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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

Variable crop residue management

Myers, Brian January 1900 (has links)
Master of Agribusiness / Department of Agricultural Economics / Jeffery R. Williams / Production agriculture is constantly evolving to become more efficient and productive. Crop residue serves as a valuable source of nutrients for the soil, but it is increasingly abundant with today’s enhanced crop genetics. If new technology can effectively provide a way to micro-manage crop residue levels within a field, the benefits will go beyond soil health. Surplus crop residue can be collected for secondary income while leaving the optimum amounts in the field to maintain the environment and soil health as well as promote future crop growth. The main objective of this study is to create a budget model that will determine the economic impact of crop residue removal on a controlled basis. The goals are to determine crop residue removal practices that are sustainable for the long-term, while also enhancing soil quality and increasing grain yield in future years. A sub-objective is to build a business case for producers to invest in variable crop residue management. The hypothesis presented in this study is that the increased complexity and price of a variable rate system is offset by more supplemental profits, increased crop yields, and better management of soil health and nutrients. The negative perceptions of crop residue removal include the fear of soil erosion or loss of soil organic matter. By developing a budget model that is easy to use, takes advantage of existing field data for inputs, and allows producers the ability to look at their operations on a sub-field level, this study aims to provide the necessary motivation to invest in new technology that will increase their productivity. By entering their site-specific crop residue return rate data into a budget model, along with prices and costs related to combine and auxiliary equipment, corn and corn stover, transportation and logistics, and nutrient replacement, they will come up with a return per acre for both constant rate and variable rate collection. The budget model determines whether it is economically viable to harvest crop residue from a continuous corn rotation at a variable rate across a field, rather than at a constant rate, using a producer’s own specific field data. To validate the concept, data from a joint study between John Deere and Iowa State is entered into the model. Prescriptions for corn stover return rates are provided from the study for pre-defined grid areas. Prescriptions are derived from a combination of data including grain yield, soil loss due to wind and water erosion, climate, topography, and soil sample data at time of planting (Nelson, et al. 2004). The average corn stover removal percentage was less for variable rate collection than constant rate collection, 26.05% to 31.85%. However, the assumption that grain yield and corn stover yield are positively correlated did not prove to be true in this case study. The variable rate plots had a lower average grain yield of 158.84 bushel/acre, compared to 160.46 for the constant rate plots, but they had more total corn stover available and therefore a higher return rate of 3.70 tons/acre, compared to 3.05 for the constant rate plots. This case study illustrates that less corn stover can be returned to the field through constant or variable rate collection while sustaining higher grain yields than a conventional harvest that would return all of the corn stover to the field. This case study demonstrates that variable rate collection can be more expensive than constant rate, but not in every situation. Every unique field site will require a specific crop residue management recommendation that is determined by both economic and environmental factors.
2

An investigation of intraperitoneal procaine penicillin G administration in lactating dairy cows

Chicoine, Alan Leonard 30 August 2007
This study describes the pharmacokinetic profile of procaine penicillin G after intraperitoneal (IP) administration in 8 lactating dairy cows. Procaine pencillin G (PPG, 21,000 IU/kg) was deposited into the abdominal cavity of each cow following an incision in the right paralumbar fossa. Blood and milk samples were taken over the following 10 days, at which point the cows were euthanized. Plasma, milk, muscle, liver, and kidney penicillin concentrations were determined by HPLC, with a limit of detection (LOD) of 5 ppb for plasma and milk samples. Noncompartmental methods were used to analyze plasma kinetics. The mean pharmacokinetic parameters (} s.d.) were: Cmax, 5.5 } 2.6 Êg/mL; Tmax, 0.75 } 0.27 h; AUC0-, 10.8 } 4.9 Êg*h/mL; MRT, 2.2 } 0.9 h. All milk from treated cows contained penicillin residues for a minimum of 3 milkings (31 h) and maximum of 5 milkings (52 h) after administration. Concentrations of penicillin G in all muscle, liver, and kidney samples taken 10 days post-administration were below the limit of detection. Necropsy examinations revealed foci of hemorrhage on the rumenal omentum of most cows but peritonitis was not observed. Systemic inflammation as determined by altered leukograms and fibrinogen was noted in one cow. The results of this study demonstrate that IP procaine penicillin G is absorbed and eliminated rapidly in lactating dairy cows.
3

An investigation of intraperitoneal procaine penicillin G administration in lactating dairy cows

