains vulnerable to yield losses in these areas. This calls for implementation of conservation agricultural practices that would improve dryland maize productivity. An on-station field trial was started in 2007 at Zeekoegat experimental farm (24 kilometers north of Pretoria), to establish the effect of different conservation agriculture practices on soil and plant properties. The experimental lay-out was a split-plot randomized complete block design, replicated three times, with each replicate split into two tillage systems (whole plots) and then each whole plot (reduced tillage (RT) and conventional tillage (CT)) was subdivided into 12 treatments (two fertilizer levels x 6 cropping patterns). The present study explored the impacts of different tillage practices, cropping patterns and fertilization levels on soil water content, soil temperature and dryland maize productivity during the 2010/11 and 2011/12 growing seasons. To improve the quality of soil water content (SWC) data, the effect of correction for concretions on soil bulk density and the relationship between volumetric soil water content (SWC) vs neutron water meter (NWM) count ratios was also investigated. Corrections for concretions on soil bulk density did not improve NWM calibrations in this study. In all seasons, significantly higher mean SWC was found under RT treatment than in CT at all depths except at 0-300 mm. For example, during the 2010/11 growing season, SWC under RT was 1.32 % and 1.10 % higher than CT for the 300 – 1350 mm and 0 – 1350 mm soil profiles, respectively. The mean weekly SWC was consistently higher for RT throughout both the growing seasons. Significantly higher SWC was also found under monoculture at all soil depths (except at 0-300 mm during 2011/12) compared to treatments under intercropping. For example, during 2010/11, at 0-300mm, SWC under maize monoculture was 1.72 % higher than under intercropping. The maximum and minimum soil temperatures were significantly higher at 100 and 400 mm soil depths under CT than under RT during 2010/11. During 2011/12, significantly higher minimum soil temperatures at 100 mm depth and lower temperature differences (maximum – minimum soil temperatures) at 400 mm depth were observed under intercropping. Despite the higher SWC and reduced soil temperature under RT, the maize seeds emergence rate was lower and plant stand was reduced. This is attributed to other factors associated with RT systems such as increased soil penetration resistance which often leads to poor root development. The lower soil temperatures under RT were generally within the range that would not be expected to inhibit growth and uptake of nutrients. Slower growth under RT resulted in lower biomass and grain yield. Plants that received high fertilizer rates grew more vigorously than plants under lower fertilizer levels when water was not a limiting factor, but produced lower grain yield due to water shortage in March, especially in 2011/12. The harvest index was therefore lower for treatments that received high fertilizer levels. Maize biomass under monoculture x low fertilizer level was significantly lower compared to other fertilizer x cropping pattern treatments. Maize plant growth under intercropping was improved throughout the seasons, which led to significantly higher grain yield than under maize monoculture. It is therefore recommended that farmers in dryland areas take the advantage of intercropping maize with legumes to obtain higher maize productivity. Further research should focus on investigating the possibility of roots restrictions occurring under RT conditions and under various environmental and soil conditions.Dissertation (MScAgric)--University of Pretoria, 2014.
lk2014
Plant Production and Soil Science
MScAgric
Unrestricted
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Chen, Ying 1957. "Soil thermal regime resulting from reduced tillage systems." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41106.
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The soil thermal regime is important to the soil and plant environment, being an influential factor in determining many processes in soil.Changes in soil bulk density, soil surface reflectance and soil temperature changes with depth and time were studied theoretically and experimental as a function of variable soil properties, soil surface state, crop cover and atmospheric conditions.
A field experiment was carried out on sandy and clayey soils with each plot being subjected to a consistent tillage and fertilizer history of either conventional ploughing, reduced energy disking or zero tillage, and fresh dairy manure or manufactured inorganic fertilizer. The measured results and the quantitative models assist hopefully in identifying how soil management affects the soil thermal regime and in making cultivation management decisions.
Soil bulk density for each fertilizer type can be predicted quantitatively from input tillage energy in a linear fashion. The reflectance of the soil surface was estimated as an integrated form of the individual reflectance and the area fractions of the soil surface components, with a soil roughness correction term. This model can cover various surface situations under different schemes of soil management. A simulation model for soil temperature was developed, which can be applied to bare soil, partially crop-covered soil and completely crop-covered soil. The models can also be used as submodels or be linked to other existing models.
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Adu-Gyamfi, Kwame. "Laboratory calibration of soil moisture, resistivity, and temperature probe - Capacitance probe." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1173385776.
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Fraser, Fiona C. "Temperature responses of nitrogen transformations in grassland soils." Thesis, University of Stirling, 2013. http://hdl.handle.net/1893/17055.
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The current literature shows that global climate is changing with temperatures generally increasing, precipitation patterns becoming less predictable and extreme weather events becoming more frequent. However, the literature is often unclear not only about how changes in temperature will affect soil processes but even about how soil temperatures themselves are changing. This thesis has found that soil temperatures over recent decades have increased at rates comparable to air temperatures (average mean of 0.71 in soil and 0.93 °C in air over the total length of the data sets used). There were differences in seasonal trends between soil and air, for example, winter air temperatures increased twice as quickly as spring air temperatures whereas in soil winter and spring temperatures were increasing at similar rates. This highlights potential problems for predicting how soil functions such as biogeochemical cycling will respond to realistic temperature change. In order to assess the effects of changing soil temperatures on particular reactions involved in soil Nitrogen cycling incubation experiments, both short and longer term in the laboratory as well as soil warming in the field were carried out. Realistic warming was found to increase the rates of protease and urease activity during all tests; however, amidase activity was only measurable after the addition of labile carbon and even then showed no temperature sensitivity. This thesis also considered the effect of temperature change on the size and structure of the soil microbial community at these realistic soil temperatures. Both in the lab and the field changes in rates of soil processes (enzyme activity) as a result of temperature change are not accompanied by a change in either size or structure of the microbial community as measured by phospholipid fatty acid analysis, suggesting high levels of functional redundancy within the soil microbial community. The effects of organic matter input in the field were found to have only small effects on the rates of enzyme activity although this was more important during laboratory incubations. Organic matter quality was also important during lab incubations where lower quality organic matter provoked greater enzyme activity in accordance with q-theory; however, there was no evidence for greater temperature sensitivity of low quality organic matter. The size and structure of the microbial community, both in the field and in the lab, were not affected by either the rate of organic matter input (in the field) or they quality of organic matter (in the lab). The size of the microbial community, however, decreased over time in both situations, the ratio of bacteria to fungi in the soil seemed to increase over time also.
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Husted, Lynn. "Low soil temperature and efficacy of ectomycorrhizal fungi." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30930.
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The influence of root-zone temperature on the efficacy of various ectomycorrhizal fungi, i.e., their ability: (1) to colonize roots in a nursery environment, (2) to persist and colonize new roots in the field and (3) to improve the growth, nutrition, and physiology of white spruce (Picea glauca (Moench) Voss) seedlings, was examined in controlled environment experiments using water baths to regulate root-zone temperature.
