Application Of Fingerprinting In The Study Of Chemical Composition Of Vermicompost

Vermicompost is a metabolite of earthworms digesting and decomposing organic matter.It can be used as a high-quality fertilizer and soil improver,and play an important role in the efficient and sustainable development of agriculture.The research on vermicompost at home and abroad mainly focuses on physicochemical properties,nutrient composition and amino acid content,but there are few reports on the specific chemical constituents of vermicompost.This article aims to study the differences in the chemical composition of vermicompost and organic fertilizer and provide references for the research and discussion of the unique chemical constituents in vermicompost,which provides a theoretical basis for comprehensive utilization of vermicompost.In this study,the most widely used gas chromatograph mass spectrometry and infrared spectroscopy in fingerprinting were used to determine chemical constituents in vermicompost and organic manure.Through analysis and comparison,specific components in vermicompost were explored.The main conclusions are as follows:1.Using N-hexane as extractant to extract manure and organic fertilizers,the extracts were analyzed by GC-MS.The results showed that 65,60,and 57 organic compounds were detected in three kinds of vermicompost,and 47,43,44 and 46 organic compounds were detected in the four types of organic fertilizers.Relative content and types of vermicompost extract chemical composition:Hydrocarbons>Esters>Silanes>Alcohols,organic fertilizers extract chemical compositionrelative content and species:Hydrocarbons>Alcohols/esters>Silanes.The highest relative content and species were found in vermicompost or organic fertilizers,which are hydrocarbons.The relative content and type of vermicompost are higher than those in alcohols,whereas the opposite is true in organic fertilizers.2.There are 23 kinds of the same components in cow dung vermicompost and pig manure vermicompost,9 kinds of the same components in cow dung vermicompost and sludge vermicompost,and 7 kinds of the same components in pig manure vermicompost and sludge vermicompost.There are 5 kinds of same components in vermicompost:heptadecane,pentadecane,4-cyclohexyl-dodecane,dodecamethyl-cyclohexasilane,dimethyl-cyclodisiloxane;Comparing the five organics with the components of the organic fertilizer,it was found that 4-cyclohexyl-dodecane,dodecamethyl-cyclohexasilane,and dimethyl-cyclodisiloxane are endemic components of vermicompost.3.Sodium pyrophosphate-sodium hydroxide extraction,sodium pyrophosphate volumetric method to determine the total humic acid component and humin acid component in vermicompost and organic manure.The results showed that the content of total humic acid component was highest in sludge vermicompost,and the content of humin acid component in cow dung vermicompost was the highest;the content of total humic acid component and humin acid component of vermicompost was lower than that of organic manure.4.Infrared spectroscopic analysis of the total humic acid component and humin acid component.The infrared spectrum of the total humic acid component in vermicompost and organic manure showed very similar infrared absorption peaks.The common absorption peaks were a hydroxyl peak near 3430 cm^-1,a double bond near 1668 cm^-1,1455 cm^-1,the alkyl peak,the C-Ocm^-1 single bond peak near 1128 cm^-1,the absorption peak near 920 cm^-1,the absorption peak near 738 cm^-1,and the absorption peak near 570 cm^-1.5.The infrared spectra of the humin acid components in the three kinds of vermicompost were analyzed and the results showed that the absorption peaks of the three vermicompost were approximately the same.The common infrared absorption peaks were:2920²924cm^-1,1654¹657cm^-1,1515¹542cm^-1,1400¹435 cm^-1,1216¹227 cm^-1,1050¹5015 cm^-1,867⁸68 cm^-1,591⁵92 cm^-1,and 494⁴95 cm^-1,but their relative intensities are different;they pass through organic fertilizers The comparison of the absorption peaks shows that the absorption peak at 2920²924 cm^-1 is the unique infrared absorption peak of the vermicompost.