Effects Of Bio-organic Fertilizer Application On Recovery Process Of Watermelon Soil Microbiome After Fumigation

Continuous monocropping often results in soil-borne diseases that restricts the sustainable development of agriculture.Development of comprehensive means to tackle soilborne disease is of great significance to maintain soil health.Soil fumigation coupled with bio-fertilizer application can effectively suppress soil-borne diseases through manipulating the soil microbiome.However,we know little about the duration of the effect of disease suppression by soil microbiome manipulation.Also,soil microbial community after fumigation has strong resilience.The process of soil microbiome reconstruction is also the process of recovery.In this study,the duration of the disease suppression effect by soil microbiome manipulation through fumigation and bio-fertilizer application was evaluated.The recovery moving of soil microbiome after dazomet fumigation and the influence of the application of bio-organic fertilizer and microbial agent on the recovery process of soil microbiome after fumigation were investigated.The main results are as follows:1.Field experiment showed that the average disease control rate of fumigation plus bioorganic fertilizer was above 60%and the yield increased by 68%in average_during the three growing seasons.It can effectively control fusarium wilt and increase the yield of watermelon.The average fumigation control rate of fumigation treatment and application of ordinary organic fertilizer or bio-organic fertilizer treatment was 9.3%,21%and 35%,respectively.Pay attention to the sustainability of combined application of bio-organic fertilizer in the season fumigation.The effect of disease prevention and yield increase in the current season was significant,and in the next two seasons decreased in turn.2.The quantity dynamic of soil culturable microorganisms was monitored in the field experiment.Fungi are significantly inhibited by fumigation,especially Fusarium oxysporum,bacteria are less affected by fumigation,the number drops by about one order.The application of bio-organic fertilizer after fumigation effectively reduced the recovery rate of pathogen,and increased the number of Bacillus,which was beneficial to diseases control.3.The lab experiment showed that the fumigation of dazomet had a strong inhibitory effect on F.oxysporum,and the number of F.oxysporum decreased by 4 and 6 orders of magnitude after constant dose fumigation and double dose fumigation treatment,respectively.Within 65 days after fumigation,the recovery rate of F.oxysporum was extremely low,and the number is maintained within 102 cfu g-1.The inhibition effect of dazomet fumigation on soil fungi was significantly higher than that of bacteria.Within 65 days of recovery,the number of bacteria shows an activation effect in the later period,while the number of fungi has been suppressed.The number of soil bacteria decreased by an order of magnitude at the end of fumigation,and returned to the initial level on the 31st day,and on the 41st-65th day,the activation rate of double dose fumigation treatment was higher than that of constant dose fumigation.The number of fungi was reduced by 5.5 and 6 orders of magnitude after constant dose fumigation and double dose fumigation treatment,respectively.And in the 65 days after fumigation,the inhibition rate was more than 85%.4.Soil bacterial community is significantly affected by fumigation,the greater the fumigant dose,the greater the impact.After fumigation,the diversity of soil bacterial community decreased,and the proportion of core microorganisms changed significantly.The relative abundance of Acidobacteria and Fusarium was lowered,and the relative abundance of Firmicutes and Actinomycetes,mainly gram-positive bacteria,was increased rapidly.Within 65 days of recovery,the community continues to recover towards the initial community over time,but it is still quite different from the initial community.5.Application of bio-organic fertilizers and microbial agent to regulate microbial restoration after fumigation,it could accelerate the restoration of soil bacteria,especially Bacillus,and inhibited the recovery of F.oxysporum.After fumigation,the earlier the application time of the bio-organic fertilizer,the better the colonization of the functional bacterium Bacillus amyloliquefaciens SQR9 and the increase in the number of bacteria.The application on the 10th day is beneficial to the colonization of Trichoderma 4742 and the increase in the number of fungi.Later application of functional microbial agent can further increase the number of functional microorganism.In summary,fumigation coupled with bio-organic fertilizer application could effectively suppress fusarium wilt of watermelon and increase the yield.In the following seasons,the effect of disease suppressiveness decreased without fumigation.The soil microbiome showed a recovery trend after fumigation.The application of bio-organic fertilizer containing Bacillus amyloliquefaciens SQR9 and Trichoderma 4742 could inhibit the recovery of F.oxysporum and facilitate the recovery of other microbial groups.Continue to apply microbial inoculants later to further consolidate this effect.The disease suppressive soil could be made by manipulating the recovery process of soil microbiome after fumigation by application of bio-organic fertilizer and microbial agens.