The Law Of Material Transformation During Chicken Manure Biocomposting With Black Soldier Fly And Evaluation Of Application Effect Of Insect Manure

As a resource insect,Black soldier fly（Hermetia illucens L.）can transform organic waste into insect sand and insect biomass,which has become increasingly active and popular in recent years.Its ability to turn waste into treasure has gained application prospects in the field of resource utilization and harmless treatment of livestock and poultry manure.Aerobic composting,as the most widely used treatment method for livestock and poultry manure,has become very mature.To explore whether the biological compost of black soldier fly has advantages in nutrient transformation and environmental benefits compared with aerobic compost?This study uses chicken manure as raw material to compare the nutrient changes,carbon and nitrogen losses,heavy metal concentrations,gas emissions of materials and other resource regeneration and environmental safety indicators between biocomposting of black soldier fly and aerobic composting.After that,the immature wormwood sand was composted for the second time,studying the law of gas emission during the process of wormwood sand composting,and evaluating the cumulative greenhouse gas emissions during the whole process of biological composting;Finally,through cucumber seedling cultivation experiments,the application effect of insect sand compost products in seedling cultivation was explored.The main results of this study are as follows:（1）The TOC concentration of biocompost of black soldier fly increased slightly at first and then decreased significantly,with a reduction range of 31.8%～28.7%,.The TOC concentration of aerobic compost materials continued to decline with the increase of treatment time,with a reduction range of 36.4%～30.9%.The TN concentration of black soldier fly biological compost decreased from 3.93%to 1.37%,with a decrease of 65.1%,while the TN content of aerobic compost had no significant change.The consumption of N was greater than that of C during biocomposting of black soldier fly,and the ratio of C/N gradually increased,while the ratio of C/N gradually decreased during aerobic compost.The three-dimensional fluorescence data of soluble organic carbon showed that,with the increase of chicken manure treatment time of biocomposting and aerobic composting,the aromatic protein and water-soluble microbial metabolites in water-soluble organic matter gradually decreased,the fulvic acid and humic acid substances gradually increased,and the material maturity increased,but the increase of fulvic acid and humic acid substances in aerobic composting was greater than that of biological composting of black soldier fly.Due to the consumption and utilization of humic acid by black soldier fly,the total humic acid content of black soldier fly biological compost decreased significantly,and the humification index decreased slightly,while the total humic acid content and humification index of aerobic compost significantly increased The DOC concentration of wormwood sand secondary composting changed slightly,with a range of 22.5g/kg～18.6 g/kg,which was much less than that of aerobic composting.The carbon loss of biological composting is only 69.5%of that aerobic composting,while the nitrogen loss of the two composting methods had no difference,which was 49.7%and 51.1%,respectively.The heavy metal indicators of the insect sand all meet the limit values in the organic fertilizer standard（NY/T 525-2021）,but the germination index is only 61.2%,which did not reach the limit value of the germination index.After secondary composting,the germination index reached the standard range.（2）In this study,the maximum emission rate of CO₂and N₂O in the biological composting process of the black soldier fly was 47.9 g·100 kg^-1·h^-1and 0.108 mg·100 kg^-1·h^-1,respectively,both lower than that of aerobic composting treatment,which is 69.3 g·100 kg^-1·h^-1and 4.58 mg·100 kg^-1·h^-1and the NH₃emission rate gradually decreased from 120 mg·100 kg^-1·h^-1to 30.2 mg·100 kg^-1·h^-1.Under the influence of temperature,the maximum NH₃emission rate of aerobic composting could reach 796 mg·100 kg^-1·h^-1.The maximum emission rate of CH₄was 56.4 mg·100 kg^-1·h^-1,which was much higher than that of aerobic composting,but lower than the 467 mg·100 kg^-1·h^-1of the control group without black soldier fly.The cumulative emissions of CO₂,CH₄,N₂O and NH₃in biocomposting of black soldier fly were 109 g/kg,43.8 mg/kg,2.18 mg/kg and1050 mg/kg,respectively,which were lower than those in aerobic compost except for CH₄.The potential value of non CO₂greenhouse effect produced in the whole process of black soldier fly biological composting and the secondary composting of insect sand was 2.14 g CO₂-eq·kg^-1,lower than 5.87 g CO₂-eq·kg^-1of aerobic composting.Among them,1.59 g CO₂-eq·kg^-1was producedduring the process of biocomposting,which was 92.9%lower than the control group of chicken manure without black soldier fly.In short,the results showed that the treatment of chicken manure by black soldier fly could effectively reduce the greenhouse benefits.（3）The experimental results of cucumber seed seedling cultivation using the secondary composting product of insect sand showed that adding 20%of the secondary compost products of black soldier fly sand was conductive to the growth of cucumber seedlings,and the emergence rate,biomass,stem diameter,plant height,growth function（G value）and healthy seedling index were higher than treatment groups with other addition ratios of insect manure,and also higher than 100%of commercial seedling growing media.This results showed that the process of black soldier fly treating chicken manure has practical application value,which can be used as fertilizer additive for plant growth and promoting crop growth.The results of this study provide data support and theoretical support for promoting the recycling and harmless treatment of livestock and poultry manure by black soldier fly.