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Browsing by Author "Goyne, Keith W."

Now showing 1 - 16 of 16
  • Assessing and managing soil quality for sustainable agricultural system
    Motavalli, Peter P.; Jintaridth, Bunjirtluk; Lehmann, Johannes; Goyne, Keith W.; Gilles, Jere L. (2008)
    Soil quality assessment is a process by which soil resources are evaluated on the basis of soil function. Soil organic matter (SOM) is one of the most widely knowledge indicators of soil quality(Gregorich et al., 1994). In general, SOC varies across landscapes, soil types and climatic zones. It is characterized by high levels of C in recalcitrant or humified forms and small changes in SOC resulting from changes in soil management are difficult to measure. An approach to evaluate the impact of agricultural management of SOM dynamics is to separate SOM into pools which will depend on differences in decomposition rates (Wander et al., 1994). In two-pool exponential decomposition models, the pool with the smallest size and most rapid turnover is termed labile and the larger pool with slow turnover is termed recalcitrant. The lability of SOM is defined as the ease and speed with which it is decomposed by microbes and depends on both chemical recalcitrance and physical protection from microbes. Changes in labile fractions of SOC provide an early indication of soil degradation or improvement in response to management practices (Islam and Weil,2000). In this research, soil samples will be collected from representative degraded and non- degraded soils at ongoing SANREM field sites, establish in-field and laboratory capacity to test soil quality, and develop analytical methodologies for the spectroscopic-based procedures. Collaboration with CGIAR system (i.e., ICRAF), USDA-ARS and USDA-NRCS are also important goals of this project due to the ongoing efforts and resources being invested at these institutions in developing low-cost methods for soil quality evaluation.
  • Assessing and managing soil quality for sustainable agricultural systems: SANREM CRSP Cross Cutting initiative
    Motavalli, Peter P.; Jintaridth, Bunjirtluk; Lehmann, Johannes; Goyne, Keith W.; Gilles, Jere L. (2008)
    A presentation about the SANREM CRSP Cross Cutting initiative in terms of assessing and managing soil quality for sustainable agricultural systems in the Altiplano of Peru and Bolivia.
  • Assessing soil quality for sustainable agricultural systems in tropical countries using spectroscopic methods
    Jintaridth, Bunjirtluk; Motavalli, Peter P.; Goyne, Keith W.; Kremer, R. J. (2008)
    Identifying and developing appropriate methods to quantify and assess changes in soil quality are essential for evaluating the extent of soil degradation and the effectiveness of improved management practices. The objective of this research, which will be conducted across a wide range of cropping systems and environments in Asia, Africa and South America, is to determine the efficacy of spectroscopic-based (i.e. near-infrared, mid-infrared, and visible range) analytical methods to evaluate soil organic matter fractions and soil quality in degraded and non-degraded soils. Initial activities of the project are to develop in-field and laboratory analytical methodologies for the spectroscopic-based procedures, conduct comparisons of use of those methodologies in different cropping systems and climates that have experienced soil degradation, and collect soil samples from representative degraded and non-degraded soils for additional characterization of their soil C and N fractions. Among the methodologies to be tested are diffuse reflectance infrared Fourier-transformed (DRIFT) mid-infrared spectroscopy, near-infrared spectroscopy (NIR), and use of the in-field potassium permanganate test. Additional assessment of the criteria used to evaluate the results from these tests will also be discussed.
