| Chemical fertilizers have always been regarded as an important way to increase crop yields in the short term.However,with the long-term and large-scale application of chemical fertilizers,it has caused problems such as soil acidification,compaction,and reduced fertility,and also brought environmental problems such as eutrophication of lake water bodies.Due to its long-lasting fertilizer effect,organic fertilizer can improve the physical and chemical properties of soil,increase soil microbial activity and diversity,and gradually replace chemical fertilizers as an important means to solve soil problems and relieve environmental pressure.Soil is an important habitat for various organisms,which contains a huge number of virus life forms.The distribution of virions is controlled by geographical separation and ecological processes,and the importance of the correlation between the diversity of soil viruses and soil nutrient content.Based on the long-term organic fertilization experiment of Jiangxi Institute of Red Soil,this study analyzed the soil virus diversity and community structure of rice fields under different organic fertilization measures from the perspectives of rice yield differences,soil nutrients,soil virus population diversity,and metagenomics.The composition and the co-evolutionary relationship of host populations,to explore the process of regulating the virus micro-ecosystem to drive the biogeochemical cycle.The main research results are as follows:(1)Under the condition of long-term organic fertilization,the application of organic fertilizer can not only significantly increase the yield of rice,but also significantly increase the content of organic matter,total nitrogen,and alkaline nitrogen in the soil.The combined application of green manure and pig manure for early-late rice increased the average yield in15 years(2006-2020)by about 25.16%(M2)and 23.50%(M3);the organic matter content increased significantly by 48.35%(M2)and 44.25%(M3);alkali hydrolyzed nitrogen 51.24%(M2),45.84%(M3);total nitrogen content increased by 55.12%(M2),50.84%(M3).However,the application of organic fertilizer has no significant effect on the total potassium and available potassium content in the soil.Green manure combined with pig manure can effectively alleviate the drop in soil p H within a certain range.Rice yield has a very significant positive correlation with soil organic matter,alkali-hydrolyzable nitrogen,available phosphorus,total nitrogen,and total phosphorus content.Organic fertilization can effectively increase rice yields in farmland.(2)Under the condition of long-term organic fertilization,paddy soil viruses are distributed in 37 families,and Microviridae is the main virus group in paddy soils in red soil regions.Green manure pig manure combined with early-early rice(M3)had significantly higher abundances in Siphoviridae,Myoviridae,and Poxviridae than other treatments.The abundance of Microviridae and Nanoviridae in early-late rice(M2)combined with green manure and pig manure was significantly higher than other treatments.Application of green manure pig manure(M2,M3)can significantly change the structure of soil virus community.(3)Under the condition of long-term organic fertilization,paddy soil virions were annotated to 44 virus functional taxa.Protein family(genetic information processing)is the most abundant functional information in green manure pig manure combined with soil viruses.Paddy soil virus predicts 83 bacterial hosts and obtains Acinetobacter,Geobacillus,Legionella,Bacillus and Streptomyces seven genera including Clostridioides and Enterobacter are abundant bacterial species in the soil,and 18% of the virus hosts are Acinetobacter.Legionella is a unique virus host in green manure combined application(M2,M3,M4),and a more abundant virus host in green manure straw returning soil(M4).(4)Through the annotation of metagenomic genes of the rice field soil virus,143 unique carbohydrate transport and metabolism genes were identified,which were identified as carbohydrate active enzymes(CAZymes)based on the open reading frame,of which Glycoside Hydrolases were the most abundant,followed by Glycosyltransferase.In summary: long-term application of organic fertilizer can significantly increase rice yield and soil nutrient content,and can also significantly change the structure of soil virus community.Microviridae is the main group of viruses in paddy soils in red soil regions.Acinetobacter is an important host of viruses,and Legionella is a unique virus host in green manure application(M2,M3,M4).Glycoside Hydrolase and Glycosyltransferase are the most abundant genes in the metagenomics of rice soil viruses. |
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