Inhibitory effect of auxiliary organic materials on ammonia volatilization in composting and the influencing factors

The straw, rape straw and mushroom residue were used as the auxiliary organic materials in the pig manure compost, and the characteristic of the ammonia volatilization and influencing factors was studied. The results showed that, the total amount of ammonia volatilization during the pig manure composting was 5.084, 6.483 and 3.013g/kg, when pig manure was mixed with straw, rape-straw and mushroom residue, respectively; which were 64.88%, 82.74% and 38.45% of the control experiment (7.836 g/kg) (pure pig manure compost) after 65 days of composting. If the quantity and velocity of the ammonia volatilization were considered, the mushroom residue was the most excellent auxiliary material. When considering the temporal aspects of the ammonia volatilization in the course of composting, the peak period was affected by straw addition significantly. The ammonia emitted fiercely in the pre-period, but the peak period was short, which suggested that the straw was an efficient organic auxiliary material for the fast compositing. After the compositing, the concentration of water-soluble NH4+-N, pH and EC decreased, however, the content of water-soluble NO3--N and total nitrogen increased, and the decomposition of organic matters and coarse-fiber were also promoted with the addition of these three organic auxiliaries. The pig manure mixed with straw or mushroom residue was better than rape straw during composting.