Master of Science / Department of Biological and Agricultural Engineering / Philip Barnes / Sediment is a large pollutant concern for the United States and is a major impairment source in water bodies (MARC 2013). Rivers and streams assessed in Kansas resulted in 87.8% being considered impaired, as well as 97.8% of the assessed lakes, reservoirs, and ponds (EPA 2012d). Tuttle Creek Reservoir is filling with sediment faster than any other federal reservoir in the region. Due to the importance of Tuttle Creek Reservoir, limiting the water impairments has been made a priority. The tributaries feeding the reservoir are all considered impaired, and TMDLs should be developed to limit the amount of sediment allowed in the water body. This study focuses on the stream energy and sediment loads occurring in a watershed in northeast Kansas over a six year period. When bankfull conditions occur, significant amounts of work are performed on the stream and excessive erosive forces may occur. The estimated bankfull discharge was 6.5 m3/s, and this event occurred every year except in 2012. At the same location the bankfull discharge was estimated, automated and grab water samples were collected and stream power was calculated. The samples were analyzed for total suspended sediment, total nitrogen, and total phosphorus, and the total annual loads were estimated. The total sediment load occurring in the watershed was 10,298,283 kilograms. The nutrient loads occurring were 78,213 kg of TN and 22,625 kg TP. Elevations were measured at equal intervals in a sub-watershed. Energy gradients were calculated, and it was observed that many of the gradients could create favorable conditions for sediment erosion to occur. The stream power estimate was 26.85 kg/m/s. At this stage larger sediment particles and load could be transported. A gully formed by overland flow entering the stream was also measured to estimate amounts of sediment being contributed from gully side conveyances within the watershed. The estimated sediment loss from the gully was 1,693,899 kg. Results of this study could help improve water quality and help quantify the amount of sediment being carried from the watershed and streambanks, so BMPs and other design features may be implemented.

Master of Agribusiness / Department of Agricultural Economics / Vincent Amanor-Boadu / Farming is an important industry in the United States. The custom harvesting industry plays a major role in feeding the world. Schemper Harvesting is a family-owned and operated custom harvesting service that employs 20-25 seasonal workers and understanding how to manage a custom harvesting business professionally and efficiently is the key for its success. Today, there is data available through JDLink on John Deere combine performance beginning in year 2012. The purpose of this study is to examine the usefulness of this JDLink data to assess the efficiency of each of Schemper Harvesting’s seven combines, including machine efficiency and different combine operators. The goal is to determine how the data can improve Schemper Harvesting’s overall performance. Statistical methods were used to analyze Schemper Harvesting’s performance. The analysis indicated that fuel is a major expense and there are ways Schemper Harvesting can conserve fuel. This information may prove valuable in being able to operate a combine more efficiently and save money on expenses. Overall, the objective is to improve Schemper Harvesting’s performance, which results in higher profit without sacrificing quality. Precision technology is an added expense to the business. Being able to justify this expense with profit is the answer. Fuel, labor and machinery are the biggest inputs in the custom harvesting business. These costs related to production agriculture have increased the demand for precision agriculture to increase efficiency and profitability. In order to compensate for the investment in technology, it has been demonstrated that it pays for itself. Making correct use of precision technology adds to productivity. With experience, operators improve increasing their overall efficiency. Incentive plans can be utilized through this data. With the availability of data, the costs and benefits of precision technology can be further evaluated. Five of the seven combines are operated by family members and the other two by non-family employees. This study shows that the performance of the non-family employees was below that of family members. The initial assessment for this difference may be attributed to experience because all the family members have been operating combines for most of their lives. This implies that employing people with excellent performance experience records and/or a need to train non-family employees to help them understand the performance expectations at Schemper Harvesting. The results indicate that tracking operational output performance indicators, such as acreage and volume harvest should be completed so that they may be assessed in concert with the technical indicators such as time and fuel use. The study provides the potential benefits of using John Deere’s JDLink data service providing telematics information for its customers with the latest precision agriculture technologies.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Donghai Wang / Lignocellulosic biomass such as agricultural residues tends to be a sustainable feedstock for production of biofuels and biobased products in the long term due to its high availability and relative low cost. However, conversion of lignocellulosic biomass to biofuels faces significant technical challenges. One of the major challenges is biomass logistics. The agricultural residues are often harvested during a limited harvest season and stored as bales with low bulk density, making them difficult to handle, transport, store, and use in their natural forms. Densification of biomass by pelleting process could significantly improve the bulk density of biomass and thus improve handling efficiency and reduce transportation and handing costs. The main focus of this research was to better understand the impacts of pelleting process as well as pelleting conditions on physical properties, chemical compositions, biomass structure, and fermentable sugar yield of sorghum stalk, corn stover, wheat straw, and big bluestem. Results showed that pelleting process can increase biomass density up to 9-12 folds. Pelleting condition such as hammer mill screen size and ring-die pelleting mill die thickness had significant effects on bulk density, true density, and durability of biomass pellets. Although the pelleting process did not show significant effects on chemical composition of biomass before dilute-acid pretreatment process, glucan content of biomass pellets increased with the increase in ring-die pelleting mill die thickness and decreased with the increase in mill screen size after dilute-acid pretreatment. Opposite trend was observed for xylan content of biomass pellets as affected by pelleting conditions after dilute-acid pretreatment process. Biomass crystallinity increased after pelleting process, but not in a significant level. Softened surface region of biomass was removed after pelleting process, making the biomass more amendable to enzymatic attack. In this study, the optimum pelleting conditions were to grind the biomass feed using a 6.5-mm mill screen and to pellet biomass using a 44.5-mm ring-die pelleting mill die thickness. Under this optimum pelleting condition, the enzymatic conversion of cellulose of wheat straw pellets was the highest (94.1%), followed by corn stover pellet (93.1%), sorghum stalk pellet (92.1%), and big bluestem pellet (91.1%).

