科研之友
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摘要
Ammonia (NH3) volatized from livestock manure is affiliated with ecosystem and human health concerns and decreased fertilizer value of manure and can also be an indirect source of greenhouse gas. Beef cattle feedlots, where thousands of cattle are grouped together to enable greater control of feed management and production, are hot spots in the agricultural landscape for NH3 emissions. Quantifying the feedlot NH3 emissions is a difficult task, partly due to the reactive nature of NH3 within and surrounding the feedlot. Our study used a dispersion model coupled to field measurements to derive NH3 emissions from a feedlot in southern Alberta, Canada. The average feedlot NH3 emission was 50 mu g m(-2) s(-1) (85 g animal(-1) d(-1)), which coincides with a low dietary crude protein content. At a location 165 m east of the feedlot, a flux gradient (FG) technique measured an average NH3 deposition of 12.0 mu g m(-2) s(-1) (west wind) and 5.3 mu g m(-2) s(-1) (east wind). Ammonia FG emission averaged 1 mu g m(-2) s(-1) with east winds, whereas no NH3 emission was found for west wind. Using soil-captured NH3, there was a decrease in deposition with distance from the feedlot (50% over 200 m). Collectively, the results of this study provide insight into the dynamics of NH3 in the agricultural landscape and illustrate the need for NH3 mitigation to improve the environmental and economic sustainability of cattle feedlots.
- 出版日期2016-8
