Doctor of Philosophy / Department of Biological & Agricultural Engineering / Ronaldo G. Maghirang / Emissions of particulate matter (PM) are an increasing concern for large open beef cattle feedlots. Research is needed to develop science-based information on PM emissions and abatement measures for mitigating those emissions. This research was conducted to (1) measure PM concentrations emitted from large cattle feedlots, (2) compare different samplers for measuring concentrations of PM with equivalent aerodynamic diameter of 10 µm or less (PM10), (3) evaluate the relative effectiveness of pen surface treatments in reducing PM10 emissions, and (4) predict PM control efficiency of vegetative barriers. Concentrations of PM with equivalent aerodynamic diameter of 2.5 µm or less (PM2.5), PM10, and total suspended particulates (TSP) upwind and downwind of two large cattle feedlots (KS1, KS2) in Kansas were measured with gravimetric samplers. The downwind and net concentrations generally decreased with increasing water content (WC) of the pen surface; for effective control of PM emissions from feedlots, it appears that pen surface WC should be at least 20% (wet basis). Three types of samplers for measuring PM10 concentrations in feedlots KS1 and KS2 were compared: Tapered Element Oscillating Microbalance™ (TEOM), high-volume (HV), and low-volume (LV) PM10 samplers. Measured PM10 concentration was generally largest with the TEOM PM10 sampler and smallest with the LV PM10 sampler. A laboratory apparatus was developed for measuring the PM10 emission potential of pen surfaces as affected by surface treatments. The apparatus was equipped with a simulated pen surface, mock cattle hooves that moved horizontally across the pen surface, and PM10 samplers that collected emitted PM10. Of the surface treatments evaluated, application of water (6.4 mm) and hay (723 g/m2) exhibited the greatest percentage reduction in PM10 emission potential (69% and 77%, respectively) compared with the untreated manure layer. Computational fluid dynamics (CFD) was applied to predict airflow and particle collection by a row of trees (2.2 m high × 1.6 m wide). Predicted particle collection efficiencies generally agreed with published data and ranged from less than 1% for 0.875-µm particles to approximately 32% for 15-µm particles.

Doctor of Philosophy / Department of Biological and Agricultural Engineering / Ronaldo G. Maghirang / Emission of particulate matter (PM) and various gases from open-lot beef cattle feedlots is becoming a concern because of the adverse effects on human health and the environment; however, scientific information on feedlot emissions is limited. This research was conducted to estimate emission rates of PM[subscript]10 from large cattle feedlots. Specific objectives were to: (1) determine feedlot PM[subscript]10 emission rates by reverse dispersion modeling using AERMOD; (2) compare AERMOD and WindTrax in terms of their predicted concentrations and back-calculated PM[subscript]10 emission rates; (3) examine the sensitivity of both AERMOD and WindTrax to changes in meteorological parameters, source location, and receptor location; (4) determine feedlot PM[subscript]10 emission rates using the flux-gradient technique; and (5) compare AERMOD and computational fluid dynamics (CFD) in simulating particulate dispersion from an area source. PM[subscript]10 emission rates from two cattle feedlots in Kansas were determined by reverse dispersion modeling with AERMOD using PM[subscript]10 concentration and meteorological measurements over a 2-yr period. PM[subscript]10 emission rates for these feedlots varied seasonally, with overall medians of 1.60 and 1.10 g /m[superscript]2 -day. Warm and prolonged dry periods had significantly higher PM emissions compared to cold periods. Results also showed that the PM[subscript]10 emissions had a diurnal trend; highest PM[subscript]10 emission rates were observed during the afternoon and early evening periods. Using particulate concentration and meteorological measurements from a third cattle feedlot, PM[subscript]10 emission rates were back-calculated with AERMOD and WindTrax. Higher PM[subscript]10 emission rates were calculated by AERMOD, but their resulting PM[subscript]10 emission rates were highly linear (R[superscript]2 > 0.88). As such, development of conversion factors between these two models is feasible. AERMOD and WindTrax were also compared based on their sensitivity to changes in meteorological parameters and source locations. In general, AERMOD calculated lower concentrations than WindTrax; however, the two models responded similarly to changes in wind speed, surface roughness, atmospheric stability, and source and receptor locations. The flux-gradient technique also estimated PM[subscript]10 emission rates at the third cattle feedlot. Analyses of PM[subscript]10 emission rates and meteorological parameters indicated that PM[subscript]10 emissions at the feedlot were influenced by friction velocity, sensible heat flux, temperature, and surface roughness. Based on pen surface water content measurements, a water content of at least 20% (wet basis) significantly lowered PM[subscript]10 emissions at the feedlot. The dispersion of particulate from a simulated feedlot pen was predicted using CFD turbulence model ([kappa]-[epsilon] model) and AERMOD. Compared to CFD, AERMOD responded differently to wind speed setting, and was not able to provide detailed vertical concentration profiles such that the vertical concentration gradients at the first few meters from the ground were negligible. This demonstrates some limitations of AERMOD in simulating dispersion for area sources such as cattle feedlots and suggests the need to further evaluate its performance for area source modeling.

