The introduction of glyphosate-resistant (GR) crops in the late 1990s changed the way producers used herbicides to control weeds. Since the introduction of GR crops producers have relied on glyphosate alone for weed control instead of utilizing multiple modes of action for weed control. This over-reliance resulted in several weed species developing resistance to glyphosate. This has resulted in organizations from the public and private sector questioning the sustainability of GR cropping systems. Researchers from Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina established 156 onarm trials to determine the sustainability of GR cropping systems. The objectives of this study were: to determine the economics of a university weed resistance best management practice (BMP) versus a producers’ normal production practice; to evaluate when a producer that is risk neutral (profit maximizing) or risk averse should adopt a weed resistance BMP; and to compare the influences of using a university weed resistance BMP to a producer’s normal production practice on the 27 most common weed species in Mississippi. In all instances, the university weed resistance BMP utilized multiple modes of action in conjunction with glyphosate. A university weed resistance BMP can provide the same level of control on 27 of the most common weeds in Mississippi that a producer has become accustomed to with a glyphosate alone system, while delaying or controlling GR weeds. A university weed resistance BMP resulted in an increase in weed control cost, but similar yields and economic returns when compared to a producer’s normal production practice. Rotating a GR crop with a different GR crop resulted in higher economic returns when compared to a continuous GR cropping system or a GR crop followed by a non-GR crop rotation. Producers are often reluctant to adopt a weed resistance BMP because of the perceived increased cost for weed control. A risk neutral or risk averse producer should adopt a weed resistance BMP and feel confident that their decision will provide weed control equivalent to a glyphosate alone weed control program before resistance developed, delay or control GR weeds and be economically sound.

A rapidly changing global agribusiness environment creates a challenge for commercially oriented agricultural producers to improve business acumen through strategy development and execution. A best management practice is broadly defined as a practice that is considered to be most effective in improving business performance. This study examined the relationship of financial leverage and management practices with financial performance on a group of Minnesota and Northwest farms. Management practices were classified into seven broad categories of management, namely strategic planning, financial management, networking, marketing, technology adoption, family relationship and human resources management. Using multiple regression analysis on 242 observations, the effects of financial leverage and management practices on revenues and profits were determined. While the relationship of best management practices with profitability is less conclusive, this study concludes statistically significant relationships between management practices and financial performance, measured in terms of revenues. There exist positive and statistically significant returns to business planning, transition management, customer management and family relationship management. / Master of Science

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / William P. Winslow III / This project is of a personal interest to me, because Junction City, Kansas has been my home town since birth. The city is a rapidly growing community with a strong military presence from nearby Fort Riley, Kansas. The project will explore the capacity for effective growth while preventing the degradation of fragile natural resources within the community. It will also provide new amenities for the people of Junction City as well as capitalize on the existing natural amenities. The project provides storm water management solutions for an existing retail development and a proposed mixed use development incorporating sustainable practices. Studying the history and progressive nature of Junction City provides an understanding of how to embrace the design within the surrounding landscape. A model for responsible mixed use retail and residential development in Junction City is provided through this project. Storm water best management strategies were also implemented to improve the oxbow wetlands by capturing the first flush storm event as well as a 25 year storm event. Finally, the project should continue to shape the history and enthusiasm of Junction City and its people.

The agriculture community is faced with new challenges to increase food production on a limited amount of suitable land to keep up with the growing population. Fertilizers and intensive cropping are needed to meet food demand, but these practices contribute to environmental degradation due to nutrients and sediment leaving fields and entering waterbodies. Non-point source (NPS) pollution from agriculture has been scrutinized for significantly contributing to eutrophication and hypoxic dead zones. To reduce the harmful impacts of NPS pollution from agriculture, producers and land users have implemented in-field and edge-of-field Best Management Practices (BMP). Water and Sediment Control Basins (WASCoBs) are an example of an in-field BMP that has helped reduce erosion and sediment loading of receiving waters. Cover crops are another in-field BMP that have been used to mitigate erosion and nutrient leaching. The impacts of WASCoBs paired with cover crops on water quality, specifically nutrient loading, is lacking in the current literature and was the focus of this research. Our study site was located in Menard County near Atterberry, IL. The farm had relatively steep topography (5-18% slopes) and suffered from severe gully erosion. In 2018, the Natural Resource Conservation Service (NRCS) partnered with the landowner and installed a series of WASCoBs to address the erosion issues. Along with the NRCS and landowner, we worked with the Illinois Farm Bureau (IFB) to investigate the impacts of WASCoBs and cover crops on nutrient and sediment runoff, hydrology, and crop yields.Four sub-watersheds were included in the study: 1) a 1.5-hectare basin treated with a WASCoB; 2) a 1.4-hectare basin treated with a WASCoB and a cover crop; 3) a 0.2-hectare gully drained watershed treated with a cover crop; and 4) a control, 3.8-hectare gully-drained watershed. ISCO automated water samplers collected runoff from storm events in a time-weighted composite sampling regime. The measured water quality parameters were total suspended solids (TSS), ammonium-nitrogen (ammonium-N), nitrate-nitrogen (nitrate-N), dissolved reactive phosphorus (DRP), and total phosphorus (TP). The WASCoB treatment reduced TSS by 98.5-99.8%, TP by 83.8-97.4%, ammonium-N by 42.3-82.9%, and nitrate-N by 32.0-59.6%, respectively. Cover crop impacts on the water quality parameters were not detected, due to poor gemination of the annual rye cover crop. The water quality improvement WASCoBs are a potential tool for farmers and land managers to reduce loading of nutrients and sediment to receiving waters.

