Richard R. Stowell

Ammonia, Hydrogen Sulfide and Odor Emissions from a Beef Cattle Feedlot

Gaseous emissions from livestock facilities represent a concern due to the potential effects of ammonia, hydrogen sulfide, nand odors on environmental quality and human health. The lack of knowledge concerning beef cattle feedlot emissions has been a major nobstacle in the development of emission reduction strategies and accurate emission modeling. Emissions from a 2,000-head research nfeedlot in eastern Nebraska were measured in this study using a wind tunnel. Flux rates of ammonia, hydrogen sulfide and odor were ndetermined to compare the effects of diet and pen cleaning frequency for a beef cattle feedlot. Meteorological parameters and soil/manure npH, nitrogen content, surface and subsurface temperature and moisture content were also measured to determine the extent to which they ninfluenced emission rates. nOur data clearly show that surface temperature plays an important role in ammonia emissions, but other kinetic factors are also nresponsible. It also shows that moisture content and temperature influence odor flux, but more research is needed to clarify this nrelationship. The data suggest diet and cleaning frequency may play a role in ammonia and odor flux.

Mask Scentometer for Assessing Ambient Odors

This article summarizes the development and operation of a mask scentometer and reports air dilution ratios measured during its use, which were used to establish the devices dilution-to-threshold settings. The mask scentometer is a facial respirator that has been modified to operate conceptually like the Barneby and Sutcliffe box scentometer. The mask scentometer is comprised of a half-face respirator with two modified, spin-on cartridges, one per side, which facilitate the mixing of ambient air with filtered air for presentation to an odor assessor at user-selected dilution ratios. The clean air cartridge includes an activated carbon filter canister with two 1/2 in. (13 mm) orifices for metering clean air into the mask chamber. The ambient air cartridge includes an adjustable dial with five different orifices for metering unfiltered ambient air into the mask for a range of flow rates. Prior to this study, the dilution ratios of air presented to an assessor using the mask scentometer were assumed to be the same as the dilution-to-threshold settings of the Barneby and Sutcliffe box scentometer, i.e., 170, 31, 15, 7, and 2 volumes of clean air per volume of ambient air. In a controlled laboratory environment, airflow rates were measured through both cartridges of a mask scentometer using a pressure transducer while twelve different assessors used the device. The flow-weighted average dilution ratios produced within the mask scentometer were 18, 4.5, 2, 1, and 0.35. Investigators using the mask scentometer to measure ambient odor concentrations are advised to use these dilution-to-threshold values.

Field Performance Evaluation of a Ventilation System: A Swine Case Study

Swine finishing facility ventilation has become relatively complex and is often mismanaged as a system. One of the few ways to truly understand these systems is to spend time systematically going through the many components of the building and how they work as a system. To learn to help producers better, a team of university Extension specialists that included agricultural engineers and animal scientists spent an extended period carefully documenting conditions in a deep-pit swine finishing building with two 1,000-head rooms. Exhaust fans connected to the manure pit and wall fans were operated at various stages as a negative-pressure ventilation system. A computerized controller activated exhaust fans, a ventilation curtain actuator, heaters, stir fans, and a spray cooling system. Gravity-controlled baffled ceiling inlets were evenly spaced in the building to provide good air distribution during cold and mild weather conditions. Following the review of current conditions and operating parameters, performance deficiencies were identified and recommendations were given regarding controller settings, inlet settings, and the transition to natural ventilation. Specific recommendations included changing minimum ventilation speed settings of fans based on animal size, removing inlet stops during warmer weather to avoid premature transition to natural ventilation, a change in how fans were staged, a change in setpoint, and the specific temperature at which the cooling system was engaged.

Validating the Odor Footprint Tool Using Field Data

Trained participants monitored odors around a 4,800-head finishing site in eastern Nebraska during 2005 and 2006. ‘Mobile odor assessors’ monitored odors within the downwind odor plume and reported that odors at off-site locations (at least 200 feet away) were consequentially annoying in 20 out of 192 assessments. On-site odor levels were considered annoying in 33 of 39 instances. For the same off-site locations and times, modeling predicted 18 annoying events, resulting in a 90% prediction rate (18 vs. 20) of annoyance frequency. The net error rates for missed annoyance for off-site locations were 9.1% and 10% based upon concentration data and annoyance ratings, respectively. Errors were mostly a result of either the predicted concentration at the receptor location was near the annoyance threshold, or the orientation of the odor plume was slightly off.

Highlights of the Air Quality Education in Animal Agriculture project

Through the Air Quality Education in Animal Agriculture (AQEAA) project, Land-Grant University specialists from across the U.S. have been collaborating in delivering applied, research-based air quality information to those who work with livestock and poultry producers. The AQEAA project developed Air Quality content on the Animal Manure Management eXtension website in collaboration with the Livestock and Poultry Environmental Learning Center (LPELC). The Air Quality web content makes widely accessible the educational resources produced by this project for use in developing the knowledge base and skills of professionals who interact [and pre-professionals who plan to interact] with livestock and poultry producers. The online materials include 18 written publications, 3 videos, and 16 recorded webinars (webcasts). Also made accessible are selected research and technology summaries as well as online content produced by other organizations. The AQEAA project also developed the skills of professionals regarding air quality topics via professional development events. Website usage information, participant polls, and stakeholder surveys provided evidence that the resources developed by this project are being utilized and that delivery of the information via eXtension has been an effective means of communicating information on this topic. Webcasts were especially effective in communicating information and providing continuing professional development. AQEAA-sponsored workshops were effective in providing in-depth air quality information and experiences to more than 300 professionals. Collaboration with the LPELC facilitated having a ready eXtension outlet for project materials and is providing continued, sustainable access to online information from this project.

