Rozprawy doktorskie: „VIRGIN SOIL”

1

Daniels, W. Lee. "Virgin hardwood forest soils of western North Carolina". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/52288.

Pełny tekst źródła

Streszczenie:

Little is known about the original properties of soils in the East. Eight virgin soils and associated southern Appalachian hardwood vegetation were studied in western North Carolina. The study sites ranged in elevation from 720 to 1200 m on steep slopes. Overall these soils are quite deep and highly weathered due to high rainfall (>200 cm) and soluble feldspathic parent material. Organic matter contents of the surface·horizons were quite high (4.5 - 16 %), and they contained moderate to strong crumb structure. All but one soil contained cambic subsurface horizons and were either Typic Haplumbrepts or Umbric Dystrochrepts. The majority of soils in the watershed are formed in colluvium, but significant amounts of residual soils occur on sideslopes, and appear to be quite stable. The present day landforms appear to be the result of periglacial activity. North-facing soils were higher in whole soil clay, organic matter, and A horizon exchangeable cations than south-facing soils. Cation exchange capacity in these soils is almost totally dependent on organic matter content, and the mineral fraction is relatively inert. All soils were in the oxidic mineralogy class. Bibbsite was common throughout all soils and hydroxy-interlayered vermiculite (HIV) is the dominant clay-sized phyllosilicate in surface horizons. Kaolinite was low in all soils, but was more abundant on south-facing slopes. The silt fractions and sand fractions contained significant quantities of weathered 2:1-type minerals The vegetation varied from mixed-mesophytic cove hardwoods on north-facing slopes to mixed oak-hickory and oak-pine on south-facing slopes. Many trees in coves exceed 1.3 m in diameter and 50 m in height. Total litter production averaged 3494 kg/ha, and the litter layers were typified by thin leaf (L), and well developed fermentation (F) and humus (H) layers. Cations and P are concentrated in the litter layers and immediate surface soil, while N is mixed deep into the profile. Due to their oxidic mineralogy, low CEC, decreasing clay content with depth, and concentration of cations and P in litter and standing biomass these soils highly resemble tropical Oxisols.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

2

Jones, Michael David. "Effects of Disturbance History on Forest Soil Characteristics in the Southern Appalachian Mountains". Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35213.

Pełny tekst źródła

Streszczenie:

Minimally disturbed virgin forest soils in the Little Santeetlah Creek (LSC) watershed of western North Carolina were sampled along with soils from the adjacent disturbed Slickrock Creek (SRC) watershed. Soils with similar elevation/landform/vegetation/parent material characteristics were initially sampled at nine random locations each on north and south aspects within each watershed with a soil push probe. Some differences in parent materials were noted on south aspects (metasandstone vs. phyllite), but parent materials under north aspect soils were identical (metasandstone). Soils in LSC were significantly deeper and relatively free of solum coarse fragments while SRC soils were shallower and higher in coarse fragments. Subsequent auger observations of three typical pedons on each aspect indicated that soils in LSC were well-developed with gradual horizon boundaries and common diffuse transition horizons, while soils in SRC were more compact in horizonation and lacked diffuse transitional horizons. Vegetation communities were similar across both watersheds, except that SRC south sites were higher in Pinus spp. Litter layer morphology differed strongly between the two watersheds. Specifically, well-developed humus (H) layers were typical in LSC, but completely absent in all typical pedons described in SRC. Data obtained from these two watersheds indicate strong differences in surface soil (O + A horizon) properties between the two. These observed differences could be due to differential anthropogenic effects, particularly logging and associated erosion in the early 1920's. However, further study over multiple disturbed watersheds in the region, and of the distribution of sediments and colluvium within them would be required to test this hypothesis.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

3

Pearlstein, Susanna Lee. "Methods for Measuring Tamarisk (Tamarix spp.) Water Use on Two Sub-Watersheds in The Western United States as Impacted by The Tamarisk Leaf Beetle (Diorhabda spp.)". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/594631.

Pełny tekst źródła

Streszczenie:

The Dolores River in Utah and the Virgin River in Nevada are ecosystems under pressure from increased groundwater withdrawal due to growing human populations, climate change and introduced species such as Tamarix spp. (tamarisk). Tamarisk is reputed to take excessive water from its environment. Controlling tamarisk is of concern in the western United States where plants grow quickly in already fragile and diminishing riparian areas. For this reason, biologic control beetles Chrysomelidae: Diorhabda carinulata were released to weaken the tamarisk population, thus reducing its water use. The studies for this dissertation were conducted between 2010 and 2011. We quantified tamarisk water use over multiple cycles of annual defoliation using sap flow measurements, leaf area index (LAI), well data, allometry and satellite imagery from EOS-1 Moderate Resolution Imaging Spectrometer (MODIS) sensor. Study objectives for the Virgin River were to measure evapotranspiration (ET) before beetles ever arrived and to examine the effects on tamarisk ET in the year after beetle arrival. This site showed plant ET from sap flow averaged about 4.3 mm m⁻² leaf day⁻¹ in 2010. In 2011, ET from sap flow averaged 6.4 mm m⁻² leaf area day⁻¹ pre beetle arrival, but dropped to 3-4 mm m⁻² leaf area day⁻¹ after beetle arrival. Stand level ET measured by MODIS was 2.2 mm d⁻¹ in 2010 and approximately 1.5 mm day⁻¹ when beetle arrival was measured in 2011. Significant visual change was apparent as the trees senesced. Results showed the first year of beetle arrival resulted in reduced ET but did not result in significant water savings. We also compared the reaction of the newly defoliated (in 2011) Virgin River site to the long-term defoliated (since 2007) Dolores River site to explore if all beetle invasions were created equal. This paper views the two sites as fairly extreme examples of tamarisk stand reaction to the beetle. While no mortality was reported at the Dolores River site, the site is much older, less photosynthetically active and covers far less ground when compared to the younger tamarisk monoculture on the Virgin River. Pre-beetle arrival Normalized Difference Vegetation Index (NDVI) values were higher on the Virgin River than on the Dolores River. Beetle arrival at each site was captured with Landsat NDVI and a reduced NDVI signal (13% drop in NDVI at Dolores River, 5% drop at Virgin River) was seen after beetle arrival.

Style APA, Harvard, Vancouver, ISO itp.

4

McClain, Mark Stephen. "The forest composition and the pedology of the undisturbed soils in an old-growth virgin beech-maple forest in east-central Indiana". Virtual Press, 1985. http://liblink.bsu.edu/uhtbin/catkey/426369.

Pełny tekst źródła

Streszczenie:

The edaphic and pedologic factors of forest soils and their influence on the naturally occurring climax vegetation in an old-growht forest in east-central Indiana were examined. The northern portion of this woods is a virgin remnant of the presettlement forest that Braun (1950) described as the BeechMaple Forest Region. This remnant is best classified as a sugar maple-American beech-slippery elm association. The undisturbed soils found were the moderately well drained Glynwood soils (Aquic Hapludalfs, fine, illitic, mesic), the somewhat poorly drained Blount soils (Aeric Ochraqualfs, fine, illitic, mesic), the poorly drained Lenawee Variant soils (Typic Haplaquepts, fine, nonacid, mixed,mesic), and the very poorly drained Lenawee (taxajunct) soils (Mollic Haplaquepts, fine-loamy, nonacid, mixed, mesic). The seasonal high water table and internal soil drainage of the soils appear to influence the survival and importance of the dominant tree species. There were 25 tree species sampled.The three most important tree species were sugar maple (Acer saccharum, Marsh.), American beech (Fagus qrandifolia Ehrh.), and slippery elm (Ulmus rubra Muhl.)on the Blount, Glynwood, and Lenawee Variant soils. The fourth most important tree species was silver maple (Acer saccharinum L.) which was restricted to the lowland-depressional forest type (Lindsey and Schmelz, 1970) inclusion represented by the Lenawee (taxajunct) soils. The distribution of tree species occurring on each of the four soils was statistically examined at the 0.05 level of significance. Sugar maple had a significantly higher mean average basal area on the Glynwood soils; American beech had a significantly higher average number of trees on the Blount soils; and slippery elm had a significantly higher proportion of trees on the Glynwood soils.Ball State UniversityMuncie, IN 47306

Style APA, Harvard, Vancouver, ISO itp.

