Water and ammonia evaporation in a compost bedded pack dairy barn with under floor aeration

Abstract. The paper reports experiences from the first composted bedded pack (CBP) barn for 330 dairy cows in Denmark. The design of the barn differs from corresponding barns in the US by including an under floor aeration system to enhance water evaporation from the CBP. As bedding material were mainly used garden residuals, chopped roots and heathland vegetation.

The water evaporation during the investigated 313 days period amounted for 6.1 t cow^-1 corresponding to 70 % of the moisture included in the added manure and bedding material. Because of the relatively large simultaneous degeneration of organic dry matter (dm) the water evaporation did not contribute to increased dm content in the CBP during the winter period. Conversely, the water evaporation in the summer period was so large that the dm content in the CBP increased significantly even though no bedding material were added during a 193 days period.

Simple flux chamber measurement showed that the ammonia emission per area units was approximately 70 % lower from the CBP areas than from the solid floor feeding place scraped each second hour. But due to the large ammonia releasing area of 10 m² per cow the emission from a CPB barn seems to be approximately 30 % larger than from a free stall barn with solid floor alleys, which are scraped each second hour. However, the study indicated that the emission from the CPB barn is lower than from slatted floor free stall housing systems also frequently used in Denmark.