Improvement Of Tobacco-planted Cinnamon Soil By Biochar And Its Microecological Mechanisam

As one of the major economic crops in our country,tobacco contributes greatly to the development of national economy and the improvement of people's living standard.However,in recent years,unreasonable land use lead to soil degradation including decreased soil organic matter,unbalance of carbon and nitrogen nutrient,low biological activity of soil,and so on.The soil borne disease of tobacco is aggravating,which give a serious threat to the sustainable production of flue-cured tobacco.In this paper,a series of experiments were conducted at tobacco experimental station in Shandong province from 2013 to 2015.Wheat straw biochar was used to amend the tobacco-planted soil,and fraction of soil organic carbon and nitrogen,microbial ecological diversity and compositions,agronomic characters,yield as well as the quality of tobacco leaves were investigated.The main results are as follows:1 Biochar promoted sequestration of soil organic carbon and nitrogenA field experiment was conducted to explore the effects of adding biochar at four levels(0,1,2 and 4 t/hm2)on the dynamic of oganic carbon and nitrogen fraction and tobacco growth in cinnamon soil of North China.The total oganic carbon(TOC),total nitrogen(TN),microbial biomass carbon(MBC)and nitrogen(MBN),dissolved oganic carbon(DOC)and nitrogen(DON)in the soil and dry matter accumulation of tobacco during different growth stages were investigated.Our results show the following: 1)TOC,TN,MBC and MBN content in the soil increased as the percentage of biochar applied was increased.They were the greatest when quantity of biochar application was 4 t/hm2.Compare to the CK treatment,TOC,TN,MBC and MBN increased 122.69%?22.55%?53.45% and 42.93% respectively during the fast-growing stage of tobacco.2)Biochar addition in the soil significantly decreased soil DOC content during center and later period of tobacco growth stage compared to the CK treatment,and the DON content were significantly lower than control during whole growth period of tobacco.The DOC and DON content both decreased as the increase of biochar application.3)In conclusion,applying biochar to the soil is benifical to the soil carbon and nitrogen sequestration,decrese the leaching of the active oganic carbon and nitrogen,improved soil biological characteristics and capacity of nutrient applying.The commented application quantity of biochar is 2 t/hm2 in tobacco-planted soil of North China.In addition,results of pearson correlation analysis showed that soil DOC and DON were negatively correlated to other indicators,while soil TN has little correlation with activated carbon and nitrogen.2 Biochar enhanced soil carbon pool management indexThe soil carbon pool management index(CPMI)is an effective index to monitor the dynamic and the quality of soil carbon.Our results show that biochar application has a significant effect on soil carbon pool management index,and the content of labile organic carbon in soil increases but carbon activity and carbon pool activity index decreases with the increase of biochar.The carbon pool activity index and carbon pool management index in biochar amended soil were significantly higher than that of the control.Compared to the CK treatment,soil carbon library management index increased by 18%,22% and 34% in the soils under biochar addition at 1,2,4 t/hm2,respectively.Effects of different rich-carbon material on soil carbon pool were evaluated and the results show that different high-carbon materials can both increase the content of soil carbon and carbon pool management index.Compared to the control,biochar(BC),turf(TS)and straw(CS)increased the soil total organic carbon by 25.48%,16.99% and 16.99%,respectively.And the carbon library management index in each treatments were respectively 16%,48% and 16% higher than that of CK.Comparative analysis of effects of different material on soil carbon pool management index showed that the content of POC is higher in BC amended soil than any other soils,and AOC and TOC content in TS and CS amended soil were higher than that of other treatments.Soil activity of carbon pool and carbon pool activity index were higher in TS and CS amended soil than BC,indicting that biochar addition is benicical to the carbon sequestration,while turf and straw are better to accelerated carbon cycle and improve the activity of carbon pool in short term.3 Biochar significantly influenced soil bacterial community structures,and enhanced soil microbial diversityResults of short-term pot experiment showed that the biochar can improve soil microbial biomass and bacterial diversity.The relative abundance of Actinobacteria,Gemmatimonadetes,Verrucomicrobia,and Planctomycetes were obviously higher than that of control,while the relative abundance of Acidobacteria,Firmicutes,TM7,and