5

Jenkins, Anthony Blaine. "Organic carbon and fertility of forest soils on the Allegheny Plateau of West Virginia". Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2486.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains x, 282 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Style APA, Harvard, Vancouver, ISO itp.

6

Al-Hawas, Ibrahim A. M. "Clay mineralogy and soil classification of alluvial and upland soils associated with Blackwater and Nottoway rivers in southeastern Virginia". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44104.

Pełny tekst źródła

Streszczenie:

Because the Coastal Plain of southeastern Virginia has not been extensively studied, thirty random samples associated with Blackwater and Nottoway rivers were collected in the spring of 1987 from Surry, Sussex, and Southampton counties. Soil classification as well as mineralogical, chemical, and physical analysis were conducted for all samples.

The purposes of this investigation were to: (1)classify the soils in this area, (2) determine the distribution of sand and clay minerals, (3) examine the weathering effect on clay minerals on different position of the landscape for different parent material sources.

The soils examined classified as follow: Aquic Hapludults 43% > Typic Hapludults 26.6% > Ultic Hapludalfs 10% > Humic Hapludults 3% = Typic Rhodudlts 3% = Aquic Hapludalfs 3% = Typic Udipsamment 3% = Typic Quartzpsamment 3% = Psammentic Hapludalfs. Qualitative analysis of clay minerals revealed that kaolinite and hydroxy interlayer vermiculite were the dominant clay minerals; that montmorillonite, mica, gibbsite quartz, and vermiculite were of lesser quantities; that chlorite, feldspar and interstratified minerals were of trace amounts. Kaolinite represents about 21-70%, HlV 11-60%, montmorillonite 0-20%, mica 0-16%, gibbsite 0-13%, quartz 1-12%, and vermiculite 0-10%. The presence of these minerals were mainly related to the acid reaction of the soil media, which was essentially attributed to Al and H ions in soil solution. From the past history and geological composition of the Piedmont it is assumed that kaolinitic minerals were transported and sedimented in the Coastal Plain. Hydroxy-interlayer vermiculite minerals was weathering from vermiculite because most of the Al was adsorbed by vermiculite to form HIV. Therfore, gibbsite was not precipitated. Montmorillonite was assumed to have formed from mica minerals. That was substantiated by statistical analysis which showed a high negative correlation between gibbsite and vermiculite (r=0.46, n=30) and between montmorillonite and mica (r=-0.6, n=10).

Master of Science

Style APA, Harvard, Vancouver, ISO itp.

7

Mayu, Philippe. "Determining parameters for stiff clays and residual soils using the self-boring pressuremeter". Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/49859.

Pełny tekst źródła

Streszczenie:

As testing stiff soils in the laboratory often leads to information which is not consistent with field performance, research was undertaken to determine in situ the soil properties. Among the devices which generated interest is the self-boring pressuremeter (SBPM). In this research, two stiff soils of the Commonwealth of Virginia were tested: A residual soil found in Blacksburg and a very stiff, non-fissured, and sensitive clay, of marine origin, known as the Miocene clay of the downtown Richmond area. Testing the residual soil of Blacksburg with the SBPM led to the following new operational approaches: (1) a systematic use of a steel-sheath known as "Chinese lantern" to protect the membrane of the probe, (2) the development of a loading frame providing adequate reaction when self-boring in stiff soils, (3) the development of a new calibration unit for the SBPM which allows to calibrate the probe under conditions more like those encountered in stiff soils and, (4) the development of a high capacity computerized data acquisition system. Testing the residual soil also allowed to establish a sound database for this soil. In the Miocene clay, the laboratory test results indicate that conventional sampling technique which consists in pushing Shelby tubes disturbs significantly the soil and leads to scattered test results. In contrast, tests performed on samples taken from high-quality block samples indicate consistent behavior patterns. SBPM test results in the Miocene clay indicate that the clay exhibits high lateral stresses. They also indicate the existence of an anisotropic state of lateral stress which can be explained from the regional topography. The soil parameters interpreted from the SBPM test results in the Miocene clay compare well with the soil parameters determined in the laboratory on the block samples.
Ph. D.
incomplete_metadata

Style APA, Harvard, Vancouver, ISO itp.

8

Thomas, Pamela J. "Characterization, classification, and productivity studies of typic hapludult mapping units in the southern Piedmont of Virginia". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/80054.

Pełny tekst źródła

Streszczenie:

Two studies were initiated in the Virginia southern Piedmont to assess characterization, classification, and productivity of soils mapped as Cecil-Pacolet (clayey, kaolinitic, thermic Typic Hapludults). Effects of erosion on Ap and Bt soil properties and soybean grain yields were studied in Pittsylvania and Lunenburg counties. Relationships between soil properties, soybean yields, and erosion classes were not observed until the soils became severely eroded. Water contents at -10kPa and -1500kPa increased as clay content increased but plant available water remained at 0.09 m³ m⁻³ across erosion classes. Available phosphorus (P) decreased with severity of erosion and was significantly correlated with soybean yield. The highest grain yields were on slightly and moderately eroded soils and were attributed to available P levels above 18 mg P kg⁻¹ critical level for optimum crop production. Low yields on the severely eroded sites corresponded to available P below 18 mg kg⁻¹. A second study on composition and variability of the Cecil-Pacolet map unit in Appomattox County showed large variation in soil properties and taxonomic classes. Variability is attributed to intrusions of mafic materials in the map unit. Variability was extreme within delineated soil bodies and was reflected in taxonomic classification in which up to six taxa can occur within the same delineation. Cecil and Pacolet soils comprise 62 percent of the map unit. Similar soils comprise 70 percent of the map unit and dissimilar soils make up the remaining 30 percent. The map unit is named Pacolet-Cecil and dissimilar soils are included in the mapping unit description.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

9

Saxton, H. Thomas. "Soil genesis studies of upland soils formed in transported materials overlying the Virginia Piedmont using trend-surface analyses". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-01102009-063235/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

10

Sponaugle, Cara L. "Properties and acid risk assessment of soils in two parts of the Cherry River watershed, West Virginia". Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4425.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains viii, 169 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 62-67).

Style APA, Harvard, Vancouver, ISO itp.

11

Sutanto, Yovita. "Manure from grazing cattle effects on soil microbial communities and soil quality in northern West Virginia pastures /". Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3933.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains vii, 72 p. : ill. (some col.), map. Includes abstract. Includes bibliographical references.

Style APA, Harvard, Vancouver, ISO itp.

12

Starner, David Eugene. "Field and laboratory characterization of soil water desorption properties and comparison of plant available water for two Virginia soils". Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53087.

Pełny tekst źródła

Streszczenie:

Soil water movement and desorption studies were conducted on two agriculturally important soil series. The soils selected were the Norfolk soil (a fine loamy, siliceous, thermic, Typic Paleudult) and the Cecil soil (a clayey, kaolinitic, thermic, Typic Hapludult). Water desorption properties were investigated in the laboratory and in situ. The soil water desorption curves developed in the laboratory for both soils were relatively uniform. This observation was also true for most horizons for the desorption curves developed from the field data. The results for the B horizons of the Cecil soil showed the greatest variability, with the field data being the most variable. Comparisons of the field and laboratory water contents at given tensions show the field values were lower than laboratory values for horizons with over 40 percent sand and less than 30 percent clay. Field values were higher than laboratory values in the B horizons of both soils. In all other horizons, the field values were close to those obtained in the laboratory. The Norfolk soil was found to contain more plant available water than the Cecil soil. The selection of an upper limit for plant available water estimation is critical, especially for the Norfolk soil. The Cecil soil yielded little water between -.05 and -.30 bars, whereas the Norfolk soil yielded a relatively large amount of water (more than 3 times greater) in this range. This would nearly double the predicted plant available water for the Norfolk soil. Results of this study show that the irrigation management of the Cecil soil would require smaller amounts of water applied frequently, whereas the Norfolk soil could hold larger amounts of plant available water applied less frequently. This would allow more time between irrigations.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

13

Miller, Jarrod O. "Soil Organic Carbon Variability by Aspect and Slope in the High Elevation Soils of the Southwest Virginia Mountains". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/41737.

