Ammonia emissions from anaerobic waste lagoons at pork production operations: Influence of climate

Abstract

Swine waste storage is a major source of agricultural ammonia (NH3) emissions. Understanding the factors that influence the magnitude of emissions is important to our understanding of NH3 loading of the atmosphere and it’s deposition on the landscape. Since swine operations occur across the United States, a better understanding of how differing climates influence NH3 emissions and how future climate change in might impact emissions is needed. Ammonia was measured from 2007 through 2009 at five swine farms using anaerobic lagoons for manure storage and processing. Three farms, located in North Carolina (NC), Indiana (IN), and Oklahoma (OK), handled the breeding to weaning of the pigs (sow farm). These farms had an annual mean sow live mass-specific emissions ranging from 62gd−1AU−1 (AU=500kg live mass) to 120gd−1AU−1. Two farms, located in NC and OK, handled the growing of the pigs to market size (finisher farm). These farms had annual mean live mass-specific emissions of36gd−1AU−1 (OK) and 104gd−1AU−1 (NC). An emissions model incorporating the influence of winds and temperature accounted for 74% of the measured emissions variability. A second emissions model including the influence of pH, suspended organic matter, and farm type-specific nitrogen excretion rates accounted for 66% of the measured emissions variability. An evaluation of the influence of warmer or cooler winters and summers using the second model shows that a 1°C increase in maximum daily mean temperature results in a 6.9% increase in annual emissions and a 9.5% increase in maximum emissions. Additional detailed studies focused on better estimating the loading of the lagoons and chemistry of the surface of the lagoons are needed to improve the estimation of NH3 emissions.