Ammonia emission from a double-sloped solid floor in a cubicle house for dairy cows

Two methods to reduce the ammonia emission from double-sloped solid floors, with a gutter at the bottom of the flat "v" and baffles dipping into the slurry, in cow houses were investigated. The effect of two extra urine gutters in the sloping floor parts and the effect of spraying water, at a rate of 6 l/d per cow after scraping with a frequency of 12 times per day, were studied. The experiment was performed over 19 weeks in two compartments of an experimental mechanically ventilated cow house, each housing ten non-lactating cows. In one compartment, a double-sloped solid floor with underfloor slurry pit and floor openings, to dump manure collected by a scraper, was constructed. A central urine gutter was permanently in use. Underfloor air flow was prevented by a high slurry level and vertical baffles dipping into the slurry; these also reduced air exchange between pit and house. The other compartment served as a reference and had a traditionally slatted floor, also with underfloor slurry pit. Ammonia emissions from both compartments were recorded continuously. Ammonia emission from the compartment with the double-sloped solid floor operating with one urine gutter and without spraying water was, on average, reduced by 50% compared with the reference compartment. Emission was further reduced, on average, by 65% compared with the reference compartment when water was sprayed. The use of three instead of one urine gutter had no significant effect on the emission, despite the fact that the mean surface area covered by a single urination was reduced from 1.15 to 0.90m(2). It was concluded that a further reduction of the distance between the urine gutters would not be expected to influence ammonia emission, since the mean surface area covered by a urination was already close to the minimum of 0.8 m(2) for slatted floors. (C) 1997 Silsoe Research Institute.