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Kyle Douglas-Mankin / Soil erosion is one of the most important of today’s global environmental problems. Over the past few decades, soil conservation practices were implemented to reduce soil erosion in the United States. However, excessive sediment still remains among the most prevalent water quality problems. Agricultural fields and in particular ephemeral gullies (EGs) are considered to be a major contributor of sediment. The overall goal of this study was to improve modeling utility to identify and quantify sources of sediment. Specific objectives were: (1) to develop and demonstrate a method of field-scale targeting using Soil and Water Assessment Tool (SWAT) and to use this method as a targeted, flexible approach to pay explicitly for sediment-yield reductions; (2) to evaluate topographic index models (Slope Area [SA], Compound Topographic Index [CTI], Slope Area Power [SAP] and Wetness Topographic Index [WTI]) and a physical-based model (Overland Flow Turbulent [OFT]) in predicting spatial EG location and lengths. Black Kettle Creek watershed was the focus of an innovative project to pay for modeled field sediment reductions. An Arc-Geographical Information System (GIS) tool bar was developed that post processed SWAT hydrologic response unit output to field boundaries and prepared maps of high-priority fields by sediment, total nitrogen, and total phosphorus and was demonstrated to be useful for field-scale targeting. Calibrated SWAT model was used to establish baseline sediment yields. Various Best Management Practices (BMPs) were simulated and payments to implement each BMP for a given field were calculated. This study helped to guide determination of appropriate farmer support payments and quantified the important influence of BMP type and site-specific conditions for use in targeting conservation practice funding to achieve maximum soil-loss reductions per dollar spent. Extreme care should be used in selecting the source of spatial model input data when using SWAT for field-level targeting. Automated geospatial models were developed in a GIS environment to spatially locate and derive length of EGs using topographic index and physical based models. EG predictions were better for the SA model among the four topographic index models tested. Individual calibration of topographic index model threshold for each application site was needed. An OFT model (physical based model), which utilized topography, precipitation, soil, landuse/landcover and SWAT-based runoff estimates, did not need individual site calibration, and may have broader applicability than empirical based models.

Doctor of Philosophy / Department of Grain Science and Industry / Keith C. Behnke / A series of experiments was conducted to compare methods used to evaluate the durability of animal feed pellets, as well as to investigate the potential for modeling the effects of formulation and processing factors on both pellet durability index (PDI) and pelleting energy consumption, measured in kilowatt hours per ton (kWh/ton). Seven different factors, including ground corn particle size, added fat level, inclusion of distillers dried grains with solubles (DDGS), feed rate, steam conditioning temperature, conditioner retention time, and pellet die thickness (L:D ratio) were examined. Each factor was evaluated at two levels, and treatments were developed in order that all factor to factor comparisons could be made. Pellet samples were analyzed according to the standard method as described in ASAE S269.4, a modification of this method, and by using the NHP100 pellet tester set to each of its four testing intervals (30, 60, 90, and 120 seconds). The standard method was found to provide the most consistent and repeatable determinations of pellet durability, and was found to correlate well with the modified method, as well as with the NHP100 results at 30 and 60 seconds. Physical attributes of feed pellets, such as pellet hardness, bulk density, and moisture content were found to have significant, but weak correlations with pellet quality. Pellet quality was found to be significantly influenced by all factors other than ground corn particle size and feed rate. Higher fat level, lower conditioning temperature, and the thinner pellet die most significantly lowered pellet quality, with increasing effect respectively. A regression model was developed that was able to predict pellet durability within an average of 1.1 PDI. Pelleting energy consumption was found to be significantly influenced by all seven factors, with the higher fat level, thinner pellet die, and higher conditioning temperature most improving efficiency, with increasing effect respectively. A regression model was developed that was able to predict energy consumption within an average of 0.3 kWh/ton. The successful creation of regression equations demonstrates that there is potential for modeling and optimizing pellet quality and energy consumption within a pelleting operation.

