Earthworm abundances in endophyte-infected tall fescue pastures in Northwest Arkansas

The ecology of organisms that co-evolve within an ecosystem is likely to be distinct from that involving organisms recently introduced into an area. To better understand the relationship of earthworms with endophyte-infected tall fescue, earthworms in novel and toxic endophyte-infected tall fescue pastures were enumerated and identified as adults or juveniles. We hypothesized that differences in endophyte infection of the fescue would influence earthworm abundances. Earthworms in two toxic and two novel endophyte-infected tall fescue fields in Fayetteville, Ark., were sampled weekly from January through July 2007. Each type of endophyte-infected pasture was established in 1997 and 2003. Sampling was carried out utilizing a physical dig-and-sort extraction method. Although variable, sampling time was a significant factor in the number of adult and juvenile worms collected. Adult earthworm abundances showed a seasonal trend of declining numbers from winter to summer, while juvenile worms showed an increase from winter to summer. Previous studies have shown that endophyte infection of plants can impact soil organisms. In this study, type of fungal endophyte infection did not appear to impact earthworm abundances; therefore, use of novel endophyte-infected fescue in a pasture is not expected to have an impact on the ecology of earthworms

Evaluating Rice Straw as a Substitute for Barley Straw in Inhibiting Algal Growth in Farm Ponds

Algal blooms disrupt aquatic ecosystems and are more common in lakes, ponds, and rivers during the summer months due to nutrient pollution. Livestock production can contribute increased quantities of nutrients to water bodies from runoff of manure. Commonly used mechanical and chemical control methods may have limited success because algae are small and propagate quickly. Barley (Hordeum vulgare) straw has been shown to inhibit the growth of algae as the straw decomposes aerobically in ponds. Therefore, barley represents a natural option for algal biomass control. However, the small amount of barley production in Arkansas limits the availability of barley straw as a solution to control algal blooms locally. Other cereal grain straws may produce similar inhibitory effects during decomposition. Rice (Oryza sativa) is produced in large quantities in Arkansas, making rice straw a locally sourced straw product. The objective of this research was to determine the efficacy of using rice compared to barley straw to inhibit algal growth in freshwater ponds. Data were collected from nine farm ponds, three treated with rice straw, three treated with barley straw, and three without amendment to serve as the experimental control. Dissolved oxygen, pH, nitrate-nitrogen (NO3--N), dissolved phosphorus (P), temperature, and turbidity were measured for 14 weeks from June 12 to September 17, 2018. Algal biomass was measured as chlorophyll-a concentration to evaluate treatment effectiveness over time. Dissolved oxygen was significantly influenced by treatment and time. The NO3--N concentration in ponds treated with rice straw was significantly greater than the control and barley treatment. Chlorophyll-a concentrations were variable, and there were no consistent trends through time within a treatment. More research under controlled conditions to understand impacts of abiotic conditions, microbial and algal community compositions, and mode of action of algal inhibition is required before cereal straw can be a reliable, locally sourced method of algal control in farm ponds

Presence of antibiotic resistance genes from wastewater treatment plant effluent in Northwest Arkansas

Antibiotic resistance genes (ARGs) among bacterial populations are causing increasing concern with medical and agricultural implications. While the effluent of wastewater treatment plants (WWTPs) is treated with a variety of antimicrobial methods, bacteria and the genetic material that is able to pass on antibiotic resistance to environmental populations are not completely destroyed. Ampicillin (amp), tetracycline (tet), and sulfonamide (sul) antibiotics have been detected in Northwest Arkansas (NWA) streams, and IncP plasmids—which are especially notorious for containing antibiotic resistance genes and have been detected after disinfection in NWA WWTPs—are known to carry ARGs for those antibiotics. The objective of this inquiry was to determine whether ARGs of commonly used antibiotics (ampC and oxa2 for ampicillin, tetA for tetracycline, and sul1 for sulfonamide resistance) were present in effluent following disinfection that demonstrated variable reduction in IncP plasmid numbers. DNA was extracted from water collected from a WWTP that uses ultraviolet light and a WWTP that uses chlorination and was participating in a pilot-scale ozonation test. Three of the four ARGs were detected using polymerase chain reaction (PCR) both before and after all three disinfection methods. The ampicillin resistance gene ampC was the only gene that was detected in less than two-thirds replications either before or after disinfection. Given the PCR results and previous quantitative PCR analysis of IncP plasmid concentrations, it appears there is little reduction of ARGs after disinfection. These data are important in understanding the role of WWTPs in contributing to the spread of antibiotic resistance in the environment