Pełny tekst źródła

Streszczenie:

Limited information is available on carbon(C)sequestered in frigid Appalachian forest soils. However,the cool moist forests of the high elevations probably hold more C than any other mineral soils in Virginia. The objectives of the study were to determine the amount and variability of soil C across aspect and slope classes in a frigid temperature regime area of Tazewell County, VA. Soils were sampled to characterize two aspect classes, N(340-90Âº) and S (160-270Âº), and three slope classes, 7-15%, 15-35%, 35-55%. Organic (L,F,H) and mineral layers and horizons (upper 5cm, A, B) were sampled at each site. Whole soil (including organic and mineral horizons) C contents on N aspects (135 Mg/ ha) were greater than on south aspects (107 Mg/ha). Average whole soil C across all sites was 112 Mg ha-1. The A horizons on N aspects (13cm) were deeper than those of the S aspects (8 cm), while average leaf litter weights were greater on the S aspects (25 Mg/ ha) versus the N (17 Mg/ ha). B horizon C was greater than 1.5 % and made up more than half of the total soil C. Carbon increased with slope on N aspects, but did not increase with slope on S aspects, because estimated solar insolation potential decreases with increasing slope on N aspects and has no trend on S-facing slopes. Total C appears to be greatest on steep N-facing slopes because cooler and moister conditions promote better mixing of organic material into the mineral soil.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

14

Klemmer, Katherine Alyn. "Cost-benefit analysis of remediation methods for the Fairfax, Virginia Texaco terminal oil plume". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06112009-063524/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

15

Norris, Patricia E. "Factors influencing the adoption of soil conservation practices in Virginia's Piedmont Bright Leaf Erosion Control Area". Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/104521.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

16

Stolt, Mark H. "An approach to studying soil-landscape relationships in Virginia". Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39797.

Pełny tekst źródła

Streszczenie:

Many conceptual soil genesis models have been developed since the advent of soil science. The most well known and frequently taught mode] is Jenny's (1941), which was derived from the ideas of Dokuchaev, and defines the five factors of soil formation (organisms, climate, topography, parent material, and time). At a local level, climate and organisms can be assumed to be a constant, therefore changes in soils (differentiation) can be said to be related to time, topography, and parent material. Given an infinite amount of time, it can be assumed that on a given parent material the factor that affects soil formation is topography or landscape position.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

17

Vanwormhoudt, An. "Soil mineralogy of an upper coastal plain landscape in Virginia". Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/41916.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

18

Bouysse-Cassagne, Thérèse. "El Sol de adentro: wakas y santos en las minas de Charcas y en el lago Titicaca (siglos XV a XVII)". Pontificia Universidad Católica del Perú, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/113464.

Pełny tekst źródła

Streszczenie:

The Sun within the World: Wakas and Saints in the Mines of Charcas and in Lake Titicaca (15th-17th Centuries)Mines and mining offer both for the Andean as the Spanish systems of beliefs the background of a setting in which were developed rites and cult complexes, and if there was an adaptation of European beliefs it is because there existed compatibilities between the two systems of representing the world. Alchemical beliefs approximated, in some manner, both the etiological myth of the Inca-Sun and the the same myth of origin of Andean gold, which was a solar myth. However, the encounter between the two systems of representation did not necessarily determine a series of syncretic practices. All appearances indicate that in Potosi, in the middle of the 17th century, the cult to the Virgin-mountain did not correspond to a popular practice, but neither did it preclude the practice of various autochthonous cults of major historical significance which, in turn, were related among themselves. In the present work, these shamanic cults are analyzed in different mines. The images that issued from them put in play a series of artifacts, of figures and entities that were also encountered in the description of the old Colla cult of the Island of Titicaca, heir of Tiwanaku. All these cults were influenced to a large degree by the religious system elaborated by the Incas.
Las minas ofrecieron tanto al sistema de creencias andino como al español el trasfondo de un paisaje en el que se desarrollaron ritos y cultos complejos, y si hubo una adaptación de las creencias europeas fue porque existían compatibilidades entre los dos sistemas de representación del mundo. Las creencias alquímicas se acercaban, de alguna manera, tanto al mito etiológico del Inca-Sol como al mito de origen del oro andino, que era un mito solar. Sin embargo, el encuentro de esos sistemas de representación no determinó forzosamente una serie de prácticas sincréticas. Todo parece indicar que en Potosí, a mediados del siglo XVII, el culto a la Virgen-cerro no correspondía a una práctica popular, pero tampoco impedía la práctica de varios cultos autóctonos de mayor profundidad histórica que, a su vez, estaban relacionados entre ellos. En el presente trabajo, estos cultos chamánicos se analizan en el caso de diferentes minas. Las imágenes que se desprenden de ellos ponen en juego una serie de artefactos, figuras y entidades que encontramos también en la descripción del viejo culto colla de la isla de Titicaca, heredera de Tiwanaku. Todos estos cultos influenciaron gran parte del sistema religioso elaborado por los incas.

Style APA, Harvard, Vancouver, ISO itp.

19

Hollywood, Amy M. "The soul as virgin wife : Mechtild of Magdeburg, Marguerite Porete, and Meister Eckhart /". Notre Dame (Ind.) ; London : University of Notre Dame, 1995. http://catalogue.bnf.fr/ark:/12148/cb37669564d.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

20

Penn, Chad John. "Phosphorus Losses in Runoff from Virginia Soils". Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28499.

Pełny tekst źródła

Streszczenie:

Previous research shows that dissolved P losses in runoff are well related to soil test P (STP), thus, various P loss prediction models incorporate the use of a STP vs. runoff DRP relationship. However, the relationship between STP and runoff DRP will vary based on soil type due to differences in soil properties. The purposes of the first two studies were to (i) investigate the effect of soil mineralogy on P sorption behavior and dissolved P in runoff and (ii) determine if any simple soil test extractions could indirectly take into account this effect of mineralogy. Nine soil types from the Virginia Piedmont, Coastal Plain, and Ridge and Valley were collected and used in a rainfall simulation study. Phosphorus retention among separated clay fractions and whole soils were related to Al bearing minerals such as hydroxy-interlayered vermiculite (HIV), gibbsite, and amorphous Al. Samples dominated by kaolinite retained very little P. Application of these results to runoff data showed that soil types with a HIV:kaolinite ratio > 0.5 caused significantly less DRP in runoff for a given soil WSP level compared to soils with a ratio < 0.5. The second study showed that the soil P vs runoff DRP relationships varied between physiographic provinces. Generally, the Coastal Plain soils resulted in a higher runoff DRP concentration for a given soil P level compared to Piedmont and Ridge and Valley soils. However, soil M3-P/Al resulted in one relationship with DRP for all three groups of soils. Results from the incubation study suggested that Al related P is more easily desorbed into solution compared to Fe related P. The final study demonstrated that phytase enzyme and high available P corn supplements in poultry diets can reduce manure WSP and total P. Results from the runoff study showed that DRP losses were related to sediment losses which consisted of > 90% manure particles. Manure particles were directly deposited into the collection container followed by desorption of P based upon the WSP content of that manure type. The results emphasized best management practices that prevent direct loss of manure particles from soil into surface waters.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

21

Baethgen, Walter E. "Plant nitrogen availability in selected Virginia soils". Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/90907.