Eight-week-old non-mycorrhizal seedlings were inoculated with 13 different inocula (1 forest floor inoculum, 12 specific fungi), then transplanted into 6, 16, or 26°C peat:vermiculite mixes for 8 weeks. Maximum root colonization occurred at 16°C for most inocula. The 6°C mix strongly reduced mycorrhiza formation with only 8 of the 13 inocula forming any mycorrhizae during the 8-week test period. Primary infection from ectomycorrhizal propagules (spores and hyphal fragments) was reduced more than was secondary infection from established mycorrhizae; once established, all inocula colonized new roots in 6°C forest soil.
Fall-lifted cold-stored seedlings infected with 8 inocula (forest floor, 7 specific fungi) were planted into 6 and 12°C forest soil mixtures with or without indigenous ectomycorrhiza inoculum. Survival and colonization of new roots by inoculant fungi was good (> 50%) for the 12-week test duration despite the significant potential for infection by indigenous inoculum. High persistence appeared to be due to successful (>75%) root colonization by the inoculant fungi in the nursery production phase, to the relative weakness of ectomycorrhizal propagules (spores and hyphal fragments) compared with live ectomycorrhizal attachments, and to the favorable pattern of lateral root egress from the container plug after planting.
Colonization of new roots by established mycorrhizae showed an effect of soil temperature in the presence, but not the absence, of indigenous inoculum. Percent new root colonization by inoculant fungi was lower in the 12°C forest soil. Rapid extension of lateral roots in the 12°C soil increased the likelihood that short roots initiated near the tips of elongating roots would be infected by indigenous fungi. There was no evidence of active or passive interactive replacement between inoculant and indigenous fungi. However, Hebeloma crustuliniforme appeared to inhibit mycorrhizal formation by indigenous fungi; roots not infected by this fungus remained non-mycorrhizal. Application of slow-release fertilizer reduced new root colonization by E-strain but had no effect on colonization by H. crustuliniforme or indigenous forest floor fungi.
Non-inoculated seedlings (controls) and seedlings inoculated with 5 different inocula (forest floor, 4 specific fungi) were planted in 6 and 12°C forest soil for 3 weeks. Inoculation influenced the rate at which seedlings acclimated to the 6°C soil with respect to resistance to water flow and net photosynthetic rate, but had no effect on pre-dawn stomatal conductance. Differences among inoculation treatments were related to the size and nutritional status of seedlings at the time of transplanting. Seedlings infected with Laccaria bicolor or E-strain exhibited the least decrease in resistance to water flow due to the relatively small size (dry weight, short root number) of their root systems at the time of transplanting. Net photosynthetic rate and new foliage production correlated positively with shoot N and P (% dry weight) and the proportion of total seedling N and P contained in shoot tissues at the time of planting.
Non-inoculated seedlings (controls) and seedlings inoculated with forest floor or 5 specific fungi were planted in 6 and 12°C forest soil for 12 weeks. The presence of "any" mycorrhiza at the time of transplanting did not improve seedling growth under the experimental conditions (i.e., cool, acidic soils with an indigenous ectomycorrhizal fungal population). On average, mycorrhizal infection increased N and P uptake at 12°C but not at 6°C. Growth response to specific fungi was very variable with some fungi depressing seedlings growth (e.g., E-strain and H. crustuliniforme) and others strongly promoting it (forest floor inoculum, L. bicolour, Thelephora terrestris). Seedling response to the various inocula was not related to the degree of mycorrhizal infection at the time of planting nor to the source of inocula; but was associated with differences in the content and distribution of nutrients at the time of transplanting and differences in total nutrient uptake, root efficiency, nutrient-use efficiency and net photosynthetic rate after transplanting. Root efficiency was not proportional to the number of short roots per unit root or to the amount of external mycelium attached to the various mycorrhizae. Implications for applied forestry and research are discussed in the final chapter.Forestry, Faculty of
Graduate
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Parks, Olivia Waverly. "Effect of water temperature on cohesive soil erosion." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49663.
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In light of increased stream temperatures due to urbanization and climate change, theeffect of water temperature on cohesive soil erosion should be explored. The objectives of this study are to: determine the effect of water temperature on the erosion rates of clay; determine how erosion rates vary with clay mineralogy; and, explore the relationship between zeta potential and erosion rate. Samples of kaolinite- and montmorillonite-sand mixtures, and vermiculite-dominated soil were placed in the wall of a recirculating flume channel using a vertical sample orientation. Erosion rate was measured under a range of shear stresses (0.1-20 Pa) for a period of five minutes per shear stress at water temperatures of 12, 20, and 27�"C. The zeta potential was determined for each clay type at the three testing temperatures and compared to mean erosion rates. The kaolinite erosion rate doubled when the temperature increased from 12 to 20�"C, and erosion of vermiculite samples tripled when the temperature increased from 20 to 27�"C. The montmorillonite samples generally eroded through mechanical failure rather than fluvial erosion, and the limited fluvial erosion of the montmorillonite-sand mixture was not correlated with water temperature. The data suggest correlation between zeta potential and erosion rate; however, due to the small sample size (n=3), statistically significant correlation was not indicated. Research should continue to explore the influence of water temperature on cohesive soil erosion to better understand the influence of clay mineralogy. Due to the high degree of variability in cohesive soil erosion, multiple replications should be used in future work. The vertical sample orientation enabled discrimination between fluvial erosion and mass wasting and is recommended for future studies.
Master of Science
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Sitter, Nicholas James. "Two-wire, low component count soil temperature sensor." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/1081.
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A two-wire, low component count soil temperature sensor was developed. The sensor uses one wire for ground and the other wire is used for both power and communication. Pulse width modulation is used to send temperature measurements to the master, where the duty cycle is proportional to the temperature. The sensor parasitically powers itself from the bidirectional data line. In order to reduce the number of components necessary, a microcontroller with an internal temperature sensor is used. Finally, the sensor can receive data from the master on the bidirectional communication line, which is used for calibrating the sensor.
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El-Bishti, Magda Bashier. "Determination of soil moisture using dielectric soil moisture sensors : effect of soil temperature and implication for evaporation estimates." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487102.