The biofiltration ability of Asparagus densiflorus to remove sulfur dioxide from the indoor atmosphere

Sulfur dioxide is an inorganic compound (IC) and air pollutant that causes health risks in humans. The buildup of sulfur dioxide (SO2) in enclosed indoor spaces is, therefore, a concern to human health, especially since the average person spends 90% of his/her time indoors. This study focused on decreasing SO2 concentration in a cost-effective and simple way—by using botanical biofiltration, or the uptake of pollutants by plants. Research in biofiltration has focused mostly on the remediation of volatile organic compounds (VOC). However, research has also shown that plant species that remediate VOC efficiently also have the potential for efficient IC remediation. Asparagus densiflorus, which has a superior capacity for VOC uptake, has not yet been tested for the uptake of SO2. In order to fill that research gap, this study measured the difference in the amount of SO2 after 3 hours in an airtight container in the presence of an Asparagus densiflorus plant divided by the amount of SO2 present in the absence of the plant. This result was considered the fraction of SO2 remediated by the plant. The results in this experiment, although showing significant fractions of SO2 removal, were too variable to be conclusive about the amount of SO2 removed from an enclosed atmosphere and, therefore, of the biofiltration ability of A. densiflorus. Nonetheless, further research using a different research design is recommended to investigate whether A. densiflorus is more efficient than other plants at removing SO2 from the atmosphere and, therefore, could be used in biofilters

Invertebrate Abundances and Diversity of a Six Year Old Organic Apple Orchard in Northwest Arkansas

Ground cover mulch applications in perennial systems can have multiple benefits, one of which may be to enhance the size and diversity of the ground surface faunal community. To determine if ground cover and organic fertilizer applications altered invertebrate communities, litters in an experimental 0.4-ha organic apple orchard in Fayetteville, Ark. were sampled during a four week period beginning in February 2012. The orchard was planted in 2006 in a replicated 4 × 3 factorial design with organic ground cover and fertilizer treatments applied annually each April. Invertebrates were extracted using Berlese funnels and hand sorting techniques. Ground covers (wood chips (W), urban compost (C), and shredded paper (P)) increased abundances per unit area, taxa richness, and diversity compared to the litter of the mowed control (M), with the largest abundances on an area basis occurring in W. Nutrient applications had little to no effect on invertebrate communities. Isopoda comprised a larger proportion of the litter community in P compared to M. Compost enhanced the proportion of Diplopoda and Haplotaxida and W enhanced the proportion of Diplopoda and Isopoda compared to M. In terms of direct abundances, Chilopoda and Gastropoda as well as Diplopoda and Isopoda were higher in W than in M. Habitat differences on the soil surface resulting from managing the orchard with different ground covers altered the community composition of the litter fauna expected to facilitate decomposition, but did not show a predominance of predators that might be expected to enhance pest control

Changing career paths in environmental, soil, and water science and crop management: Survey results

Periodic assessment of goals is critical to maintaining a successful academic program. Two surveys were designed and distributed to alumni and potential employers of graduates of the Department of Crop, Soil, and Environmental Sciences (CSES) in the summer of 2002 to assess the profitability of advanced degrees in terms of earning potential and to determine sectors of the workforce currently employing department graduates. The CSES Alumni Satisfaction Survey was sent to 792 department alumni, including graduates of the previous Agronomy program as well as the current Crop, Soil, and Environmental Sciences program. The CSES Employer Survey was distributed to 281 professionals and provided valuable information concerning current workforce requirements of college graduates. Survey results suggested that alumni career paths are changing; alumni are employed quickly, but fewer alumni are self- or government-employed while more are working in industry positions. Results from the CSES Employer Survey suggest that alumni are earning salaries typical for this region. Alumni salaries also indicated that advanced degrees are profitable in that the number of alumni reporting higher-end salaries increased to a greater extent among M.S. and Ph.D. graduates. These results will be used to enhance recruitment of prospective students and to improve advisement of current departmental students. Ultimately, the CSES Department hopes to increase enrollment, student satisfaction with degree programs, and career preparedness

