Keywords: 
• chicken manure /
• aerobic composting /
• sulfur /
• ferrous sulfate /
• nitrogen conservation /
• compost bioreactor

Abstract: An experiment was conducted to study nitrogen conservation affected by sulfur (S) and ferrous sulfate FeSO4·7H2O additions to chicken manure in compost bioreactors under strictly controlled aerobic conditions. Compared to the non-amended control (CK)， S addition (treatment T1) slightly affected both compost temperatures and the duration of the thermophilic period， but the addition of FeSO4·7H2O (treatment T2) did not significantly affect either compost temperatures or the duration of the thermophilic period. Addition of S in combination with FeSO4·7H2O (treatment T3) resulted in a longer duration of the thermophilic period and an accelerated organic matter decomposition. The addition of S， FeSO4·7H2O or both significantly reduced pH， but increased NH+4-N and total N content of compost. After 25 days of composting， NH+4-N and total N contents of compost increased by 157.60% and 2.75% in treatment T1， 86.64% and 9.04% in treatment T2， and 238.08% and 15.82% in treatment T3. The additions of S， FeSO4?7H2O or both increased electrical conductivity (EC) of the compost， but the germination indicators (GI) of radish seeds were greater than 50% in the composts from the three treatments. The results of this study suggest that the addition of S or FeSO4·7H2O was effective in N conservation in livestock manure composting， with addition of S in combination with FeSO4·7H2O being the most effective.