Nitrogen Transformation and Loss during the Composting Process of Livestock and Poultry Manure with or without Bio-Fermentation Agent

The composting experiment using chicken manure, pig manure, fungus chaff and biogas residue as mixed media was conducted for 30 days with or without amendment of the bio-fermentation agent. The nitrogen transformation, changes of compost temperature and organic carbon in the mixture were investigated during the whole process. The results demonstrated that addition of the bio-fermentation agent improved the compost temperature, prolonged the high-temperature stage, expedited the process of organic carbon decomposition and lowered the C/N ratio. The amendment of bio-fermentation agent was beneficial to the transformation of organic nitrogen to ammonium (NH₄⁺-N) in the early composting stage (the first 9 d), but to the form of nitrate (NO₃^--N) afterwards. Compared to the non-bio-fermentation agent treatment, the composting process was reduced by 9 d to maturity. The acid hydrolysis organic nitrogen (THN) was increased with the addition of bio-fermentation agent during the early composting period by increasing the hydrolysis of the protein. The formation of amino acid nitrogen (AAN) and amide nitrogen (AN) in the compost, with amendment of bio-fermentation agent in early stage, revealed the reason why the mineralization of organic N was fast during the composting process. Although the addition of fermentation agent accelerated the organic nitrogen to transform into available forms, it did not cause massive N loss in the whole composting process.