The fate and distribution of copper-based crop protectants, applied to tomato fields to protect against disease, were investigated in a greenhouse-scale simulation of farming conditions in a coastal environment. Following rainfall, 99% of the applied copper was found to remain on the fields sorbed to the soil and plants; most of the soil-bound copper was found sorbed to the top 2.5 centimeters of soil. Of the copper leaving the agricultural fields, 82% was found in the runoff with the majority, 74%, sorbed to the suspended solids. The remaining copper, 18%, leached through the soil and entered the groundwater with 10% in the dissolved phase and 8% sorbed to suspended solids. Although only one-percent of the copper was found to leave the field, this was sufficient to cause high copper concentrations (average 2102 ± 433 mg/L total copper and 189 ± 139 mg/L dissolved copper) in the runoff. Copper concentrations in groundwater samples were also high (average 312 ± 198 mg/L total copper and 216 ± 99 mg/L dissolved copper). Sedimentation, a best management practice for reducing copper loadings, was found to reduce the total copper concentrations in runoff by 90% to a concentration of 245 ± 127 mg/L; however, dissolved copper concentrations remained stable, averaging 139 ± 55 mg/L. Total copper concentrations were significantly reduced by the effective removal of suspended solids with sorbed copper. This research was supported by a grant from the Virginia Department of Agriculture and Consumer Services. Funding was also provided by Sea Grant. / Master of Science

Increasing awareness of hypoxia in coastal marine regions across the globe has led to creation of nutrient reduction strategies to protect water resources and organisms living in affected waters. In the Mississippi River Basin, the Governor’s Action Plan has called for a 45% load reduction of both, total nitrogen (N) and total phosphorus (P), to reduce the Gulf of Mexico hypoxic zone to a manageable size. Objectives of this dissertation aimed to determine nutrient reduction efficiencies of low-grade weirs, and to evaluate abundance and composition of microbial communities involved in key processes of denitrification following low-grade weir implementation in the Mississippi Delta. Results of this dissertation evidenced the efficiencies of low-grade weirs to reduce nutrient runoff to downstream waters as a viable BMP. Average median load reductions in N, P, and sediment of -5%, 23%, and 29%, respectively, were determined in ditches with low-grade weirs. Results highlighted more efficient reductions in P and sediment, and greater variability in N reductions during storm events, prompting management considerations toward BMP successes and limitations. Valuable insight towards seasonal nutrient fluxes in agricultural runoff due to spring fertilizer applications, increased rainfall patterns in the winter and spring, and drying-wetting cycles, was also evidenced by the data collected. It was determined that utilizing a three-scale sampling regime was most effective for capturing patterns of microbial community abundance and composition in ditches with low-grade weirs. Preliminary evidence towards weir proximity influencing microbial community abundance, and relationships between microbes and soil carbon and N was also found. Utilizing the three-scale sampling regime, microbial communities in multiple drainage ditches, with and without weirs, were investigated. Outcomes showed that weirs increased soil moisture, which subsequently increased functional gene abundance of 16S rRNA and nirS. Furthermore, weir implementation and associated constructions were not found to directly influence microbial community diversity, abundance, or chemical parameters. Results from this dissertation support the potential benefits of weirs to create suitable environments to physically reduce P and sediment loads and for denitrifying microbes to remediate N from agricultural runoff.

