| In recent decades,my country’s arable soil has had serious problems such as excessive application of chemical fertilizers,low soil carbon levels,insufficient exogenous carbon supplementation,and serious agricultural carbon emissions,which have led to the decline of soil nutrient availability,carbon and nitrogen imbalances,and low organic matter content.Soil compaction and serious compaction,etc.,at the same time led to a decline in crop yield and quality.Tobacco occupies an important position in my country’s taxation and national economy.Tobacco is also an important economic crop in agricultural production.With the over-utilization of arable soil and insufficient maintenance awareness,the quality of tobacco-growing soil has deteriorated,tobacco plant development is not healthy,flue-cured tobacco leaf production and quality decline,and tobacco industry availability is not high,which restricts the sustainable development of high-quality tobacco OTUput and production in my country.A suitable soil improvement technology or material to improve these problems.Tobacco planting in my country has a long history,but due to long-term repeated planting of a single crop（tobacco）and insufficient maintenance of the tobacco-growing soil,the soil for tobacco-growing in the main tobacco production areas has been seriously degraded and the quality of tobacco leaves has been greatly reduced.In order to change the status quo,this research carried OTU basic research experiments on biochar in 2018-2020,as well as biochar application experiments in field and potted plants.Through comparative analysis of biochar with different raw materials and carbonization temperature,the biochar that is more suitable for tobacco-growing soil is selected.When carrying OTU biochar application experiments,peanut shell biochar was used as the main research material,the application effect of different amounts of biochar in tobacco planting soil,the application effect of biochar on different tobacco planting types,and the application of biochar as the main research material.The effect of applying high-carbon materials with different carbon to nitrogen ratios on tobacco-growing soil was used as a test method to study the soil carbon pool,nitrogen,physical structure,conventional nutrients,tobacco plant development dynamics,and rhizosphere microorganisms under the influence of biochar.And the changing law of tobacco yield.The main results and conclusions of this study are as follows:1 Analysis of biochar produced by different biomass raw materials at different carbonization temperaturesThrough the given carbonization technology and process conditions,predict and guarantee the final biochar characteristics of the known biomass,which is of great significance for the improvement of agricultural soil quality and sustainable development.By studying the biochar produced by three kinds of agricultural waste biomass of wheat straw,peanut husk and rice husk under the three carbonization conditions of 450℃,550℃ and 650℃,the yield,pH,and pH of biochar were mainly analyzed.The content of ash and basic chemical elements provide predictive indicators for the applicability of biochar in tobacco-growing soil.The results showed that as the carbonization temperature increased,the content of flat H,ash,phosphorus,potassium and hydrogen in the produced biochar increased,while the content of total carbon,stable carbon and total nitrogen decreased.Among different biomass raw materials,the biochar produced by peanut shell has higher pH,total carbon,stable carbon and P content.The carbonization temperature of biomass raw materials is a decisive factor in the physical and chemical characteristics of biochar.From the perspective of improving tobacco-growing soil and tobacco development and yield quality,the biochar produced from peanut shells at a carbonization temperature of 450℃ is more suitable for application in tobacco-growing soil.2 The effect of biochar on the change of organic carbon content in tobacco-growing soilThe effects of different amounts of biochar on the changes of tobacco-growing soil carbon pool were studied through fi eld experiments and pot experiments with different amounts of biochar.The results showed that biochar increased the content of different types of organic carbon in the soil.In the field experiment,the biochar at different growth stages of tobacco increased the organic carbon content,and with the increase of the amount of biochar,the different organic carbon content increased.Among them,the total organic carbon（TOC）content of the field experiment treatment with the amount of biochar of 2 t ha-1 can be 37.23%higher than the T0(biochar 0 t ha-1)40 days after transplanting;in the field and pot experiments,the total organic carbon（TOC）content is 37.23%;The soil microbial biomass carbon（MBC）of the charcoal treatment also showed significant