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The reliability and accuracy of several sensors that employ the relationship between dielectric constant and soil moisture constant, e, in particular capacitance sensors were investigated. Results obtained from laboratory examinations ,of a Theta probe, TP, selected as a representative model for capacitance sensors, suggested that the sensor output was affected by temperature variations, electrical conductivity levels, spatial variation in sample bulk density as well as the level of compaction of the soil surrounding the sensor's rods. Detailed in situ e data collected usmg capacitance sensors were used to calculate sub-daily estimates of evaporation, E, using the soil water balance method, combined with the zero-flux-plane (ZFP) approach, for plots of bare soil, rapeseed and a maize field. These sensors comprised Theta probes (TP), Profiles probes (PP), ECH20 probes (EP) and Aquaflex sensors (AF). / The field output data of these sensors were analysed and compared with e obtained with both, the gravimetric and neutron probe method. The absolute values of B as measured by the various capacitance sensors differed considerably. Furthermore, the outputs of these sensors (apart from the AF probes) were found to be affected by temperature, which would result in an anomalous course of diurnal E. Also, B-data were subject to noise which required smoothing to ensure a physically realistic variation in E, when compared to estimates with the Penman-Monteith equation, EPAf, and the eddy-covariance method (maize field). E was determined from diurnal changes in vertically integrated soil moisture content above the ZFP. Smoothed values of Bwere temperature-corrected using fieldbased and laboratory-based correction equations. A considerable difference between field- and laboratory-based temperature corrections procedures was noticed, and correction factors strongly depended on B. As this resulted in an overly complicated correction procedure, which consequently gave unreliable E-values, it was then decided to use a constant correction factor (based on the field correction procedure), for each capacitance probe. For the bare soil plot, with the exception ofPP and EP only Bprofiles obtained with the TP and AF sensors produced relatively reliable E values when compared to Enf. By contrast, when these capacitance sensors were used under a canopy, all sensors yielded satisfactory E-values. This was most likely caused by reduced amplitudes of soil temperatures under the canopy and the fact that the dimensions of most sensors do not allow installation in the top soil (~3-5cm) layer at which most evaporation would take place in bare soils. We therefore recommended that these sensors can be used for diurnal B measurements and E determination under canopy provided that an appropriate temperature-correction procedure for each sensor is applied. To obtain reliable Band E estimates in bare soil, more research needs to be done. For more reliable e and E estimations in bare soils further extensive field trials would be strongly advised
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Post, Donald F., Jamie P. Dubay, and Allan D. Matthias. "The Effects of Rock and Green Waste Mulches on Soil Moisture and Soil Temperature." Arizona-Nevada Academy of Science, 2000. http://hdl.handle.net/10150/296563.
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Tucker, Alison. "The effects of cyclic freeze-thaw on the properties of high water content clays /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63372.
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Jefferson, Ian. "Temperature effects on clay soils." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/7233.
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Temperature changes occur in soils in a number of ways, e. g. landfill liners, around buried services and during sampling. An experimental programme was conducted to examine the effect of temperature (between 10 to 80 °C) on the volume change and shear behaviour of saturated clays. Testing included Liquid Limit (cone penetrometer), residual shear strength (modified Bromhead Ring Shear), laboratory vane shear ( at moisture contents between the Liquid and Plastic Limits) and oedometer tests. An extensive literature survey indicated that kaolinites and smectites would show extremes of thermal behaviour. To examine this two artificially pure clays were tested: English China Clay (a well crystallised kaolinite) and Wyoming Bentonite (a monovalent smectite). To supplement this four British soils were tested: Keuper Marl, Lower Lias Clay, London Clay and Oxford Clay. Full material data were obtained coupled with careful control of stress and thermal histories. It is concluded that two types of extreme thermal response exists: a thermomechanical and a thermo-physicochemical change exhibited by kaolinite and smectite respectively. The temperature sensitivity of clays relative to a particular parameter is positively related to its specific surface area. A quick and repeatable method to qualitatively assess this has been developed: the LUT method. Its advantages include that no temperature calibrations are needed and it has a relatively large operating temperature range, 10 to 80 °C having been successfully used. The consolidation pressure (in the oedometer) needed to change the nature of a soil's thermal response is negatively related to its specific surface area. This, it is postulated, occurs at the same 'critical' contact stress for all clays, i. e. the interparticle threshold stress at which a thermo-physicochemical response changes to a thermo-mechanical one. This threshold stress occurs at a anisotropic consolidation pressure of 60 kPa for a well crystallised kaolinite , at 250 kPa for reconstituted London Clay and at 480 kPa for a mono-valent smectite. Furthermore, greater parallel particle alignment or reconstituting a sample enhances a soil's temperature sensitivity in the oedometer. The thermal changes to consolidation and permeability coefficients can be typically predicted by the corresponding change to the dynamic viscosity of water. Deviations occur with smectites at normal stresses greater than 480 kPa, while for Keuper Marl this occurred at normal stresses of 50 kPa and greater than 850 kPa. Keuper Marl exhibits a greater temperature sensitivity of different parameters than predicted by index tests. This is strongly dependent on consolidation pressure and temperature. At elevated temperatures (>40 °C) and under increasing consolidation pressure, ped units tend to collapse, but once the pressure is removed ped reformation occurs. Thus knowledge of thermal and stress histories, coupled with full material data, is essential to effectively predict temperature effects on the engineering behaviour of soils with any degree of confidence.
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Thunholm, Bo. "Temperature and freezing in agricultural soils as related to soil properties and boundary conditions /." Uppsala : Sveriges lantbruksuniv, 1990. http://epsilon.slu.se/avh/1990/99-0948795-0.gif.
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Chiu, Sing-Lok. "Behaviour of normally consolidated clay at elevated temperature." Thesis, The University of Sydney, 1996. http://hdl.handle.net/2123/18126.
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Not much has research work been done so far on temperature-related behaviour of clays. This theme has not received much attention of research workers in this field for a long time until the late 1960s when Campanella and Mitchell published their paper on "Influence of Temperature Variations on Soil Behaviour" in 1968 (Campanella and Mitchell, 1968). What followed was a special conference on this subject held in Washington in 1969, addressing a variety of research results in this field at that time. However, the interest of most research workers in the following two decades has been in soil models and their numerical implementation. Most research funds have been channelled towards studies concerning basic soil properties and the implementation of the results of research than to other topics in the same time. In recent years, rapid industrialization and implementation of many military technologies into civil industries have taken place in many western countries and a few other countries in Asia. This gave rise to a variety of problems related to the disposal of nuclear waste particularly in the late 1980s. A series of studies regarding disposal problems of nuclear waste were then carried out in Italy and the United States (Hueckel et al, 1990). In Australia, the first project related to this topic was awarded in 1991 to the Centre for Geotechnical Research (CGR) at School of Civil and Mining Engineering, University of Sydney. This thesis contains the results obtained from triaxial tests performed at different elevated temperatures using a new triaxial apparatus called HTTA (High Temperature Triaxial Apparatus) specially designed for and forming part of, the work in this research. The thesis also contains a comparison of the experimental results and the predictions by different Cam-clay models including the revised Camclay model developed in this research. Specimens of a remoulded clay, Kaolin CIC, have been tested at various I temperatures ranging from ambient temperature of 22±2°C to 100±5°C with two triaxial apparatuses. The first apparatus for tests at ambient temperature is a Bishop- Wesley-Type hydraulic triaxial apparatus; the other is a modified triaxial apparatus specially tailored and assembled for performing triaxial tests on the specimens at various elevated temperatures. The triaxial tests on the specimens were conducted at room temperature as well as at two elevated temperatures, namely 50°C and 100°C. Stress-strain response of the specimens at different temperatures was observed. Attempts have been made in different ways to investigate whether soil properties of the selected clay would change with temperature. Further, the attempts made were also to see what have been changed in the stress-strain behaviour of the clay at different elevated temperature. Then, the test results from different elevated temperatures were compared with those obtained from the tests at room temperature; and also compared with the predictions by the Cam-clay models.
