Evaluating on-farm sampling strategies and corresponding gas emission estimation methods for livestock and poultry barns

Abstract

The need for gas emission research is driven by multiple stakeholders to address avariety of concerns and priorities that stem from environmental, human, and animal impacts of gas emissions from barns. In this work, I first provide background on the mechanism of gas emission from these systems and an overview of emission estimation strategies in the literature. This is followed by a presentation of two thesis projects, which demonstrate outcomes and challenges related to different emission estimation strategies. In the first project, I investigate airflow patterns and estimate ammonia (NH3) and carbon dioxide (CO2) emissions using a multi-airspace model for a naturally ventilated deep-pit cattle barn, with discrete gas concentration data. The second project uses a mass balance approach to estimate volatile solids (VS) losses and NH3 emissions from a naturally ventilated poultry barn based on material flows in and out of a barn. Each estimation strategy is evaluated based on the practicality of the sampling approach in specific housing styles, and whether emission estimates are comparable to current emission estimation methods for each system. Findings from these two projects show that, ultimately, there will always be limitations to the various available emission estimation strategies, particularly related to in-barn sample collection. Understanding the appropriate application of each of these approaches is important when selecting an emission estimation approach that will allow researchers to obtain representative emission estimates from a variety of livestock and poultry systems.