Chicoine, Alan Leonard 30 August 2007 (has links)
This study describes the pharmacokinetic profile of procaine penicillin G after intraperitoneal (IP) administration in 8 lactating dairy cows. Procaine pencillin G (PPG, 21,000 IU/kg) was deposited into the abdominal cavity of each cow following an incision in the right paralumbar fossa. Blood and milk samples were taken over the following 10 days, at which point the cows were euthanized. Plasma, milk, muscle, liver, and kidney penicillin concentrations were determined by HPLC, with a limit of detection (LOD) of 5 ppb for plasma and milk samples. Noncompartmental methods were used to analyze plasma kinetics. The mean pharmacokinetic parameters (} s.d.) were: Cmax, 5.5 } 2.6 Êg/mL; Tmax, 0.75 } 0.27 h; AUC0-, 10.8 } 4.9 Êg*h/mL; MRT, 2.2 } 0.9 h. All milk from treated cows contained penicillin residues for a minimum of 3 milkings (31 h) and maximum of 5 milkings (52 h) after administration. Concentrations of penicillin G in all muscle, liver, and kidney samples taken 10 days post-administration were below the limit of detection. Necropsy examinations revealed foci of hemorrhage on the rumenal omentum of most cows but peritonitis was not observed. Systemic inflammation as determined by altered leukograms and fibrinogen was noted in one cow. The results of this study demonstrate that IP procaine penicillin G is absorbed and eliminated rapidly in lactating dairy cows.
4

The influence of residue chemical composition on gross rates of nitrogen mineralisation

Gibbs, Paul A. January 1998 (has links)
No description available.
5

Effect of planting management factors on canola performance in high-residue cropping systems

Showalter, Baylee M. January 1900 (has links)
Master of Science / Department of Agronomy / Kraig Roozeboom / Winter survival of canola (Brassica napus L.) is a challenge for producers using high-residue, no-tillage, or reduced tillage systems. In addition, as hybrid cultivars have become more available in recent years, this has brought about questions regarding best management practices to aid in mitigating winter survival challenges associated with high residue production systems. Overcoming production challenges will allow producers to diversify their no-till cropping systems with an oil seed crop having strong domestic demand. This research was undertaken to identify practices that could improve performance of canola in high-residue cropping systems. Two sets of experiments were conducted at twelve sites across Kansas from 2014 to 2016 to evaluate practices that could improve stand establishment, winter survival, and yield of winter canola. The objective of the first study conducted at 10 site years was to determine the effect of residue management, seeding density, and row spacing on stand establishment, winter survival, and yield. An innovative residue management system being developed by AGCO Corp. was compared to cooperating canola producers’ no-till residue management and planting methods in wheat residue. This on-farm experiment was conducted at ten environments across Kansas. AGCO treatments were 20 or 30-in row spacing and three seeding rates for a total of six treatments. Producer treatments included their preferred row spacing, seeding rate, and residue management practices. Winter survival increased by 11% to 29% as seeding rate decreased in 20-in rows at four of the five harvested environments. At Stafford and Kingman, the lowest yielding AGCO treatment produced 3.7 to 4.2-bushel acre⁻¹ more than the respective cooperator treatments. Reduced seeding rates in the AGCO system produced yields similar to or superior than the cooperator practice in all environments. Producers have been turning to planting canola in wide rows to facilitate residue management with strip tillage or planter residue management attachments. The objective of the second study conducted at three site-years was to determine the effect of seeding rate on winter survival and yield of hybrid and open-pollinated winter canola cultivars in 30-in rows. Treatments were four genotypes and five seeding rates for a total of twenty treatments. Winter survival increased with the lowest seeding rate at one of the three environments. At two of the three environments neither genotype nor seeding rate affected yield. These results indicate that seeding rates can be reduced from those typically used by canola producers in high residue, no-till or reduced tillage systems if residue can be adequately removed from the seed row. Both hybrid and open-pollinated winter canola cultivars responded similarly to seeding rate in 30-in rows in these experiments, indicating that similar seeding rates could be used for each type of cultivar. Management practices such as, narrow row spacing, reducing seeding rates, and adequately managing residue at planting may result in small improvements to establishment, winter survival and yield.
6

The mechanism of Bayer residue flocculation.