differences compared with the control withOTU biochar;the soluble organic carbon（DOC）and easily oxidizable organic carbon（EOC）of the treatment group were also significantly higher than the control group.Low-to-medium biochar(0-1.5 t ha-1)treatment can reduce soil CO2 emission rate,while high-level biochar(2 t ha-1)treatment can increase soil CO2 emission rate,with a dosage of 2 t ha-1 The total CO2 emission rate of the treatment is 11.64%higher than that of the treatment withOTU biochar,and the total CO2 emission rate of the treatment with a biochar dosage of 0.5 t ha-1 is 24.81%lower than that of the treatment withOTU biochar.Biochar can obviously promote the increase of soil organic carbon mineralization rate(Cmin),and Cmin will increase with the increase of biochar input.Biochar reduces MBC/TOC,However,the DOC/TOC has been significantly improved.Biochar shows a significant increase in soil organic carbon in different types of soils,but the increase range is different.The red soil with low pH and low organic matter is more sensitive to biochar,and the increase of organic carbon content is greater,while the dark umber with high pH value and high organic matter content has a weaker response to biochar.High-carbon materials with different carbon to nitrogen ratios,mainly biochar,have different effects on soil organic carbon.High-carbon materials with medium carbon to nitrogen ratio（C/N=20）have a more obvious effect on soil organic carbon,which can increase total organic carbon by 31.19%,soluble organic carbon 22.27%,microbial biomass carbon 41.10%.Chemical fertilizers also show the effect of treatment on soil organic carbon in different types of soil,but the improvement is far less than that of biochar.From the results of the study,it can be seen that biochar improves the level of soil carbon pool and the rate of soil carbon mineralization,while the low-to-medium biochar dosage can reduce soil CO2 emissions,and the high biochar dosage promotes CO2 emissions.Biochar has a significant effect on increasing the organic carbon content of low pH and low organic matter soils.High-carbon materials with a medium carbon to nitrogen ratio have a more obvious promotion effect on soil organic carbon.3 The effect of biochar on the change of nitrogen content in tobacco-growing soilThe level of soil nitrogen is an important reference indicator that reflects the soil’s ability to support plants.With the large-scale application of chemical nitrogen in the agricultural production process,soil carbon and nitrogen are imbalanced and soil quality is seriously affected.This study studied the effects of biochar on the changes of nitrogen in tobacco-growing soil through field experiments and pot experiments with different amounts of biochar.The results showed that biochar increased the total nitrogen（TN）content in the soil at different growth stages of tobacco.And the total nitrogen（TN）content of the soil increased with the increase of biochar input.The treatment with a biochar dosage of 2 t ha-1 can be up to 12.8%higher than the control treatment withOTU biochar.With the passage of tobacco growth period,the content of total nitrogen（TN）and soluble organic nitrogen（DON）in the soil of each treatment showed a downward trend.In the different growth stages of tobacco,the DON content of the biochar treatment was lower than that of the control treatment,but in the early tobacco growth period,the soil DON content increased with the increase of the biochar dosage,and the soil DON increased with the biochar application amount in the later growth period.However,it first increased and then decreased,reaching the maximum value at 1.5 t ha-1 treatment.With the increase of the tobacco transplanting days,the soil microbial biomass nitrogen（MBN）first increased and then decreased,reaching its peak in the prosperous period（70 days after transplanting）;the soil MBN content of the treatment group was significantly higher than that of the control Group,and increased with the increase of the amount of biochar,the treatment with 2 t ha-1 of biochar can be up to 51.04%higher than the control withOTU biochar.Biochar increases the content of soil alkali hydrolyzed nitrogen（AN）,and with the increase of the amount of biochar,it first increases and then decreases.Under the influence of biochar,the content of nitrate nitrogen and ammonium nitrogen in the soil also has a significant increase trend.The soil nitrogen mineralization rate increases with the input of biochar.Biochar significantly increased MBN/TN,but DON/TN decreased with the application of biochar.Biochar has different effects on soil nitrogen in different types of soil.In red loam,biochar can increase the total nitrogen content of the soil,and the increase rate is higher than that of chemical fertilizers.In yellow umber,cinnamon and dark umber,biological char can increase the total nitrogen