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Dilawari, Geetika. "Analysis of the influence of soil temperature and soil surface conditions on soil moisture estimation using the Theta Probe." [Ames, Iowa : Iowa State University], 2006.
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Fuhrer, Oliver. "Inverse heat conduction in soils : a new approach towards recovering soil moisture from temperature records /." Zürich : ETH IKF, 2000. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=114.
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Wraith, Jon M. "Soil Temperature Influence on Water Use and Yield Under Variable Irrigation." DigitalCommons@USU, 1989. https://digitalcommons.usu.edu/etd/1996.
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The need for efficient use of water resources has increased the importance of optimum soil water usage in agricultural systems. Soil temperature has been shown to be important in influencing the early development of many plant species. Many agricultural regions have suboptimal soil temperature regimes for plant growth, and some cultural practices have been shown to reduce near-surface soil temperatures. The seasonal influence of soil temperature on soil water extraction and aboveground and belowground plant growth under variable irrigation was investigated at the USU Greenville Farm in Logan, UT. Soil surface mulches and buried heat cables were used to modify soil temperature. A line-source sprinkler system provided a gradient of water application.
During 1987 yields were mainly influenced by irrigation. During 1988 greater soil temperature differences resulted in significant plant growth and yield responses. Soil water depletion corresponded to soil temperature treatments during the early part of the growing seasons. Depth of maximum soil water depletion was about 20 cm deeper for warm treatments. Water uptake rates of earlier-maturing plants in warm treatments were reduced later in the season, so that cumulative seasonal soil water depletion was similar for all temperature treatments. Although depth of rooting was somewhat greater under high than low irrigation during 1988, low irrigation treatments depleted soil water to greater depth. There was no interactive response of plant growth and yield or of soil water depletion to soil temperature and irrigation treatments.
Modifications were made to a computer simulation model of the soil-plant-atmosphere system in order to more mechanistically simulate plant water uptake and to include influences of soil temperature on seasonal rooting growth and soil water extraction. The model adequately simulated both the pattern and magnitude of soil temperature influences on soil water depletion, and conclusions drawn from model simulations agreed with field observations during 1987 and 1988.
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Andersson, Stefan. "Influence of liming substances and temperature on microbial activity and leaching of soil organic matter in coniferous forest ecosystems /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5850-1.pdf.
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Fokin, Maria. "Efficiency of soil washing in hydrocarbon removal: the role of temperature, surfactant concentration and soil mineralogy." Doctoral thesis, Urbino, 2020. http://hdl.handle.net/11576/2675698.
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Schaffer, Joseph F. "Verification and Adaptation of an Infiltration Model for Water at Various Isothermal Temperature Conditions." Digital WPI, 1999. https://digitalcommons.wpi.edu/etd-theses/1061.
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"A series of one dimensional horizontal infiltration experiments were performed to investigate the predictive capabilities of the Kao and Hunt model. By modifying pristine laboratory apparatus, a reasonable range of soil temperatures was achieved. Experiments were run at approximately 5°C, 20°C, and 35°C. Distilled water was used as an infiltrating liquid and silica powder was used as soil. The infiltrating liquid was dispensed into the column at zero pressure head. The results of the experiments show that the model is adaptable to a range of temperature conditions by modifying terms for the liquid effects of the model, viscosity and surface tension. Experimental data and model predictions differed by 30 percent at most. Although the change in the rate of infiltration across the range of temperatures is perceivable, it is small in comparison to the effects caused by heterogeneity encountered in nature. "
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Penn, Madeleine Lisa Mary. "Electrokinetic soil remediation : effects of pH, temperature and chemical reactions." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266331.
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Husein, Dima A. "Soil-Pile Interaction of Geothermal Foundation Subjected to Temperature Cycling." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1563974820049641.
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Burdt, Amanda Corrine. "Hydric soil properties as influenced by land-use in Southeast Virginia wet flats." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/10132.
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The accuracy of the growing season used by regulators in hydric soil and wetland hydrology and the validity of ignoring land use in these definitions is questionable. This study compared measured air and soil temperature with various growing season dates and indicators, and determined the relationships between the hydrology, air and soil temperature. Water table depths, air temperature at 1-m height, soil temperature at 15-, 30-, and 50-cm depths, and CO₂ efflux were measured at 12 plots representing three landuse treatments (forest, field, and bare ground) at two restored wet flats in the thermic Great Dismal Swamp ecosystem. The forest was driest treatment. The forest air was the warmest in winter and coldest in summer, opposite of the bare ground. The forest soil at 50 cm was the warmest in winter and coolest in summer, opposite of the bare ground. Land use affected hydrology, air, and soil temperatures through the presence of surface litter and differences in shading, albedo, and ET. The regulatory frost-free period fell in between the measured frost-free period and the measured 5°C soil temperature period. Based on CO₂ efflux and soil temperature at 50 cm, the biological growing season of native plants and microbes should be year-round for forested areas, one week shorter for early-successional fields, and two weeks shorter for active cropland rather than March to November for all land uses. Changing the growing season definition of forested, thermic wet flats to year-round designation must be considered and studied carefully to avoid jeopardizing wetland hydrology qualifications.Master of Science
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Svensson, Magnus. "Modelling soil temperature and carbon storage changes for Swedish boreal forests." Licentiate thesis, KTH, Land and Water Resources Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1711.
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With the use of a process-orientated ecosystem model andmeasurements conducted at different Swedish coniferous forestsites, abiotic and biotic interactions between tree and soilwere identified and related to governing factors. Two differentmodelling approaches to describe soil temperatures at two sitesincluding hydrological transects were tested (I). The approachin which both canopy and soil were considered proved to be amore flexible tool to describe soil temperatures, especiallyduring snow-free winter periods. Five sites along a climatetransect covering Sweden were used to describe soil carbon poolchanges during an 80-year period simulation (II). The dynamicmodelling approach, with a feedback between abiotic and bioticsub-models, was successful in describing simplified patterns offorest stand dynamics and furthermore in differentiatingbetween climate and nitrogen availability factors. The largereffect of nitrogen availability compared to climate on soilcarbon pool changes was clearly shown.
Keywords:SPAC; soil surface energy balance; Norwayspruce; canopy; LAI; climate; nitrogen; CoupModel
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Glorioso, Mario. "DRYING CHARACTERISTICS OF SATURATED FINE-GRAIN SOIL SLURRIES AT CONSTANT TEMPERATURE." MSSTATE, 2002. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07192002-133443/.
