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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The influence of soil characteristics and fertilizer treatment on growth and chemical composition of Pinus resinosa.

Cotton, Donald. R. January 1964 (has links)
Vast areas of abandoned or sub-marginal land exist. In Quebec alone it has been estimated that there are about 1,400,000 acres of abandoned farmland (32). Some of this land is being turned into tree farms and more of it could be so utilized if some problems could be overcome. The chief difficulties existing are mainly those of uneven topography, poor drainage and low fertility status of the soil. This latter problem could be possibly the easiest difficulty to overcome provided adequate knowledge existed of the effects of fertilization on reforested areas. To assess relative fertility levels of soils for purposes of reforestation methods of soils analysis as well as plant analysis may be useful. These must be developed in conjunction with fertilizer application experiments either in the field or in the greenhouse under a controlled environment.
2

Technique for determining soil potassium availability using K-42.

Nutall, W. F. January 1965 (has links)
The advent of radioactive isotopes as tracers in fertilizers, led to a new concept of determining availability of soil nutrients to the plant (Fried and Dean, 1952; Larson, 1952). [...]
3

Studies on salt movement and on tracing water movement in soils.

Hamid, Abdul. January 1966 (has links)
Inadequate drainage is a challenging problem in both humid and arid regions of the world. In arid regions water logging is the basic cause of salinity and alkalinity, and they go hand in hand. One of these conditions usually indicates the presence of the other. [...]
4

The effects of fire frequency and fire intensity on AM fungal spore abundance, species variety and percent root colonization at Schenck Forest and James Goodwin Forest

Rabe Ranjanivo, Mialy-Tiana 05 February 2003 (has links)
Two greenhouse studies were undertaken: (1) To assess the effects of prescribed fire frequency on AM spore abundance, species variety, and AM percent root colonization of Sudan grass Sorghum sudanese L., between an annually burned site, and a seven-year burned site on a loblolly pine, Pinus taeda L. stand, at Schenck Forest, Wake County, NC., (2) To determine the effects of two levels of fire intensity of pile burning (343oC- 371oC and >470oC), at two depths (0-2cm and 3-6cm), by year and season, on AM fungal spore abundance, AM species variety, and AM percent root colonization of Sudan grass Sorghum sudanese L. at James Goodwin Forest, Moore County, NC. All soil samples were air-dried at room temperature (23oC), stored at 4oC prior to use as inoculum in a greenhouse trap culture. At Schenck Forest, repeated fire was found to impact AM spore abundance though less affecting the species variety. The seven-year burned site had higher number of spores overall. The percent root colonization study revealed non-significant effects of repeated fire between the annually burned and the seven-year burned sites. The percent AM fungal root colonization in spring was always significantly higher than in summer at the annually burned site, but always higher in summer than in spring at the seven-year burned site. Summer had significantly more spores than spring. At James Goodwin Forest, fire disturbance coupled with mild soil surface erosion induced a highly significant difference in AM percent colonization between the control and the disturbed sites pre-burn and burn. Fire disturbance significantly affected AM root colonization by depth compared with unburned. The response of AM root colonization to disturbance is very significantly site specific. The effect of fire intensity is significantly affected by vertical distribution of the propagules. Species variety at both Schenk Forest and James Goodwin Forest non-significantly decreased, propagules survived from high intensity fire but spore numbers were significantly reduced.
5