Drainage ditches, or grassed waterways, collect nutrient-laden runoff from agricultural fields and transport it to nearby waterbodies. The high nitrogen and phosphorus content in this water leads to negative effects, such as eutrophication in the receiving waters. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors are intended to reduce flow rate and stimulate denitrification and sedimentation. Using experimental ditch segments and simulated runoff, this study evaluated nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors and 3) vegetated ditches with combination woodchip and biochar bioreactors. Biochar was added in an effort to increase phosphorus removal. Inlet and outlet concentrations of nitrate, ammonium and phosphate were measured for each of the three treatments in triplicate. There were no statistically significant differences between treatments on load removed for any of the three nutrients of interest. Issues in measuring outlet flow rate made drawing definitive conclusions on nutrient load reductions difficult. Further experimentation using adjusted outlet flow measuring methods and bioreactor design would help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology in agricultural grassed waterways. / Master of Science / Drainage ditches, or grassed waterways, are located at the edge of agricultural fields where runoff migrates naturally. These ditches help to direct runoff from the field to receiving waterbodies while reducing erosion. Agricultural runoff often contains high levels of nitrogen and phosphorus from fertilizer added to promote crop growth. When runoff with a high nutrient content reaches a waterbody, it reduces the quality of the water for the plants and animals that live in it and for human recreation or consumption. In-ditch bioreactors are a simple, inexpensive treatment technology that could potentially remove nitrogen and phosphorus from agricultural runoff. In-ditch bioreactors have the potential to remove nitrogen from the water by creating optimal conditions for the microorganisms that transform nitrogen in the water to nitrogen in the air. Phosphorus removal has the potential to be enhanced by in-ditch bioreactors that reduce flow and allow for phosphorus to settle out of the water. In addition, settling of phosphorus may be increased by adding a material, such as biochar, that phosphorus can attach to. Using experimental ditch segments and simulated runoff, this study looked at nutrient removal in 1) vegetated ditches, 2) vegetated ditches with woodchip bioreactors installed and 3) a vegetated ditch with combination woodchip and biochar bioreactors installed. Concentrations of two nitrogen compounds and one phosphorus compound were measured before and after passing through each ditch. There were no significant differences between any of the three ditch types on how much of each compound they could remove. These results are inconclusive due to inaccuracies in measuring flow rate at the outlet of the ditches. Further experimentation using improved flow measuring techniques and bioreactor designs would likely help establish whether in-ditch bioreactors are suitable for use as a nutrient removal technology.

The effect of urbanization on previously agricultural watersheds is an increasingly important issue for watershed planners. Urbanization increases runoff and pollutant loadings to the watershed outlet. Watershed planners in areas that previously had little impervious cover must now consider the effects of new roads and buildings on hydrologic processes. The ANSWERS-2000 watershed model was modified to simulate watersheds with mixtures of agricultural and urban areas. In addition, components were added to simulate atmospheric deposition and urban management practices, including wet ponds, dry ponds, and infiltration trenches. The modified model was evaluated on two watersheds in Blacksburg, Virginia, including a subwatershed of Stroubles Creek and a large parking lot on the Virginia Tech campus with a dry pond at its outlet. The model predicted the hydrology and pollutant losses for the year 1999 from the Stroubles Creek watershed within 50% of the observed values after calibration. Prediction errors were much higher for the parking lot and dry pond simulation of the period of time from August 1995 to February 1996. For the parking lot inflow to the dry pond, errors ranged from 0 to 100%. For the dry pond effluent, errors for runoff and sediment losses were -11.5 and 60.1%, respectively, and nutrient losses were poorly predicted (greater than 100% error). There was considerable uncertainty as to the quality of the observed data and this may account for some of the predicted sediment and nutrient loss errors. The modified model was applied to the Battlefield Green Watershed in Hanover County, Virginia to demonstrate the watershed response to development in that watershed. As simulated, sediment and nutrient losses were 30 to 50 times higher after development. The model is intended for use on watersheds with an impervious cover of 30% or less, due to the increased difficulty in accurately quantifying the hydrology of highly urbanized watersheds and because of uncertainty in atmospheric deposition rates on such watersheds. The pond subroutines are very simplified, and limit simulation to ponds with simple geometries. / Master of Science

