Ammonia loss from simulated post-collection storage of scraped and flushed dairy-cattle manure

A series of laboratory scale studies were conducted, over a period of 23 d, to evaluate NH3 losses from simulated storages of scraped manure and flushed manure on the basis of similar: (i) exposed-surface-area to volume ratio (ESAVR), and (ii) exposed-surface-area (ESA). Based on similar ESA; NH3 flux during the 23-d study period from the storage of scraped manure ranged from 2.7 to 1.4 g m−2 d−1 compared to a range of 2.2 to 1.8 g m−2 d−1 from storage of flushed manure. This resulted in significantly higher total NH3 loss from the storage of scraped manure (2034 ± 107 mg) compared to that from the storage of flushed manure (1739 ± 53 mg). Ammonia flux ranging from 5.9 to 2.4 g m−2 d−1 was observed from the storage of scraped manure with similar ESAVR to that of the flushed manure storage. In the latter case, however, the total NH3 losses from either type of storage were not significantly different. The mean cumulative NH3 lost from the simulated storages of flushed manure was 1739 ± 53 mg, while the mean loss from the simulated storages of scraped manure was 1752 ± 56 mg. The results from this study indicate that for geometric similar post-collection storages (i.e. similar ESA), flushing manure mitigates NH3 emissions more than scraping manure, during post-collection storages: at least within the initial 23-d storage duration simulated in this study. In contrast, however, there was no indication of any advantage of using one system over the other if the post-collection storages were based on similar ESAVRs.

► Ammonia emissions from storage of scraped and flush manures were evaluated.
► Ammonia emissions were the same from storages with similar exposed-surface-area to volume ratios.
► Flushing mitigates ammonia emissions more than scraping if storages are geometrically similar.