Effects of Design Changes on Sediment Retention Basin Efficiency

Markusic, Melanie Sue 28 February 2007 (has links)
Sediment pollution from construction sites has been of increasing concern since the impacts on nearby streams can be severe. Controlling erosion is the most effective approach to reducing sediment loads, but construction sites typically have large areas of exposed soil during the active phase of clearing and grading. As a result, sediment traps and basins are required to capture eroded sediment on most of these sites. The purpose of this research was to determine the trapping efficiencies of sediment basins of various designs installed on active construction sites. Five traps and one basin were monitored in the Piedmont of North Carolina, all on highway construction sites except one trap on a private development. Automatic samplers were installed to measure flow and to obtain representative samples during storm events. The basins were surveyed after storms to determine the change in volume after repeated surveys. Trapping efficiency was calculated from the sediment accumulation within the traps or basin and the amount of sediment discharged, the sum of which was the total sediment entering the device. Particle size distribution in the sediment deposits was also determined. Two standard traps with rock outlets were found to have 37% and 46% trapping efficiencies after three storm events. A standard trap with silt fence baffles was found to have 45% and 36% efficiency rates during two time periods. Two additional traps, which had been sized for a 25-year storm event, instead of the standard 10-year event, had retention efficiencies of 96% and 99%. A sediment basin with porous baffles and a skimmer outlet had a retention efficiency of 99.8%. One standard trap had particle size distributions for sand, silt, and clay of 34%, 36%, and 30% while a standard trap with a permanent pool had particle size distributions of 55%, 25%, and 20%. The standard trap with silt fence baffles had a distribution of 36%, 50%, and 14%. The 25-year traps had distributions of 75%, 18%, and 7%; and 55%, 20%, and 25%, respectively. The skimmer basin had a distribution of 62%, 28%, and 10%. The higher proportion of sand in the more efficient devices suggests that the less efficient traps are releasing significant amount of sand-size sediment. Larger basins and surface outlets clearly provide greater sediment trapping on construction sites.
6

Polyacrylamide Use for Erosion and Turbidity Control on Construction Sites

Hayes, Sara 08 April 2003 (has links)
Sediment is the most widespread pollutant of streams and rivers in North Carolina. Construction sites are a source of accelerated erosion contributing to the sediment problem. This study was conducted to determine if the application of polyacrylamide (PAM) to soil surfaces on construction sites reduces erosion and turbidity. Polyacrylamide has been demonstrated to greatly reduce erosion in furrow irrigation, and there is limited evidence it controls erosion when applied to bare soil. Two PAM products applied at manufacturers recommended rates (11.2 and 1.68 kg ha-1) and one half the recommended rates (5.6 and 0.84 kg ha-1) with and without grass seeding and mulching were tested on three North Carolina Department of Transportation construction sites in Raleigh and near Fayetteville. Runoff volumes, turbidity levels, and eroded sediment data were collected after natural rain events. On a 2:1 cut slope, turbidity and sediment loss were significantly decreased with application of seed/mulch. Erosion rates were 20 times greater on bare soil after seven rain events, with or without PAM, compared to treatments receiving seed/mulch. Polyacrylamide applied with seed/mulch produced slight reductions in turbidity and sediment loss in early rain events. At the higher rate, PAM applied directly on a more moderate, 4:1 fill slope decreased sediment loss and turbidity in the first few rain events following application compared to bare soil, with decreases diminishing over time. A sandy fill slope had inconsistent results between PAM treatments but reductions in turbidity and sediment from seed/mulch applications.
7

Assessing the Reliability of Hydrologic Characterizations of Four Wetland Plant Communities

