Iowa hog farmers have demonstrated continuous improvement in all phases of production over the past several decades. The pork industry’s commitment to natural resources and the environment is reflected in a new report from the Environmental Protection Agency and pig farmers are proud to celebrate their accomplishments on Earth Day.

U.S. agriculture’s contribution to greenhouse gas emissions continues to lag far behind other sectors, according to the latest Inventory of Greenhouse Gas Emissions and Sinks Report by EPA released on April 15. And, pork industry greenhouse gas emissions are among the lowest of all livestock.

The various categories of agricultural non-carbon dioxide emissions assessed include enteric fermentation in domestic livestock, livestock manure management and row crop production.

The EPA report shows agriculture accounted for just 9 percent of U.S. GHG emissions in 2013. In comparison, power plants were the largest source of emissions, accounting for 31 percent of total U.S. greenhouse gas pollution. The transportation sector was the second largest source, at 27 percent. Industry and manufacturing were the third largest source, at 21 percent.

Furthermore, the EPA report says the agriculture sector was only responsible for 7.7 percent of total carbon dioxide equivalent emissions in 2013. 

The three primary greenhouse gas emissions associated with agriculture are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), with methane and nitrous oxide the primary greenhouse gases emitted by agricultural activities. Methane emissions from enteric fermentation and manure management represent 25.9 percent and 9.6 percent of total methane emissions from anthropogenic activities, respectively

Enteric Fermentation
Methane is produced as part of normal digestive processes in animals. This microbial fermentation process, referred to as enteric fermentation, produces CH4 as a byproduct, which can be exhaled or eructated by the animal. Ruminant animals such as cattle, buffalo, sheep and goats are the major emitters of CH4 because of their unique digestive system. Non-ruminant animals such as swine and horses emit significantly less methane on a per-animal mass basis.

Emissions of methane from swine totaled just 2.5 million metric tons of CO2 equivalent in 2013, compared to 117.1 MMT CO2 for beef cattle and 41.6 MMT CO2 for dairy cows. In 1990, total swine emissions of methane were 2.0 MMT CO2. The minimal increase in swine methane emissions from 1990 to 2013 comes despite a 23 percent increase in the number of hogs on inventory, a 50 percent increase in total pork production and a 40 percent increase in yearly slaughter over that time.

Continuous improvement in efficiency enabled by modern production systems, technology and genetics has greatly enhanced environmental efficiency in the pork industry as well.

Manure Management
The treatment, storage and transportation of livestock manure can produce anthropogenic methane and nitrous oxide emissions. Hog manure is a valuable organic fertilizer that is readily used by farmers to help build the beneficial carbon content and moisture-holding capacity of soils.

Methane emissions from manure management practices increased 65 percent increase from 1990 to 2013 with swine and dairy cow manure contributing the majority of the increase. Swine emissions increased 48 percent and dairy emission jumped 115 percent. This is primarily due to the increased use of liquid manure systems in both industries, which also allows for more effective and efficient fertilizer use.

The EPA report further demonstrates hog farmers’ devotion to environmental stewardship and continuous improvement. Between 1990 and 2013, the U.S. pork industry has increased production from 15.3 billion pounds to 23.2 billion pounds produced on a pounds-of-pork basis while reducing its carbon footprint.

A University of Arkansas study completed in 2012 concluded that efficiencies of modern pork production enabled pig farmers to reduce their water usage 41 percent, land use by 78 percent and overall carbon footprint by 35 percent from 1959 to 2009.

What the swine industry has been able to accomplish very successfully over the past 50 years is to significantly reduce its environmental impact and natural resource use nearly 50 percent across the board per 1,000 pounds of dressed carcass produced.

Iowa’s environmentally conscious pork producers join in the world’s celebration of Earth Day.