  • Assessing soil quality for sustainable agricultural systems in tropical countries using spectroscopic methods
    Jintaridth, Bunjirtluk; Motavalli, Peter P.; Goyne, Keith W.; Kremer, R. J. (2008)
    Soil quality assessment is a process by which soil resources are evaluated on the basis of soil function. The need for an effective, low-cost method to evaluate soil quality is important in developing countries because soil degradation is a major impediment to sustainable crop growth. Soil organic matter (SOM) or soil organic C (SOC) is an important indicator of soil quality (Gregorich et al., 1994) because it affects many plant growth factors, including water-holding capacity and long-term nutrient availability. In general, SOC varies across landscapes, soil types and climatic zones and is characterized by both labile and recalcitrant or humified forms. There are many techniques that measure the size and turnover time of SOC pools to evaluate soil quality in the laboratory or the field to help guide sustainability of agricultural management practices. Among these methods are several spectroscopic procedures which are rapid and relatively low-cost. The KMnO4 method developed by Weil (2003) has been adapted for field use and measures a labile C fraction. Near infrared (NIR) spectroscopy has also been adapted for field use and could provide a rapid method to measure soil C fractions (Shepherd et al., 2007). Another technique which has been studied is the use of diffuse reflectance infrared Fourier-transformed (DRIFT) mid-infrared spectroscopy which can identify labile and recalcitrant C in soil (Ding et al., 2002). However, many of these techniques have not been assessed under a wide range of soil types and cropping systems.
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    Beyond neonicotinoids - Wild pollinators are exposed to a range of pesticides while foraging in agroecosystems
    Main, Anson R.; Hladik, Michelle L.; Webb, Elisabeth B.; Goyne, Keith W.; Mengel, Doreen (2020-11-10)
    Pesticide exposure is a growing global concern for pollinator conservation. While most current pesticide studies have specifically focused on the impacts of neonicotinoid insecticides toward honeybees and some native bee species, wild pollinators may be exposed to a broader range of agrochemicals. In 2016 and 2017 we collected a total of 637 wild bees and butterflies from the margins of cultivated agricultural fields situated on five Conservation Areas in mid-northern Missouri. Pollinators were composited by individual genera (90 samples) and whole tissues were then analyzed for the presence of 168 pesticides and degradation products. At least one pesticide was detected (% frequency) in the following wild bee genera: Bombus (96%), Eucera (75%), Melissodes (73%), Pnlothrix (50%), Xylocopa (50%), and Megachile ( 17%). Similarly, at least one pesticide was detected in the following lepidopteran genera: Hemaris (100%), Hylephila (75%), Danaus (60%), and Colitis (50%). Active ingredients detected in >2% of overall pollinator samples were as follows: metolachlor (24%), tebuconazole (22%), atrazine (18%), iinidadoprid desnitro (13%), bifenthrin (9%), flumetralin (9%), p, p'-DDD (6%), tebupirimfos (4%), Iludioxonil (4%), flutriafol (3%), cyproconazole (2%), and oxacliazon (2%). Concentrations of individual pesticides ranged from 2 to 174 ng/g. Results of this pilot field study indicate that wild pollinators arc exposed to and are potentially bioaccumulating a wide variety of pesticides in addition to neonicotinoids. Here, we provide evidence that wild bee and butterfly genera may face exposure to a wide range of insecticides, fungicides, and herbicides despite being collected from areas managed for conservation. Therefore, even with the presence of extensive habitat, minimal agricultural activity on Conservation Areas may expose pollinators to a range of pesticides. Published by Elsevier B.V.
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    Certain Soil Surfactants Could Become a Source of Soil Water Repellency after Repeated Application
    Song, Enzhan; Goyne, Keith W.; Kremer, Robert J.; Anderson, Stephen H.; Xiong, Xi (MDPI, 2021-09-30)
    Repeated application of soil surfactants, or wetting agents, is a common practice for alleviating soil water repellency associated with soil organic coatings. However, wetting agents are organic compounds that may also coat soil particle surfaces and reduce wettability. For this experiment, hydrophobic sands from the field and fresh, wettable sands were collected and treated with either a polyoxyalkylene polymer (PoAP) or alkyl block polymer (ABP) wetting agent, or water only treatments served as a control. Following repeated treatment application and sequential washings, dissolved and particulate organic carbon (OC) were detected in the leachates of both sand systems. The total amount of OC recovered in leachates was 88% or less than the OC introduced by the wetting agents, indicating sorption of wetting agent monomers to soil particle surfaces regardless of soil hydrophobicity status. While ABP treatment did not alter solid phase organic carbon (SOC) in the sands studied, PoAP application increased SOC by 16% and 45% which was visible in scanning electronic microscopy images, for hydrophobic and wettable sands, respectively. PoAP application also increased the hydrophobicity of both sands that were studied. In contrast, ABP treatment increased the wettability of hydrophobic sand. Our results provide strong evidence that certain wetting agents may increase soil hydrophobicity and exacerbate wettability challenges if used repeatedly over time.