Due to development of once natural landscapes, also referred to as urbanization, stormwater management has evolved in an effort to address and counteract impairment of waterways in the United States by extensively implementing best management practices (BMPs) or Green Stormwater Infrastructure (GSI). Facilities are installed without any requirement of long-term monitoring; instead relying on lab-tested or assumed pollutant removal efficiencies that often do not translate into field implementation and do not perform as intended and required by regulatory agencies. Monitoring studies have often been applied with variable standards, which lead to inconsistent results and inconclusive data. This study aims to synthesize essential components of a GSI monitoring program based on a review of existing programs (Technology Assessment Protocol – Ecology [TAPE], Technology Assessment Reciprocity Partnership [TARP], etc.). Data from past protocols was used in tandem with historic precipitation data to develop a methodology for creating a local or small region-specific protocol. This methodology was applied to the case study area of Fairfax, Virginia. Results from the study indicate that historic precipitation data and past protocol recommendations can be effectively applied in a local setting to create a more suitable protocol adapted for GSI monitoring in order to confirm designed efficiency. / Master of Science / Due to development of once natural landscapes, also referred to as urbanization, stormwater management has evolved in an effort to address and counteract impairment of waterways in the United States by extensively implementing best management practices (BMPs) or Green Stormwater Infrastructure (GSI). Facilities are installed without any requirement of long-term monitoring; instead relying on lab-tested or assumed pollutant removal efficiencies that often do not translate into field implementation and do not perform as intended and required by regulatory agencies. Monitoring studies have often been applied with variable standards, which lead to inconsistent results and inconclusive data. This study aims to synthesize essential components of a GSI monitoring program based on a review of existing programs (Technology Assessment Protocol – Ecology [TAPE], Technology Assessment Reciprocity Partnership [TARP], etc.). Data from past protocols was used in tandem with historic precipitation data to develop a methodology for creating a local or small region-specific protocol. This methodology was applied to the case study area of Fairfax, Virginia. Results from the study indicate that historic precipitation data and past protocol recommendations can be effectively applied in a local setting to create a more suitable protocol adapted for GSI monitoring in order to confirm designed efficiency.

Construction and maintenance can have huge implications on the long-term functioning of GSI facilities. GSI facilities investigated were bioretention, permeable pavement, sand filters, infiltration trenches, and vegetated swales. This study first highlights the most important construction and maintenance items based on relevant studies and state stormwater manuals. Fairfax County, VA was used as a case study to evaluate the County's current stormwater program and illuminate common maintenance issues found for each GSI type. Data analysis of 3141 inspection records illustrated particular deficiencies for each GSI type and that there are differences between public and private facilities, most likely depending on site conditions and frequency of routine maintenance. Sediment accumulation was found to be the most common maintenance issue (27.8% of inspections), supporting the importance of adequate pretreatment and good housekeeping when implementing GSI. The Northern Virginia Soil and Water Conservation District (NVSWCD) performed a study surveying 63 public bioretention facilities in which they measured ponding depth, filter media depth, ponding area, and infiltration rates. The NVSWCD concluded that deficiencies found in facilities could mostly be attributed to inadequacies during construction. By comparing current post-construction inspections performed by the County to the NVSWCD data, it was found that these County inspections are failing to detect these inadequacies in bioretention facilities from improper construction. It is recommended that MS4s thoroughly record and track construction and post-construction inspection items to improve the longevity of its facilities and better inform future decision making regarding GSI. / Master of Science / Studies have shown that the proper construction and maintenance of green stormwater infrastructure (GSI) is a critical factor concerning its long-term performance; however, little research has been conducted on the necessary protocols and frequency to ensure its longevity. Many MS4s and stormwater managers are implementing these facilities without providing the adequate institutional framework to ensure the proper construction and maintenance. This study concentrates on illuminating the construction and maintenance factors critical for the performance of GSI. Facility types investigated were bioretention, permeable pavement, sand filters, infiltration trenches, and vegetated swales. The effects of local site-conditions and level of routine maintenance on frequency of facility deficiencies was quantified using 3141 records of maintenance and inspection data from Fairfax County, VA. Sediment and debris accumulation were found to be the most common deficiency highlighting the importance of good housekeeping and pretreatment devices. The Northern Virginia Soil and Water Conservation District (NVSWCD) performed a comprehensive review of 63 bioretention facilities in which they inspected elements considered critical to pollutant removal performance including ponding depth, filter media depth, and infiltration rates. By comparing the findings from the NVSWCD to current post-construction inspections performed by the County, it was found that current inspection protocols are missing important design components of bioretention facilities. This study also highlights the importance of thorough and thoughtful databases to track and record inspection and maintenance data surrounding GSI. The proper construction and maintenance of GSI is ultimately dependent on a multitude of factors including site-conditions, facility design specifications, and institutional support.