Covering of liquid manure storage facilities causes additional costs. Furth
ermore, the building of rigid covers such as tent roofs over large slurry l
agoons is prohibitively expensive. Therefore, emission reducing effects and
floating behaviour of low-cost covers were investigated. Such alternative
cover materials are granules, chopped straw and rape oil.
Tests took place both in the laboratory and in the field. On-farm studies s
erved to determine emissions from liquid manure surfaces in large slurry st
orage facilities. Laboratory tests were carried out in transparent Perspex
containers on a 651 scale. The floating behaviour of the covers and the sed
imentation of slurry during storage and after homogenization were observed.
The ammonia emission was also measured here and sampling for odour measure
ments and chemical analysis was carried out.
Cover materials showed very different behaviour. The granules made a closed
cover within a few hours after homogenization, while rape oil rose to the
surface only during a period of several days. Chopped straw made a solid fl
oating layer infiltrated with slurry.
Laboratory scale and on-farm studies with granules and straw as covers redu
ced odour emission by about 83-91%. Ammonia emission decreased by about 80-
91%. The emission reduction of 85% for a 6 mm rape oil layer was similar to
the other covers, but the 3 mm oil layer showed an insufficient effect. (C
) 1999 Silsoe Research Institute.