Co-composting of wheat straw and dairy waste

An experiment was conducted to investigate the feasibility of co-composting of wheat straw and dairy waste.Wheat straw was co-composting with biogas residues,biogas slurry,dairy manure,and dairy slurry,respectively,and pure wheat straw composting was regarded as control,in which C/N ratio was regulated to 35∶1 using urea.The results indicated that the high temperature durations above 50 ℃ for five composts were 30 d,17 d,41 d,12 d and 24 d,respectively,which reached the sanitary standard of aerobic composting.The organic carbon contents of five composts decreased by 14.00%,5.50%,15.80%,4.45% and 10.70% at the end of experiment,respectively.The contents of nitrogen,phosphorus and potassium increased gradually during composting.At the end of composting,the organic matter content was 590.28-701.86 g/kg.The total nutrient content(N+P2O5+K2O) was 46.54-89.45 g/kg.Among five treatments,total nutrients in the co-compost of straw and dairy manure was the highest(89.45 g/kg),followed by co-compost of wheat straw and biogas residues(69.61g/kg).Given long high-temperature duration and high total content of nitrogen,phosphorus and potassium,co-composting of wheat straw and dairy manure or biogas residues is suitable in practical application.But it is economical for the co-composting of wheat straw and biogas slurry or dairy slurry,because of high ratio of 1.8 t biogas slurry or dairy slurry to 1.0 t wheat straw.