Concentrated animal feeding operations emit trace gases such as ammonia (NH 3 ), methane (CH 4 ), carbon dioxide (CO 2 ), and nitrous oxide (N 2 O). The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emission rates. The objective of this study was to determine the emission rates of , respectively. The open lot areas generated the greatest emissions of NH 3 , CO 2 , and N 2 O, contributing 78, 80, and 57%, respectively, to total farm emissions. Methane emissions were greatest from the lots in the spring (74% of total), after which the wastewater pond became the largest source of emissions (55% of total) for the remainder of the year. Data from this study can be used to develop trace gas emissions factors from open-lot dairies in southern Idaho and potentially other open-lot production systems in similar climatic regions.

No abstract

Airborne microorganisms and microbial by-products from intensive livestock and manure management systems are a potential health risk to workers and individuals in nearby communities. This report presents information on zoonotic pathogens in animal wastes and the generation, fate, and transport of bioaerosols associated with animal feeding operations and land applied manures. Though many bioaerosol studies have been conducted at animal production facilities, few have investigated the transport of bioaerosols during the land application of animal manures. As communities in rural areas converge with land application sites, concerns over bioaerosol exposure will certainly increase. Although most studies at animal operations and wastewater spray irrigation sites suggest a decreased risk of bioaerosol exposure with increasing distance from the source, many challenges remain in evaluating the health effects of aerosolized pathogens and allergens in outdoor environments. To improve our ability to understand the off-site transport and diffusion of human and livestock diseases, various dispersion models have been utilized. Most studies investigating the transport of bioaerosols during land application events have used a modified Gaussian plume model. Because of the disparity among collection and analytical techniques utilized in outdoor studies, it is often difficult to evaluate health effects associated with aerosolized pathogens and allergens. Invaluable improvements in assessing the health effects from intensive livestock practices could be made if standardized bioaerosol collection and analytical techniques, as well as the use of specific target microorganisms, were adopted.

Animal manures are commonly used to enhance soil fertility, but there are growing concerns over the impact of this practice on the development and dissemination of antibiotic resistance. The aim of this field study was to determine the effect of annual dairy manure applications on the occurrence and abundance of antibiotic resistance genes (ARGs) in an agricultural soil during four years of crop production. Treatments included (i) control (no fertilizer or manure), (ii) inorganic fertilizer and (iii) dairy manure at three application rates. Quantitative PCR was used to determine absolute (per g dry soil) and relative (per 16S rRNA gene) abundances of ARGs in DNA extracted from soils. Six ARGs and one class 1 integron were targeted. This study found that (i) manure application increases ARG abundances above background soil levels; (ii) the higher the manure application rate, the higher the ARG abundance in soil; (iii) the amount of manure applied is more important than reoccurring annual applications of the same amount of manure; (iv) absolute abundance and occurrence of ARGs decreases with increasing soil depth, but relative abundances remained constant. This study demonstrated that dairy manure applications to soil significantly increase the abundance of clinically relevant ARGs when compared to control and inorganic fertilized plots.

1,3-Dichloropropene (1,3-D), which consists of two isomers, (Z)- and (E)-1,3-D, is considered to be a viable alternative to methyl bromide, but atmospheric emission of 1,3-D is often associated with deterioration of air quality. To minimize environmental impacts of 1,3-D, emission control strategies are in need of investigation. One approach to reduce 1,3-D emissions is to accelerate its degradation by incorporating organic amendments into the soil surface. In this study, we investigated the ability of four organic amendments to enhance the rate of degradation of (Z)- and (E)-1,3-D in a sandy loam soil. Degradation of (Z)- and (E)-1,3-D was well described by first-order kinetics, and rates of degradation for the two isomers were similar. Composted steer manure (SM) was the most reactive of the organic amendments tested. The half-life of both the (Z)- and (E)-isomers in unamended soil at 20 degrees C was 6.3 days; those in 5% SM-amended soil were 1.8 and 1.9 days, respectively. At 40 degrees C, the half-life of both isomers in 5% SM-amended soil was 0.5 day. Activation energy values for amended soil at 2, 5 and 10% SM were 56.5, 53.4 and 64.5 kJ mol-1, respectively. At 20 degrees C, the contribution of degradation from biological mechanisms was largest in soil amended with SM, but chemical mechanisms still accounted for more than 58% of the (Z)- and (E)-1,3-D degradation. The effect of temperature and amendment rate upon degradation should be considered when describing the fate and transport of 1,3-D isomers in soil. Use of organic soil amendments appears to be a promising method to enhance fumigant degradation and reduce volatile emissions.