Pełny tekst źródła

Streszczenie:

Surface and subsoil samples were collected from agriculturally important soils of Coastal Plain, Piedmont and Ridge and Valley regions of Virginia for the purpose of determining the contribution of different soil N fractions to plant available N. Soil samples were analyzed for exchangeable and non-exchangeable NH₄⁺-N, NO₃⁻-N, total N, and organic matter contents. The samples were also subjected to the anaerobic incubation procedure as an index of organic N availability. Plant available N was measured by N uptake of successive wheat crops grown in the greenhouse. Multiple linear regression models for different groups of samples were used to determine the contribution of the different soil N fractions to the plant available N supply, and to predict N uptake by wheat. Best models were selected considering fit, significance of the regression coefficients, and predictive ability. Due to the high correlation among the different soil N fractions, important collinearity was present and affected the linear models. These effects were reduced by utilizing biased techniques. All the soils provided significant amounts of N to the wheat in both the first and second crops. Exchangeable NH₄⁺-N and NO₃⁻-N were the major initial sources of plant available N. Non-exchangeable NH₄⁺-N was also a significant contributor to the plant available N supply for most soils. The results of the biological and chemical indices of organic N availability were highly correlated among each other, and with plant N uptake by the first and second wheat crops. Plant N uptake was associated with the variation observed in the different soil N fractions, indicating that wheat is a good indicator crop for plant N availability experiments. The procedures used to detect and combat collinearity were effective in producing more stable models with better predictive ability. Further research should be conducted under field conditions to study the contribution of non-exchangeable NH₄⁺-N to plant N availability.
M.S.

Style APA, Harvard, Vancouver, ISO itp.

22

MacPherson, Colin J. "The spirit, grace, and soul of science, or, The virgin who was a wife". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0007/MQ30667.pdf.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

23

Segarra, Eduardo. "A dynamic analysis of the crop productivity impacts of soil erosion: an application to the Piedmont area of Virginia". Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/51930.

Pełny tekst źródła

Streszczenie:

This study was born out of the desire to analyze the complex soil management problem faced by individual economic agents as well as society. The focus of this study, however, was on the theoretical formulation and estimation of partial equilibrium dynamic economic models directed toward optimizing the private use of the soil resource. In particular, four empirical representative farm models were formulated. Solutions to the four representative farm models showed that sizable reductions in topsoil loss, which contributes to non-point source pollution, and aggravates the crop productivity impacts of soil erosion, can be accomplished by adopting alternative support practices. Because of the change in support practices, reductions in the present value of net returns are expected, but this decrease in return was found to be minimal when compared to reductions in topsoil loss. Policy implications as well as several policy recommendations stemming from those results, with respect to soil conservation, are outlined and analyzed.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

24

White, Angela Paige. "An Examination of Virginia Soil and Water Conservation District Employee Job Satisfaction". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26752.

Pełny tekst źródła

Streszczenie:

The studyâ s purpose was to determine the job satisfaction level of Virginia Soil and Water Conservation District (SWCD) employees during fiscal year 2007-2008. Employee characteristics were identified; three measures of job satisfaction were attained (intrinsic, extrinsic, general satisfaction); and satisfaction levels on 12 specific job aspects were determined. The relationship between job satisfaction and four independent variables (age, gender, education level, primary job responsibility) was assessed. The instrument consisted of an employee characteristics survey, the Minnesota Satisfaction Questionnaire (MSQ) 1977 Short-Form, derived from the MSQ 1967 Long-Form (Weiss, Dawis, England, & Lofquist, 1967), and a modified 2002 Virginia Association of Soil and Water Conservation Districts (VASWCD) survey. Descriptive research statistics were utilized. A total of 185 employees participated, which was an 80% response rate. The majority of employees were characterized as: non-Hispanic, white, female, average age 41 years, married with no children 18 and under living in the home, bachelorâ s degree, average tenure of 6.52 years, full-time, permanent position, average hourly wage of $14.45 and annual salary of $36,373.54, primary job responsibility â technical.â The MSQ found respondents generally and intrinsically satisfied. Greater satisfaction was expressed for variety and social services. Overall respondents were undecided about extrinsic job aspects. Advancement was an area of dissatisfaction. The modified VASWCD survey found respondents satisfied overall. Respondents were â very satisfiedâ with work schedule, type of work, and board relationships. Employees were less satisfied with health insurance benefits, new employee orientation, and compensation. They were â dissatisfiedâ with career advancement opportunities and life insurance. Differences in total intrinsic, extrinsic, and general job satisfaction, as measured by the MSQ, based on the independent variables were determined. A one-way ANOVA and Tukeyâ s post-hoc test were utilized. Since the population of this study violated Leveneâ s Test of Homogeneity, the ANOVA could not be performed for age and intrinsic and general job satisfaction. The ANOVA was performed for all other variables. There was not a significant difference in extrinsic satisfaction among respondents of the various age groups. There were no significant differences in intrinsic, extrinsic, or general job satisfaction for the variables of gender, education level, or primary job responsibility.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

25

Selig, Marcus Franklin. "Soil Co2 Efflux and Soil Carbon Content as Influenced by Thinning in Loblolly Pine Plantations on the Piedmont of Virginia". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/33866.

Pełny tekst źródła

Streszczenie:

The thinning of loblolly pine plantations has a great potential to influence the fluxes and storage of carbon within managed stands. This study looked at the effects of thinning on aboveground carbon and mineral soil carbon storage, 14-years after the thinning of an 8-year-old loblolly pine plantation on the piedmont of Virginia. The study also examined soil respiration for one year following the second thinning of the same stand at age twenty-two. The study was conducted using three replicate .222 hectare stands planted using 3.05 by 3.05 meter spacing in 1980 at the Reynolds Homestead in Critz, VA. Using two different sample collection methods it was determined that soil carbon was evenly dispersed throughout thinned plots, and that random sampling techniques were adequate for capturing spatial variability. Soil carbon showed a significant negative correlation with soil depth (p=0.0001), and by testing the difference between intercepts in this relationship, it was determined that thinning significantly increased soil carbon by 31.9% across all depths (p=0.0004). However, after accounting for losses in aboveground wood production, thinning resulted in an overall 10% loss in stand carbon storage. However, this analysis did not take into account the fate of wood products following removal. Soil respiration, soil temperature, and soil moisture were measured every month for one year near randomly selected stumps and trees. In order to account for spatial variation, split plots were measured at positions adjacent to stumps and 1.5 meters away from stumps. Soil temperature and moisture were both significantly affected by thinning. Regression analysis was performed to determine significant drivers in soil CO2 efflux. Temperature proved to be the most significant driver of soil respiration, with a positive correlation in thinned and unthinned stands. When modeled using regression, thinning was a significant variable for predicting soil respiration (p < 0.0009), but explained only 3.4% of the variation. The effects of thinning were responsible for decreased respiration, however, when coupled with increased temperatures, soil respiration was elevated in thinned stands.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

26

Geiman, Christopher Matthew. "Stabilization of Soft Clay Subgrades in Virginia Phase I Laboratory Study". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32499.