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This study addresses the need for investigation of drying-rate characteristics of fine-grain soils. The research was an attempt to develop a parameter for use in thermal consolidation and/or shrinkage modeling. The investigation required the development of new test methods. During the study, a strong correlation between plasticity indices and certain drying characteristics was noted and discussed in detail. An argument is presented for the superiority of the Drying-Rate Test in comparison with current laboratory procedures for determining Atterberg Limits.
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Jahnke, Sebastian Ingo. "Pipeline leak detection using in-situ soil temperature and strain measurements." Diss., University of Pretoria, 2018. http://hdl.handle.net/2263/66579.
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This project investigated whether by measuring temperature and strain changes in the ground
around a pipeline a leak can be detected using fibre optic instrumentation. The concept entails
installation of an optic fibre along the length of the pipeline in the pipe trench when a new pipe
is installed. Alternatively, the possibility also exists to retrofit such a leakage detection system
by burying it near (above) existing pipes, although this has not been investigated in this project.
The success of such a leakage detection system is based on the hypothesis that the
temperature differential between the water in a pipeline and the ground around the pipe will
result in a detectable temperature change in the ground when a leak occurs. Softening of the
pipe support due to leaking water should result in strain changes in the soil immediately around
the pipe and in the pipe itself, both of which should be detectable. All three of these quantities,
i.e. ground temperature, ground strain and pipe strain can be measured using fibre optic
technology. This study is based on detecting temperature and strain changes using fibre
Bragg grating sensors (FBGS) at discrete locations along the length of a pipe.
The success of a system based on temperature measurement implies that temperature
changes caused by a leak should be distinguishable from naturally occurring temperature
cycles. Installations were therefore conducted to measure ground temperature changes to a
depth of 3m over the course of a year and comparing those to temperature changes measured
in active water mains over the same period in Pretoria. A temperature differential that always
exceeded 2°C was recorded, indicating that the system has potential to provide a means of
leak detection. A laboratory study was carried out to observe temperature changes associated with an
advancing wetting plume caused by a simulated leak using thermistors buried in fine sand.
Depending on the magnitude of the soil-water temperature differential, a rapid drop in
temperature was observed at monitoring locations during the progression of the wetting plume
(the water temperature is typically lower than the soil temperature). However, an initial shortduration
increase (spike) in temperature was consistently observed at measurement locations
upon first passage of the wetting front. It is hypothesised that this spike is caused by the
release of free surface energy upon wetting of the soil. As expected, immediately following
this spike after the passage of the wetting front, a significant and rapid change in temperature
was noted during the tests. The temperature reduction is dependent on the temperature
differential between the water and the surrounding soil and illustrated the potential of the
proposed method of leak detection (i.e. detecting leaks by observing a reduction in ground
temperature).
After the laboratory phase, a field study was conducted during which a 110 mm diameter 12
m long uPVC pipe was installed with sensor arrays consisting of both temperature and total
strain FBGS. Thermistors were used as temperature sensors as in the case of the laboratory
investigation. Strain sensors used were discrete optical strain gauges or fibre Bragg grating
sensors (FBGS). Fifty percent of the FBGS were epoxied to the pipe to measure pipe strains,
while the remaining 50% were free-floating, situated in a thin oil-filled plastic tube buried in the
corner of the pipe trench. The purpose of the epoxied FBGS was to measure pipe strain
changes, while the purpose of the free-floating FGBS was to detect temperature-induce strain
changes. During a leak, strain changes were recorded in the free-floating FBGS several times
exceeding the values expected based on the temperature changes measured by the
thermistors. In addition, very significant pipe strain changes were observed. These
observations indicate that significant ground and pipe strains occur due to wetting and
subsequent softening of the soil caused by the leak. The change in total strain and
temperature observed during a leakage event provided strong evidence that both parameters
can be used to effectively indicate the presence of a leakage event.
A complication identified in the study is that network pressure fluctuations result in significant
pipe strains which would complicate leak identification. It is therefore recommended that the
leakage detection system should comprise of an optic fibre separated from, but in close
proximity to the pipe. This study should be followed up to investigate the performance of a
leakage detection system based on distributed strain measurement and the potential of
retrofitting the proposed detection system to existing pipelines.Dissertation (MEng)--University of Pretoria, 2018.
Civil Engineering
MEng
Unrestricted
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Whittington, Ruth. "What's the Holdup? Temperature Limitations to Enzyme-Catalyzed Arctic Soil Decomposition." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1557487398712549.
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Acosta, Alvaro. "Estimating diurnal patterns of water uptake by roots from detailed measurement of soil moisture and soil temperature gradients." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269928.
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Low, Spencer Nishimoto. "An Exploration of Soil Moisture Reconstruction Techniques." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9169.
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Satellite radiometers are used to remotely measure properties of the Earth's surface. Radiometers enable wide spatial coverage and daily temporal coverage. Radiometer measurements are used in a wide array of applications, including freeze/thaw states inference, vegetation index calculations, rainfall estimation, and soil moisture estimation. Resolution enhancement of these radiometer measurements enable finer details to be resolved and improve our understanding of Earth. The Soil Moisture Active Passive (SMAP) radiometer was launched in April 2014 with a goal to produce high resolution soil moisture estimates. However, due to hardware failure of the radar channels, prepared algorithms could no longer be used. Current algorithms utilize a narrow spatial and temporal overlap between the SMAP radiometer and the SENTINEL-1 radar to produce high resolution soil moisture estimates that are spatially and temporally limited. This thesis explores the use of resolution enhancing algorithms to produce high resolution soil moisture estimates without the spatial coverage limitations caused by using multiple sensors. Two main approaches are considered: calculating the iterative update in brightness temperature and calculating the update in soil moisture. The best performing algorithm is the Soil Moisture Image Reconstruction (SMIR) algorithm that is a variation of the Radiometer form of the Scatterometer Image Reconstruction (rSIR) algorithm that has been adapted to operate in parameter space. This algorithm utilizes a novel soil moisture measurement response function (SMRF) in the reconstruction. It matches or exceeds the performance of other algorithms and allows for wide spatial coverage.
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Kjellander, Kalle. "Two Simple Soil Temperature Models: Applied and Tested on Sites in Sweden." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255003.
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Adlam, Leah Seree. "Soil climate and permafrost temperature monitoring in the McMurdo Sound region, Antarctica." The University of Waikato, 2009. http://hdl.handle.net/10289/2764.
