Ethephon[(2‐chloroethyl)phosphonic acid] reduces barley (Hordeum vulgare L.) plant height and lodging potential, but variable effects on yield components and yield also have been reported, depending on ethephon rate, cultivar, and environment. This study was conducted to investigate environment– and cultivar–by‐ethephon‐rate interactions for barley grown under Manitoba conditions. ‘Argyle’, ‘Bedford’, and ‘Samson’ barley were sown on each of two dates in 1986 and 1987, and on single dates in 1988 and 1989, at Portage la Prairie, MB on Neuhorst clay loam (fine‐loamy, frigid aquic Haploboroll). Ethephon was applied at Zadoks GS45‐47 at 0, 120, 240, 360, or 480 g ha−1. Plant height, Belgian lodging index, yield components, and yield were determined at maturity. Plant height reductions due to ethephon were unaffected by environment, and the percentage height reduction was described as a quadratic function of ethephon rate with higher increments of ethephon producing smaller increments of height reduction. Lodging only occurred in 1986, and ethephon at 240 g ha−1 eliminated lodging in most cases. Environment‐by‐cultivar‐by‐ethephon treatment interactions are significant for grain yield, spikes per square meter, and kernels per spike. Grain yield was not consistently affected by ethephon. Spikes per square meter sometimes increased, but was more often unaffected by ethephon. Kernels per spike was often reduced by ethephon. Kernel mass decreased with increasing rates of ethephon for Argyle and Bedford, but remained stable for Samson. Grain yield increased for Argyle and Bedford in cases where ethephon reduced lodging and increased spikes per square meter. Grain yield tended to decrease in cases where lodging was not a factor and ethephon reduced kernels per spike and/or kernel mass. Year‐to‐year variation in rainfall amount and distribution, and temperature may explain some of the observations made. In Manitoba, a maximum rate of 240 g ha−1 of ethephon should be used only in cases where the risk of severe lodging is high.

The livestock industry in the United States is heavily reliant on antibiotics for disease prevention and disease treatment. These compounds are excreted into manure, which is applied to farmland as fertilizer. Once introduced to the soil environment, there is risk that these compounds can accumulate and create selective pressure for antibiotic resistant bacteria, or

Antibiotic resistant gene dissipation in soil microcosmsCore ideas (3-5 impact statements, 85 char max for each)The dissipation of manure associated ARGs was not impacted by soil vegetative growth.Five of six quantified ARGs dissipated over time with half-lives ranging from 4.7 to 10.7 d.

The livestock industry in the United States relies on antibiotics for disease prevention and treatment. As a result, antibiotic-laden manure is frequently applied to farmland to recycle nutrients. In the soil environment, antibiotics may accumulate and create selective pressure for antibiotic resistance in bacteria or travel to nearby water resources. This in vitro incubation study evaluated whether prairie buffer strips on farmland enhance degradation of three antibiotics-tetracycline, sulfamethazine, and tylosin-compared with degradation in soil from row crops adjacent to the strips.Soil from prairie strips of varying establishment ages and adjacent row crops were evaluated from three central Iowa sampling locations. Antibiotics mixed with swine manure slurry were added to soils at a starting concentration (10 μg kg -1 ) that reflects common veterinary antibiotic concentrations in soil and runoff after manure application. Antibiotic concentrations were quantified at six time points throughout a 72-d incubation period and fit to a first-order model to calculate decay rate constants and half-lives. The mean half-life for tetracycline was 0.54 d longer in prairie strip soil than row crop soil, whereas sulfamethazine and tylosin demonstrated no significant difference in persistence in strip or crop soil. Time since the establishment of the prairie strip did not affect antibiotic persistence. Concentrations of each antibiotic decreased to near-background levels throughout the incubation period. This study suggests that prairie strips do not consistently enhance antibiotic degradation in farm fields, but that antibiotics are unlikely to persist throughout the growing season in soil under strip or crop management.