Effect of pH, temperature, amount of litter and storage density on ammonia emissions from stable manure

Abstract

SUMMARYIn laboratory tests using stable manure consisting of wheat straw and slurry, ammonia emission was found to have two peaks corresponding to the population dynamics of proteolytic bacteria and amino acid-degrading bacteria respectively. Cumulative ammonia emissions over 14 days were 0·8–23·2% of the initial total nitrogen (Nt) and were both abiotically and biotically induced. Changes in pH had the most significant effect on the abiotically induced ammonia emissions. After 14 days of decomposition, at pH values of 6·0 and 7·5, abiotically induced emissions remained close to the limit of detectability, whereas at pH 9·0 as much as 9·8% of the initial Nt was lost. An increase in storage pressure from 0 to 400 and 800 kp/m2 generally decreased the biotic emissions to 9·6, 2·8 and 2·3%; while increasing the amounts of litter (2·5, 5·0 and 15·0 kg straw/LAU per day) led to a decline not only in the biotic (17·1, 12·8, 3·5%) but also in the abiotic emissions (6·1, 5·5, 1·6%). Varying the temperature (20, 30 and 40 °C) resulted in biotically induced emissions of 7·9, 11·7 and 11·6%, respectively, and abiotically induced emissions of 1·1, 1·4 and 2·2% of the initial Nt. At temperatures of 30 and 40 °C, the amount of microbially digested sources of carbon available was obviously sufficient to permit almost total reincorporation of NH4+ from 4 days onwards.