| With the changes in the industrial structure of rural areas in China,the increasing improvement of people’s living conditions,and the rapid development of urban industrialization,it is inevitable to generate a large amount of agricultural waste.Unreasonable disposal has caused serious resource depletion and environmental pollution,which has attracted widespread attention from society.Therefore,adopting economic and effective technology for resource utilization of agricultural waste has important social significance and value.Composting is an important means and technology for the reduction,recycling and harmless utilization of agricultural wastes,and is also one of the most widely used methods at present.However,the traditional composting technology also has the disadvantages of low abundance of beneficial microorganisms in the composting raw materials,long composting cycle,and easy to produce odor gas,which limits the market value and application of composting products.This study takes discarded cabbage leaves as the research object and conducts simulated anaerobic fermentation experiments under the addition of different exogenous composting catalytic agents to select the optimal composting conditions;The composition and structural characteristics of solid and liquid phase products in the composting process of Chinese cabbage leaves were analyzed by three-dimensional fluorescence spectroscopy（3D-EEM）,ultraviolet visible spectroscopy（UV-Vis）,Total organic carbon（TOC）,element analysis and other methods;Finally,through the application of compost products to cultivate crops,the impact of compost on soil improvement and plant growth was further evaluated.The research results indicate that:（1）Adding two microbial agents,EM bacteria and photoactive bacteria,rich in photosynthetic bacteria,actinomycetes,yeast,and lactic acid bacteria,not only can reduce emissions of greenhouse gases such as CO2and CH4during the composting process,maintain the composting system temperature,but also help reduce the loss of nutrients and enrich microbial diversity.In addition,the addition of bacterial bran is conducive to creating a more stable composting environment and improving the level of humification.Through composting,60 to 65%of liquid products and 30 to 35%of solid products are obtained.The solid and liquid products obtained are mainly composed of humus like substances,protein like substances,and organic acids,with a total organic carbon content of 20-30 g/L,making them an organic fertilizer with a high carbon content.（2）In the process of composting,the organic matter was degraded under the action of microorganisms.The total organic matter content of the addition of photoactive bacteria degraded 50.96±12.74%,and the total organic matter content of the EM bacteria degraded 50.88±5.7%,indicating that the efficiency of the two bacterial agents on microbial degradation of organic matter was not very different.With the continuous advancement of the composting process,aromatic substances in the raw materials are continuously degraded,generating a large number of macromolecular substances rich in functional groups such as carboxyl and carbonyl groups.During the composting process,there were significant changes in material composition,such as the intensity of protein like fluorescence peaks that are larger in the early stage of composting,but gradually weakening as composting progresses;The fluorescence peak of humic substance did not appear at the initial stage of composting.As the compost gradually matured,humic substance gradually became the substance with the highest fluorescence intensity,and the overall humification and aromatization levels of the compost significantly increased.It is shown that the microbial diversity index（OTUs number,Chao 1 index,and Shannon index）of compost extracts added with photoactive bacteria is higher than that of compost extracts added with EM bacteria,indicating that adding photoactive bacteria during composting is more beneficial to improving the quality of compost products than adding EM bacteria.Based on the above humification indicators,adding photoactive bacteria and adding EM bacteria to compost can improve the hydrolysis efficiency and humification degree of compost in a relatively short time,and increase the diversity of microbial communities in the compost extract.（3）The addition of compost significantly improved the physical and chemical properties of the soil,and also promoted the growth of the substrate.Applying compost products can improve soil enzyme activity and microbial activity,increase the abundance and diversity of soil microbial communities,and effectively improve the aboveground and underground biomass of Chinese cabbage and tomato,as well as,the content of organic acids,lycopene and chlorophyll in tomato,which has a significant effect on promoting local growth of plants on the ground.At the same time,this experiment compared three additional fertilization modes when planting plants,and comprehensive analysis of soil properties and plant growth conditions showed that combined fertilization（combined application of solid and liquid products）had the best application effect.This study optimizes traditional composting technology and uses the anaerobic composting method of waste vegetable leaves to prepare water-soluble organic fertilizer,which is conducive to the comprehensive utilization of waste vegetable leaves,improving the application value of agricultural waste recycling,and providing reference opinions and suggestions for further promoting the strategy of rural revitalization and green sustainable development. |
