Pwgg. Koerkamp et al., LITTER COMPOSITION AND AMMONIA EMISSION IN AVIARY HOUSES FOR LAYING HENS - PART 1 - PERFORMANCE OF A LITTER DRYING SYSTEM, Journal of agricultural engineering research (Print), 70(4), 1998, pp. 375-382
The effects of a litter drying system are reported on the composition
of the litter and the emission of ammonia from a tiered wire floor avi
ary housing system for laying hens. Air velocities above the litter, a
mixture of droppings and sand, were increased by means of air that wa
s sucked from the top of the room and blown through holes in ducts at
floor level. The dry matter content of the litter was higher (above 90
0 g/kg) and the total ammoniacal nitrogen (0.7 g/kg) and pH (7.3) of t
he litter were remarkably lower than in aviaries without forced drying
of litter (dry matter 750-850 g/kg, total ammoniacal nitrogen 2-3 g/k
g, pH about 8.6). Concentrations of ammonia in the exhaust air were be
low 5 p.p.m. and the emission of ammonia from the house reached a stab
le emission level of about 2.0 mg/h per hen when hens were about 30 we
eks old. This emission was caused by the litter and the manure on the
belts, and was reached when manure on the belts was removed daily and
about 500 m(3)/h of air were blown evenly over the litter by means of
three ducts. The litter drying system effectively maintained the dry m
atter content of the litter at a high level and minimized the degradat
ion of nitrogenous components into ammonia. A possible increase of the
volatilization rate of ammonia because of higher air velocities was o
f minor importance. (C) 1998 Silsoe Research Institute.