Conk, Carlin Elizabeth 14 May 2008 (has links)
Previous field work characterized the wetness requirements of four plant communities by modeling their hydrologic regimes in three reference wetlands and correlating the results. The objectives of this work were to: 1) determine whether the modeled predictions were accurate by growing four tree species that represented different plant communities under the modeled hydrologies in the greenhouse, and 2) determine how different tree species adapt to saturated soil conditions. Bald cypress (Taxodium distichum), sweet bay (Magnolia virginiana), pond pine (Pinus serotina), and swamp chestnut oak (Quercus michauxii) were grown in greenhouse experiments under three hydrologic regimes: i) ponded for 100 d, ii) ponded for 15 d, and iii) unsaturated. Loamy sand and sapric materials from a restored Carolina Bay were the substrate materials used to represent mineral and organic soils. Bald cypress (representing Non-riverine Swamp Forest) adapted well to 100 d of ponding by producing lateral roots near the surface, aerenchyma tissue in roots and stem, and increasing P uptake. In organic soils ponded for 100 d, bald cypress had significantly greater height, diameter, and total biomass than all other tree species. Sweet bay (representing Bay Forest) adapted well to 100 d of ponding by producing adventitious roots on the submerged portion of the stem. Pond pine (representing Pond Pine Woodland) was intolerant to 100 d of ponded conditions and 75% of the seedlings died in the ponded experiments. Swamp chestnut oak (representing Non-riverine Wet Hardwood Forest) was intolerant to ponding and all seedlings died in ponded treatments. A rhizotron study was conducted to further observe and quantify biological, morphological, and physiological changes in two wetland tree species with differing tolerances to saturated conditions. Bald cypress and swamp chestnut oak seedlings were grown under ponded and unponded conditions for 106 d in rhizotrons containing the same soils used in the container study. Within 2 wk of ponding, bald cypress (BC) seedlings in both organic and mineral soils began to produce lateral roots within the top 36 cm of soil. The swamp chestnut oak (SCO) seedlings subjected to ponding did not produce many new roots, and root death was observed within 4 wk of flooding. Scanning electron microscopy images of basal stems and roots of BC subjected to saturation showed substantial development of aerenchyma, which may have aided in the overall tolerance of BC to ponded conditions. This study showed BC seedlings developed numerous adaptations to saturated conditions, which allowed them to grow in wet organic soils of the Coastal Plain. Results from the container and rhizotron experiments showed that modeling of the long-term hydrology of natural communities was accurate in predicting the preferred wetness requirements of representative trees in three of the four plant communities evaluated.
8

Phosphorus Dynamics from Broiler Breeder Diets in Manure, Soil, and Corn.

Casteel, Shaun Nathan 27 April 2009 (has links)
Studies of broiler breeder diet modifications to reduce phosphorus (P) excretion have evaluated bird performance, but no studies have quantified the effects of P in the manure and the impacts to soil and plant availability once soil-applied. Four diets were formulated by factoring two levels, 0.40 and 0.22% available P (NRC, Low, respectively), with or without phytase during the breeder laying phase (wk 22 to 64). Breeders fed phytase produced manures with 15% lower total P concentration, but did not change manure water-soluble P (WSP). However, P in the breeder manures was > 92% orthophosphate. The incubation of the four unique manures in samples of Portsmouth (Typic Umbraquult) and Wagram (Arenic Kandiudult) series generally did not differ in concentrations of Mehlich-3 P, soil WSP, total inorganic P, and total P. Phosphorus-based applications of breeder manures (NRC, Low) and triple superphosphate (TSP, Ca[H2PO4]2 H2O) were applied to a P-deficient, Portsmouth soil in the greenhouse to determine the response of corn (Zea mays). Corn growth was equal among P sources in the initial study, but it tended to be greater in the soils amended with breeder manures in the residual study due to the P applied and the apparent liming effect of the soil. The NRC and Low breeder manures were applied at 39 kg P ha-1 in 2007 at Salisbury (Typic Rhodudult), Lewiston (Aquic Paleudult), and Plymouth (Typic Umbraquult), which ranged in soil P levels. Plymouth included TSP and an untreated control. Corn growth was equal among soils amended with the breeder manures NRC and Low in all site-years and grain P removal was equal five out of six site-years. Grain production, grain P removal, and applied P recovery were equal among P sources in 2007, but the breeder manure treatments were greater than TSP in 2008. Breeder manures should be considered equivalent to TSP in P impacts to the soil and plant availability.
9

Performance of Mulches and Polyacrylamide for Erosion Control and Vegetative Establishment