content of the soil.The increase of total nitrogen by charcoal is lower than that of chemical fertilizers,but in general,biochar can increase the total nitrogen content in the four soils.In the four types of soil,biochar has a significant effect on improving soil microbial biomass nitrogen and soluble organic nitrogen,and the increase rate can reach 34.24%and 9.45%.Chemical fertilizers can improve the organic nitrogen of these two soils,but the effect is not significant.High-carbon materials with different carbon-to-nitrogen ratios based on biochar can increase the content of soil total nitrogen and organic nitrogen.However,as the carbon-to-nitrogen ratio of high-carbon materials increases,the content of total nitrogen and soluble organic nitrogen decreases.The nitrogen content of microbial biomass increased.To sum up,it can be seen that biochar has a significant impact on the level of nitrogen in the soil.While increasing the total nitrogen content of the soil,it also increases the content of soil AN and MBN,which greatly promotes the OTUput capacity of soil available nitrogen.At the same time,the nitrogen content of different types of soil promotes each other,and with the different application of biochar,the degree of soil nitrogen level is also different,and the change law of soil nitrogen in different growth periods of tobacco is also different.In different types of soil,biochar can increase the soil nitrogen content,especially in red loam soil,the increase of biochar on the total nitrogen content of the soil is even greater than that of chemical fertilizers.High-carbon materials with a high carbon to nitrogen ratio are conducive to the increase of soil microbial biomass carbon,but for total nitrogen and soluble organic carbon,high-carbon materials with a high carbon to nitrogen ratio will reduce it.4 The impact of biochar on other basic physical and chemical characteristics of tobacco-growing soilSoil mineral elements,bulk density,pH and other physical and chemical characteristics are important factors that change the degree of soil health,and they are also key indicators that affect the healthy development of tobacco and the improvement of yield and quality.The results of this study showed that soil available phosphorus（AP）and available potassium（AK）increased with the application of biochar,and at the same time,total phosphorus and total potassium in the soil increased with the increase of biochar application.Biochar also has a promoting effect on the content of magnesium and iron in the soil.With the passage of tobacco growth period,the content of phosphorus and potassium in the soil of each treatment is reduced.Different amounts of biochar have an effect on the phosphorus,potassium and other minerals in the soil.The degree of influence of the elements is different.The activity of UR,SU,PO and CA in the soil varies with the application of biochar.However,the SU and PO increased with the increase of the amount of biochar.The activity of UR and CA showed a trend of first enhancement and then weakening with the increase of the amount of biochar,and reached the peak at 1.5 t ha-1.The soil pH did not change much in different growth periods of tobacco,and biochar significantly increased the soil pH.The treatment with a biochar dosage of 2 t ha-1 was up to 5.46%higher than the control treatment withOTU biochar.The impact of soil bulk density（pb）on biochar is reduced.Compared with the treatment withOTU biochar,the biochar treatment can reduce pb by up to 32.34%.In different types of tobacco-growing soils,the effects of biochar on soil pH,bulk density,enzyme activity,electrical conductivity and other indicators are different,especially the changes in soil pH,which are affected to a greater extent with the change of soil types.difference.In different types of tobacco-growing soils,biochar can reduce soil bulk density,increase soil enzyme activity,increase soil conductivity,pH and humidity,but in red soil,biochar has a significant effect on soil pH,while it has an obvious effect on dark brown soil.The effect of improving soil pH is relatively weak.In terms of soil enzyme activity,biochar has a more obvious effect on improving the enzyme activity of red loam,and the soil enzyme activity of dark umber soil of 4 planting tobacco soil is the highest.High-carbon materials with different carbon to nitrogen ratios based on biochar have different effects on soil pH,bulk density,electrical conductivity and humidity.High-carbon materials with high carbon-nitrogen ratio have a greater increase in soil pH,and at the same time have a significant effect on reducing soil bulk density.However,in terms of soil electrical conductivity,materials with high carbon-nitrogen ratio do not have a significant effect on improving soil pH withOTU low carbon-nitrogen ratio.High-carbon materials with a carbon-to-nitrogen ratio