Jones, Franca January 1998 (has links)
The aim of this study was to determine the mechanism of Bayer residue flocculation. Hematite was chosen as the test substrate as it is a common Bayer residue mineral. Batch settling tests were used to gain an understanding of the aggregation mechanism and to compare the effect of different parameters on flocculation performance. Flocculant adsorption isotherm measurements were related to changes in flocculation performance. Infrared spectroscopy was used to ascertain the configuration of adsorbed flocculant on the hematite surface.Batch settling tests showed that under strong caustic conditions hematite is naturally coagulated and that flocculation occurs via a bridging mechanism. This was confirmed by results which showed that factors which affect the bridging efficiency of the flocculant had an impact on aggregation. In particular, temperature and caustic concentration were found to greatly influence flocculation performance. This is due mainly to changes in the viscosity of the liquor, but may also be linked to the kinetics of particle-particle and particle-flocculant collisions resulting in a less efficient aggregation process. Ionic strength did not impact on performance as the flocculant was at a limiting size for synthetic liquors containing TC >/= 50 and TA >/= 10.Increasing ionic strength did not increase the adsorption density of the flocculant on hematite nor did altering the salt cation species from Na(subscript)2+ to Ca(subscript)2+. It can be concluded, therefore, that the flocculant is chemisorbed through surface complexation, since if it were electrostatically bound an increase in flocculant adsorption should have been observed with increasing ionic strength or cation charge. The surface complexation mechanism was supported by infrared results which showed that the flocculant vibrational bands were shifted on adsorption. The magnitude and direction of ++ / the shift suggests a bridging bidentate structure at pHs >/+ 11, while a monodentate structure exists at pH 7. In the presence of calcium there is also some electrostatically adsorbed flocculant at pH 7, with the calcium being in a bidentate chelating structure, but this is not observed at much higher pHs.The flocculant had an adsorption isotherm best described by a Langmuir-Freundlich expression with a monolayer coverage of ~ 164 mu g m(subscript)-2 of hematite. The adsorption density was lowered by the presence of carbonate and silicate and the action of both is thought to be due to their adsorption on active sites blocking polymer adsorption. Carbonate has an impact on flocculant adsorption at concentrations > 10 mg g(subscript)-1 while in the case of silicate ~0.2 mg g(subscript)-1 is required for the adsorption density of the flocculant to be affected. While it has been confirmed that silicate does adsorb on hematite, it was not possible to determine whether this was adsorption of a silicate species or an aluminosilicate species.X-ray photoelectron spectroscopy (XPS) showed conclusively that sodium is not involved in the adsorption of the carboxylate to the hematite surface. The lower peak shift between the backbone carbon and the carboxylate carbon suggests that the carboxylate is bonded directly to iron which has a low effective charge.Flocculant adsorption was atomistically modelled using decanoate and decandioate molecules. Modelling supported the results from XPS and infrared analysis and showed the carboxylate oxygen atoms in both organic molecules bonded directly to the surface iron atoms. Adsorption was preferred on near unhydrated surfaces with the most stable adsorption configuration being a non-symmetrical bridging bidentate structure as inferred from the infrared results.
7

Pesticide residues in cucumbers cultivated in Bangladesh

Haag, Jennie, Landahl, Anna January 2014 (has links)
Pesticides are widely used for preventing crop losses due to pest attack. In Bangladesh, the food safety and health of farmers are being compromised as a result of poor regulation concerning usage of pesticides in food production. The aim of this study was to identify and quantify pesticides applied on cucumber crops in Bangladesh. A method for extraction and clean-up was developed to allow the quantification of four pesticides by GC-ECD in vegetable samples, specifically cucumber. The accuracy of the method was validated using recovery and its precision by studying the standard deviation and relative standard deviation. Analysis of cucumber samples obtained in the field showed no traces of the target pesticides. The results indicate that different types of chemicals are used on the examined crops. It is also believed that the growth habit of cucumber may affect the exposure to pesticides. To overcome the health hazards, restrictions regarding the types and quantities of chemicals used on the fields need to be implemented. Further studies would benefit from being executed in a controlled environment, and monitoring of which substances that are applied at which amounts.
8

Molecular and isotopic characterisation of animal fats in archaeological pottery

Dudd, Stephanie Noelle January 1999 (has links)
No description available.
9

Detection of organic gunshot residue using High Performance Liquid Chromatography/Mass Spectrometry

Bartram, Kylie 19 February 2021 (has links)
Gunshot residue (GSR) has been analyzed in forensic laboratories since 1933 when the dermal nitrate test originated. (1) Detection and analysis of GSR has since developed with the invention and implementation of instrumentation. Since the 1960s, inorganic gunshot residue (IGSR) has been the primary focus for GSR analysis. (2) As disadvantages like omitting lead from ammunition and the transient properties of IGSR are researched, it is clear that a new approach is needed. Organic gunshot residue (OGSR) analysis has the potential to become the novel approach for GSR analysis because OGSR does not have the same transient properties as IGSR. (3) The compounds are lipophilic and are therefore more likely to remain on the shooter’s hands or face. (4) OGSR can be analyzed through a myriad of instrumentations, including High Performance Liquid Chromatography/Mass Spectrometry(HPLC/MS). Analysis with HPLC/MS allows for customizable mobile phases, gradients, columns, and ionization to ensure the complete detection of OGSR. Using a Shimadzu Ultra Performance Liquid Chromatography (UPLC) coupled with an AB Sciex Q-Trap 4000 MS/MS, a method is optimized for the detection of Diphenylamine (DPA), Nitroglycerin (NG), and Ethyl Centralite (EC). The next steps for experimentation are summarized and include an elution study and a time-course study.
10

Blood Residues on Archaeological Objects - A Conservation Perspective

Wilson, Andrew S., Tuross, N., Wachowiak, M.J. January 1996 (has links)
No

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