Doctor of Philosophy / Department of Biological and Agricultural Engineering / Wenqiao Yuan / Donghai Wang / Corncobs were used as the feedstock to investigate the effect of operating conditions and crude glycerol (solvent) on bio-oil production. The highest bio-oil yield of 33.8% on the basis of biomass dry weight was obtained at 305°C, 20 min retention time, 10% biomass content, 0.5% catalyst loading. At selected conditions, bio-oil yield based on the total weight of corn cobs and crude glycerol increased to 36.3% as the crude glycerol/corn cobs ratio increased to 5. Furthermore, the optimization of operating conditions was conducted via response surface methodology. A maximum bio-oil yield of 41.3% was obtained at 280°C, 12min, 21% biomass content, and 1.56% catalyst loading. A highest bio-oil carbon content of 74.8% was produced at 340°C with 9% biomass content. A maximum carbon recovery of 25.2% was observed at 280°C, 12min, 21% biomass content, and 1.03% catalyst loading. The effect of biomass ecotype and planting location on bio-oil production were studied on big bluestems. Significant differences were found in the yield and elemental composition of bio-oils produced from big bluestem of different ecotypes and/or planting locations. Generally, the IL ecotype and the Carbondale, IL and Manhattan, KS planting locations gave higher bio-oil yield, which can be attributed to the higher total cellulose and hemicellulose content and/or the higher carbon but lower oxygen contents in these feedstocks. Bio-oil from the IL ecotype also had the highest carbon and lowest oxygen contents, which were not affected by the planting location. In order to better understand the mechanisms of hydrothermal conversion, the interaction effects between cellulose, hemicellulose and lignin in hydrothermal conversion were studied. Positive interaction between cellulose and lignin, but negative interaction between cellulose and hemicellulose were observed. No significant interaction was found between hemicelluose and lignin. Hydrothermal conversion of corncobs, big bluestems, switchgrass, cherry, pecan, pine, hazelnut shell, and their model biomass also were conducted. Bio-oil yield increased as real biomass cellulose and hemicellulose content increased, but an opposite trend was observed for low lignin content model biomass.

The well-known and widely accepted Penman combination equation was applied to climatic data collected in a desert environment to predict actual evapotranspiration if the desert region were developed into irrigated agriculture. The Penman evaporation estimates from desert climate data were compared to Bowen ratio ET measurements collected on irrigated alfalfa fields in the general vicinity. Six variations of the wind function in Penman's equation were tested. From these six the best fit-model was determined. surprisingly, Penman's original equation provided the best fit (in mean hourly units W m⁻²) as PLE₁ = 0.953LE + 43. The s.e. was 51 W⁻², r² = 0.953, and n = 298 hourly points. A calibrated wind function was developed and named 'Sonoran'. The Sonoran wind function PLE₆ = 0.954LE + 24, s.e. = 48.8 r² = 0.956 provided virtually imperceptible improvements over Penman's original wind function.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 337-367.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6121. Adviser: Peter James Garlick. Includes bibliographical references (leaves 72-89) Available on microfilm from Pro Quest Information and Learning.

Doctor of Philosophy / Biological & Agricultural Engineering / Mark E. Casada / Ronaldo G. Maghirang / Wind erosion is an important problem in many locations, including the Great Plains, that needs to be controlled to protect soil and land resources. This research was conducted to assess the effectiveness of vegetation (specifically, standing vegetation and tree barriers) as controls for wind erosion. Specific objectives were to: (1) measure sand transport and abrasion on artificial standing vegetation, (2) determine porosity and drag of a single row of Osage orange (Maclura pomifera) barrier, (3) assess effectiveness of Osage orange barriers in reducing dust, (4) predict airflow through standing vegetation, and (5) predict airflow and particle collection through Osage orange barriers. Wind tunnel tests were conducted to measure wind speed profiles, relative abrasion energies, and sand discharge rates for bare sand and for two vegetation heights (150 and 220 mm) at various densities of vegetation. Results showed that vegetation density was directly related to threshold velocity and inversely related to sand discharge. The coefficient of abrasion was adversely affected by saltation discharge but did not depend on wind speed. Field tests measured the aerodynamic and optical porosities of Osage orange trees using wind profiles and image analysis, respectively, and an empirical relationship between the two porosities was derived. Vertical wind profiles were also used to estimate drag coefficients. Optical porosity correlated well with the drag coefficient. Field measurements also showed a row of Osage orange barrier resulted in particulate concentration reduction of 15 to 54% for PM2.5 and 23 to 65% for PM10. A computational fluid dynamics (CFD) software (OpenFOAM) was used to predict airflow in a wind tunnel with artificial standing vegetation. Predicted wind speeds differed slightly from the measured values, possibly due to oscillatory motions of the standing vegetation not accounted for in the CFD simulation. OpenFOAM was also used to simulate airflow and particle transport through a row of Osage orange barrier. Predicted and measured wind speeds agreed well. Measured dust concentration reduction at two points (upwind and downwind) were also similar to the predicted results.