Thesis (Ph.D.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2008/01/12). Includes bibliographical references.

Ph.D., Faculty of Science, University of the Witwatersrand, 2011 / Atmospheric deposition of sulfur (S) and nitrogen (N) as a result of fossil fuel combustion is known to impact ecosystem structure and function. Potential impact includes acidification of soil and surface water and mobilisation of metal ions, with the resultant loss of plant productivity, changes in plant species diversity and changes in biotic communities in aquatic ecosystems. Rates of S (~8 kg S ha-1 year-1) and N (>6 kg S ha-1 year-1) deposition to the grasslands of the South African Highveld are comparable to other industrialised areas where ecosystem impacts have been observed. As part of a larger project, this work investigated four aspects of ecosystem impact: changes in soil and river water chemistry as well as S and N mineralisation rates. Reassessment of the soil chemistry at 18 sites on the South African Highveld after a 16-year period showed increases in both acidic and basic ion concentrations for individual sites and when the values for these sites were averaged to represent the study region. Grouping the soils by clay content showed that all sites with less than 25% clay (16 of 18 sites) showed significantly reduced pH(H2O) values. Sites with less than 4% clay showed increased exchangeable acidity and decreased acid neutralising capacity. Spatial scaling and mapping from site to soil form and land type, showed that across 92% of the study area the pH(H2O) values had been reduced. This method identified the sandier soils, near the southern and eastern boundaries of the study area where rainfall is higher, as sensitive to additional acidic inputs via atmospheric deposition. Clay-rich soils occur in the drier central part of the study area, close to emission sources. It is suggested that this proximity to emission sources results in the co-deposition of basic and acidic ions, adding to the buffering capacity of the soils, resulting in small but significant increases in soil acidity status over the 16 years. Sulfur and N mineralisation rates, using the in situ incubation method at 11 sites, were found to range between -0.66 and 1.09 μg SO42- g-1 soil day-1 and -0.97 and 1.21 μg N g-1 soil day-1. This translated into an annual flux of between -40 and 9.9 kg S ha-1 and between 27 and 81 kg N ha-1 from the soil organic pools. The use of the in situ incubation technique to determine S mineralisation is a new Theresa Bird 9505067D development and is proposed for in-field studies where S and N cycling are of interest as the method allows for concurrent mineralisation rate determination. It was found that from a biogeochemical perspective the Highveld grasslands are under researched with respect to S and N and complete assessments of the S and N cycles are proposed. The S budget proposes accretion of S in the soil organic pool due to continued inputs via deposition and low losses to the atmosphere or deeper soil horizons. Nitrogen, however, appears to limit productivity in these grasslands because atmospheric inputs and mineralisation rates are approximately equal to plant uptake. In the assessment of river water quality it was hypothesised that between 1991 and 2008 concentrations of dissolved salts, sulfate, nitrate and ammonium would increase in surface waters at five sites draining the Highveld grasslands. The Department of Water Affairs water quality monitoring database was accessed to assess for spatial and temporal differences in water quality. Significant spatial differences were found; however, over time few significant increases were found to support the hypothesis: sulfate, nitrate-plus-nitrite, and ammonium were observed to increase at one site each. In addition, the export of nitrogen, as mass load, from natural grasslands was found to be negligible at <2 kg N ha-1year-1. A conceptual framework proposes that soil texture, distance from emissions and land use are key drivers in the response of the grassland soils and surface waters to atmospheric S and N deposition. Although the study identified the soils most sensitive to deposition, it is proposed that processes in the Highveld grasslands are not yet negatively affected by the additional sulfur and nitrogen inputs. Continued monitoring for impacts on ecosystem structure and function is advocated.