Pełny tekst źródła

Streszczenie:

Many pavement subgrades in Virginia consist of wet, highly plastic clay or other troublesome soils. Such soils can be treated with traditional lime and cement stabilization methods. Alternatives, including lignosulfonates and polymers, are available, but their performance record is mixed and solid engineering data is lacking, which prevents reliable design. The goal of this research was to screen a suite of traditional and non-traditional stabilizers against three Virginia soils that have caused problems during construction or resulted in poor performance in service. The selected stabilizers were: quicklime, hydrated lime, pelletized lime, cement, lignosulfonate, synthetic polymer, magnesium chloride, and a proprietary cementitious stabilizer. A laboratory procedure was developed and applied to three Virginia soils obtained from Northern Virginia, Staunton, and Lynchburg. Key findings from the research include that (1) traditional lime and cement stabilizers were far more effective than liquid stabilizers (lignosulfonate, synthetic polymer, and magnesium chloride) in increasing strength, (2) the liquid stabilizers were ineffective on soils with high moisture content, (3) the proprietary cementitious stabilizer was more effective in increasing strength than lime for all cases tested, but not was not as effective as the cement stabilizer, (4) quicklime and hydrated lime increased workability of the soils although they did not produce strengths comparable to cement, (5) the strength of soils stabilized with cement and the proprietary cementitious stabilizer can be estimated based on the water-amendment ratio of the mixture, and (6) the strength of soils stabilized with lime can be estimated based on a combination of plasticity index and water-amendment ratio of the mixture.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

27

Slagle, April. "Background concentrations of trace elements in three West Virginia soils MLRA-126 /". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1380.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains xi, 163 p. : ill. (some col.), maps. Vita. Includes abstract. Includes bibliographical references (p. 72-77).

Style APA, Harvard, Vancouver, ISO itp.

28

Ott, Emily Thomas. "Soil Genesis and Vegetation Response to Amendments and Microtopography in Two Virginia Coastal Plain Created Wetlands". Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83529.

Pełny tekst źródła

Streszczenie:

Wetlands serve important ecosystem functions such as carbon sequestration but are often affected by disturbances like urban development, agriculture, and road building. For wetlands created to mitigate losses, it is important that the ecosystem functions successfully replicate those of natural wetlands. Created wetlands have frequently not provided these functions due to issues including low organic carbon (OC), high soil bulk density (BD), lost topsoil, incorrect hydrology, and failure of targeted vegetation establishment. Organic matter (OM) amendments help created wetlands attain these functions quicker, but, their long-term effects are seldom reported. This research's purpose was to measure the long-term effects of treatments at a sandy tidal freshwater wetland created in 2003 (WWE) and a fine-textured, non-tidal wetland created in 2002 (CCW). We tested OM treatments, topsoil amendment, and microtopography effects on soil and vegetation properties at WWE and OM treatments at CCW. Pedogenic changes in soil morphology, physical and chemical properties were detected by comparing data to previous studies at these sites. At both sites, litter and biomass parameters were measured to estimate total mass C. Herbaceous biomass was measured at WWE. At WWE, no long-term OM treatment effects from 78 or 156 Mg ha-1 were observed. Soils in pits had higher OC, lower BD, and lower chroma than soils on mounds. Sandy and loamy HSFI's developed at WWE within four years, but there were fewer sandy indicators after 12 years. Loamy HSFI's were lost at CCW from 2003 to 2016. Plots at WWE that were amended with topsoil had higher soil mass C than the sandy soil due to a finer texture, but total mass C did not vary. At CCW, long-term OM treatment effects were observed, including lower BD, higher soil mass C, and higher tree mass C with increasing compost rates up to 224 Mg ha-1. Overall, the ideal compost loading rate for constructed wetlands varied with wetland type and mitigation goals. Compost rates of 112 Mg ha-1 are sufficient for short term establishment of wetland vegetation and hydric soil properties, but higher rates near 224 Mg ha-1 may be required for effects that last over 10 years.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

29

Harman, Michael B. "Preferential flow and phosphorus translocation in benchmark soils of West Virginia". Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5758.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 2008.
Title from document title page. Document formatted into pages; contains ix, 124 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Style APA, Harvard, Vancouver, ISO itp.

30

Tuladhar, Amulya Ratna. "Mine soil properties influencing white pine (Pinus atrobus L.) growth in Southwest Virginia". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101329.

Pełny tekst źródła

Streszczenie:

Thirty-six eight-year-old white pine (Pinus strobus L.) trees were used to identify minesoil, plant moisture, and foliar nutrient properties influencing white pine growth on reclaimed mine sites in southwest Virginia. PRESSAll (SAS Views, 1984) was used to determine relationships between soil properties and growth, soil properties and functional environmental factors (plant moisture stress and foliar nutrients), and between functional environmental factors and growth. PRediction Error Sum of Squares (PRESS), Mean Square Error (MSE), and Multiple Correlation Coefficient (R²) were used as criteria for variable selection and model validation. Rooting-volume index, the reciprocal of the electrical conductivity (EC), and extractable P in the soil-sized fraction of the minesoils were the best validated variables, predicting tree heights with the smallest amount of unit error (APRESS of 0.86 m) and accounting for the highest R² ( R² = 53.06%). The depth of the rooting volume had the greatest effect on 2 early growth (R² = 7 .91%), but variation in the last four years of height growth appeared to be a function primarily of rooting volume (R² = 51.40, p < 0.0001). Relationships between soil properties and 2 functional environmental factors varied widely (R² = 0.00-27 .50%). Plant moisture stress was most highly associated with the volume of the soil-sized fraction (R² = 13.6%), foliar phosphorus with soil pH (R² = 22.5%), and foliar cations with anaerobic-mineralizable nitrogen (R² = 0.00-27 .5%). The relationship between functional environmental factors and growth was uniformly weak (R² = 0.00-14.97%). Plant moisture stress was consistently related to overall height and its increment over the last four years, but foliar nutrients were erratically related to growth. No significant relationships between other functional environmental factors and growth were detected. Minesoil indices for individual trees ranged from 47-147 (base age 50). The depth of minesoil for site index 80 (average for Southern Appalachia) was 40 cm.
M. For.

Style APA, Harvard, Vancouver, ISO itp.

31

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.

Pełny tekst źródła

Streszczenie:

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

Style APA, Harvard, Vancouver, ISO itp.

32

Norris, Robert Brooke. "Winter Annual Cover Crops Interseeded into Soybean in Eastern Virginia: Influence on Soil Nitrogen, Corn Yield, and In-Season Soil Nitrogen Tests". Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51173.

Pełny tekst źródła

Streszczenie:

The diverse cropping system of eastern Virginia's coastal plain offers limited opportunity to establish winter annual cover crops (WCC) for nitrogen (N) scavenging. The winter fallow niche after double-crop or full-season soybean (Glycine max L. Merr.) encompasses the majority of acres left fallow. Our objective was to evaluate interseeded WCC N scavenging performance following soybean and N supplying capacity to subsequent corn (Zea mays L.). Field studies were conducted at four different locations in each of the two study years. The experimental design was split plot with cereal rye, hairy vetch, and RV mix WCC as main plots and ten fertilizer nitrogen (FN) rates in a factorial arrangement (0 and 45 kg FN ha-1 as starter; and 0, 45, 90, 135, and 180 kg FN ha-1 at sidedress) to corn as subplots. The highest N uptake for cereal rye at winter dormancy was 18 kg N ha-1, but the average was 6-7 kg N ha-1. At WCC termination average N uptake for cereal rye was 35 and 40 kg N ha-1 in 2013 and 2014, respectively. Average biomass dry matter (DM) at WCC termination for cereal rye, cereal rye + hairy vetch mix (RV mix), and hairy vetch was 2356, 2000, and 1864 kg ha-1 in 2013; and 2055, 2701, and 692 kg ha-1 in 2014, respectively. Average cereal rye N uptake was 35 kg N ha-1 in 2013 and 40 kg N ha-1 in 2014. Significant differences for residual soil nitrogen were most apparent for soil nitrate (NO3-N) at lower depths (15-30 and 30-60 cm) during WCC termination and in the upper 0-15 cm during corn growth stage (GS) V4 of both years. Corn grain yield plateau following hairy vetch WCC was 0.7 and 0.6 Mg ha-1 higher than when following cereal rye WCC at zero and 45 kg ha-1 starter FN, respectively. Average agronomic optimum FN rates (AONR) were 26 and 9 kg ha-1 lower following hairy vetch than cereal rye WCC at zero and 45 kg ha-1 starter FN, respectively. Estimated hairy vetch FN reductions by FN replacement and AONR difference methods were 48 and 18 kg FN ha-1 in plots receiving zero starter FN; and 58 and -43 kg FN ha-1 in plots receiving 45 kg ha-1 starter FN. In-season soil N tests did not offer adequate information in order to predict sidedress FN reductions. These findings suggest that cereal rye and RV mix have the potential to scavenge and conserve residual soil N and hairy vetch is more than capable to supply PAN to subsequent corn when interseeded into soybean.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

33

Li, Renssheng. "Nitrogen cycling in young mine soils in Southwest Virginia". Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39924.