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    A chronosequence of soil health under tallgrass prairie reconstruction
    Li, Chenhui; Veum, Kristen S.; Goyne, Keith W.; Nunes, Marcio R.; Acosta-Martinez, Veronica (2021-08)
    Soil health changes induced by prairie reconstruction (cultivated fields to tallgrass prairie) were assessed in Central Missouri within sites representing a chronosequence of 0, 2, 3, 4, 6, 9, 10, 11, 12, and 13-yr postreconstruction. In addition, a nearby remnant native prairie, two long-term reconstructed prairies (-25 and -57-yr post-reconstruction), and a biofuel prairie 9-yr post-reconstruction were evaluated for comparative purposes. From 0 to 8-yr, prairie reconstruction increased soil aggregation, total soil organic carbon (SOC), total nitrogen (TN), active C and N (permanganate oxidizable C and total protein), and mineralizable C and N (soil respiration and potentially mineralizable nitrogen), becoming more similar to levels in the remnant prairie. Further, four enzymes involved in the cycling of C (13-glucosidase), N (13-glucosaminidase), P (acid phosphatase), and S (arylsulfatase) demonstrated amplified activities within samples collected to a depth of 15-cm. Over time, the ratios of active C to SOC and active N to TN declined, reflecting the conversion of active C/N pools into more stable C/N pools due to continued organic inputs and increased microbial activity. In contrast, from 8- to 13-yr post-reconstruction, the number of these same soil health indicators declined, which may be attributed to historical land use, the improvement of prairie reconstruction and management strategies, and ecological processes related to succession. Overall, prairie reconstruction holds great potential for soil health restoration in degraded agricultural landscapes, and further study is needed to understand how historical land use and prairie reconstruction practices affect soil health and ecological resilience.
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    Clothianidin decomposition in Missouri wetland soils
    Beringer, Chelsey J.; Goyne, Keith W.; Lerch, Robert N.; Webb, Elisabeth B.; Mengel, Doreen (2021-01)
    Neonicotinoid pesticides can persist in soils for extended time periods; however, they also have a high potential to contaminate ground and surface waters. Studies have reported negative effects associated with neonicotinoids and nontarget taxa, including aquatic invertebrates, pollinating insect species, and insectivorous birds. This study evaluated factors associated with clothianidin (CTN) degradation and sorption in Missouri wetland soils to assess the potential for wetland soils to mitigate potential environmental risks associated with neonicotinoids. Solid-to-solution partition coefficients (K-d) for CTN sorption to eight wetland soils were determined via single-point sorption experiments, and sorption isotherm experiments were conducted using the two most contrasting soils. Clothianidin degradation was determined under oxic and anoxic conditions over 60 d. Degradation data were fit to zero- and first-order kinetic decay models to determine CTN half-life (t(0.5)). Sorption results indicated CTN sorption to wetland soil was relatively weak (average K-d, 3.58 L kg(-1)); thus, CTN has the potential to be mobile and bioavailable within wetland soils. However, incubation results showed anoxic conditions significantly increased CTN degradation rates in wetland soils (anoxic average t(0.5), 27.2 d; oxic average t(0.5), 149.1 d). A significant negative correlation was observed between anoxic half-life values and soil organic C content (r(2) = .782; p = .046). Greater CTN degradation rates in wetland soils under anoxic conditions suggest that managing wetlands to facilitate anoxic conditions could mitigate CTN presence in the environment and reduce exposure to nontarget organisms.
