Effects of calcium magnesium phosphate fertilizer, biochar and spent mushroom substrate on compost maturity and gaseous emissions during pig manure composting.

This study used a laboratory-scale system to investigate the effects of calcium magnesium phosphate fertilizer (CaMgP), biochar, and spent mushroom substrate (SMS) on compost maturity and gasous emissions during pig manure composting. The results showed that the addition of CaMgP, Biochar or SMS had no negative effect on the quality and maturity of compost, and all three additives could reduce the emissions of ammonia (NH3), hydrogen sulfide (H2S), dimethyl sulfide (Me2S) and dimethyl disulfide (Me2SS). Among them, the effect of adding CaMgP on NH3 emission reduction was the most obvious, reduced 42.90%. The emission reduction of CaMgP to H2S was similar to that of SMS, which decreased by 34.91% and 32.88% respectively. The emission reduction effects of the three additives on Me2S and Me2SS were obvious, all of which were over 50%. However, only adding SMS reduced the N2O emission by 37.08%.