Pełny tekst źródła

Streszczenie:

Deficiency of available nitrogen (N) is one of the major factors limiting the establishment of a long term self-sustaining vegetative community on mine soils. This investigation was conducted to study the nature of N form and dynamics in southwest Virginia mine soils. Fresh mine spoils contained a large amount of indigenous N, ranging from 650 to 2500 mg/kg soil, which complicated N studies. Most of the indigenous N was "geologic N" which was unavailable to plants. The geologic N came from either 2:1 silicate minerals (fixed NH₄⁺) or coal fragments (nonhydrolyzable organic N). Active N, consisting of hydrolyzable organic N and exchangeable N, comprised the minor fraction of indigenous N available to plants.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

34

Wentz, Jerome C. "West Virginia coal fly ash sorption of BTEX". Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3759.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--West Virginia University, 2004.
Title from document title page. Document formatted into pages; contains vi, 93 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 47-52).

Style APA, Harvard, Vancouver, ISO itp.

35

Hall, David Shane. "Soil-plant root relationships of herbaceous biomass crops grown on the Piedmont of Virginia". Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08182009-040419/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

36

Fajardo, Gabriela Isabel. "Physical and Chemical Soil Properties of Ten Virginia Department of Transportation (VDOT) Mitigation Wetlands". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31304.

Pełny tekst źródła

Streszczenie:

In 1998, the Virginia Department of Transportation (VDOT) adopted standards for soil handling and amendments to improve created non-tidal wetland soil conditions. This study was conducted in sites where these new reconstruction practices were supposedly being implemented. Specific objectives were (i) to determine the relative effects of soil reconstruction practices on mitigation site soils, (ii) to assess the degree to which hydric soil indicators were present, and (iii) to evaluate the relative edaphic potential of mitigation site soils. Soil physical, chemical and morphological properties were analyzed in ten mitigation wetlands located in Virginiaâ s Piedmont and Coastal Plain. Surface soil pH was high due to liming, although some sites demonstrated low subsoil pH, indicating the presence of sulfidic materials. Nutrient levels varied, while C:N ratios were low (<25:1), suggesting a high quality organic matter complex. Organic amendments were generally applied at a rate of 4% soil organic matter content. Actual measured carbon content was <2.6% (<50 Mg ha-1). Sites not receiving organic materials and associated tillage had root-limiting bulk densities at the surface, while the majority of sites had root-limiting subsoil (30 cm) bulk densities due to weakly developed soil structure and a lack of deep ripping practices. Many sites also contained high sand content (>50%), which may negatively affect other soil properties. Nine sites had confirmed Hydric Soil Indicators, with their occurrence in a site as high as 70%. Soil reconstruction methods need to incorporate higher organic amendment rates and/or routine disking/ripping practices to improve mitigation wetland soil conditions.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

37

Lopez, Alfredo R. "Biodegradability of dicamba and 2,4-D in riparian wetland soils". Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06082009-170726/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

38

Wiseman, P. Eric. "Soil Carbon Dioxide Efflux Across Four Age Classes Of Plantation Loblolly Pine (Pinus taeda L.)On The Virginia Piedmont". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35770.

Pełny tekst źródła

Streszczenie:

Soil carbon dioxide efflux resulting from microbial and root respiration is a major component of the forest carbon cycle. We undertook this investigation to better understand the nature of soil carbon dioxide efflux of plantation loblolly pine, an important ecological and economical resource in the southeastern United States. Specifically, we hoped to learn how soil carbon dioxide efflux differs both spatially and temporally for four age classes of plantation loblolly pine on the Virginia piedmont. During a 12-month period, soil carbon dioxide efflux was repeatedly measured for four age classes of plantation loblolly pine using a dynamic, closed-chamber infrared gas analyzer. The age classes examined were 1- to 2-year-old, 4- to 6-year-old, 8- to 12-year-old, and 20- to 25-year-old stands. Mean soil carbon dioxide efflux rates measured during the 12-month study were 1.72, 2.58, 2.84, and 2.90 micromole/sq m/s for 1- to 2-year-old, 4- to 6-year-old, 8- to 12-year-old, and 20- to 25-year-old stands, respectively. Stand age had a significant effect on efflux rate during 10 of the 12 monthly sampling sessions. Additionally, mean efflux rates were consistently higher near the tree and a significant positional difference was detected during 8 of the 12 monthly sampling sessions. Mean soil carbon dioxide efflux rates, by position, for the 12-month study were 2.72 and 2.28 micromole/sq m/s for the near and away measurement positions, respectively. Based on monthly mean soil carbon dioxide efflux rates, annual carbon losses were estimated at 651, 976, 1074, and 1082 g C/sq m/yr for 1- to 2-year-old, 4- to 6-year-old, 8- to 12-year-old, and 20- to 25-year-old stands, respectively. Regression analysis was used to examine the influence of soil and climatic factors on seasonal changes in soil carbon dioxide efflux. The most influential factors affecting soil carbon dioxide efflux during the 12-month study were soil temperature, soil moisture, stand age, and measurement position. We believe respiring roots significantly influence soil carbon dioxide efflux of plantation loblolly pine and account for differences observed between stands of different ages as well as spatial differences observed within a given stand.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

39

Christopher, Edwin A. "Post harvest evaluation of best management practices for the prevention of soil erosion in Virginia /". Blacksburg, Va. : Virginia Polytechnic Institute and State University, 2002. http://scholar.lib.vt.edu/theses/available/etd-04092002-100746.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

40

Christopher, Edwin A. Jr. "Post Harvest Evaluation of Best Management Practices for the Prevention of Soil Erosion in Virginia". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31665.

Pełny tekst źródła

Streszczenie:

Poor harvesting practices can accelerate soil erosion and decrease water quality and site productivity. Forestry Best Management Practices (BMPs) were developed to protect water quality, primarily by minimizing erosion during and after timber harvests. Although properly employed BMPs mitigate against the immediate potential for soil loss, little information exists regarding their long-term effectiveness. Since 1993, the Virginia Department of Forestry (VDOF) has conducted random water quality audits on forest harvesting operations. The VDOF will recommend remedial BMPs immediately if there is an active water quality law violation, and these recommendations are usually obviously clear to all parties. However, the potential for water degradation is more controversial and debates can arise over these recommendations. The VDOF, as in most states, does not have the resources to make visits to post harvest sites over time. Therefore, it is imperative that the BMPs employed at the closeout of the timber harvest be sufficient to ensure erosion control until the site has recovered, yet, BMP evaluations should represent real or potential problems. This study was undertaken to provide a quantitative analysis of erosion rates over time on VDOF random audited harvest sites and to identify key factors of erosion rates for log decks, skid trails, access roads, harvest areas, and stream crossings within each of Virginia's physiographic regions. A secondary objective was to provide a greater level of decision support for VDOF field staff, through the identified key factors which would indicate potential problem areas of erosion and water quality degradation particularly from logging activities and temporary roads. To better understand the primary causes of erosion over time the Dissmeyer and Foster Universal Soil Loss Equation (USLE) was used to establish quantitative erosion rates which officials can use to focus BMP recommendations. Such a decision support system for field staff, based on quantifiable erosion estimates, provides a proactive targeted prevention assessment prior to the development of actual water pollution problems. Analyses of logged tracts throughout Virginia revealed that estimated erosion rates were not statistically significant between physiographic provinces as well as VDOF audit classifications. Timber access roads were the greatest source of erosion in the Piedmont and Mountains, while harvested areas were the largest identified erosion area in the Coastal Plain, based upon the disturbance categories ratio to the total tract area. Estimated erosion rate trends over time indicated that the majority of disturbance categories were essentially recovered between eight to ten years after harvest. Further, disturbance categories in the Coastal Plain recovered faster than the other province. Erosion rates could not be explained by the year since harvest, since numerous variables interact to cause erosion. Overall predicted erosion rates and VDOF audit classifications of problems did not have consistent agreement. This indicates the need for additional calibration of VDOF ratings and perhaps the establishment of more quantifiable BMP inspection criteria.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