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A soil climate monitoring network, consisting of seven automated weather stations, was established between 1999 and 2003 in the McMurdo Sound region of Antarctica. Soil temperature, soil water content, air temperature, relative humidity, solar radiation, and wind speed and direction are recorded hourly and downloaded annually. Two 30 m deep permafrost temperature monitoring boreholes were established adjacent to the soil climate stations in the Wright Valley and at Marble Point in January 2007. Sixteen thermistors (accurate to ±0.1°C) were installed in each borehole measuring temperature once every hour and recording the mean every six hours. One year of permafrost temperatures were available (January 2007 to January 2008). The overall aim of this thesis was to make use of the soil climate monitoring database from 1999 to 2007 to investigate Antarctic soil climate. Active layer depth (depth of thawing) varied inter-annually, with no significant trend between 1999 and 2007. The active layer increased with decreasing latitude (R2 = 0.94), and decreased with increasing altitude (R2 = 0.95). A multiple regression model was produced whereby active layer depth was predicted as a function of mean summer air temperature, mean winter air temperature, total summer solar radiation and mean summer wind speed (R2 = 0.73). Annual temperature cycles were observed at all depths in the boreholes. At Marble Point, an annual temperature range of lt;1°C occurred at 15.2 m, lt;0.5°C at 18.4 m and lt;0.1°C at 26.4 m and at Wright Valley, an annual temperature range of lt;1°C occurred at 14.0 m, lt;0.5°C at 17.2 m and lt;0.1°C at 25.2 m. Given that the depth of Zero Annual Amplitude determined depends on the sensitivity of the measurement method, it is suggested that instead of referring to a depth of Zero Annual Amplitude , the depth at which the annual temperature range is less than a given value is a more useful concept. Mean annual and mean seasonal air and soil temperatures varied inter-annually and there was no significant trend of warming or cooling over the 1999 - 2007 period. Mean annual air temperatures were primarily influenced by winter air temperatures. Mean annual and mean summer soil temperatures were warmer than air temperatures due to heating by solar radiation. Mean summer air temperatures correlated well with the Southern Annular Mode Index (SAMI) at all sites (0.61 lt; R2 lt; 0.73) except Victoria Valley; however there was no correlation between mean annual or mean winter temperatures and the SAMI. Air temperature was linearly correlated with near-surface soil temperature (1.3 - 7.5 cm) (R2 gt; 0.79). Near-surface soil temperature was strongly correlated with incoming solar radiation at Victoria Valley (0.14 lt; R2 lt; 0.76) and Granite Harbour (0.49 lt; R2 lt; 0.82), but was not significantly correlated at other sites (0 lt; R2 lt; 0.57). There was no significant correlation between air temperature and wind speed, air temperature and solar radiation and near-surface soil temperature and wind speed, despite occasions of strong correlation on the diurnal time scale. Diurnal summer cycles in air and soil temperatures were driven by solar radiation. Multiple regressions combining the effects of air temperature, solar radiation and wind speed approximated near-surface soil temperatures well at every site during both summer and winter (0.88 lt; R2 lt; 0.98).
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Cheng, Song. "Influence of soil temperature on ecophysiological traits of four boreal tree species." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ52716.pdf.
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Mellander, Per-Erik. "Spring water stress in Scots pine : interaction of snow and soil temperature /." Uppsala : Dept. of Environmental Assessment, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s287.pdf.
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Brewer, Robert Wayne. "Summer Regional United States Diurnal Temperature Range Variability With Soil Moisture Conditions." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428939308.
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Elias, Elimoel Abrão. "Modelagem analítica do perfil de temperatura no solo." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/11/11131/tde-20092004-171810/.
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A temperatura do solo influencia a maioria dos processos físicos, químicos e biológicos que ocorrem no solo. O modelo analítico exponencial-senoidal em uma dimensão descreve razoavelmente bem a temperatura no solo, T (oC), como função do tempo, t (s), e da profundidade, z (m), 0 ≤ z < ∞. A temperatura da superfície pode ser representada pela soma de duas senóides, uma relacionada com variações de temperatura anuais, outra com variações diárias, cada uma tendo uma amplitude constante. Uma correção para a variação temporal de amplitude diária é aqui introduzida. A equação do calor é resolvida analiticamente, com pouco aumento em complexidade em relação à solução tradicional. Predições de temperatura obtidas pela nova solução analítica foram comparadas com predições obtidas da solução usual, que trata a amplitude diária como constante. Para comparar as predições, foram necessários valores experimentais de certos parâmetros que aparecem nestas equações; foi suficiente usar valores típicos, obtidos na literatura. Predições são comparadas utilizando quatro conceitos: (i) profundidade de amortecimento, D; (ii) profundidade de penetração, zM; (iii) erro quadrático médio (EQM); e (iv) erro quadrático médio na forma de uma integral (EQMI). O conceito de zM foi aqui introduzido, acompanhado por uma equação simples que permite calcular qual é a profundidade zm tal que, se temperatura T(zM,t) for aproximada como Ta (valor médio da temperatura ao longo do ano, em zM), o erro em tal aproximação será igual ou menor um certo valor previamente definido, por exemplo, de 0,1 oC. O conceito de EQMI, também introduzido nesta tese, substitui o somatório que aparece no EQM por uma integral definida, e serve para comparar dois modelos analíticos, o que era o caso desta tese. Valores de D e zM mostram que a correção é desprezível para z > 0,6 m. Valores de EQM mostram que a correção é considerável para z = 0,1 m. Nesta profundidade, o valor máximo foi EQM = 0.30 oC para dias inteiros, e EQM = 0.29 oC para meses inteiros. Valores de EQMI foram praticamente iguais aos valores de EQM. Para qualquer profundidade a correção introduzida, ainda que considerável, é pequena. Entretanto, a única informação adicional requerida para aplicar a equação nova é a informação de variação temporal da amplitude diária. Desta forma, pode-se sugerir que a nova equação seja preferida, quando esta informação esteja facilmente disponível a partir de dados experimentais.Soil temperature influences many physical, chemical and biological processes that occur in soil. The exponential-sinusoidal one-dimensional analytical model reasonably describes soil temperature, T (oC), as a function of time, t (s), and depth, z (m), 0 ≤ z < ∞. Surface temperature may be represented by the sum of two sinusoids, one related to annual and the other to daily temperature variations, each one having constant amplitude. A correction for the temporal variation of daily amplitude is introduced here. The heat equation is solved analytically, with minimal increase in complexity compared to the traditional solution. Temperature predictions obtained from the novel analytical solution are compared with predictions from the usual solution that treats the daily amplitude as a constant. Comparisons demanded experimental parameters, which were obtained from scientific literature. Predictions are compared using four concepts: (i) damping depth, D; (ii) penetration depth, zM; (iii) root mean squared error (RMSE); and (iv) root mean squared error defined by a definite integral (RMSEI). The concept of zM was introduced here, through a simple equation, which allows calculation of the depth zm, at which T(zM,t) can be approximated to Ta (average annual value of soil temperature at zM). The concept of RMSEI was also introduced here, and replaces a sum by a definite integral. The RMSEI can be used to compare analytical models, as it was the case here. Values of D and zM show that the correction is negligible for z > 0,6 m. Values of RMSE show that the correction is considerable for z = 0,1 m. For individual days, at a depth z = 0,1 m, the maximum value was RMSE = 0.30 oC; for whole months, the maximum value was RMSE = 0.29 oC. RMSEI values were practically the same as RMSE values. The correction introduced here was small at all depths. However, the only additional information required to apply the novel equation is information on temporal variation of daily amplitude, so this equation should be preferred when such data are readily available.
