Carbon dioxide emission and water evaporation from deep litter systems

Carbon dioxide emission and water evaporation from deep litter systems are important parameters to consider when designing ventilation and heating in livestock buildings. The objective of these investigations was to determine the CO2 emission and water evaporation from deep litter with different bedding materials and also the water evaporation from a manure alley (solid floor). Five different studies are presented, two with deep litter for young cattle and three with deep litter for growing/finishing pigs. The bedding materials used were; long straw, chopped straw, chopped straw with reduced (25%) bedding amount, chopped straw with additives (four different), wood shavings and a mixture with 60% peat and 40% chopped straw. The investigations with deep litter for young cattle were conducted during two 6-month periods and the investigations with deep litter for growing/finishing pigs were conducted during three growing periods. Animal density in the pens varied between 27-101 and 22-90 kg m(-2) for cattle and pigs, respectively. Ventilated chambers (bottom area 0.25 m(2)) placed on the top of the litter were used in four studies. In a fifth study, with deep litter for growing/finishing pigs, the measurements were at building scale in the ventilated air when pigs were moved outside the research building. The average CO2 emission rate measured by ventilated chambers varied between 24.0-87.9 and 23.0-82.2 g m(-2) h(-1) for cattle and pigs, respectively. The average water evaporation varied between 109.2-159.8 (cattle) and 70.3-190.6 g m(-2) h(-1) (pigs). From the manure alley (solid floor), the average water evaporation rates in two studies (cattle) were 73.2 and 110.5 g m(-2) h(-1). The water evaporation rate varied during the measuring periods, with the minimum occurring during winter months. For young cattle, long straw as bedding material had a significantly higher CO2 emission rate compared with chopped straw. The mixture of peat and chopped straw had a significantly lower CO2 emission rate and water evaporation rate than long straw and chopped straw. For growing/finishing pigs, wood shavings as the bedding material had a significantly lower CO2 emission rate and water evaporation rate compared with long or chopped straw. The four different additives used had no significant effect on the CO2 emission rate or the water evaporation rate. The CO2 emission rate measured at building scale was lower than from the measurements with ventilated chambers, between 12.9 and 21.9 g m(-2) h(-1), and the water evaporation rate was between 135.6 and 210.5 g m(-2) h(-1) (C) 2000 Silsoe Research Institute.