Transformation of Organic Matter and the Emissions of Methane and Ammonia during Storage of Liquid Manure as Affected by Acidification

Abstract

Acidification of livestock manure can reduce emission of the greenhouse gases methane (CH) and nitrous oxide (NO), as well as ammonia (NH). We examined the relation between emission of these gases and transformation of organic matter as affected by acidification. Liquid cattle manure was acidified with sulfuric acid to pH 5.5 at a pilot scale (100 L), and we measured effects on CH, NO, CO and NH emissions and on transformation of pH buffer components and organic matter. Acidification reduced NH emissions by 62% (47 d) and emission of CH by 68% (57 d). Emissions of NO were negligible, probably due to the absence of a surface crust. Reductions in NH and CH emission were highest at the start but declined over time concomitantly with a gradual increase in the stored liquid manure pH. Acidification did not significantly affect CO emissions. Emission of CO was high, five- to ten-fold of CH emissions, until Day 16 of storage, after which the CO emission rate declined to around twice the CH emission rate; consequently, the majority of C loss during the early stages of storage was CO. Cumulative emission of C in CO and CH closely matched depletion of dissolved organic carbon (DOC), suggesting that DOC may be a predictor for CH emission from dilute slurries. volatile fatty acid and total ammoniacal nitrogen concentrations in surface layers were substantially higher than at the center of stored liquid manure, perhaps resulting from microbial activity at the surface. This pattern deserves attention when predicting NH emission from stored slurry.

Dynamics of Different Buffer Systems in Slurries Based on Time and Temperature of Storage and Their Visualization by a New Mathematical Tool

“…At the end of the storage period, a decrease in the carbonate buffer was also observed in warmly stored slurries ( Figures 6-8). The resulting emissions depend on several factors such as storage temperature or the presence of an adapted microbial community in pre-stored slurry [48].…”

Reduction in Methane Emissions From Acidified Dairy Slurry Is Related to Inhibition of Methanosarcina Species

“…The large volumes of manure produced annually from intensive dairy farming operations areusually stored in slurry form ( VanderZaag et al, 2013 ), which create environments conducive to CH 4 production ( Grant et al, 2015 ; Petersen, 2018 ). To reduce CH 4 emissions from such storage systems, strategies such as reduction of aged manure (inoculants), crust development for potential aerobic CH 4 oxidation, and manure acidification using sulfuric acid (H 2 O 4 ) have been reported ( Petersen et al, 2012 ; Sommer et al, 2017 ; Habtewold et al, 2018 ). Sulfuric acid-based acidification of liquid dairy manure has primarily been used to abate ammonia (NH 3 ) emissions, but can also reduce CH 4 emissions ( Ottosen et al, 2009 ; Petersen et al, 2012 ; Fangueiro et al, 2015 ; Sommer et al, 2017 ).…”

“…To reduce CH 4 emissions from such storage systems, strategies such as reduction of aged manure (inoculants), crust development for potential aerobic CH 4 oxidation, and manure acidification using sulfuric acid (H 2 O 4 ) have been reported ( Petersen et al, 2012 ; Sommer et al, 2017 ; Habtewold et al, 2018 ). Sulfuric acid-based acidification of liquid dairy manure has primarily been used to abate ammonia (NH 3 ) emissions, but can also reduce CH 4 emissions ( Ottosen et al, 2009 ; Petersen et al, 2012 ; Fangueiro et al, 2015 ; Sommer et al, 2017 ). For instance, CH 4 emissions from cattle slurry were reduced by 68% by acidification to pH 5.5 with H 2 SO 4 ( Sommer et al, 2017 ).…”

Tradeoffs in US dairy manure greenhouse gas emissions, productivity, climate, and manure management strategies

“…Wooden covers can reduce CH 4 emissions more than a natural crust, though may have the potential to increase N 2 O emissions [36]. Manure acidification is another option for reducing emissions in liquid and anaerobic systems [37], with one recent study finding a 68% reduction [38]. Manure aeration or temperature reductions can also offer GHG mitigation opportunities [8], potentially up to 20% [9].…”