Liao Wenhua, Liu Chunjing, Gao Zhiling
a College of Resources and Environmental Sciences , Hebei Agricultural University , Lekai South Street 2596, Baoding , People's Republic of China.
J Air Waste Manag Assoc. 2018 Jul;68(7):700-712. doi: 10.1080/10962247.2018.1453392. Epub 2018 May 9.
Patches of dung and urine are major contributors to the feedlot gas emissions. This study investigated the impacts of dung deposition frequency (partly reflecting animal stocking density of a feedlot), dairy feedlot floor conditions (old floor indicated with the presence of consolidated manure pad [CMP] vs. new floor with the absence of consolidated manure pad [CMPn]), and application of dicyandiamide (DCD) and hydroquinone (HQ) on nitrous oxide (NO) and methane (CH) emissions from patches in the laboratory, and the integrative impacts were expressed in terms of global warming potential (CO-equivalent). Dung deposition frequency, feedlot floor condition, and application of inhibitors showed inverse impacts on NO and CH emissions from patches. Greenhouse gas (GHG) emissions from the dung, urine, and dung+urine patches on the CMP feedlot surface were approximately 7.48, 87.35, and 7.10 times those on the CMPn feedlot surface (P < 0.05). Meanwhile, GHG emissions from CMP and CMPn feedlot surfaces under high deposition frequency condition were approximately 10 and 1.7 times those under low-frequency condition. Moreover, application of HQ slightly reduced the GHG emission from urine patches, by 14.9% (P > 0.05), while applying DCD or DCD+HQ significantly reduced the GHG, by 60.3% and 65.0%, respectively (P < 0.05). Overall, it is necessary to include feedlot management such as animal stocking density and feedlot floor condition to the process of determining emission factors for feedlots. In the future, field measurements to quantitatively evaluate the relative contribution of nitrification and denitrification to the NO emissions of feedlot surfaces are highly required for effective NO control.
This study shows that feedlot CH and NO emissions inversely respond to the dicyandiamide (DCD) application. Applying DCD significantly reduces GHG emissions of feedlot urine patches. Feedlot floor condition and stocking density strongly impact feedlot GHG emissions. Including feedlot floor condition and stocking density in the feedlot EF determining process is necessary.
粪便和尿液斑块是饲养场气体排放的主要来源。本研究在实验室中调查了粪便沉积频率（部分反映饲养场动物存栏密度）、奶牛饲养场地面状况（存在固结粪垫[CMP]表示旧地面，不存在固结粪垫[CMPn]表示新地面）以及双氰胺（DCD）和对苯二酚（HQ）的施用对斑块中氧化亚氮（N₂O）和甲烷（CH₄）排放的影响，并以全球变暖潜能值（CO₂当量）来表示综合影响。粪便沉积频率、饲养场地面状况和抑制剂的施用对斑块中N₂O和CH₄排放呈现相反的影响。CMP饲养场表面粪便、尿液以及粪便 + 尿液斑块的温室气体（GHG）排放量分别约为CMPn饲养场表面的7.48、87.35和7.10倍（P < 0.05）。同时，高沉积频率条件下CMP和CMPn饲养场表面的GHG排放量分别约为低频率条件下的10倍和1.7倍。此外，施用HQ使尿液斑块的GHG排放量略有降低，降低了14.9%（P > 0.05），而施用DCD或DCD + HQ则使GHG排放量显著降低，分别降低了60.3%和65.0%（P < 0.05）。总体而言，在确定饲养场排放因子的过程中，有必要将饲养场管理措施（如动物存栏密度和饲养场地面状况）考虑在内。未来，为有效控制N₂O排放，迫切需要进行实地测量以定量评估硝化作用和反硝化作用对饲养场表面N₂O排放的相对贡献。
本研究表明，饲养场CH₄和N₂O排放对双氰胺（DCD）的施用呈反向响应。施用DCD可显著降低饲养场尿液斑块的GHG排放量。饲养场地面状况和存栏密度对饲养场GHG排放有强烈影响。在饲养场排放因子确定过程中纳入饲养场地面状况和存栏密度是必要的。
