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Permeable synthetic covers for controlling emissions from liquid dairy manure.

VanderZaag, A.C., Gordon, R.J., Jamieson, R.C., Burton, D.L., and Stratton, G.W. (2010). "Permeable synthetic covers for controlling emissions from liquid dairy manure.", Applied Engineering in Agriculture, 26(2), pp. 287-297.


Liquid manure storages emit greenhouse gases (GHGs) and ammonia (NH3), which can have negative effects in the atmosphere and ecosystems. Installing a floating cover on liquid manure storages is one approach for reducing emissions. In this study, a permeable synthetic cover (Biocap™) was tested continuously for 165‐d (undisturbed storage + 3‐d agitation) in Nova Scotia, Canada. Covers were installed on three tanks of batch‐loaded dairy manure (1.3 m depth × 6.6 m2 each), while three identical tanks remained uncovered (controls). Fluxes were measured using steady‐state chambers. Methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) were measured by absorption spectroscopy, and NH3 was measured using acid traps. Results showed covered tanks consistently reduced NH3 fluxes by approximately 90%, even though a surface crust formed on controls after about 50 days. Covers continued to reduce NH3 flux during agitation. Covered tanks also emitted significantly less CO2 and N2O than the controls (p‐value <0.01). However, CH4 fluxes were not reduced, and therefore overall GHG fluxes were not substantially reduced. Short‐term trends in CH4, CO2, and N2O flux provided insight into cover function. Notably, bubble fluxes were a key component of CH4 emissions in both treatments, suggesting the covers did not impede CH4 transport.

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