Effects Of Carbon To Nitrogen Ratio And Ventilation On Mixed Composting Of Dairy Manure And Tobacco Stem

The comprehensive utilization of agricultural wastes such as dairy manure and tobacco stem is one of the main research directions of bioengineering and organic fertilizer development.A large number of studies mainly focused on composting of dairy manure and stem were concentrated on a single material,while there were less studies on mixed composting.In this study,using dairy manure and tobacco stem as raw materials,a different carbon and nitrogen ratios experiment was conducted to screen the suitable carbon and nitrogen ratios of the composting of dairy manure and tobacco stem.And then conducted a different ventilation composting experiment under suitable conditions of C/N ratio to select the suitable ventilation of mixed composting,which could provide a certain theoretical basis and technical support on the harmless and resource utilization.Main results for this study were as follows:1.Different C/N ratios had effects on the duration of thermophilic phase(?50?),the electrical conductivity,germination index,nutrients content of composting and so on.When the C/N ratio was 22: 1(T22),the duration of thermophilic phase was 16 d.At the end of the composting,the electrical conductivity was 886 ?s·cm-1 and germination index was 121.3%,and the contents of total nitrogen,total phosphorus and total potassium were 3.86%,0.65% and 1.83%,increasing by 53.2%,35.4% and 16.6% as compared with the initial content,respectively.When C/N ratio was 19: 1(T19),the duration of thermophilic phase was 12 d.At the end of the composting,the electrical conductivity was 953 ?s·cm-1 and germination index was 118.5%,and the contents of total nitrogen and total potassium were 4.19% and 1.00% respectively,increasing by 60.0% and 29.9% as compared with the initial content,respectively.When C/N ratio was 25: 1(T25),the duration of thermophilic phase was 8 d.At the end of the composting,the electrical conductivity was 972 ?s·cm-1 and germination index was 78.9%.The content of total nitrogen and total potassium were 3.02% and 2.42%,increasing by 15.3% and 30.8% as compared with the initial content respectively.Comprehensive analysis,the longest duration of thermophilic phase,the highest germination index,higher nutrient contents were noticed under T22 treatment,so the mixed composting effect of dairy manure and tobacco stem was the best under T22 treatment.2.It exhibited significant differences among the duration of thermophilic phase(?50?),the electrical conductivity,germination index and nutrients content of composting under different ventilation conditions.As compared with those in control(W0),the duration of thermophilic phase prolonged for 5 d under ventilation with 12 hours condition.At the end of the composting,the electrical conductivity was decreased by 9.59% and the germination index was increased by 54.88% as compared those in control,respectively.Moreover,the total contents of nitrogen,phosphorus and potassium was increased by 10.60%,47.73% and 10.91% compared with those in control,respectively.It recorded that there was no significant difference in duration of thermophilic phase bettwen ventilation with 6 h(W6)and control.At the end of the composting,the electrical conductivity was decreased by 6.33% and the germination index was increased by 47.70% as compared those in control,respectively.Moreover,the total contents of nitrogen,phosphorus and potassium was increased by 8.02%,25.00% and 10.91% compared with those in control,respectively.It was concluded that the longest duration of thermophilic phase,the maximum decreses percent of the electrical conductivity,the greater increses percent of the total contents of nitrogen and phosphorus were under W12 treatment,which was benifical for improvement of compost maturity and release of nutrients.In this study,two important parameters of mixed composting of dairy manure and tobacco stem were obtained by composting experiments,the best C/N ratio and ventilation was 22: 1 and 12 hours,respectively.In conclusion,it could improve efficiently composting effects and product quality of the mixed composting of dairy manure and tobacco stem when C/N ratio was 22: 1 and ventilation time was 12 hours.