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    Evaluating phytochemical and microbial contributions to atrazine degradation
    Hatch, K. M.; Lerch, R. N.; Kremer, R. J.; Willett, C. D.; Roberts, C. A.; Goyne, Keith W. (Academic Press, 2022-11)
    The inclusion of warm-season grasses, such as switchgrass (Panicum virgatum) and eastern gamagrass (EG) (Tripsacum dactyloides), in vegetated buffer strips has been shown to mitigate herbicide contamination in runoff and increase herbicide degradation in soil. The mode of action by which buffer strip rhizospheres enhance herbicide degradation remains unclear, but microorganisms and phytochemicals are believed to facilitate degradation processes. The objectives of this study were to: 1) screen root extracts from seven switchgrass cultivars for the ability to degrade the herbicide atrazine (ATZ) in solution; 2) determine sorption coefficients (Kd) of the ATZ-degrading phytochemical 2-beta-D-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DBG) to soil and Ca-montmorillonite, and investigate if DBG or ATZ sorption alters degradation processes; and 3) quantify ATZ degradation rates and soil microbial response to ATZ application in mesocosms containing soil and select warm-season grasses. Phytochemicals extracted from the roots of switchgrass cultivars degraded 44-85% of ATZ in 16-h laboratory assays, demonstrating that some switchgrass cultivars could rapidly degrade ATZ under laboratory conditions. However, attempts to isolate ATZ-degrading phytochemicals from plant roots were un-successful. Sorption studies revealed that DBG was strongly sorbed to soil (Kd = 87.2 L kg-1) and Ca-montmorillonite (Kd = 31.7 L kg � 1), and DBG driven hydrolysis of ATZ was entirely inhibited when either ATZ or DBG were sorbed to Ca-montmorillonite. Atrazine degradation rates in mesocosm soils were rapid (t0.5 = 8.2-11.2 d), but not significantly different between soils collected from the two switchgrass cultivar mesocosms, the eastern gamagrass cultivar mesocosm, and the unvegetated mesocosm (control). Significant changes in three phospholipid fatty acid biomarkers were observed among the treatments. These changes indicated that different ATZ-degrading microbial consortia resulted in equivalent ATZ degradation rates between treatments. Results demonstrated that soil microbial response was the dominant mechanism controlling ATZ degradation in the soil studied, rather than root phytochemicals.
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    Field-level characteristics influence wild bee functional guilds on public lands managed for conservation
    Main, Anson R.; Webb, Elisabeth B.; Goyne, Keith W.; Mengel, Doreen (2019-01)
    Throughout the Midwestern US, many public lands set aside for conservation engage in management activities (e.g., agriculture) that may act as stressors on wild bee populations. Several studies have investigated how wild bees respond to large-scale agriculture production; however, there has been limited assessment of how wild bees may be impacted by agricultural activity on public lands or how local variables may influence bee communities in these same areas. In this study, we assessed the abundance and richness of wild bee floral and nesting guilds at 30 agricultural field margins located on five Conservation Areas in Missouri. Generally, regardless of guild, bee abundance and richness was greater in field margins with more floral diversity and taller vegetation. Bee guilds responded negatively to agricultural production in Conservation Areas with fewer soil- and cavity-nesting bees collected in margins adjacent to annually cropped fields. Although fewer diet specialists were collected, specialist bee abundance and richness was greater in margins near fields that were uncropped (i.e., vegetated, but not row-cropped) during the previous year. Overall, the percentage of trees and shrubs within 800 m of study fields (i.e., "woodland") was negatively associated with abundance and richness of bees, but specifically, reduced richness of soil-nesters and diet specialists. Our findings indicate agricultural management activities on public lands may lead to decreased abundance and richness of wild bee guilds. If public lands are to be managed for species diversity, including wild bees, maintaining diverse plant communities with taller vegetation (>100 cm) near cultivated fields and/or modifying agricultural production practices on public lands may greatly improve the conservation of local bee communities. (C) 2019 The Authors. Published by Elsevier B.V.
