Effects of Cattle Slurry Acidification on Ammonia and Methane Evolution during Storage

Abstract

Slurry acidification before storage is known to reduce NH(3) emissions, but recent observations have indicated that CH(4) emissions are also reduced. We investigated the evolution of CH(4) from fresh and aged cattle slurry during 3 mo of storage as influenced by pH adjustment to 5.5 with sulfuric acid. In a third storage experiment, cattle slurry acidified with commercial equipment on two farms was incubated. In the manipulation experiments, effects of acid and sulfate were distinguished by adding hydrochloric acid and potassium sulfate separately or in combination, rather than sulfuric acid. In one experiment sulfur was also added to slurry as the amino acid methionine in separate treatments. In each treatment 20-kg portions of slurry (n = 4) were stored for 95 d. All samples were subsampled nine to 10 times for determination of NH(3) and CH(4) evolution rates using a 2-L flow-through system. In all experiments, the pH of acidified cattle slurry increased gradually to between 6.5 and 7. Acidification of slurry reduced the evolution of CH(4) by 67 to 87%. The greatest reduction was observed with aged cattle slurry, which had a much higher potential for CH(4) production than fresh slurry. Sulfate and methionine amendment to cattle slurry without pH adjustment also significantly inhibited methanogenesis, probably as a result of sulfide production. The study suggests that complex microbial interactions involving sulfur transformations and pH determine the potential for CH(4) emission during storage of cattle slurry, and that slurry acidification may be a cost-effective greenhouse gas mitigation option.

Manure management for greenhouse gas mitigation

“…In 2012, around 10% of the total slurry volume was acidified by one of several technologies, which adjust slurry pH either in slurry channels, in the store before spreading, or during spreading. Interestingly, acidification by sulphuric acid has also been found to reduce CH 4 emissions from cattle slurry by 67% to 87% (Petersen et al, 2012), and from pig slurry by 94% to 99%, (S. O. Petersen; unpublished results) during 3-month storage periods. Mechanisms of inhibition likely involve sulphur transformations, as significant CH 4 mitigation is also achieved with sulphate or reduced S amendment alone (Petersen et al, 2012), and with even a moderate reduction of pH by sulphuric acid (Table 4).…”

“…Interestingly, acidification by sulphuric acid has also been found to reduce CH 4 emissions from cattle slurry by 67% to 87% (Petersen et al, 2012), and from pig slurry by 94% to 99%, (S. O. Petersen; unpublished results) during 3-month storage periods. Mechanisms of inhibition likely involve sulphur transformations, as significant CH 4 mitigation is also achieved with sulphate or reduced S amendment alone (Petersen et al, 2012), and with even a moderate reduction of pH by sulphuric acid (Table 4). Mitigation of CH 4 emissions is of course achieved only if slurry is acidified before storage.…”

Methane, nitrous oxide emissions and mitigation strategies for livestock in developing countries: A review

“…In Vietnam, parts of both liquid and solid manure produced by pig farms are applied to fish ponds and used to feed fish for local consumption (Vu et al, 2012). Modern technology, such as manure separation, anaerobic digestion, aeration, use of additives and inhibitors (Petersen et al, 2012;Zaman & Nguyen, 2012;Gebrezgabher et al, 2015;Kinyua et al, 2016), to treat manure and slurry from ruminates and nonruminants, may not represent a feasible option to reduce GHG emissions in developing countries. The main reasons are high costs, low accessibility, high technology required, lack of knowledge, and insufficient legislation.…”

Rekenregels voor de enterische methaan-emissie op het melkveebedrijf en reductie van de methaan-emissie via mesthandling, het handelings-perspectief van het voerspoor inzichtelijk maken met de Kringloopwijzer

“…Het reducerend effect kan variëren tussen 47% en 99% (Tabel 6.12), maar voor melkvee zijn weinig gegevens beschikbaar. Petersen et al (2012) voegden zwavelzuur toe aan melkveedrijfmest en vonden een reductie in CH4-emissie van 67-87% (en bijna 100% reductie in NH3-emissies). Hetzelfde toevoegmiddel gaf voor varkensdrijfmest een reductie tussen 94 en 99% (Petersen et al, 2014).…”