Comparison of techniques for ammonia emission mitigation during storage of livestock manure and assessment of their effect in the management chain

Abstract

The reduction of ammonia (NH3) emissions associated with manure management requires identification and implementation of effective techniques. The objective of this study was to measure potential ammonia emissions from animal manure and evaluate emission reductions for five mitigation techniques (straw, sawdust, clay, oil and sulphuric acid). Although numerous studies have evaluated individual mitigation techniques, the variability of their effect with different types of slurries has not been fully investigated. Furthermore, the assessment of ammonia emissions from the subsequent land application of stored manure (or slurry) using different techniques would indicate the practical consequences of the entire slurry management chain. The effects of mitigation techniques were evaluated using a model to simulate field application of slurry. Three techniques were compared: broadcast spreading, band spreading and closed-slot injection. Simulations utilised data from experiments conducted at a controlled temperature on six slurries of three different types: pig, cattle and digestate. Ammonia emissions from the raw slurries (i.e., untreated slurry) were determined using the dynamic chamber technique and compared with those from the slurries treated using each of five mitigation techniques. A subsample of one 1 L of each slurry was transferred into 2 L plastic bottles. An airflow of 1 L min–1 across the headspace was established and then emissions were measured over a period of 24 h. The air outlet was connected to two serial acids traps filled with 1% boric acid. The quantity of NH3 trapped was determined by titration. Acidification and oil addition were the most effective techniques, reducing ammonia emission from raw slurries by more than 95% and 80%, respectively. The mitigation effects of straw and sawdust were higher for cattle slurry and digestate than for pig slurry, while clay had an opposite effect. The overall assessment of ammonia emissions from storage and subsequent field application showed that acidification followed by closed-slot injection emitted at most 12% of the emissions from the reference system, while emissions from acidification followed by band spreading were between 14% and 22% of those from the reference system. The latter appears to be both more effective than broadcast spreading and technically more easily operated than a closed-slot injector.

Strategies to reduce nutrient pollution from manure management in China

“…Slurry acidification is being explored at the research scale to assess its potential to reduce NH 3 emission during storage [32] and processing, and after field application [33] . The co-benefits of slurry acidification can be reductions in methane emissions during slurry storage [34] , possibly because of inhibited methanogenesis in acidic conditions.…”

Influence of Treatments and Covers on NH3 Emissions from Dairy Cow and Buffalo Manure Storage

“…The higher NH3 emission fluxes observed for the LFD, as suggested by References [6,27], could be explained with the higher ammoniacal nitrogen in LFD at the beginning of the experiment (2.46 against 1.85 g kg −1 of CS) and the higher pH (7.9 instead of 7 of RS). On the other hand, it was observed a decreasing trend of ammonia emission fluxes for both materials.…”

“…Unfortunately, straw mitigation performances could be also affected by the DM content of the slurry; specifically, it was found by Finzi et al [6] that straw has a lower mitigation effect on the emissions for pig slurry characterized by a low DM content. Indeed, in this context, the straw precipitation would be facilitated, as it happened during the trial after the first week of monitoring.…”

“…Specifically, Kirchmann and Losses [5] indicate that NH 3 volatilization could amount up to 20-40% of the initial total nitrogen content. Additionally, Finzi et al [6] reported that animal manure storage is responsible for approximately 19% of the loss of the total nitrogen excreted by animals under ammonia form.…”

“…Unfortunately, covers, and particularly the biologically based ones, are not widespread due to the difficulties in creating a cover layer and in maintaining it (the effectiveness of covers is reduced if the covering material surface cracks [19] or sinks [17]) as well as the expensive cost [3]. Moreover, even though several studies have investigated mitigation techniques for the emissions occurring during the manure storage, their effect could vary depending on characteristics of the animal manure investigated [6].…”