Intensive poultry production in the lower Fraser Valley of British Columbia has resulted in large quantities of poultry manure being spread on limited land space. This manure is spread on land situated above the Abbotsford aquifer. Due to the high amount of nitrogen and phosphorus present in poultry manure, there is a danger of these nutrients leaching into the groundwater of the aquifer as nitrates. High levels of nitrates in drinking water have been linked to various health hazards such as Methemoglobinaemia, stomach cancer, and gastric cancer. The leaching problem is further compounded by the fact that the region has porous soils, a high water table, and very high annual rainfall. This problem was addressed by analyzing several dietary treatments having varying levels of crude protein from a high of 25% CP (crude protein) to a low of 18% CP and supplemented with the commercial amino acids L-LYS , DL-MET , L-THR, and L-TRY . A linear programming model was used to determine the least cost diet from the various dietary treatments. The most efficient dietary treatment was then identified by Manure disposal options such as storage, land application, and transportation were also considered along with their associated costs. Linear programming was used to identify the least cost manure disposal strategy complying with British Columbia environmental regulations by using a combination of the three options. The results from the two models above were then combined to identify the optimum manure management strategy for a poultry farm in the Fraser valley complying with environmental regulations. The results indicate that diets containing lower levels of crude protein and supplemented with amino acids costs less than those containing higher levels of crude protein. These diets perform better because the nitrogen in the protein is utilized more efficiently thereby resulting in less nitrogen excretion in the manure. Manure that contains low amounts of nitrogen costs less to dispose than that having high amounts of nitrogen. Use of diets containing low levels of crude protein and supplementing them with commercial amino acids can lower the costs of poultry farmers significantly while complying with environmental regulations.

Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2008/07/30). Includes bibliographical references.

Thesis (Ph. D., Environmental Science)--University of Idaho, June 2009. / Major professor: J.D. Wulfhorst. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (doctoral)--Wageningen University, Delft, The Netherlands 2008. / Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.)--Murdoch University, 2009. / Thesis submitted to the Faculty of Sustainability, Environmental and Life Sciences. Includes bibliographical references (leaves 201-242)

Intensive poultry production in the lower Fraser Valley of British Columbia has resulted in large quantities of poultry manure being spread on limited land space. This manure is spread on land situated above the Abbotsford aquifer. Due to the high amount of nitrogen and phosphorus present in poultry manure, there is a danger of these nutrients leaching into the groundwater of the aquifer as nitrates. High levels of nitrates in drinking water have been linked to various health hazards such as Methemoglobinaemia, stomach cancer, and gastric cancer. The leaching problem is further compounded by the fact that the region has porous soils, a high water table, and very high annual rainfall. This problem was addressed by analyzing several dietary treatments having varying levels of crude protein from a high of 25% CP (crude protein) to a low of 18% CP and supplemented with the commercial amino acids L-LYS , DL-MET , L-THR, and L-TRY . A linear programming model was used to determine the least cost diet from the various dietary treatments. The most efficient dietary treatment was then identified by Manure disposal options such as storage, land application, and transportation were also considered along with their associated costs. Linear programming was used to identify the least cost manure disposal strategy complying with British Columbia environmental regulations by using a combination of the three options. The results from the two models above were then combined to identify the optimum manure management strategy for a poultry farm in the Fraser valley complying with environmental regulations. The results indicate that diets containing lower levels of crude protein and supplemented with amino acids costs less than those containing higher levels of crude protein. These diets perform better because the nitrogen in the protein is utilized more efficiently thereby resulting in less nitrogen excretion in the manure. Manure that contains low amounts of nitrogen costs less to dispose than that having high amounts of nitrogen. Use of diets containing low levels of crude protein and supplementing them with commercial amino acids can lower the costs of poultry farmers significantly while complying with environmental regulations. / Land and Food Systems, Faculty of / Graduate

Runoff from agricultural lands carrying microorganisms from livestock manure can contaminate the food and water supplies of both animals and humans. Planning and design of animal waste best management practices (BMPs) thus becomes more important as livestock populations become more concentrated. A computer model is proposed to predict the effects of animal waste BMPs on the bacteria concentration of runoff from agricultural lands. The model uses Monte Carlo simulation to combine the deterministic relationships resulting from previous modeling efforts with statistical knowledge concerning rainfall events and temperature variation. Model output is in the form of monthly maximum and minimum log bacteria concentrations of runoff resulting from a storm assumed to occur immediately after manure is applied to the land. The effects of implementing such BMPs as waste storage, filter strips, and incorporation of manure into the soil can be compared. Data and information collected from the Owl Run watershed in Fauquier County, Virginia is used to demonstrate the model applicability and potential. Long-term manure storage is determined to be the most appropriate practice for reducing bacteria concentrations for the study site. Incorporation of manure is as effective as long-term storage, but requires additional labor. Buffer strips significantly reduce bacteria concentrations, but not as effectively as long-term storage or incorporation. Additional efforts are needed to investigate the most influential variables and to make the temperature simulation submodel more computationally efficient. Once BMPs have been implemented on the study site, more data should be collected to test the accuracy of the model. / Master of Science

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 124-131). / xv, 131 leaves, bound ill. (some col.) 29 cm