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    Framework for using downscaled climate model projections in ecological experiments to quantify plant and soil responses
    Owen, Rachel K.; Webb, Elisabeth B.; Goyne, Keith W.; Svoma, Bohumil M.; Gautam, Sagar (2019-09)
    Soil and plant responses to climate change can be quantified in controlled settings. However, the complexity of climate projections often leads researchers to evaluate ecosystem response based on general trends, rather than specific climate model outputs. Climate projections capture spatial and temporal climate extremes and variability that are lost when using mean climate trends. In addition, application of climate projections in experimental settings remains limited. Our objective was to develop a framework to incorporate statistically downscaled climate model projections into the design of temperature and precipitation treatments for ecological experiments. To demonstrate the utility of experimental treatments derived from climate projections, we used wetlands in the Great Plains as a model ecosystem for evaluating plant and soil responses. Spatial and temporal projections were selected to capture variability and intensity of projected future conditions for exemplary purposes. To illustrate climate projection application for ecological experiments, we developed temperature and precipitation treatments based on moderate-emissions scenario climate outputs (i.e., RCP4.5-650 ppm CO2 equivalent). Our temperature treatments captured weekly trends that represented cool, average, and warm temperature predictions, and our daily precipitation treatments mimicked various seasonal precipitation trends and extreme events projected for the late 21st century. Treatments were applied to two short-term controlled experiments evaluating (1) plant germination (temperature treatment applied in growth chamber) and (2) soil nitrogen cycling (precipitation treatment applied in greenhouse) responses to projected future conditions in the Great Plains. Our approach provides flexibility for selecting appropriate and precise climate model outputs to design experimental treatments. Using these techniques, ecologists can better incorporate variation in climate model projections for experimentally evaluating ecosystem responses to future climate conditions, reduce uncertainty in predictive ecological models, and apply predicted outcomes when making management and policy decisions.
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    Impacts of neonicotinoid seed treatments on the wild bee community in agricultural field margins
    Main, Anson R.; Webb, Elisabeth B.; Goyne, Keith W.; Abney, Robert; Mengel, Doreen (2021-09-10)
    Wild bees support global agroecosystems via pollination of agricultural crops and maintaining diverse plant communities. However, with an increased reliance on pesticides to enhance crop production, wild bee communities may inadvertently be affected through exposure to chemical residues. Laboratory and semi-field studies have demonstrated lethal and sublethal effects of neonicotinoids on limited genera (e.g., Apis, Bombus, Megachile), yet full field studies evaluating impacts to wild bee communities remain limited. Here, we conducted a two-year field study to assess whether neonicotinoid seed treatment and presence in environmental media (e.g., soil, flowers) influenced bee nest and diet guild abundance and richness. In 2017 and 2018, we planted 23 Missouri agricultural fields to soybeans (Glycine max) using one of three seed treatments: untreated (no insecticide), treated (imidadoprid), or previously-treated (untreated, but neonicotinoid use prior to 2017). During both years, wild bees were collected in study field margins monthly (May to September) in tandem with soil and flowers from fields and field margins that were analyzed for neonicotinoid residues. Insecticide presence in soils and flowers varied over the study with neonicotinoids infrequently detected in both years within margin flowers (0%), soybean flowers (<1%), margin soils (<8%), and field soils (similar to 39%). Wild bee abundance and species richness were not significantly different among field treatments. In contrast, neonicotinoid presence in field soils was associated with significantly lower richness (ground- and aboveground-nesting, diet generalists) of wild bee guilds. Our findings support that soil remains an underexplored route of exposure and long-term persistence of neonicotinoids in field soils may lead to reduced diversity in regional bee communities. Future reduction or elimination of neonicotinoid seed treatment use on areas managed for wildlife may facilitate conservation goals to sustain viable, diverse wild bee populations. Published by Elsevier B.V.
