EFFECTS OF FLOOR DESIGN AND FLOOR CLEANING ON AMMONIA EMISSION FROM CUBICLE HOUSES FOR DAIRY-COWS

To obtain more detailed knowledge of low-emission floor systems for da iry cow houses an experiment was set up in which the traditional slatt ed floor and two different solid floor systems were compared: a non-sl oped (L) and a 3% one-sided sloped floor (S), both systems combined wi th a highly frequent (96 times per day) or normal (12 times per day) r emoval of manure by a scraper. For both the slatted and solid floor sy stems ammonia emissions were measured continuously over two separate t wo-week periods. On the solid floors also the development of urease ac tivity was recorded. Urease activity was measured as the accumulation of ammoniacal nitrogen in a urea solution (10 g urea-N l(-1)) in conta ct with the floor surface. Activity has been expressed as g NH3 m(-2) h(-1). The ammonia emission from the compartment with the L12 variant was almost equal to the emission from the compartment with a slatted f loor. The S12 variant reduced ammonia emission by 21% compared to the slatted floor. Raising the scraping frequency from 12 to 96 times per day led to a 5 percentage point increase in ammonia emission reduction (L96: 5%; S96: 26%). During the last testing period, just before remo val of the cows, ammonia emission from the compartment with the S12 va riant was 30-35 g NH3 h(-1) (10 cows). After removal of the cows this level decreased to 3-17 g NH3 h(-1) (average: 8.7 g NH3 h(-1)). This s uggested incomplete suppression of ammonia emission from the slurry pi t by the solid floor system. Covering the openings through which the s lurry collected by the scraper system was dropped in the pit reduced e mission to 4-10 g NH3 h(-1) (average: 5.5 g NH3 h(-1)). However, cover ing only decreased ammonia emission when the inside temperature was hi gher than the outside temperature. The rate of formation of urease act ivity differed considerably between the two-week periods, partly due t o differences in temperature regime. At and below 10 degrees C average daily temperature almost no formation of urease activity was observed , whereas at about 20 degrees C the formation rate reached values up t o about 0.04 g NH3 m(-2)h(-2). Up to an urease activity of about 2 g N H3 m(-2)h(-1), ammonia emission increased with increasing urease activ ity. At higher levels of urease activity either the amount of urea on the floor surface or the rate of volatilization of ammonia from a urin e puddle or from the slurry pit to the inside air limited the ammonia emission.