Babcock, Deanna 28 April 2008 (has links)
The application of mulch products to disturbed soil is frequently used to decrease soil erosion. The addition of polyacrylamide (PAM) has been demonstrated to reduce erosion even further. We conducted rainfall-simulator and field tests on several types of mulch, hydromulch, and erosion control blankets with varying rates of PAM to determine the relative improvements in erosion control and vegetative establishment achieved by different groundcovers and PAM. We also compared applications of granular (37 and 74 kg ha-1) and aqueous (37 kg ha-1) PAM with straw. The tests were done on 2- x 1-m soil boxes tilted to 32% slope and three field locations with similar slopes. Under simulated rainfall, the addition of 37 kg ha-1 aqueous PAM to any mulch type tended to reduce runoff turbidity, TSS, and sediment loss, with reductions of 50% or more in some cases. In the absence of PAM, increasing hydromulch rate from 1971 kg ha-1 to 2957 kg ha-1 significantly reduced turbidity for an experimental cotton product but not for wood fiber. Granular PAM, when applied at a rate equal to that of aqueous PAM, had a significantly higher mean turbidity and TSS; total sediment loss was reduced by dry-PAM only at the higher rate. The lower rate of granular PAM apparently did not reduce erosion but did flocculate the sediment captured in the runoff collection bucket, reducing turbidity. In field experiments, bonded fiber matrix had significantly lower biomass and vegetative cover than all other treatments at one site but differences were not significant at other sites. In one instance where a cotton fiber matrix test product washed off the slope face, runoff turbidity and TSS was significantly higher than other treatments. There were no instances of straw with PAM significantly improving biomass or vegetative cover compared to straw alone.
10

Using Apparent Electrical Conductivity (ECa) via Electromagnetic Induction (EMI) to Characterize Soils and the Stratigraphy for Wetland Restoration

Davis, Karen Melissa 05 July 2007 (has links)
Wetland restoration can be difficult due to the time consuming efforts it requires to evaluate the soils and vegetation within the area being considered. The objective of this study was to determine whether apparent soil electrical conductivity (ECa) measured via electromagnetic induction (EMI) (a non-contact method) could be used to identify soil particle size distribution, map units, and selected chemical properties at a Carolina bay wetland restoration site, Juniper Bay. Surveys of ECa were performed at Juniper Bay in December 2000, June 2001, October 2005, and December 2005 using the EM38, GEM-2, and GEM-300 in the horizontal and vertical dipole positions. Cores were dug to depths of 6.1 and 15.2 m based on an equilateral triangle grid and adequate representative sampling of soil map units. Pits were dug to 1- and 1.5-m depths. Core and pit samples were analyzed for particle size distribution and soil chemical properties. Surficial samples were collected from 0- to 15-cm and 15- to 30-cm depths; chemical properties were evaluated on these samples. Correlations of ECa with soil particle size distribution and chemical properties were determined. Linear models were derived relating soil clay content and ECa. Soil ECa was compared with soil organic C and water table depth to determine if either property could be detected using EMI. Also, ECa from different survey dates were compared to determine whether there were short-term (within a day) and long-term (months to years) temporal changes in ECa. The ECa from the initial overall December 2000 survey was strongly correlated with soil core clay content at depths from 0.61 to 1.22 m and 2.74 to 3.96 m. The reason for this is unknown. Initial overall December 2000 ECa was also strongly correlated with pit clay content. No other soil core or pit particle size analysis properties had strong significant and consistent correlations with ECa for the December 2000 survey or for any of the other surveys. Few chemical properties were correlated with ECa; however, ECa was weakly correlated with pit organic C. Results showed that ECa could not be used to delineate soil map unit, but the map unit ECa means were different. However, ECa could not detect water table depth at Juniper Bay. Soil ECa was found to be temporally variable, and ECa surveyors should be conscious of potentially varying conditions from survey to survey. Along with ground-truthing, ECa modeling could be used to estimate clay content at certain depths and locations within Juniper Bay. This could aid wetland restoration by identifying locations of aquitards, which might have been penetrated by drainage ditches. Filling the ditches in the correct places could allow restoration to progress faster and more efficiently.

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