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    Influence of Repeated Application of Wetting Agents on Soil Water Repellency and Microbial Community
    Song, Enzhan; Pan, Xiaowei; Kremer, Robert J.; Goyne, Keith W.; Anderson, Stephen H.; Xiong, Xi (MDPI, 2019-08-20)
    Wetting agents are the primary tool used to control soil water repellency (SWR) and localized dry spot (LDS), especially on sand-based soils. However, the effect of repeated applications of wetting agents on soil microbial populations is unknown. This two-year field experiment investigated six wetting agents representing different chemistry effects on a creeping bentgrass (Agrostis stolonifera L.) putting green with existing SWR. Four out of the six wetting agents improved soil volumetric water content in the second growing season, while others showed no effect. This result was negatively correlated to the development of LDS, and positively correlated to occurrence of an air-borne turf disease. Soil microbial populations, determined by soil phospholipid fatty acid (PLFA) analysis, found that none of the treatments applied caused a shift in microbial populations between fungi and bacteria, or gram-positive and gram-negative bacteria. The stress indicators such as saturated to mono-unsaturated fatty acids were not affected by the wetting agents applied as well. However, the wetting agent that contains alkyl block polymers (ABP; Matador) with proven capability for removal of soil organic coatings showed inhibition of microbial populations at one evaluation timing. This result suggested a temporary restriction in soil carbon availability for soil microorganisms following repeated ABP application, which likely contributed to the elevated LDS development observed. Another wetting agent, a combined product of a nonionic surfactant plus acidifiers (NIS; pHAcid), which is designed to reduce inorganic carbonates while enhancing wetting, elevated all soil microbial populations tested at the end of the experiment, indicating a desirable improvement in soil health. However, repeated application of NIS did not reduce SWR at the conclusion of this experiment, which, in combination with a previous report, suggested a minimal disturbance of soil organic coatings of the hydrophobic sand. Overall, this experiment suggested that soil microbial populations can be affected by wetting agents which may further influence SWR, yet the actual effect on soil microorganisms varies depending on the chemistry of the wetting agents.
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    Projected climate and land use changes drive plant community composition in agricultural wetlands
    Owen, Rachel K.; Webb, Elisabeth B.; Haukos, David A.; Goyne, Keith W. (2020-07)
    Playa wetlands in the Great Plains, USA support a wide variety of plant species not found elsewhere in this agriculturally-dominated region due to the ephemeral presence of standing water and hydric soils within playas. If longer dry periods occur due to climate change or if changes in surrounding land use alter sediment accumulation rates and water storage capacity in playas, plant communities could experience decreased diversity, with lasting effects on ecosystem services provided by playas in the Great Plains and at a continental-level in North America. We quantified potential changes in playa wetland plant community composition associated with predicted changes in precipitation and land use in the Great Plains through the end of the 21st century. We conducted two six-month greenhouse experiments mimicking field conditions using intact mesocosms collected from playas in Nebraska and Texas. In the precipitation experiment, treatments derived from historical precipitation observations and three future moderate emissions (CMIP5 RCP4.5) downscaled climate projections were applied to mesocosms. For the land use experiment, treatments were simulated by nitrogen (N) applications to soil ranging from 0 to 100 mg-N L-1 with each precipitation event under historical rainfall patterns, representing increasing and decreasing area in agricultural use in playa watersheds. Plant communities tended to shift toward more native species under projected future climate conditions, but as N runoff increased, native species richness decreased. Agricultural land-use surrounding playas may have a greater effect on wetland plant communities than future alterations to hydrology based on climate change in the Great Plains; thus, efforts to reduce nutrient runoff into playas would likely mitigate loss in ecosystem function in the coming decades.
