• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 220
  • 177
  • 50
  • 26
  • 26
  • 26
  • 26
  • 26
  • 24
  • 12
  • 7
  • 5
  • 3
  • 3
  • 2
  • Tagged with
  • 592
  • 99
  • 98
  • 77
  • 70
  • 66
  • 64
  • 61
  • 57
  • 56
  • 54
  • 53
  • 53
  • 51
  • 48
  • 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.
161

Chemically enhanced gravitational solid-liquid separation for the management of phosphorus in liquid swine manure

Agomoh, Ikechukwu Vincent 11 September 2012 (has links)
This laboratory column (125 cm high, 15 cm diameter) research investigated solids and P removal from liquid swine manure amended with calcium carbonate, magnesium sulphate, alum and polyacrylamide (PAM). Results showed that PAM was the most effective amendment for enhancing solids removal from manure containing 1% initial total solids (TS). The effectiveness of PAM was lower at 5% and 8% than at 1% due to resuspension of solids occurring at settling times beyond 4 h. After 24 h of settling, P removal from non-amended manure was comparable to that in amended manure and decreased with TS concentration for all amendments except alum, which was equally effective at all TS concentrations. These results indicate that, for manure containing 1% TS, P can be adequately removed by gravity separation without addition of chemical amendments while alum is a more effective amendment for removing P from manure containing higher (5% and 8%) TS.
162

La perméabilité des réservoirs à lisier en béton /

Denis, Jacques January 1989 (has links)
Two underground concrete manure reservoirs of 70 m$ sp3$ were tested for their infiltration rate to water as well as to 1% and 3% total solid dairy manure. Positive and negative infiltration were measured for the water test while only negative infiltration was measured with the manure. / Positive infiltration is met when the water table into the soil is above the liquid level into the reservoir. In that case, the water is moving from the outside to the inside of the reservoir. An opposite situation is met when the infiltration is negative. / From the results, the infiltration rate varied from 0.00 to 6.684 $ times$ 10$ sp{-7}$ m/s. The minimum value was recorded at the reservoir 55 with 1% of total solid manure and the maximum value was recorded with same reservoir with positive pressure to water.
163

Evidence for Participation of Anammox in Nitrogen Attenuation Observed in Groundwater Impacted by a Manure Lagoon

Carson, Lucas William 16 January 2012 (has links)
Decades of agricultural use of fertilizer and manure has resulted in nitrogen being the most common groundwater contaminant. Of the known processes for nitrogen attenuation, both denitrification and anammox produce a complete transformation of nitrogen species to dinitrogen gas (N2); however, denitrification is typically also associated with the release of N2O and CO2, both greenhouse gases. Anaerobic ammonium oxidation (Anammox), which has been recently discovered to be more prevalent in groundwater environments than previously thought, simultaneously removes NH4+ and nitrate (NO3-), does not require dissolved organic carbon (DOC), and does not produce greenhouse gas by-products. This study evaluates the natural occurrence of anammox in a manure lagoon plume, as well as the feasibility of enhancing anammox activity by mixing NH4+ rich groundwaters and NO3- rich groundwaters together. Fifteen experiments were undertaken with NH4+-N concentrations ranging between 5-100 mg/L, and a NO3--N ranging from 5-88 mg/L. These experiments suggest a nitrogen removal rate (based on NH4 + removal in anaerobic conditions) from anammox generally in the range of 0.1-0.2 mg/L/day. Based on an absence of dissolved oxygen (DO), and concomitant loss of NO3--N with associated 15N-NO3- enrichment (2.1-8.7‰ ) in 11 experiments, it is considered unlikely that nitrification was the cause of the NH4+ loss observed in these experiments. Concurrent 15NNH4+ enrichment of 4.1-11.5‰ was observed in these 11 experiments. Real-time quantitative polymerase chain reaction (qPCR) DNA analyses were used to show the presence of anammox bacteria and to demonstrate temporal population increases during the experiments (up to 16.3% anammox in total bacteria population) in the three experiments analyzed. Although anammoxrelated N removal rates were modest in these trials, such rates could be significant with respect to the multi-year residence times associated with most groundwater flow systems.
164

Surface irrigation adapted to the land spreading of dairy farm effluent

Ali, Inamullah January 2005 (has links)
An important number of Canadian dairy farms manage their manure as solids and in doing so, must handle large volumes of manure seepages and milk house wastewater (dairy farm effluent-DFE). The present project adapted surface irrigation as a more economical and sustainable method of disposing of this large volume of DFE on cropped land near their storage facility. The experimental surface irrigation system consisted of a gated pipe installed perpendicular to the slope of the field allowing the discharged DFE to run down the slope. / The adaptation of the system and the measurement of its environmental impact were conducted on two dairy farms, A and B, in the region South West of Montreal where their DFE were characterized. In 2003 and 2004, DFE was applied on one of two 0.5 and 0.3ha plots, on each farm, to observe losses through the subsurface drainage system, by means of sampling wells, and effects on soil nutrient levels. / The DFE collected in 2002 and 2003 had a lower nutrient content than that collected in 2004 because of higher precipitations. The DFE generally contained between 150-500 mg/L of TKN, 15 to 40 mg/L of TP and 500 to 700 mg/L of TK. / DFE losses through the subsurface drainage system were observed on both farms during each irrigation test. Nevertheless, outlet losses were observed only when irrigating under wet soil conditions or when applying more than 50mm of DFE. Outlet losses represented at the most 1.2% of the total DFE volume applied and 0.32% of the nutrient and bacterial loads. / Although only 65 to 75% of the soil surface was covered by the applied DFE, the irrigation sessions did provide some additional soil moisture for crops, increasing yield by 31% in 2004. Once absorbed by the soil, the applied DFE did not increase the soil nutrient level and variability in the presence of crop. Thus, the DFE contributed to the irrigation and fertilization of the plots. / Surface irrigation to spread low nutrient DFE, as compared to the conventional tanker system reduced the application costs from $3.05/m3, to $0.95/m3.
165