41

Carr, Jeffery A. "Harvesting impacts on steep slopes in Virginia". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42203.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

42

Marra, Michael A. "Switchgrass potential on reclaimed surface mines for biofuel production in West Virginia". Thesis, West Virginia University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1522523.

Pełny tekst źródła

Streszczenie:

The high cost and environmental risks associated with non-renewable energy sources has caused an increased interest in, and development of renewable biofuels. Switchgrass (Panicum virgatum L.), a warm season perennial grass, has been investigated as a source of biofuel feedstock due to its high biomass production on marginal soils, its tolerance of harsh growing conditions, and its ability to provide habitat for wildlife and soil conservation cover. West Virginia contains vast expanses of reclaimed surface mine lands and could potentially benefit from the production of switchgrass as a biofuel feedstock. Furthermore, switchgrass production could satisfy Surface Mining Reclamation and Control Act of 1977 (SMCRA) requirements for reclamation bond release to mine operators. Three separate studies will be discussed in this thesis to determine if switchgrass grown on reclaimed surface mines can produce yields similar to yields from stands grown under normal agronomic conditions and what common surface mining reclamation practices may be most appropriate for growing switchgrass. The first study examined yield production of three commercially-available, upland switchgrass varieties grown on two reclaimed surface mines in production years two, three and four. The Hampshire Hill mine site, which was reclaimed in the late 1990s using top soil and treated municipal sludge, averaged 5,800 kg (ha-yr)^-1 of switchgrass compared to 803 kg (ha-yr)^-1 at the Hobet 21 site which was reclaimed with crushed, unweathered rock over compacted overburden. Site and variety interacted with Cave-in-Rock as the top performer at the more fertile Hampshire Hill site and Shawnee produced the highest yields at Hobet 21 (7,853 kg ha^-1 and 1,086 kg ha^-1 averaged across years, respectively). Switchgrass yields increased from 2009 to 2010, but declined from 2010 to 2011. Switchgrass yields from farmlands in this region averaged about 15000 kg (ha-yr)^-1 in the research literature, so switchgrass grown on reclaimed lands appears to be about 50% lower. A second study to determine optimal nitrogen and mulch rates for switchgrass establishment began in June 2011 on two newly-reclaimed surface mines. Both sites were seeded at a rate of 11.2 kg pure live seed (PLS) ha^-1 of Cave-in-Rock on replicated treatments of 0, 33.6 and 67.0 kg N ha^-1, and high and low mulch rates of mulch applied as hydromulch. Switchgrass cover, frequency and yield improved with the addition of any amount of N fertilizer compared to no N application. There was no significant difference in yield associated with high and low levels of N. We also observed that yields were not affected by application of additional mulch. The final study compared a one- and two-harvest system in the fourth year of production at the Hampshire Hill and Hobet 21 sites. There was no increase in yield production utilizing a two-harvest system (2922 kg (ha-yr)^-1, averaged across site) compared to a one-harvest system (3029 kg (ha-yr)^-1). The data also showed that re-growth collected from July to October in the two-harvest system added negligible yield and that yield collected in July was comparable in one- and two-harvest systems.

Style APA, Harvard, Vancouver, ISO itp.

43

Raphael, De La Madrid Lucia Del Carmen. "L'essai de soi, relectures de l'oeuvre de Virginia Woolf". Phd thesis, Université de la Sorbonne nouvelle - Paris III, 2009. http://tel.archives-ouvertes.fr/tel-00951445.

Pełny tekst źródła

Streszczenie:

"L'essai de soi ", en tant que méthode littéraire, crée dans l'œuvre de Woolf, Les Vagues, une nouvelle façon de faire littérature, ainsi qu'une nouvelle pensée philosophique. À fin de comprendre comment l'essai exerce une influence sur le travail de Woolf, J'ai analysé Les Essais de Michel de Montaigne, comme une méthode, comme l'exegium, dans ses multiples connotations ainsi que comme processus qui donne naissance à l'essai en tant que genre littéraire, dans son acception moderne. À travers " l'essai de soi " Montaigne et Woolf élaborent leurs propres autoportraits avec des mots. Pour une meilleure compréhension de ce processus j'ai établi des échos avec des philosophes contemporains et avec l'analyse des spécialistes. Pour une meilleure compréhension de " l'essai de soi " par rapport au travail de Woolf, je propose la définition des principes qui définissent la méthode de Montaigne. Ces principes ont été développés comme des axes de " l'essai de soi " sa définition et son interaction à chaque moment de son écriture. Dans le sens d'un " jeu d'abymes ", j'ai visé le centre d'un entrecroisement d'hommages. Celui que Montaigne rend à Etienne de la Boétie, et la relation littéraire que Woolf établit avec Montaigne. Les deux auteurs développent son écriture comme une sorte d'autobiographie, mais ils vont au-delà de ce genre, par le registre du passage du temps et les transformations qui s'opèrent au moment de l'écriture. Les personnages de Woolf sont construits à partir de la variété de multiplicités que chacun en soi, celle que les autres et le regard des autres lui apportent. Les Vagues est une radiographie de l'esprit humain qui est au même temps approche philosophique, l'écriture suit ce que Montaigne décrit comme une forme elliptique de création. Les deux auteurs se basent sur l'expérience humaine, celle qui est commune à tous, là au chacun se rencontre avec l'autre. À travers ce processus, Woolf traduit la philosophie de Montaigne en style narratif.

Style APA, Harvard, Vancouver, ISO itp.

44

Genthner, Michael Hoffman. "The variability and geomorphology of Appling, Cecil, and Davidson soils on sideslopes in the Virginia Piedmont". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-06112009-063114/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

45

Severson, Erik D. "Hydropedology of Problematic Interfluve Transported Soils in the Central Virginia Piedmont". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73101.