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Silva, Elienai Ferreira da [UNESP]. "Variabilidade espaço-temporal da emissão de CO2 do solo em curto período sob influência de eventos de precipitação." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/138071.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A emissão de CO2 do solo (FCO2) em áreas agrícolas é um processo resultante da interação de diferentes fatores, tais como as condições de clima e solo. Nesse sentido, objetivou-se, com este estudo, investigar a variabilidade espaço-temporal da FCO2, temperatura (Tsolo), umidade (Usolo) e porosidade livre de água (PLA) do solo e suas interações, em área de reforma do canavial. O estudo foi conduzido em área de cana-de-açúcar sob reforma, na qual foi instalada malha amostral de 90 × 90 m2 contendo 100 pontos espaçados entre si em 10 m. Nestes pontos foram avaliadas a FCO2, Tsolo e Usolo em 10 avaliações ao longo de um período de 28 dias. Para as avaliações da FCO2, foi utilizado o sistema portátil LI-8100A. Concomitantemente à avaliação de FCO2, foram determinadas a Tsolo (termômetro integrante do sistema LI-8100A) e a Usolo (aparelho TDR). A emissão de CO2 e a Usolo foi maior no dia 276, com maior valor médio de 4,67 µmol m-2 s-1 e 31,75% em função das precipitações na área de estudo. Contrariamente os menores valor médios foram observados para PLA 19,17% e para a Tsolo 20,90 ºC. Os modelos de regressão linear utilizando somente a Usolo e a PLA explicaram 85% e 80%, respectivamente, da variabilidade temporal da FCO2, indicando que ao longo do tempo, a emissão de CO2 foi controlada pela variação do conteúdo de água e aeração do solo. Por outro lado, não foram encontrados modelos lineares ou quadráticos significativos (p>0,05) entre a FCO2 e a Tsolo. Os modelos ajustados para descrever a variabilidade espacial da FCO2, Tsolo, Usolo e PLA foram esféricos e exponenciais, sendo o modelo esférico predominante. Com exceção de alguns dias específicos, a partir dos mapas não foi possível a visualização de regiões características da área que indicassem um padrão de variabilidade espacial. Possivelmente o fato da amostragem ter sido conduzida em uma escala reduzida pode ter colaborado para um comportamento aleatório das variáveis no tempo. A variabilidade espaço-temporal da emissão de CO2, temperatura, umidade e a aeração do solo é afetada pelas precipitações na área de estudo, e pode ser dividida em três períodos: antes, durante e após as precipitações. Valores mais elevados da emissão de CO2 do solo são observados durante as precipitações e menores valores antes e pós-precipitações.
Soil CO2 emission (FCO2) in agricultural areas is a process that results of the interaction of different factors such as climate and soil conditions. In this sense, the aim of this study was to investigate the spatial and temporal variability of FCO2, soil temperature (Tsoil), soil moisture (Msoil) and air-filled pore space (AFPS) and their interactions in a sugarcane field reform. This study was conducted in a 90 × 90- m sampling grid with 100 points spaced at distances of 10 m; at these points, 10 measurements were performed over a period of 28 days. In order to measure the FCO2, it was used a LI-8100A. Along with the measurements of FCO2, Tsoil and Msoil were also measured. It was observed an increase of 78% in FCO2 due to the rainfall in the study area. The linear regression models using only Msoil and AFPS explained 85% and 80%, respectively, of the variability of FCO2, indicating that over the time, the emission of CO2 was controlled by varying the content of water and soil aeration. The adjusted models to describe the spatial variability of FCO2, Tsoil, Msoil and AFPS were spherical and exponential. However, the spherical model was more predominant. We did not identify spatial variability using the maps for some days. Probably this happened because we used the small scale. It can have collaborated for random behavior. The spatiotemporal variability of CO2 emission, temperature, moisture and air-filled pore space was affected by rainfall in the study area. We can divide this variability in three periods: before, during and after rainfall. The higher values of CO2 emissions was observed during rainfall and lower values before and after rainfall.
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Reynolds, Lorien. "Soil-Climate Feedbacks: Understanding the Controls and Ecosystem Responses of the Carbon Cycle Under a Changing Climate." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20465.
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Soil organic matter (SOM) decomposition and formation is an important climate feedback, with the potential to amplify or offset climate forcing. To understand the fate of soil carbon (C) stores and fluxes (i.e., soil respiration) under future climate it is necessary to investigate responses across spatial and temporal scales, from the ecosystem to the molecular level, from diurnal to decadal trends. Moreover, it is important to question the assumptions and paradigms that underlie apparently paradoxical evidence to reveal the true nature of soil-climate feedbacks. My dissertation includes research into the response of soil respiration in Pacific Northwest prairies to warming and wetting along a natural regional climate gradient (Chapter II), and then delves deeper into the mechanisms underlying SOM decomposition and formation, examining the temperature sensitivity of SOM decomposition of prairie soils that were experimentally warmed for ~2 yr, and a forest soil in which litter-inputs were manipulation for 20 yr (Chapter III), and finally testing soil C cycling dynamics, including mineral-associated C pools, decomposition dynamics, and the molecular nature of SOM itself, under litter-manipulation in order to understand the controls on SOM formation and mineralization (Chapter IV).
This dissertation includes previously published and unpublished coauthored material; see the individual chapters for a list of co-authors, and description of contributions.
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de, la Mota Daniel Francisco Javier. "Water Fluxes in Soil-Pavement Systems: Integrating Trees, Soils and Infrastructure." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/99419.
Full textAbstract:
In urban areas, trees are often planted in bare soil sidewalk openings (tree pits) which recently are being covered with permeable pavements. Pavements are known to alter soil moisture and temperature, and may have implications for tree growth, root development and depth, drought resilience, and sidewalk lifting. Furthermore, tree pits are often the only unsealed soil surface and are important for water exchange between soil and atmosphere. Therefore, covering tree pits with pavement, even permeable, may have implications for the urban water balance and stormwater management. A better understanding of permeable pavement on tree pavement soil system functioning can inform improved tree pit and street design for greater sustainability of urban environments.
We conducted experiments at two sites in Virginia, USA (Mountains and Coastal Plain) with different climate and soil. At each location, we constructed 24 tree pits in a completely randomized experiment with two factors: paved with resin-bound porous-permeable pavement versus unpaved, and planted with Platanus x acerifolia 'Bloodgood' versus unplanted (n = 6). We measured tree stem diameter, root growth and depth, and soil water content and temperature over two growing seasons. We also monitored tree sap flow one week in June 2017 at the Mountains. In addition, we calibrated and validated a soil water flow model, HYDRUS-1D, to predict soil water distribution for different rooting depths, soil textures and pavement thicknesses.
