Effect Of Exogenous Organic Materials On The Salinity Reduction Of Salinized Soil In Facilities

Facility agriculture is an important part of the vegetable industry,but secondary salinization of facility soils to different degrees due to replanting index and over-fertilization has seriously restricted the development of the vegetable industry,so improving salinization of facility soils has become a research hotspot.In this thesis,the differences in salt reduction of four kinds of decomposed organic materials,namely,natural mushroom residue,chicken manure,vegetable straw and cow manure,on facility soils were comparatively studied through pot experiments,with a view to providing technical support for salt reduction of secondary salinized soils.With the help of energy spectroscopy,fluorescence spectroscopy,infrared spectroscopy and high-throughput sequencing,we analyzed the structure of exogenous organic material components,soil microbial community,soil salinity and nutrients,and comprehensively analyzed the salinity reduction effect of different organic materials on the salinized soil in facilities.The main results of this study are as follows:1.The analysis showed that the organic materials such as decomposed cow manure,chicken manure,straw and mushroom residue all possessed complex functional groups,mainly C-H,C=C,C=O,O-H,C-O,N-H,and the main elements were C and O;the main components were fulvic acid-like,huminic acid-like substances and protein-like substances,and the content of humus-like substances all reached 60%～80%of the overall fluorescence intensity.Three-dimensional fluorescence analysis showed that straw and cow manure DOM substances were influenced by the combined effect of autogenous and exogenous sources,with strong autogenous characteristics;chicken manure DOM substances were influenced by the combined effect of autogenous and exogenous sources,with low autogenous characteristics;and mycorrhizal DOM substances were dominated by exogenous substances.2.Rendering of cow manure,chicken manure,straw and mushroom residues significantly reduced water-soluble salts in salinized soils.Three levels of organic materials were added(low amount,1.25 g·kg^-1 organic carbon;medium amount,2.50 g·kg^-1 organic carbon;high amount,5.00g·kg^-1 organic carbon),and the comprehensive analysis showed that the low level had the best effect on salt reduction,such as the low level（19.6%total salt reduction）,medium level（19.0%）,and high level（9.2%）of cattle manure had more significant differences.Further analysis of salt ion removal by low levels of organic materials showed that different organic materials had no significant effect on soil SO₄^2-（p>0.05）,and all significantly reduced water-soluble K⁺,Na⁺,Ca²⁺,Mg²⁺,HCO₃^-,and Cl^-contents in soil（p<0.05）,with cow manure treatment having better effects on Ca²⁺,Mg²⁺,HCO₃^-,and Cl^-improvement than the other The straw treatment significantly reduced the soil Na⁺content by 13.7%.3.Based on the corresponding relationship between microorganisms and salt ions,the interaction analysis of organic materials,microorganisms,and soil salt-based ions showed that organic materials significantly increased the abundance and diversity of microbial communities in soil,and the dominant phyla of bacteria and fungi were the same as without organic materials,but organic materials increased the relative abundance of Bacteroidetes（over 1.70%）and Mucorales（over 1.18%）of bacteria;increased the relative abundance of（1.97%or more）of fungi.The correlation analysis of structural components of organic materials,soil microorganisms and soil environmental factors showed that soil organic matter（32.0%contribution）and soluble organic carbon（15.1%contribution）had a greater influence on soil bacterial communities;soil K⁺（20.4%contribution）and p H（13.0%contribution）had a greater influence on soil fungal communities;fulvic acid-like substances in organic materials,fulvic acid-like substances and fulvic acid-like substances in organic materials had a greater influence on soil fungal communities;and fulvic acid-like substances in organic materials had a greater influence on soil fungal communities.Humic acid-like substances were important influencing factors for total soil water-soluble salts.In summary,the application of rotted cow manure,chicken manure,straw and mushroom residue into the salinized soil of the facility can serve to reduce the salinity of the salinized soil of the facility,increase the soil nutrients and promote the activity of soil microorganisms.