Cattle Feedlot Soil Moisture and Manure Content: I. Impacts on Greenhouse Gases, Odor Compounds, Nitrogen Losses, and Dust

Abstract

Beef cattle feedlots face serious environmental challenges associated with manure management, including greenhouse gas, odor, NH3, and dust emissions. Conditions affecting emissions are poorly characterized, but likely relate to the variability of feedlot surface moisture and manure contents, which affect microbial processes. Odor compounds, greenhouse gases, nitrogen losses, and dust potential were monitored at six moisture contents (0.11, 0.25, 0.43, 0.67, 1.00, and 1.50 g H2O g(-1) dry matter [DM]) in three artificial feedlot soil mixtures containing 50, 250, and 750 g manure kg(-1) total (manure + soil) DM over a two-week period. Moisture addition produced three microbial metabolisms: inactive, aerobic, and fermentative at low, moderate, and high moisture, respectively. Manure content acted to modulate the effect of moisture and enhanced some microbial processes. Greenhouse gas (CO2, N2O, and CH4) emissions were dynamic at moderate to high moisture. Malodorous volatile fatty acid (VFA) compounds did not accumulate in any treatments, but their persistence and volatility varied depending on pH and aerobic metabolism. Starch was the dominant substrate fueling both aerobic and fermentative metabolism. Nitrogen losses were observed in all metabolically active treatments; however, there was evidence for limited microbial nitrogen uptake. Finally, potential dust production was observed below defined moisture thresholds, which were related to manure content of the soil. Managing feedlot surface moisture within a narrow moisture range (0.2-0.4 g H2O g(-1) DM) and minimizing the accumulation of manure produced the optimum conditions that minimized the environmental impact from cattle feedlot production.

Greenhouse Gas Emissions from Beef Feedlot Surface Materials as Affected by Diet, Moisture, Temperature, and Time

“…Although manure constituent metabolism was not measured during this study, other researchers have investigated the hierarchy of manure substrate metabolism. Generally, manure constituents are consumed due to the ease with which organisms can metabolize the substrate and the energy available to the organism for growth (Mackie et al, 1998;Varel, 2001, 2002;Miller and Berry, 2005). Miller and Varel (2002) observed a hierarchy of substrate utilization during manure slurry incubations.…”

Surface Application of Soybean Peroxidase and Calcium Peroxide for Reducing Odorous VOC Emissions from Swine Manure Slurry

“…The pH of the manure in this latest experiment was about 2 pH units higher than the previous experiment. Since VFAs are more volatile in their non-ionized form at lower pH values, the difference in VFA emissions between the two experiments was likely due to differences in manure pH (Miller and Berry, 2005).…”

A Runoff and Sediment Routing Model for Open Lot Beef Feeding Facilities

“…Future work should seek to quantify properties that control moisture loss rates from the manure pack as well as its moisture retention characteristics. Work by Miller and Berry (2005) provides insight into some of the properties that may influence evaporative water losses, as it was related to both the current moisture level and the manure to soil content of the media. However, based on the current information available, it appears that a curve number approach remains the best option for estimating runoff volumes, with a CN of 91 most appropriate for earthen lots and a slightly higher curve number (93) for paved lots.…”