have little effect on soil moisture.It can be seen that biochar plays an important role in regulating soil mineral nutrients,pH,enzyme activity and physical structure,which also lays a good foundation for the growth of soil microorganisms and crops.However,different types of tobacco-growing soils have different responses to biochar,and biochar has a significant effect on increasing the pH and enzyme activity of red loam.High carbon materials with high carbon to nitrogen ratio have a greater impact on soil pH and soil bulk density.5 The effect of biochar on the bacterial diversity of tobacco-growing soilThe pot experiment shows that the alpha diversity index of soil bacteria is significantly increased under the influence of biochar.With the change of the amount of biochar applied,the degree of influence of biochar on the a diversity index of soil bacteria is different.Under the action of biochar,the number of soil bacterial OTU increased significantly,and compared with the control group,the treatment with a dosage of 2%can increase the bacterial OTU number by 7.62%.Through PCA analysis,it is found that under the influence of biochar,soil bacterial communities develop in a specific direction and the degree of influence is related to the amount of biochar.Actinobacteria,Proteobacteria,Chloroflexi,Acidobacteriota,Firmicutes,Gemmatimonadota,Myxococcota in each treatment soil（Myxococcus phylum）and Bacteroidota（Bacteroidota）are the dominant bacteria phyla.The abundance of Actinobacteriota,and Bacteroidota in biochar-treated soil was higher than that of the control,but Chloroflexi and Firmicutes.The abundance of Firmicutes is lower than that of the control,while biochar has no significant effect on the abundance of Gemmatimonadota and Myxococcota.In summary,biochar changes the diversity and abundance of soil bacteria,and at the same time drives the development of soil fungal communities in a specific direction.6 The effect of biochar on fungal diversity in tobacco-growing soilThis study shows that biochar can increase the fungal alpha diversity index,especially the Shannon index.The most abundant fungal species in each treatment was Ascomycota,which accounted for abOTU 85%of the total number of fungal communities.The top 3 populations with the highest abundance in each treatment were Mucoromycata,Basidiomycota,Ascomycota.Through Venn diagram analysis,it is found that the amount of fungal OTU has an increased influence on biochar.And it increased with the increase of the amount of biochar.The number of fungal OTU treated with 1 t ha-1 of biochar was 10.12%higher than that of the control.Biochar increases the abundance of Mucoromycata and SARKnorank,but reduces Basidiomycota（Basidiomycota）abundance,and only Ascomycota（Ascomycota）treated with a high amount of biochar has a higher abundance than the According to the photos,the Ascomycota（Ascomycota）treated with other biochar were lower than the control.PCA analysis shows that biochar.The community structure of soil fungi can be changed to make it develop in a specific direction,and with the change of biochar application rate,this impact.The loudness also changes accordingly.It can be seen that biochar can affect the community structure and abundance of soil fungi,but different biochar.The amount has different effects on soil fungi;under the influence of biochar,soil fungi develop in a specific direction;there are many soil fungi.The species characteristics and population abundance have a greater impact on the living environment,and biochar can change the soil’s true quality by changing soil environmental factors.Bacterial diversity and community structure.7 The effect of biochar on the dynamic changes of tobacco plant development,the physical and chemical characteristics of tobacco leaves,and the yield and quality of tobaccoField experiments show that biochar can increase the chlorophyll content in leaves,improve the photosynthetic characteristics of tobacco leaves,and promote the accumulation of dry matter in tobacco plants.Biochar has an effect on the mineral elements in tobacco leaves during the field growth period.Phosphorus,potassium,magnesium,iron and boron in the leaves will increase with the application of this biochar.At the same time,biochar has a positive effect on increasing the leaf area and root vitality of tobacco during the growth period.Biochar can significantly improve the physical indicators of flue-cured tobacco leaf.Under the influence of biochar,the length and width,tensile strength,single leaf weight and filling value of flue-cured tobacco have increased,while the stem content and leaf density have decreased.At the same time,Nicotine,total sugar,reducing sugar,K and K/Cl in the flue-cured tobacco increased with the input of biochar,but reduced the Cl+ content in the leaves the amount.The total amount of neutral aroma components in tobacco