A existência de especificidade temporal na produção do confinamento de bovinos, que limita o período de negociação e busca por preços mais atrativos, corrobora com a necessidade do uso de mecanismos de hedge. Este pode ser feito pelo confinador com o uso da BM&F Bovespa, via contratos futuros e de opções, ou diretamente com os frigoríficos, por meio de contratos a termo. O objetivo desta dissertação é identificar fatores determinantes para a utilização de hedge (contratos futuros, de opções e termo) por confinadores. Foram realizadas pesquisas com confinadores participantes de eventos realizados em Ribeirão Preto-SP, em 2012 e 2013, e por telefone em 2014. Para a análise dos dados foram utilizadas estatísticas descritivas. Em seguida, com uso do Teste Exato de Fisher, foi analisada a associação das características dos confinamentos e pecuaristas ao uso do hedge. Com o intuito de identificar os determinantes para o uso de ferramentas de gestão de preços, foram elaborados modelos de regressão logística. Os resultados indicaram que o tamanho do confinamento, a escolaridade do gestor, o controle acurado de custos, o confinamento exclusivo, a utilização de hedge para os grãos, uso anterior de ferramentas e a parceria com frigoríficos têm relação com a utilização de uma ou mais formas de gestão de risco de preços do boi gordo. / The existence of temporal specificity in the production of feedlot cattle, which limits the period of negotiation and search for more attractive prices, confirms the necessity of using hedging mechanisms by feedlot cattle producers. The hedging can be done via BM&F Bovespa, through futures and options, or directly with slaughterhouses, through forward contracts. The aim of this study is identify determinants for using hedge (futures contracts, options contracts and forward contracts) by feedlot cattle producers. Surveys were applied to participants of events in Ribeirão Preto-SP, in 2012 and 2013, and via phone in 2014. Descriptive statistics of data were obtained and the determinants for using hedge were investigated using hypothesis tests. The relations between the producer\'s and feedlot\'s characteristics with hedging use were tested by Fisher Exact Test. In order to identify the determinants for the use of hedge, logistic regression models were implemented. The results have indicated that the size of the confinement, the manager\'s educational level, the high cost control, the feedlot as the only activity, the use of hedging for grains, the prior use of these tools and the partnership with slaughterhouses are related to the use of one or more ways to manage price risk of cattle.

A existência de especificidade temporal na produção do confinamento de bovinos, que limita o período de negociação e busca por preços mais atrativos, corrobora com a necessidade do uso de mecanismos de hedge. Este pode ser feito pelo confinador com o uso da BM&F Bovespa, via contratos futuros e de opções, ou diretamente com os frigoríficos, por meio de contratos a termo. O objetivo desta dissertação é identificar fatores determinantes para a utilização de hedge (contratos futuros, de opções e termo) por confinadores. Foram realizadas pesquisas com confinadores participantes de eventos realizados em Ribeirão Preto-SP, em 2012 e 2013, e por telefone em 2014. Para a análise dos dados foram utilizadas estatísticas descritivas. Em seguida, com uso do Teste Exato de Fisher, foi analisada a associação das características dos confinamentos e pecuaristas ao uso do hedge. Com o intuito de identificar os determinantes para o uso de ferramentas de gestão de preços, foram elaborados modelos de regressão logística. Os resultados indicaram que o tamanho do confinamento, a escolaridade do gestor, o controle acurado de custos, o confinamento exclusivo, a utilização de hedge para os grãos, uso anterior de ferramentas e a parceria com frigoríficos têm relação com a utilização de uma ou mais formas de gestão de risco de preços do boi gordo. / The existence of temporal specificity in the production of feedlot cattle, which limits the period of negotiation and search for more attractive prices, confirms the necessity of using hedging mechanisms by feedlot cattle producers. The hedging can be done via BM&F Bovespa, through futures and options, or directly with slaughterhouses, through forward contracts. The aim of this study is identify determinants for using hedge (futures contracts, options contracts and forward contracts) by feedlot cattle producers. Surveys were applied to participants of events in Ribeirão Preto-SP, in 2012 and 2013, and via phone in 2014. Descriptive statistics of data were obtained and the determinants for using hedge were investigated using hypothesis tests. The relations between the producer\'s and feedlot\'s characteristics with hedging use were tested by Fisher Exact Test. In order to identify the determinants for the use of hedge, logistic regression models were implemented. The results have indicated that the size of the confinement, the manager\'s educational level, the high cost control, the feedlot as the only activity, the use of hedging for grains, the prior use of these tools and the partnership with slaughterhouses are related to the use of one or more ways to manage price risk of cattle.

Master of Science / Department of Agronomy / Jay M. Ham / The potential environmental impact of animal feeding operations on air quality has created the need for accurate air emissions measurements. Of particular concern are ammonia emissions from cattle feedlots, operations that contribute a large portion of the agricultural ammonia emissions inventory. Micrometeorological methods are ideal for emissions measurements from large, open-source areas like feedlot pens; however, theoretical assumptions about the boundary layer must be made, which may not hold true above the heterogeneous, fetch-limited surface of the feedlot. Thus, the first objective of this work was to characterize the surface boundary layer of an open-air cattle feedlot and provide insight into how micrometeorological techniques might be applied to these non-ideal sites. Eddy covariance was used to measure fluxes of momentum, heat, water, and carbon dioxide from a commercial cattle feedlot in central Kansas. Data supported the use of eddy covariance and similar methods (i.e., relaxed eddy accumulation) for flux measurements from both cattle and pen surfaces. The modeled cumulative source area contributing to eddy covariance measurements at a 6 m sample height was dominated by just a few pens near the tower, making the characteristics of those pens especially important when interpreting results. The second objective was to develop a system for measuring ammonia fluxes from feedlots. A new type of relaxed eddy accumulation system was designed, fabricated, and tested that used honeycomb denuders to independently sample ammonia in up-moving and down-moving eddies. Field testing of the relaxed eddy accumulation system at a feedlot near Manhattan, KS showed fluxes of ammonia ranged between 60 and 130 μg m-2 s-1 during the summer of 2007. Even in the high ammonia environment (e.g., 300-600 μg m-3), the honeycomb denuders had enough capacity for the 4-hour sampling duration and could be used to measure other chemical species that the denuders could be configured to capture. Results provide a foundation for emissions measurements of ammonia and other gases at cattle feedlots and help address some of the challenges that micrometeorologists face with any non-ideal source area.