Infiltration and short-term movement of nitrogen in a silt-loam soil typical of rice cultivation in Arkansas

Rice production in Arkansas is one of the top three crop commodities in terms of cash receipts. Researchers and farmers report that nitrogen (N) needs to be managed according to a variety of factors with two important ones being soil and fertilizer type. The objectives of this experiment were to determine: 1) the degree to which floodwater-incorporated N applied as urea or as ammonium sulfate infiltrates intact cores (7.2-cm dia., 10-cm depth) containing DeWitt siltloam soil, and 2) the distribution of N during 12 h of ponding. Inorganic-N concentrations were analyzed at 2-cm depth intervals in cores following removal of the flood. Nitrogen from applied fertilizer was recovered as ammonium. Ammonium sulfate-N remained in the top 4 cm of soil with concentrations of 375 µg N g-1 in the surface 2 cm and 300 µg N g-1 at the 2 - 4 cm depth after 12 hr of ponding. At all depth intervals below 4 cm, ammonium sulfate-N remained below 30 µg N g-1. In contrast, after 12 h of ponding, N in soil receiving urea was 105 µg N g-1 in the top 2 cm and 173 µg N g-1 at 2-4 cm. At 4-6, 6-8, and 8-10 cm, N was 109, 108, and 35 µg N g-1, respectively, after 12 h of ponding. These results demonstrate immediate and deeper movement of ammonium into silt loam soil receiving urea as compared to ammonium sulfate, demonstrating how the form of N in fertilizer affects its movement into the soil profile

Microbial biomass and nitrogen availability under the invasive plant species Lonicera japonica and native grasses in wetland soil

Invasive plants decrease aboveground biodiversity and suitable wildlife habitat. Wetlands are especially valuable ecosystems because they provide habitat, floodwater control, and function as filters for urban runoff. Wetland soils also act as sinks for nutrients. This characteristic reduces levels of excess nutrients often found in adjacent aquatic systems. The importance of soil functions in wetlands necessitates further investigation of the effects of invasive species on belowground nutrient pools. Approximately 75% of a small neighborhood wetland located in Fayetteville, Ark., has been invaded by Lonicera japonica. The effects of L. japonica and its replacement with native grasses on soil microbial biomass and nutrient pools were evaluated. Eight plots were established in April 2003. Four were left vegetated with the invasive species L. japonica while the other four were revegetated with transplants of five native grass species: Andropogon gerardii, Schizachyrium spp., Sorghastrum nutans, Panicum virgatum, and Tripsacum dactyloides. Soil samples were taken three times over the growing season, once prior to the removal of L. japonica and twice after transplanting occurred. Microbial biomass, soil carbon and nitrogen, Mehlich III- extractable phosphorus, pH, moisture content, and inorganic nitrogen were analyzed and significance was tested using a one-way ANOVA test (

The effect of turning frequency on in-vessel compost processing and quality

Composting can contribute to the zero waste initiative on the University of Arkansas (UA) campus. In-vessel systems like Earth Tubs™ are purported to provide better control of temperature and moisture during the composting process. Turning materials helps facilitate microbial activity and thermophilic composting. The goal of this research was to determine if turning frequency affects processing or final quality of compost made with pre- and post-consumer food waste feedstock and a wood chip bulking agent. Turning frequencies (treatment) of 3 days/week and 7 days/ week were evaluated simultaneously throughout three sequential runs. Temperature, pH, electrical conductivity (EC), and moisture content (MC) were measured weekly during vessel filling. When the vessels reached one-half to two-thirds volumetric capacity, the compost entered a 30- day composting period during which no food waste or wood chips were added to the vessels, but turning continued. Total C, N, C:N ratio, and hot water extractable C (HWEC) and N (HWEN) were also measured at the conclusion of composting. Recommended values for temperature, pH, MC, and total C:N ratio are all possible to reach when composting with Earth Tubs™, but there is little to no effect of 3 days/week versus 7days/week treatment on final quality of compost, and quality is not consistent over time between runs. Further research would need to be done to assess whether Earth Tubs™ are a viable option for large-scale food waste composting at UA, and whether the logistics of having the vessels off-site lend themselves to a sustainable campus-wide composting program