Rapid Phytate Quantification in Manures and Runoff Sediments using HPIC

Rippner, Devin A. 02 August 2013 (has links)
Accurate quantification of phosphorus (P) fractions in manures and agricultural runoff is vital to understanding P dynamics in the environment. Phytate is an organic form of P, with 6 phosphate groups, which is found in manures, but is difficult to quantify due to its affinity for complex formation with aluminum (Al) and iron (Fe). The objective of the first study was to measure if high concentrations of aluminum (Al) and iron (Fe) hinder accurate quantification of phytate in dairy manure and broiler litter when measured by high performance ion chromatography (HPIC). In this study dairy manure and broiler litter samples were spiked with Al, Fe, and phytate. Samples were alkaline extracted, acidified,cleaned up and filtered, and then phytate was analyzed with HPIC. High concentrations of Fe did not hinder phytate recovery in manure or litter samples. While phytate recovery was close to 100% at typical manure and litter Al concentrations, high concentrations of Al inhibited phytate recovery in litter samples and in some manure samples. Overall, alkaline extraction of dairy manure and broiler litter and analysis with HPIC proved to be a relatively accurate, fast and cheap within normal Al and Fe ranges, compared to the commonly used NMR method. The developed method was then used to measure the concentration of phytate P (Pp) rather than the entire phytate molecule (6 moles Pp per mole phytate) in runoff waters and in an adsorption study. Phytate P has not been previously measured in runoff, due to the low concentrations of Pp found in runoff and the complexity Pp extraction from runoff. Runoff treatments were dairy manure with and without added Pp (DM, DM+Pp), broiler litter with and without added Pp (BL, BL+Pp), and control, with and without two levels of Pp (control, control Pp low, control Pp high). Runoff was collected under simulated rainfall and analyzed for total and dissolved reactive P (DRP). Runoff was also separated into sediment (>0.45"m) and liquid (<0.45"m and lyophilized) fractions for Pp analysis by high performance ion chromatography (HPIC). The new method for Pp analysis recovered 70% of Pp spiked into runoff samples. Phytate P was found only on the sediment fraction of runoff and was not detected in the liquid fraction, even when it was lyophilized and extracted. This agreed with the adsorption study, which showed strong adsorption of Pp. Phytate P loss from control Pp high was significantly greater than Pp loss from control. �When control Pp high was removed from analysis, Pp loss from BL, BL+Pp, DM, and DM+Pp was significantly greater than from control. Phytate P in the manures appeared to behave differently than pure Pp salts, likely to do the formation of protein-phytate and cation-phytate complexes in the manures. Phytate P had no effect on DRP in runoff for any treatment, indicating no significant release of inorganic P through competitive binding. The majority of P lost in runoff was in fractions other than DRP and Pp in the sediment fraction. Efforts to control the erosive loss of soil during rainfall events appear to be the best way to reduce total P loss, irrespective of the presence of Pp. / Master of Science
166

Agroecosystem management effects on carbon and nitrogen cycling across a coastal plain catena

Gacengo, Catherine N. Wood, C. W. Shaw, Joey N., January 2008 (has links) (PDF)
Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Includes bibliographical references (p. 126-136).
167

The effects of green manure rotation crops on soils and potato yield and quality /

Barker Plotkin, Jeremy Matthew, Porter, Gregory A., Griffin, Timothy. Honeycutt, C. Wayne. January 2000 (has links)
Thesis (M.S.) in Plant, Soil and Environmental Science--University of Maine, 2000. / Includes vita. Advisory Committee: Gregory A. Porter, Assoc. Prof. of Agronomy, Advisor; Timothy Griffin, Extension Sustainable Agriculture Specialist and Assoc. Prof., Sustainable Cropping Systems; C. Wayne Honeycutt, Lead Scientist, USDA-ARS New England Plan, Soil and Water Laboratory. Includes bibliographical references (leaves 88-96).
168

Satellite mapping of past biosolids (sewage sludg) [sic] and animal manure application to agriculturel [sic] fields in Wood County, Ohio

Wang, Jingjing. January 2009 (has links)
Thesis (M.S.)--Bowling Green State University, 2009. / Document formatted into pages; contains xiii, 114 p. : ill., maps. Includes bibliographical references.
169

Matching the availability of N mineralised from green-manure crops with the N-demand of field vegetables /

Båth, Birgitta. January 2000 (has links)
Thesis (doctoral)--Swedish University of Agricultural Sciences, 2000. / Includes bibliographical references.
170

Can Dairy Manure be Profitably Composted in Maine?

Grant, Anne January 2003 (has links) (PDF)
No description available.

Page generated in 0.0738 seconds