Iowa State University in the Forefront of Air Emissions Research at Midwest Swine Facility

September 3rd, 2013

AMES, Iowa — A first-of-its-kind study by Iowa State University scientists is seeking to fill the information gap that exists on air emissions from swine facilities.

“Farmers need reliable data to determine if air emissions are above regulatory thresholds and to help make better decisions on where to invest in emission controls,” said Hongwei Xin, professor in Iowa State’s Department of Agriculture and Biosystems Engineering.

“But research and information on ammonia and greenhouse gas emissions from swine operations — particularly from breeding, gestation and farrowing facilities in the Midwest — has been meager,” Xin said.

Funded in part by the Iowa Pork Producers Association (IPPA), Xin and his research team are beginning to fill the information gap. Since January 2011, his research team has been quantifying ammonia and greenhouse gas emissions from a 4,300 sow breeding, gestation and farrowing facility located in central Iowa. The facility is owned and operated by Iowa Select Farms, the largest pork producer in Iowa.

Dr. Howard Hill, veterinarian and strategic counsel for Iowa Select Farms, said he welcomed the opportunity to work with IPPA and “world-class scientists at Iowa State University.”

“Working with Dr. Xin and his graduate students has been a great experience for our production staff. Establishing air emission values that accurately represent modern, high tech livestock facilities will be a benefit to all of Iowa’s pork producers,” Hill said.

The U.S. Environmental Protection Agency estimates that agriculture (crop and animal production) is responsible for 6.3 percent of the nation’s total greenhouse gas emissions. The greenhouse gases emitted from activities related to animal agriculture include carbon dioxide, methane and nitrous oxide.

“The study is the first of its kind in the nation, when it comes to the intensity and duration of monitoring and quantifying the greenhouse gas emissions from swine operations. Our study is much more systematic than previous work done sporadically using intermittent monitoring of greenhouse gas emissions,” Xin said.

Because Iowa leads the nation with more than 17 percent of the breeding pig inventory, research on ammonia and greenhouse gas emissions conducted at Iowa farms can be effective in establishing accurate baseline emission rates for similar facilities in the Midwest.

“You have to first know what the baselines are, then you can potentially set reduction goals,” Xin said, “and if you want to reduce emissions, you need to know where to do it. What are the hot spots where we can do something about mitigation? In our study we are looking at the sources of emissions, from the barn to the manure storage area. Different gases may come from different sources. Our study will pinpoint the major sources for certain gases.”

Although the study does not include testing technologies designed to mitigate emissions, Xin noted that a lot of work has gone into developing mitigation techniques for certain gases. He hopes more work will be done to make them more affordable for producers.

“We have to make sure that producers can employ the technology without driving themselves out of business,” Xin said.

The project concluded monitoring in early June and final data processing is underway. Xin said he expects the 29-month study will help provide information and implications in areas that include:
• The number of sows needed to produce 100 pounds of ammonia per day — a figure that triggers the need for a farm to report ammonia emissions to the EPA.
• The benchmark values for ammonia and greenhouse gas emissions from facilities for each production stage — breeding/gestation, farrowing and manure storage.
• Identification of hot spots of different gaseous emissions for potential mitigation. For example, barns may be the primary source of ammonia emissions and manure storage (both deep pits and outside storage) may be the main source for methane and nitrous oxide emissions.
• Methane may be the predominant emission, making up 95 percent or more of total greenhouse gas emissions from a farm.

“Results of this study will provide a benchmark for the industry, especially in the area of greenhouse gas emissions reporting. We want to know what the numbers are out there. With Iowa being the number one pork producer in the nation, we need to study practices that are representative of our production situation,” Xin said.

Xin brings his own personal motivation to research and extension programs. He says it began with his upbringing in rural China, where he learned to “cherish and appreciate the greatness of farmers.” It was that young experience with hard, on-farm manual labor and periodic hunger that eventually led him on a career path to improve and modernize agricultural operations.

In the big picture of agriculture and the role Iowa agriculture has globally, Xin, the father of two, says he thinks of his children and future generations as he pursues research that supports “feeding the world, while conserving natural resources.”

“I want to make a difference in ensuring our children and their children have sufficient and quality food to eat and a healthy environment to live in,” Xin said.


Hongwei Xin, Agricultural and Biosystems Engineering, (515) 294-4240,
Ed Adcock, Agriculture and Life Sciences Communication Service, (515) 294-2314,