Using Webcasts to Highlight Air Quality Research

Eleven web-based seminars addressing air quality topics in animal agriculture have been broadcast to a national audience over the past two years as part of an ongoing USDA NIFA-funded effort referred to as the Air Quality Education for Animal Agriculture (AQEAA) project. AQEAA’s goal is that many people will use the science-based resources developed in the project to make well-informed decisions about air quality matters, especially when considering and implementing new practices or policies. The purpose of the webinars is to expose livestock industry stakeholders and air quality policymakers to research expertise in air quality topics of concern. On average, about 100 ‘attendees’ participate in the live broadcasts, with 3-5 times this number accessing the archived webcasts. Webcast attendees are generally ‘multipliers’ who interact with and influence a number of producers. Feedback from attendees indicates that the webinars suit the target audience’s desire for useful information that is readily accessible and fairly easy to understand.

Assessment of Ventilation Management Training Workshops

To achieve optimum swine performance, producer understanding of environmental control systems in mechanically or naturally ventilated facilities is extremely important. A ventilation workshop: “Managing Your Unseen Employee: The Ventilation System” was established. The primary objective of the training was to give swine producers and managers enough quality information so they could go back to their operations and properly assess their own ventilation systems and make appropriate adjustments as needed. The training workshops were established to be a multi-state and multi-disciplinary effort between South Dakota, Nebraska, Iowa and Minnesota universities. Ag engineers and animal scientists from each state participated in developing the workshop materials and delivery of the program. Four basic needs emerged that would enhance program delivery. These needs included basic environmental factors and their effects on pigs, ventilation system design principles, trouble-shooting ventilation problems, and hands-on demonstrations of instrumentation and ventilation equipment. A 1.8 m by 2.4 m by 2.4 m mobile ventilation room was used for the hands-on training. The mobile ventilation room was equipped with two variable-speed, 30-centimeter fans and one 30-cm, single-speed fan; a four-stage controller; and three types of air inlets. From 2002 to 2007, over 1000 people producing over 20 million pigs participated in more than 60 workshops. The backgrounds of participants included managers, feed consultants, extension educators, and veterinarians. Key points gained by producers included proper ventilation settings, trouble-shooting techniques, temperature control, and the effects of static pressure on airflow.

The real world of ventilation troubleshooting: a swine case study.

Swine finishing facility ventilation has become relatively complex and is often mismanaged as a system. One of the few ways to truly understand these systems is to spend time systematically going through the many components of the building. To learn to help producers better, a team of university Extension specialists that included agricultural engineers and animal scientists spent an extended period carefully documenting conditions in a deep-pit swine finishing building with two 1,000-head rooms. Exhaust fans in the pit and walls operated at various stages throughout the year as a negative-pressure ventilation system. A computerized controller activated exhaust fans, a ventilation curtain actuator, and heaters. Gravity baffled ceiling inlets were evenly spaced in the building to provide good air distribution during cold and mild weather conditions. Following the review of current conditions and operating parameters, performance deficiencies were identified and recommendations were given regarding controller settings, inlet settings, and curtain management. The overall operating characteristics of the ventilation system and air quality in the animal space were documented ventilation and related management changes were discussed with the owner/operator.

Behavioral Responses of Weaned Pigs to Differing Zone-Heating Systems

Research was conducted to assess the effects of the type of zone heater and floor mat used in a wean-to-finish building, and the resulting thermal environment created for newly weaned pigs, on piglet activity. Gas-fired brooder heaters were compared to electric heat lamps and farm-cut wood (OSB) sheathing was compared to commercial [unheated] rubber floor mats in two 2x2 factorial trials. Air temperatures were the same, averaging 23.5 ± 1.3 oC. During the first seven days in the facility, newly weaned piglets spent about 84.5% of their time on the mat regardless of treatment. During the remainder of the zone-heating period, though, fewer piglets were observed on the mats of pens with gas-fired heaters as compared to electric lamps (80% of pigs vs. 85%). Similarly, fewer piglets were observed on the rubber mats as compared to the OSB sheathing (81% of pigs vs. 84%). Most of this time was accounted for as more time animals laid somewhere else. Trends in time spent standing on mats were opposite those for lying off of the mats. Mat surface temperature averaged 4 oC warmer with gas-fired heaters than with electric heat lamps (30 vs. 34 oC). A smaller difference existed between the OSB and rubber mat surface temperatures (31.5 vs. 33 oC). Piglet surface temperatures differed by no more than 1 oC between treatments. It was concluded that relatively minor differences in piglet activity may arise as piglets grow in size that are attributable to the type of heat source and mat used in the zone-heating area.