Influence of microbial inoculants on humic acids in compost of chicken manure

Chicken manure and rice stalk were composted in windrow and microbial inoculants of Bacillus spp.were added.The composting lasted for 42 days.During the composting,content of total humic acids in both the inoculated compost and the control dropped in the earlier stage and then rose in the later stage.In the first 3 days the inoculated compost and the control had almost the same content of total humic acids,however,at the seventh day content of total humic acids in the inoculated compost began to surpass the control.In the end of composting,content of total humic acids in the inoculated compost was 23.1% and the control was 17.2%.Content of free humic acid,soluble humic acid and humo acid had the similardynamic with that of total humic acids,which dropped in the earlier stage and then rose in the later stage.However,content of fulvic acid rose in the earlier stage and then dropped in the later stage.In the end of composting,content of all the humic acids above in the inoculated composted was significantly higher than the control,which indicated that the microbial inoculants tested could promote the production of humic acids during composting.