Trees in paved tree pits grew larger, with stem diameters 29% (Mountains) and 51% (Coastal Plain) greater. Roots developed faster under pavement, possibly due to the increased soil water content and the extended root growing season (14 more days). Tree transpiration was 33% of unpaved and planted pit water outputs, while it was 64% for paved and planted pits. In June 2016, planted pits had decreased root-zone water storage, while unplanted pits showed increased storage. A water balance of the entire experimental site showed overall decreased soil water storage due to tree water extraction becoming the dominant factor. HYDRUS-1D provided overall best results for model validation at 10 cm depth from soil surface (NSE = 0.447 for planted and paved tree pits), compared to 30- and 60 cm depths. HYDRUS-1D simulations with greater pavement thickness resulted in changes in predicted soil water content at the Coastal Plain, with higher values at 10- and 30-cm depths, but lower values at 60-cm depth. At the Mountains, virtually no difference was observed, possibly due to different soil texture (sandy vs clayey).
Tree pits with permeable pavement accelerated tree establishment, but promoted shallower roots, possibly increasing root-pavement conflicts and tree drought susceptibility. Paved tree pits resulted in larger trees, increasing tree transpiration, but reduced soil evaporation compared to unpaved pits. Larger bare soil pits surrounded by permeable pavement might yield the best results to improve urban stormwater retention. Also, HYDRUS 1D was successful at simulating soil water content at 10-cm depth and may be valuable to inform streetscape design and planning.PHD
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Bai, YanYing. "Distribution of soil temperature regimes and climate change in the Mojave Desert region." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957301331&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268844053&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.
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Kim, YoungSeok. "Elasto-viscoplastic modeling and analysis for cohesive soil considering suction and temperature effects." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144866.
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Matheron, Michael, Martin Porchas, and Michael Maurer. "Effect of Temperature and Moisture on Survival of Phytophthora in Citrus Grove Soil." College of Agriculture, University of Arizona (Tucson, AZ), 2000. http://hdl.handle.net/10150/223839.
Full textAbstract:
Before replanting a citrus grove in Arizona, different preplant cultural activities may be performed, such as immediate replanting of the new citrus grove, allowing soil to lay fallow for various lengths of time, or planting the site to alfalfa for one or more years before the new citrus grove is established. A study was conducted to compare the effect of these different cultural preplant practices on the survival of Phytophthora in citrus grove soils. In June, 1998, and July, 1999, a total of 18 soil samples were collected within mature lemon groves. Each initial bulk sample was pretested, found to contain Phytophthora parasitica, then thoroughly mixed and partitioned into 1-liter plastic containers, which were subjected to different environmental and cultural conditions. The soil in each 1-liter container was tested for the presence of P. parasitica 1 and 3.5 to 4 months later. All soil samples then were placed in the greenhouse and a 6-month-old Citrus volkameriana seedling was planted in soil samples not containing plants. Three 1-liter sub-samples from each of ten 7-liter volumes of soil incubated outside for three months were also planted to citrus in the greenhouse. The soil containing plants in the greenhouse was watered as needed for 3 months, then again tested for the presence of Phytophthora. Irrigating soil infested with Phytophthora parasitica, whether it was planted to a host (citrus) of the pathogen, planted to a non-host (alfalfa) of the pathogen, or not planted at all, did not lower the pathogen to nondetectable levels. Phytophthora became and remained nondetectable only in the soil samples that were not irrigated and subjected to mean temperatures of 35 to 37° C (94 to 98° F). On the other hand, the pathogen was detectable in some soil samples subjected to dryness at lower mean temperatures of 26 to 30° C (79 to 86° F) after a citrus seedling subsequently was grown in the soil for 3 months. A dry summer fallow period following removal of a citrus grove (including as much root material as possible) was the only cultural practice among those tested that reduced the level of Phytophthora to nondetectable levels in all soil samples tested.
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Putkonen, Jaakko Kalervo. "Climatic control of the thermal regime of permafrost, Northwest Spitsbergen /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6724.
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Stomph, Tjeerd Jan. "Seedling establishment in pearl millet (Pennisetum glaucum (L.) R.Br.) : the influence of genotype, physiological seed quality, soil temperature and soil water." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276632.
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Moore, Amber Dawn. "Nitrogen availability of anaerobic swine lagoon sludge sludge source and temperature effects /." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011119-215624.
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Increased numbers of swine producers in North Carolina will be removing sludge from their lagoons in the next few years, mainly due to an increase in lagoons exceeding sludge capacity. Information on availability of nitrogen (N) in the sludge is needed to make improved recommendations about its use as a nutrient source for crops. The objectives of this study were to investigate possible affects related to lagoon sludges from different companies and operation types and to evaluate effects of seasonal temperatures and various application dates on the availability of N in lagoon sludge. Two separate incubation studies and one greenhouse study were conducted to quantify the N availability of the sludge. Sludges were mixed with a Wagram soil (loamy, siliceous, thermic Arenic Kandiudult) and incubated for one year at fluctuating seasonal temperatures based on four application dates (Feb. 26, June 4, Sept. 3, and Dec. 3). A second incubation experiment was conducted using sludges from three different company and operation-types. Samples were analyzed monthly for nitrate and ammonium. These sludges were also applied as the primary N source for bermuda grass, which was grown in the greenhouse, harvested and analyzed for total N. Operation effects were not detected in the incubation and greenhouse experiments. Company effects were detected in the incubation experiments yet considered to be negligible because differences were only significant (p < 0.05) at weeks 0, 2, 3, and 8. A quadratic plateau curve fit to N mineralization data for all sludge sources (r^2 = 0.52) demonstrated that most of the active organic N was mineralized after 8 weeks of incubation. Nitrogen availability for all sludges averaged 45 percent after 8 weeks for the incubation study, but only 20 percent for the 14-week greenhouse study. This may have been related to inconsistent moisture throughout the soil in pots. In the incubators with fluctuating temperatures, NH4 remained in the soil for 4 months in the simulated winter application and for only 1 month for the simulated fall and summer applications, illustrating a direct influence of temperature changes on nitrification. Sludge N availability was fit to a nonlinear regression model for a first order reaction as follows: Nt = No (1 - e^(-kt)) + Nos where: Nt = total inorganic N concentration, over time (mg N/kg); No = potentially available organic N (mg N/kg); k = first order rate constant (month^-1); t = time (month); and Nos = inorganic N concentration when time = 0. Rate constants (k) increased between simulated applications as follows: fall (0.07) < winter (0.075) < spring (0.22) < summer (0.36). Sludge applied during simulated winter temperatures released N at a relatively constant rate, as compared to simulated summer temperatures, which increased rapidly during the first 6 months, then stabilized to allow minimal increase of mineralized N for the remainder of the incubation.Predicted N availability for all temperature treatments after one year of incubation averaged 74 percent of the total N applied, supporting agronomic recommendations of 60 percent first-year plant-available N for incorporated swine lagoon sludge (NCCES, 1997). Year-long coefficients are unable to provide N availability information for short time length for growing seasons. To account for this, N availability for each month after sludge application was estimated using the first order equations for each simulated application date.