A new environmental study found that pig farms are generating less manure-nutrient content associated with odor. Data gathered from more than 106,000 samples at 182 North Carolina farms shows significant reductions in ammonia levels and manure nutrient content. The improvements are attributed to gains in feed efficiency, which means it takes less feed to raise a pig.

The study, funded by the Pork Checkoff, Des Moines, Iowa, and conducted by Harper Consulting, Bowling Green, Ky., in consultation with Southern Utah University, Cedar City, Utah, found that North Carolina pig farmers have significantly increased feed efficiency over the past 17 years. Long-term, continuous improvement resulted in trending reductions in nutrient content in manure lagoons at the farms. Specifically, data gathered from more than 106,000 samples at the 182 participating North Carolina pig farms showed a reduction of 35% to 78% in the nutrient content from hog finishers in primary lagoons, and a reduction of 17% to 68% in primary lagoons for sow farms. Also, the study showed a reduction of 22% to 54% in ammonia levels.

“For an industry that is continually striving to become more sustainable, this study shows that pig farmers are making significant progress toward reducing the environmental impact of their farms,” says Lowry Harper, president of Harper Consulting.
  
The analysis also showed considerable improvements in pig farms’ nutrient output, with major decreases in all nutrient concentrations, except for copper. The modeling conducted suggested decreased emissions, including ammonia.  

While the study looked at North Carolina farms, the findings can likely be replicated throughout the country, as U.S. pig farmers adopt better genetics and target nutrition and greater veterinary care.

The study shows hog farms’ contributions to nutrient levels and ammonia emissions have declined significantly over the last two decades. Other activity – increasing human population and growth in associated emission sources like automobiles, industry and human waste processing – has likely contributed to a general increase in ammonia emissions in the state.

The study also found that “advancements in swine production practices, changes in feed formulation, improved swine genetics, reduced nutrient excretion and other management changes have resulted in reduced nutrients in both primary and secondary lagoons.”