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    Reduced species richness of native bees in field margins associated with neonicotinoid concentrations in non-target soils
    Main, Anson R.; Webb, Elisabeth B.; Goyne, Keith W.; Mengel, Doreen (2020-01-01)
    Native bees are in decline as many species are sensitive to habitat loss, climate change, and non-target exposure to synthetic pesticides. Recent laboratory and semi-field assessments of pesticide impacts on bees have focused on neonicotinoid insecticides. However, field studies evaluating influences of neonicotinoid seed treatments on native bee communities of North America are absent from the literature. On four Conservation Areas of Missouri, we sampled row-cropped (treated, n = 15) and reference (untreated, n = 9) agricultural fields, and their surrounding field margins for neonicotinoids in soil and non-target vegetation (i.e., native wildflowers). Wildflowers were further collected and screened for the presence of fungicides. Concurrently, we sampled native bees over three discrete time points throughout the agricultural growing season to assess potential impacts of seed treatment use on local bee populations over time. Neonicotinoids were detected in 87% to 100% of treated field soils and 22% to 56% of reference field soils. In adjacent field margin soils, quantifiable concentrations were measured near treated (53% to 93% detection) and untreated fields (33% to 56% detection). Fungicides were detected in < 40% of wildflowers, whereas neonicotinoids were rarely detected in field margin vegetation (< 7%). Neonicotinoid concentrations in margin soils were negatively associated with native bee richness (beta = -0.21, P < 0.05). Field margins with a combination of greater neonicotinoid concentrations in soil and fungicides in wildflowers also contained fewer wild bee species (beta = -0.21, P < 0.001). By comparison, bee abundance was positively influenced by the number of wildflower species in bloom with no apparent impact of pesticides. Results of this study indicate that neonicotinoids in soil are a potential route of exposure for pollinator communities, specifically ground-nesting species. Importantly, native bee richness in non-target field margins may be negatively affected by the use of neonicotinoid seed treatments in agroecosystems.
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    Vegetative buffer strips show limited effectiveness for reducing antibiotic transport in surface runoff
    Moody, Adam H.; Lerch, Robert N.; Goyne, Keith W.; Anderson, Stephen H.; Mendoza-Cozatl, David G.; Alvarez, David A. (Wiley, 2023-01)
    Vegetative buffer strips (VBS) have been demonstrated to effectively reduce loads of sediment, nutrients, and herbicides in surface runoff, but their effectiveness for reducing veterinary antibiotic (VA) loads in runoff has not been well documented. The objective of this study was to determine the effectiveness of VBS vegetation and width on surface runoff loads of the VAs sulfamethazine (SMZ) and lincomycin (LIN). Experimental design of the plots (1.5 x 25 m) was a two-way factorial with four vegetation treatments (tall fescue [Festuca aruninacea Schreb.]; tall fescue with switchgrass [Panicum virgatum L.] hedge; warm-season native grass mix; and continuous fallow control), and four buffer widths (0, 2, 5, and 9 m). Turkey litter spiked with SMZ and LIN was applied to the source area (upper 7 m) of each plot, and runoff was collected at each width. Runoff was generated with a rotating boom simulator. Results showed VA loads in runoff at the 0-m sampler ranged from 3.8 to 5.9% of applied, and overall VA transport in runoff was predominately in the dissolved phase (90% for SMZ and 99% for LIN). Among vegetation treatments, only tall fescue significantly reduced loads of SMZ and LIN compared with the control, with load reductions of similar to 30% for both VAs. Estimated field-scale reductions in VA loads showed that source-to-buffer area ratios (SBARs) of 10:1 to 20:1 reduced VA loads by only 7 to 16%. Overall, the grass VBS tested here were less effective at reducing SMZ and LIN loads in surface runoff than has been previously demonstrated for sediment, nutrients, and herbicides.