Seasonal and spatial variations in aerial ammonia concentrations in deep pit beef cattle barns

Authors: CORTUS, ERIN - University Of Minnesota; HETCHLER, BRIAN - University Of Minnesota; Spiehs, Mindy; RUSCHE, WARREN - South Dakota State University

Submitted to: Waste to Worth Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/2/2019
Publication Date: 4/1/2019
Citation: Cortus, E., Hetchler, B., Spiehs, M.J., Rusche, W. 2019. Seasonal and spatial variations in aerial ammonia concentrations in deep pit beef cattle barns. In: Proceedings of Waste to Worth Conference, April 22-26, 2019, Minneapolis, Minnesota. Available: https://lpelc.org/seasonal-and-spatial-variations-in-aerial-ammonia-concentrations-in-deep-pit-beef-cattle-barns/

Interpretive Summary:

Technical Abstract: There are known benefits and challenges to finishing beef cattle under roof. The accumulated manure is typically stored in a bedded pack (mixture of bedding and manure) or in a deep pit below a slatted floor. Previous research measured particulate matter, ammonia and other gases in bedded pack barn systems. However, deep pit manure storage results in different aerial nutrient losses and manure value compared to solid manure storage and handling. Few studies have looked at concentrations at animal level or aerial/temperature distributions in the animal zone. There is little to no documentation of the air quality impacts of long-term deep pit manure storage in naturally ventilated finishing cattle barns. The objective of this work is to describe the seasonal and spatial variations in aerial ammonia concentrations in deep pit beef cattle barns. Ammonia concentration was measured among four pens in three beef cattle barns with deep pit manure storage during summer and fall conditions in Minnesota. Concentration was measured below the slatted floor (above the manure surface), 4-6 inches above the floor (floor level) and 4 ft above the floor (nose level). While collecting samples from within a pen, samples were also collected from the north and south wall openings surrounding the pen. To supplement the concentration data, surface temperatures, air speed at cow level, and surface manure samples were also collected. Barn F finished beef cattle breeds under a monoslope roof, in four pens, with feed alleys on north and south side of pens. Two pens were empty and the other two pens partially filled during the fall sampling period. Barn H finished dairy steers under a gable roof in a double-wide barn, in twelve pens over a deep pit and two pens with bedded packs, with a feed alley down the center of the barn. Four (east end) and eight (west end) pens shared common deep pits. Barn R finished dairy steers under a gable roof with four pens and a feed alley on the north side of the pens. All pens shared a common deep pit. Two pens were empty of cattle during the summer and fall sampling periods. The ammonia concentration levels differed based on the location in the pen area. As expected, the ammonia concentration above the manure surface was the greatest, and at times more than 10x the concentration at floor and nose level. The barn with the highest ammonia concentration also had the highest manure nitrogen levels (Total N and Ammonium-N). Based on July and September measurements, higher ammonia concentration levels also coincided with higher ambient temperatures. The presence and size of cattle in the pens did not strongly influence ammonia concentrations at any measurement height within a barn on sampling days. Ammonia concentration is variable between barns, and within barns. However, at animal and worker level, average concentrations for the sampling periods were less than 10 ppm. Higher gas levels can develop in the confined space below the slatted floor.