Aerobic Composting And Anaerobic Digestion:Fertility Evaluation And Their Effects On Grape Growth

The aerobic composting and medium temperature anaerobic digestion of the pilot plant were designed aiming to develop a technology that the livestock manure and farmland straw can be harmlessly treated and utilized.Using corn stalks and chicken manure as raw materials,respectively,the aerobic composting and medium temperature(37 C)anaerobic digestion pilot experiment were carried out and the aerobic composting products and anaerobic digestion biogas slurry were applied to the grape field to investigate the influence of fertilizer on grape growth and ecological risk under two different treatments.The results of aerobic compost showed that the number of days with the temperature above 60?were16 and the pH was maintained in the range of 7-9 when the composting of chicken manure and corn stalk were mixed in a 2:1 ratio,which met the requirements of aerobic composting on temperature and pH.The GI of the aerobic composting products was more than 90%after 25 days and reached the standard of complete maturity.The results of anaerobic digestion showed that chicken manure and corn stalk were mixed in a 4:1 ratio,the temperature was maintained at 32.2-39.4? and the pH was maintained at 7.88-8.11,which met the requirements of anaerobic digestion for temperature and pH.The gas production of the anaerobic digestion was decreased and maintained at a lower level after 35 days,indicating the end of anaerobic digestion of raw materials.The fertilization experiments in grape field showed that the contents of available nitrogen,available phosphorus and available potassium in the soil,which were dealed with aerobic composting products and anaerobic digestion biogas slurry,were significantly higher than those in non-fertilization group.Meanwhile,the group of the anaerobic digestion biogas slurry was higher than the aerobic composting product in the early stage,while it was lower than the aerobic composting product in the final stage.The N,P and K nutrient contents in the grape leaves were in the following order:composting group>biogas slurry group>non-fertilization group.After the harvest of the grapes,the order of hundred-grain weight of the grapes:biogas slurry group>composting group>non-fertilization group,the sort of acid-sugar ratio:composting group>biogas slurry group>not fertilization group.Compared with non-fertilization group,total soluble sugar content of aerobic composting group and anaerobic digestion biogas slurry group increased by 4.75%and 1.71%,total titratable acid content decreased by 4.76%and 3.20%,and Vc content increased by 14.76%and 5.70%,respectively.Aerobic composting products significantly reduced the direct ecotoxicity risks of Cr,Pb,As,Zn,Cu,Mn and Ni in soil.Anaerobic digestion of biogas slurry significantly reduced the direct ecotoxicity risks of Ni,As,Zn,Mn,Mn and Pb in the soil.In the experiment,the order of increase of heavy metals in grape leaves was:non-fertilization group>composting group>biogas slurry group.Considering the production efficiency,fertilizer efficiency and ecological risk of aerobic composting and anaerobic digestion of biogas slurry,the aerobic composting method was chosed to treat chicken manure and corn stalk.