Preparation Of Multifunctional Compound Fungicide And Its Improvement Effect On Straw Return

In recent years,soil acidification,agglomerate fragmentation,and deterioration of soil quality have been caused by the excessive application of nitrogen fertilizers.As a food by-product,corn stover is produced about 1 billion tons per year,and returning the straw to the field not only returns nutrients to the soil but also improves the structure and function of the soil.However,the direct return of straw to the field not only has a low conversion rate of humus but also causes the spread of diseases.To promote the decomposition of maize stover and solve the adverse effects of the direct return of maize stover to the field and the problem of soil compaction acidification caused by excessive fertilization,a multifunctional microbial agent with nitrogen fixation,rot promotion,disease inhibition and growth promotion was developed,and the soil research results were as follows:(1)Micro bacterium sp with nitrogen fixation and decay promotion functions was selected.H2,Streptomyces falters werraensis F3 and Bacillus amyloliquefaciens JF-1.The antagonism test showed that the three did not antagonize each other.The optimal ratio and growth conditions were determined by OD600 growth determination and response surface experiments.The conditions were: the temperature was 28.5±0.6 °C,the p H was 7.34±0.4,and the bacterial ratio was 1:2:1(Micro bacterium: Streptomyces werraensis: Bacillus amyloliquefaciens),and the enzyme activity peak of the complex agent configured by this condition was: CMC: 20.41 U/m L,FPA: 18.46U/m L,β-case: 22.64 U/m L,nitrogenase activity: 556.32 nmol·m L-1·h-1;The results of potting experiments showed that the degradation rate of corn stover was 67.5% at 180 days,which was37.91% higher than the natural degradation.In the growth promotion experiment,the compound fungus HY-1 increased the plant height of maize seedlings with 20 days of growth by 31.42%,stem thickness by 46.86%,fresh weight by 39.33% and dry weight by 90.91%,so the compound fungus HY-1 had good functions of promoting rot and growth and nitrogen fixation.(2)Compared with the initial blank soil,the soil p H increased by 0.72 units,soil organic carbon increased by 46.10%,cation exchange increased by 20.49%,total nitrogen increased by64.25%,available nitrogen increased by 46.91%,and soil nitrogen was increased,which further confirmed the nitrogen fixation ability of compound agent HY-1.The combined effect of compound fungic agent HY-1 and straw increased the number of large soil aggregates,among which(2-0.25mm)particle level had the most significant effect.The organic carbon content of aggregates at different particle levels in soil increased.The combined application of compound fungi and straw increased the content of humus in the loose-knotted,stable and tight-knotted state.In the loose nodal humus,the organic carbon content and Δlg K of humic acid(HA)and fulvic acid(FA)increased significantly,and the PQ value increased significantly.In the stable humus,the content of HA organic carbon increased,but the content of FA decreased.There was no significant difference in Δlg K in HA,and the significance of Δlg K in FA increased.PQ values increase significantly.The increase of Δlg K indicated that the humus structure was "younger",the increase of PQ value represented the deepening of the humification process,and the combination of compound fungus HY-1 and straw increased the soil humus content,promoted the humification process,promoted the formation of HA in the soil,and transformed the FA of stable humus into HA.(3)The soil treatment of compound fungus HY-1 added to straw returned the largest number of unique OTUs,and α-diversity showed that the addition of straw significantly increased the richness of soil bacteria.Principal component analysis showed that the combination of complex agent HY-1 and straw produced substantial changes in the microbial community.At the phylum level,Proteobacteria,Gemmatimonadota,Acidobacteriota,Actinobacteriota,and Bacteroidia are the main phylums,and after the combination of the complex agent HY-1 and straw,The relative abundance of Proteobacteria in soil increased significantly,the phylum Acidobacteriota decreased significantly,and the phylum Proteobacteria increased.Redundancy analysis(RDA)showed that p H and cation exchange(CEC)were major drivers of differences in microbial community structure.Among the core microorganisms of the phylum TOP20,Proteobacteria,as the largest phylum in soil,accounted for 39.76% of the soil and increased by 7.24% under the synergistic effect of compound fungi and straw.In the functional analysis of COG,the synergistic effect of compound fungicide and straw improved the ribosomal structure and biosynthesis function of soil microorganisms,the biosynthetic function of cell wall/membrane/coating,and the function of inorganic ion transport metabolism.In summary,the compound fungus HY-1 has an obvious nitrogen fixation effect,which promotes the rotting of straw and promotes the growth of maize,and the combined application of compound fungus HY-1 and maize stover increases the stability of agglomerates,promotes the humification process,and enriches the diversity of microorganisms.It has a significant improvement effect on black soil.