Geotextile fabric-straw manure storage covers for odor, hydrogen sulfide, and ammonia control

Manure storages are a major odor source. Straw and/or geotextile fabric covers can be used to reduce these odor emissions. Thirty-eight 160-L (42-gal) open-topped PVC pipes (columns) containing swine or dairy manure were used in a 2 × 4 × 4 factorial experimental design consisting of two manure sources, four thicknesses of straw, and/or four thicknesses of geotextile fabric. Collected air samples were tested for odor strength using a dynamic olfactometer, for hydrogen sulfide (H₂S) concentration using a Jerome? meter, and for ammonia (NH₃) using a boric acid trap. The main effects of straw thickness and time significantly affected odor, H₂S, and NH₃ reduction, while the main effects of manure type and geotextile thickness did not affect these reductions. The recommended minimum thickness of straw may be 20 cm (7.9 in.), since little additional odor reduction, H₂S, or NH₃ was gained by increasing thickness to 30 cm (11.8 in.). However, 30-cm (11.8-in.) depth may be needed to keep the straw material afloat or to keep the upper portion dry to allow the straw to absorb gases and/or act as a biofilter. Even though the geotextile did not significantly impact reduction of odor, H₂S and NH₃, the fabric may play a role in creating a barrier between the manure and straw to increase the life and effectiveness of the straw cover.