More than 1 billion broiler chickens (Gallus gallus domesticus) are produced annually in Arkansas, with nearly 900 Gg of waste (i.e., litter) generated. Poultry litter is typically land applied as a means of disposal to nearby pastures as an organic fertilizer. Aside from essential plant nutrients, poultry litter also contains heavy metals, yet little is known about the potential of these metals to leach from soils with a history of litter application. The objective of this study was to continuously monitor the seasonal and annual effect of poultry litter application rate on soil leachate concentrations and leaching losses of metals (As, Cd, Se, Cr, Mn, Fe, Ni, Cu, and Zn) and dissolved organic carbon (DOC) from tall fescue (Festuca arundinacea Shreb.) pasture using automated equilibrium‐tension lysimeters over a 2‐yr period. Average annual drainage was 447, 235, and 592 mm in Year 1 (May 2003 through April 2004) and 833, 589, and 827 mm in Year 2 (May 2004 through April 2005) for control, low‐ (5.6 Mg ha−1), and high‐litter (11.2 Mg ha−1) treatments, respectively. Drainage was similar among treatments during all time periods except for Winter (November through January) Year 1. Flow‐weighted mean concentrations of Mn during Spring Year 1 (February through April 2004) and Ni and Cu for the whole year differed among litter treatments, but there were no consistent trends. In Spring Year 2 (February through April 2005), flow‐weighted mean concentrations of Cr and Fe differed among litter treatment, but there were no consistent trends. Metal leaching losses did not differ among litter treatment during Year 1. In Year 2, leaching losses of Zn, Fe, and As differed among litter treatments during Summer, Fall, and Winter, respectively, but there were no consistent trends. Results indicate that poultry litter application rate did not affect metal leaching within two the first 2 yr of altered management; thus simply reducing application rates in areas with a history of litter application may not ensure a short‐term reduction of potential further surface and groundwater impairment.

Concentrations of DIBOA [2,4-dihydroxy-1,4-(2H)-benzoxazine-3-one] and BOA [2-(3H)-benzoxazolinone], described previously as major allelochemicals inSecale cereale(rye), were determined in eight field-grown cultivars, harvested at booting, using high-performance liquid chromatography (HPLC). Allelochemicals were also quantified in greenhouse-grown cultivar ‘Bates’ harvested 30, 45, 60, and 75 days after planting (DAP). The total production of DIBOA and BOA from field-grownS. cerealeranged from 137 to 1,469 μg g−1dry tissue among the eight cultivars. ‘Bonel’ cultivar had the highest hydroxamic acid (HA) content and ‘Pastar’ the lowest. Bonel also showed the highest activity onEleusine indica(goosegrass) and Pastar the least, in culture plate bioassays using aqueous extracts. HA content in shoot tissue varied withS. cerealematurity. The greatest level of HA in greenhouse-grown Bates was obtained 60 DAP compared to 30 DAP.

Rice ( L.) production is unique among staple food crops because the majority of the growing season typically occurs under flooded-soil conditions. Flooding the soil leads to anaerobic conditions, which are a precursor to methane (CH) production. However, no known research has investigated CH emissions from the drill-seeded, delayed-flood rice production system common in Arkansas, the leading rice-producing state in the United States. Therefore, research was conducted in 2011 to determine the effects of vegetation (rice and bare soil), chamber location (in- and between-rice rows), and nitrogen (N) fertilization (optimal and no N) on CH emissions from a silt-loam soil. Methane fluxes measured weekly from flooding until flood release were affected by vegetation, chamber location, and sample date ( < 0.05). In-row CH fluxes were <0.7 mg CH-C m h until 20 d after flooding (DAF) and <1.0 mg CH-C m h from between-row and bare soil until 41 DAF and were unaffected by fertilization over time. The largest weekly measured CH flux (31.9 mg CH-C m h) was observed from in-row rice at 41 DAF. Post-flood-release CH fluxes were affected by vegetation, fertilization, chamber placement, and sample date ( < 0.05) and accounted for approximately 3 to 7% of the season-long CH emissions. Methane emissions averaged 195 kg CH-C ha per growing season and were unaffected by fertilization. Direct measurement of CH emissions from drill-seeded, delayed-flood rice grown on a silt-loam soil will improve the accuracy of assessments of the carbon footprint and long-term sustainability of rice.

Jefferson counties in Arkansas to assess nonpoint source water pollution. During these 3 years, 59-62 lake and river/ stream sites were sampled eight times and screened for 17 pesticides commonly used in Arkansas. Pesticides were extracted by solid-phase extraction (SPE) disks. Extracts were analyzed by gas chromatography-electron capture detection (ECD) and high-performance liquid chromatography-UV detection (LCUV). Detections were confirmed by gas chromatography-mass spectroscopy (MS) or co-chromatography. The 256 detections during the survey represented 14 pesticides. Metolachlor (25% of total detections), atrazine (22%), norflurazon (16%), and cyanazine (14%) were the most commonly detected compounds. A total of 5% of the total detections was above health advisories. Spring and summer samples provided 73% of the total pesticide detections. Rivers and streams were responsible for 62% of the detections. The highest number of repeated detections of the same pesticide at a site was for cyanazine (six of eight sampling periods).

The stability of various pesticides in water at 4 °C was compared with their stability on C-18 SPE disks under three storage regimes. The disk storage regimes involved using the disk to extract the chemical from water, removing the disk and placing it in a plastic bag, and then storing it at either -20 or +4 °C for 1 day and then -20 °C for the remainder of the storage period. The storage periods included 0, 3, 30, 90, and 180 days. The percent recovery of each chemical was determined and used to compare storage treatments. Results indicate that the pesticides have equivalent or greater stability on solid-phase extraction disks compared to their storage in water at 4 °C. The data suggest that freezing the disk after pesticide loading is the most favorable storage option. Results show that field extraction/storage methodology is feasible, which could improve the reliability of future environmental water sampling procedures.