leaves increases with the input of biochar,and the yield of tobacco leaves and the proportion of upper and middle tobaccoIt has also improved.Biochar also showed improvement in tobacco plant development indicators on different types of tobacco-growing soils.bio-charcoal.In the red soil,it can increase the dry matter quality of tobacco plants by 23.78%,root vitality by 24.82%,and leaf SPAD value by 28.06%.It also significantly improves the photosynthetic characteristics of tobacco leaves.In yellow umber soil,cinnamon soil and dark umber soil,biochar also has a significant improvement effect on tobacco plant development indicators,but the improvement range is not as obvious as in red loam soil.Biochar-based materials with different carbon-to-nitrogen ratios and high-carbon materials have different effects on tobacco plant development indicators.The effect of high-carbon materials with medium carbon-nitrogen ratio on tobacco plant development indicators is higher than that of high-carbon materials with low carbon-nitrogen ratio and high carbon-nitrogen ratio.Among them,medium carbon-nitrogen ratio and carbon-nitrogen ratio of 20 can improve tobacco plant biology The amount is 24.73%,the root vitality is 52.81%,and the leaf SPAD value is 31.78%.At the same time,it also significantly improves the photosynthetic characteristics of tobacco leaves.In summary,it can be seen that biochar is of great significance to the improvement of tobacco development indicators and the improvement of flue-cured tobacco production and quality.Different amounts of biochar have different effects on tobacco development.At the same time,biochar has different effects on tobacco plant development indicators on different types of tobacco-growing soils,and it is most prominent in red loam soil.High carbon materials with medium carbon to nitrogen ratio have the most obvious effect on improving tobacco plant development.8 The relationship between tobacco-growing soil carbon and nitrogen,rhizosphere microorganisms and tobaccoBoth carbon and nitrogen play an important role in the soil,and at the same time they exist in a situation that complements each other or restricts each other.There is a balance between different types of soil carbon and nitrogen,and the level of this balance is an important reference index for soil quality.Soil carbon and nitrogen levels are closely related to tobacco rhizosphere microbial communities and tobacco growth and development indicators.This study shows that soil TOC,MBC,Cmin,C/N show a very significant positive correlation,but the above indicators show a significant relationship with MBC/MBN,Negative correlation.At the same time,the organic carbon content of different types of soil has a mutual promotion relationship,and the soil TN content is related to Cmin and Nmin.And C/N both show a very significant positive correlation,and MBC and DON show a significant positive correlation,and MBC/MBN showed a very significant negative correlation;MBN and DON,Cmin,Nmin,C/N showed a very significant positive correlation;DON and the carbon to nitrogen ratio（C/N）shows a very significant positive correlation.At the same time,there are differences in the nitrogen content of different types of soil.The role of mutual promotion.According to the results of RDA analysis,soil organic carbon（TOC）,pH,soil moisture（SH）and soil volume,eight（pb）has a greater impact on the diversity of soil bacteria,and pH has a greater impact on Bacillus and Mothercoccus.（Blastococcus）and Nocardioides have a significant impact on norankfJG30-KF-CM45 has significant effects,TOC and pb have significant effects on Bacillus and norankfGeminieoccaceae.Soil organic carbon（TOC）,pH and bulk density（pb）have a greater impact on fungal diversity,while soil Aspergillus,Cladosporium,Norank-o-Hypocreales,UnclassifiedfAspergillaceae,UnclassifiedfMicroascaceae and Verticillium Community abundance is greatly affected by environmental changes.Biochar mainly affects soil microorganisms by affecting the physical and chemical properties of the soil.Diversity and community abundance.Principal component analysis（PCA）of tobacco plant development indicators and soil carbon indicators found that the tobacco plant development indicators are significantly positively correlated with soil total organic carbon（TOC）and microbial biomass carbon（MBC）.In summary,the soil-microbe-tobacco plant is an organic whole.Biochar affects the soil microorganisms and tobacco plants by affecting the tobacco-growing soil.At the same time,the development of microorganisms and tobacco plants will in turn affect the nutrient status and soil nutrition.Ecological environment,which is a virtuous circle,is also an important significance of biochar in soil improvement for tobacco planting and sustainable development of tobacco production. |
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