Nitrospira were obviously lower than that of control.In the field study,we investigated and analysed shifts in bacterial microbiome in cinnamon soil under field conditions 3 years after the addition of biochar at 10,20,and 40 t/hm2.We also analysed relationships between bacterial community and edaphic physicochemical characteristics.Our results showed that the soil p H,moisture content,total nitrogen(TN),and total organic carbon(TOC)content were significantly higher 3 years after the addition of biochar,but dissolved organic carbon(DOC)content and soil bulk density(BD)were lower.Furthermore,the content of soil microbial biomass carbon(MBC)increased with an increase in biochar.Illumine sequencing indicated that biochar amendments increased the bacteria diversity and changed the community structure.Results of the taxonomic classification showed that the dominant bacteria phyla were Proteobacteria,Bacteroidetes,Acidobacteria,Actinobacteria,and Verrucomicrobia across all of the samples.The relative abundance of Bacteroidetes increased in biochar amended soil,but Verrucomicrobia decreased.At the genus level,biochar addition at 40 t/hm2 decreased the relative abundances of Ohtaekwangia,Sphingobium,and Chitinophaga but enhanced the relative abundances of Pseudomonas and Lysobacter.Results of the redundant analysis(RDA)showed that soil bacterial community composition was highly associated with soil environmental factors,such as TN,TOC,and DOC.In summary,the application of biochar changed the soil's physicochemical properties,which likely drove the ecological succession of soil microbial communities,and changes of abundance of some functional bacteria may affect the soil ecological function.4 Biochar significantly changed soil fungal community structuresResults of long-term field experiment showed that,the addition of biochar had no significant influence on the alpha diversity of the soil fungus communities,but significantly changed the composition of the fungal communities.Species annotation results showed soil fungi across all the samples were classified into six phyla:Ascomycota,zygomycota,Basidiomycota,Chytridiomycota,Glomeromycota and Microsporidia.The relative abundances of Ascomycota,Zygomycota and Basidiomycota accounted for over 90% of all the annotated sequences.Biochar addition significantly increased the relative abundances of Ascomycota and Basidiomycota,while decreased the relative abundance of Zygomycota.At the genus level,biochar addition significantly increased the relative abundances of Alternaria,Conocybe and Aspergillus but reduce the the relative abundances of Actinomucor and Gibberella.The results of redundant analysis(RDA)and Mantel showed that soil fungal community structure was closely related to soil environmental factor,such as DOC,p H and Moisture.Pearson correlation analysis also showed that there was a strong correlation between the relative abundance of dominant genus and most of the soil physical and chemical indexes.5 Biochar enhanced the tobacco production and improved the quality of flue-cured tobacco leavesThe results of field experiment showed that the addition of biochar can promote the growth of flue-cured tobacco.75 days after transplanting,the height,stem circumference and maximum leaf area of tobacco plant in T2 treatment were 6.48%,4.00% and 23.54% higher than that in CK treatment,respectively.Biochar application promoted the dry matter accumulation of flue-cured tobacco during center and later period of tobacco growth,the dry matter accumulation of tobacco plant was the the greatest as the quantity of biochar application was 2 t/hm2,and it was 16.70% larger than that of the CK treatment at 90 d after the transplanting of tobacco plant.Biochar can help to control the main disease of flue-cured tobacco,and the disease incidence of tobacco weather fleck and tobacco black shank were 17.26-52.19% and 9.01-50.00% lower in biochar amended soil than in nonamended soil,respectively.The application of biochar increased the yield and economic benefits of tobacco.Compared to the CK treatment,the yield and economic benefits increased by 7.05% and 15.76% in the treatment under biochar amended at 2 t/hm2.In addition,the biochar can adjust the carbon and nitrogen metabolism of tobacco leaves,which is beneficial to the transformation of carbon and nitrogen metabolism in flue-cured tobacco.The mineral nutrition of tobacco leaf is balanced,and neutral aroma substances are abundance.In this study,biochar application at 1-4 t/hm2,can delayed maturity period of lower leaver by 2-6 days.An excessive dose of biochar will inhibit the growth of tobacco during early stage after transplanting,and reduce dry matter accumulation of tobacco plant during whole growth period.Further researches focused on effects of different dosage of biochar on different types of soils were in urgent need.