Pełny tekst źródła

Streszczenie:

Interpreting soil wetness in upland transported soils on flat broad summits in the central Piedmont of Virginia containing chroma ≥ 3 redoximorphic features (RMFs) can be difficult. It is imperative to understand their saturation regimes because onsite wastewater disposal systems, which are sited based upon soil evaluations, have failed prematurely when installed into these problematic soils. My objectives were to determine if soil morphology was an accurate predictor of soil wetness and permeability, to differentiate interpretations for colluvial soils from residual soils, and to determine the effect of canopy cover on seasonal wetness. Soil morphology, soil wetness regimes in open and wooded canopies, and in-situ saturated hydraulic conductivity were documented in transported Appomattox, Bentley, Brockroad, Catharpin, and Dothan and residual Clifford, Minnieville, and Penhook soil series at eight sites. Transported soils had average winter water levels, and met 30-day and 20-day NRCS oxyaquic criteria at 81, 66, and 91 cm, respectively. Transported soils with depleted ped faces, Fe- concentrations, and chroma 3 depletions were saturated an average of 41, 23, and 41% of the winter, respectively. Residuum found ≥ 1.5 m beneath transported soils exhibited little saturation, thus confirming epiaquic conditions. Residual soils did not perch water for extended periods; and were saturated for significantly (p<0.001) shorter durations and shallower depths (average 93 and 82 cm for 30-day and 20-day oxyaquic criteria, respectively). Transported soils under clear cuts had significantly (p<0.001) shallower average water levels (79 cm) and 30-day and 20-day oxyaquic conditions (51 and 88 cm, respectively) than wooded locations (87 and 83 cm average water levels and 30-day oxyaquic water table, respectively). In-situ hydraulic testing confirmed the presence of low permeability layers as determined by soil evaluation. Restrictive layers were thicker and less permeable in transported soils than in residual soils. In summary, water perches seasonally for extended periods over thick impermeable layers in transported soils. A recommended best management practice for problematic transported soils would be to not install septic systems in zones of saturation and low permeability, including the 1.5 m below a discontinuity. Drainfield designs should utilize permeable saprolite beneath transported material and an upslope curtain drain.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

46

Lukezic, Craig. "The Effect of Soils on Settlement Location in Colonial Tidewater, Virginia". W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539625336.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

47

Schooley, Therese Nowak. "Historical Use of Lead Arsenate and Survey of Soil Residues in Former Apple Orchards in Virginia". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33674.

Pełny tekst źródła

Streszczenie:

Inorganic pesticides including natural chemicals such as arsenic, copper, lead, and sulfur have been used extensively to control pests in agriculture. Lead arsenate (PbHAsO4) was first used in apple orchards in the late 1890's to combat the codling moth, Cydia pomonella (Linnaeus). The affordable and persistent pesticide was applied in ever increasing amounts for the next half century. The persistence in the environment in addition to the heavy applications during the early 1900's may have led to many of the current and former orchards in this country being contaminated. In this study, soil samples were taken from several apple orchards across the state, ranging from Southwest to Northern Virginia and were analyzed for arsenic and lead. Based on naturally occurring background levels and standards set by other states, two orchards sampled in this study were found to have very high levels of arsenic and lead in the soil, Snead Farm and Mint Spring Recreational Park. Average arsenic levels at Mint Spring Recreational Park and Snead Farm were found to be 65.2 ppm and 107.6 ppm, respectively. Average lead levels were found to be 354.5 ppm and 442.3 ppm, respectively. Based on these results, Virginia needs to look at setting standards for lead and arsenic in soil to determine if cleanup of former agricultural lands will be necessary.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

48

McElligott, Kristin Mae. "Soil Respiration and Decomposition Dynamics of Loblolly Pine (Pinus taeda L.) Plantations in the Virginia Piedmont". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/75154.

Pełny tekst źródła

Streszczenie:

Forests of the southeastern U.S. play an important role in meeting the increasing demand for forest products, and represent an important carbon (C) sink that can be managed as a potential tool for mitigating atmospheric CO2 concentrations and global climate change. However, realizing this potential depends on full accounting of the ecosystem carbon (C) budget. The separate evaluation of root-derived, autotrophic (RA) and microbially-derived heterotrophic (RH) soil respiration in response to management and climate change is important, as environmental and ecological factors often differentially affect these components, and RH can be weighed against net primary productivity (NPP) to estimate the C sink or source status of forest ecosystems. The objective of this research was to improve the quantitative and mechanistic understanding of soil respiratory fluxes in managed loblolly pine (Pinus taeda L.) plantations of the southeastern U.S. To achieve this overall objective, three studies were implemented to: 1) estimate the proportion and seasonality of RH:RS in four stand age classes, and identify relationships between RH:RS and stand characteristics 2) evaluate the effects of forest nutrient management and throughfall reduction on factors that influence RH and decomposition dynamics, including litter quality, microbial biomass, and enzyme activity and 3) evaluate the sensitivity of sources of RH (mineral soil-derived heterotrophic respiration; RHM, and leaf litter-derived heterotrophic respiration; RHL) to varying soil and litter water content over the course of a dry down event, and assess whether fertilization influences RH. Stand age and measurement season each had a significant effect on RH:RS (P < 0.001), but there were no interactive effects (P = 0.202). Mean RH:RS during the 12-month study declined with stand age, and were 0.82, 0.73, 0.59, and 0.50 for 3-year-old, 9-year-old, 18- year-old, and 25-year-old stands, respectively. Across all age classes, the winter season had the highest mean RH:RS of 0.85 while summer had the lowest of 0.55. Additionally, there were highly significant (P < 0.001) and strong (r > 0.5) correlations between RH:RS and peak LAI, stem volume, and understory biomass. Fertilization improved litter quality by significantly decreasing lignin:N and lignin:P ratios, caused a shift in extracellular enzyme activity from mineral soil N- and P-acquiring enzyme activity to litter C-acquiring enzyme activity, and increased microbial biomass pools. Throughfall reduction decreased litter quality by increasing lignin:N and lignin:P, but also increased C-acquiring enzyme activity. RHL was more sensitive to water content than RHM, and increased linearly with increasing litter water content (R2 = 0.89). The contribution of RHL to RH was greatest immediately following the wetting event, and decreased rapidly to near-zero between three – 10 days. RHM also had a strong relationship with soil water content (R2 = 0.62), but took between 200 – 233 days to attain near-zero RHM rates. Fertilization had no effect on RHM (P = 0.657), but significantly suppressed RHL rates after the wetting event (P < 0.009). This research provides estimates of RH:RS in managed loblolly pine systems that can be used to improve regional ecosystem C modeling efforts, and demonstrates the need to consider the impact of stand age and seasonal patterns to identify the point at which plantations switch from functioning as C sources to C sinks. Additionally, it demonstrates that the controls over RH are dynamic and influenced in the short-term by fertilization and changed precipitation regimes, with the greatest impact on properties affecting litter RH compared to mineral soil. Future research should work to improve the mechanistic understanding of the seasonal and spatial variability of RH and related controlling biotic and abiotic parameters to remedy the variability in existing RS and ecosystem C models. Understanding how management and climate change may impact factors that control RH will ultimately improve our understanding of what drives changes in forest C fluxes.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

49

McMahon, Paul Christopher. "Simulation of corn yield by a water management model for a Coastal Plain soil in Virginia". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53719.

Pełny tekst źródła

Streszczenie:

DRAINMOD, a water management simulation model for artificially-drained soils, was evaluated for a Virginia Coastal Plain soil by comparing predicted and measured water table depths from a subirrigation/controlled drainage site over a period of three years. Water table elevations predicted by the model were in good agreement with measured water table elevation data with an average deviation of 9.47 cm for the three years of record. The YIELD version of DRAINMOD was used to predict corn yield for the subirrigation/controlled drainage site. Average corn yield predictions by the model agreed reasonably well with the observed average corn yield data with relative errors of 19.2, 4.4, and 8.1 percent for 1984, 1985, and 1986, respectively. Additionally, corn yields predicted for a conventional drainage system were considerably lower than those predicted for subirrigation/controlled drainage, reaffirming the need for irrigation of corn in the Coastal Plain region of Virginia. Research results indicate that DRAINMOD is a powerful tool for the design and evaluation of subirrigation/controlled drainage practices in the Virginia Coastal Plain. Simulations were performed for a 20-year period to determine the effects of system design on corn yield. An economic analysis was performed to determine optimal system design for maximizing profits from corn production. A drain spacing of 21.3 m, a drain depth of 110 cm, and a 65 cm weir depth were the design parameters recommended as optimal for maximizing profits from subirrigation/controlled drainage of corn on a Myatt fine sandy loam soil in the Virginia Coastal Plain.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

50

Groeschl, David A. "Forest soil and vegetation characteristics in two forest types following wildfire in the Shenandoah National Park, Virginia". Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-11242009-020129/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

Rozprawy doktorskie na temat „VIRGIN SOIL”

Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych