Effect of Different Treatments on Composting of High Water Content Dairy Manure

In view of the characteristics of high water content of the dairy manure,it is uneconomical to compost it with the amendment of lower water content.In the present study,dairy manure was composted at a relatively high initial water conten(t70%～80%),using grinded dry maize straw as amendment,compared the forced aeration static bed composting with the rotating aerobic composting,as well as the effect of air-drying dehydration as pre-treatment on composting.The results showed that the thermophilic temperatures of all treatments were attained soon after the composting start and maintained above 50 ℃ for 8 to 12 d,which was enough to satisfy the requirements of sanitary standard for the non-hazardous(GB 7959—1987).At the end of composting,the water content declined below 40%;the C/N ratio,WSOC and NH4+-N content below 20,16 g·kg-1 and 0.4 g·kg-1,respectively.Moreover,the NH4+-N/NO3--N of all treatments except that the treatment was composted in static bed equipment at lower initial water content were less than 0.5,indicated that these treatments matured very well.The germination test showed that the GI of all treatments were more than 50%,moreover,the treatment by static bed equipment at relatively high initial water content and air-drying dehydration as pre-treatment composting attained to 80%,indicated that composting had eliminated the phytotoxicity of the compost.It is better to compost of dairy manure and grinded dry maize straw at relatively high initial water content in static bed equipment.It is cost effective to compost directly with the dairy manure of air-drying dehydration pre-treatment which could reduce the amount of compost amendment.