Effects Of Different Particle Sizes Of Biochar On Soil Properties And Tobacco Plant Growth

In order to investigate the effects of different particle sizes of biochar on tobacco soil properties and tobacco plant growth,pot and field experiments were conducted in the Tobacco Science Park of Henan Agricultural University,Xuchang City,Henan Province from April to October 2017 and April to October 2018.Five particle sizes of biochar were set up:CK(without biochar),T1(5002 000 micron),T2(250500 micron),T3(20250 micron),T4(<20 micron).The application rate of biochar in pot experiment was 100 g/pot,and the ratio of biochar to soil mass was 0.5%,and that in field experiment was 100 kg/mu.The application rate of chemical fertilizer was 5 g per pot,3 kg/mu of nitrogen fertilizer in field,and the ratio of nitrogen(N),phosphorus(P205)and potassium(K20)was 1:1.5:3.The effects of different particle sizes of biochar on soil quality,tobacco plant growth,development and yield and quality were studied.The main results were as follows:?.Effects of Biochar with Different Sizes on Soil Physical Properties1.Effect on soil bulk density.The soil bulk density of flue-cured tobacco at different growth stages was reduced by different particle sizes of biochar,and the smaller the particle size of biochar,the larger the decline.However,the differences among different particle sizes of flue-cured tobacco at different periods were inconsistent.In addition to 30 days after transplantation,T4 had significant difference compared with CK in other growth stages,and T1 had significant difference compared with CK only 75 days after transplantation.At 45 days after transplantation,T2-T4 treatment was at the same significant level,and significantly higher than T1 and CK treatment.2.Effect on field water holding capacity.The field water holding capacity of all treatments decreased slowly during the whole growth period,and reached the lowest value in 75 days.Compared with CK,T1-T4 significantly increased field water holding capacity at all stages,and the overall performance was T4>T3>T2>T1>CK.Compared with T1,T2-T4 treatment had significant difference at 0 d and 30 d after transplantation,but there was no significant difference between the other treatments.There was no significant difference between T2-T4 treatments during the whole growth period.3.Effects on soil aggregates.The aggregate content of>2mm was T4>T3>T2>T1>CK,and T4 treatment was significantly higher than other treatments.For the average weight diameter(MWD)of aggregates,the treatment of biochar particle size significantly increased MWD.T2-T4 treatment was at the same significant level and significantly higher than CK and T1 treatment,and T4 treatment had the most stable aggregate structure.?.Effects of Biochar with Different Sizes on Soil Carbon Parameters1.The effect on total organic carbon(TOC)in soil.The TOC content in the soils of all treatments decreased slowly with the development of tobacco growing period,ranging from 7.37g.kg-1 to 12.07g.kg-1.Compared with CK treatment,T1-T4 treatment significantly increased TOC by 43.29%?46.85%,but there was no significant difference between biochar treatment in the whole growth period.2.Effects on soil microbial biomass carbon(MBC).Biochar with different particle sizes had a negative stimulating effect on MBC content in soil.Thirty to sixty days after transplanting,T1 and T2 treatments could significantly increase the MBC content of soil.75 to 90 days after transplanting,the MBC content of all biochar particle size treatments was significantly reduced,and the decreasing extent increased with the reduction of biochar particle size.3.Effects on the content of soil oxidizable organic carbon(ROC).The application of biochar could significantly increase ROC content in soil,and the increase rate increased with the decrease of biochar particle size.During the whole growth period of Flue-cured tobacco,the content of soil readily oxidized organic carbon increased gradually.Except 30 days after transplantation,the ROC content of T1 treatment was significantly lower than that of other biochar particle size treatments,and the ROC content of T2 and T3 treatment was significantly different only 60 days after transplantation.The ROC content of T4 treatment was significantly higher than that of other treatments at all stages.4.Effects on soil soluble organic carbon(DOC).Compared with CK,the content of DOC in T2-T4 treatment increased significantly in all stages,with an increase of 40.37%-78.85%.The content of DOC in soil treated with T1 was significantly higher than that of CK only 30 days after transplantation.In addition,T4 treatment had the most obvious effect on the increase of DOC content in soil,and it was significantly higher than other treatments in each period.5.The impact on carbon pool management index(CMPI).Activated organic carbon(LOC),carbon pool activity index(AI)and soil carbon pool management index(CMPI)were significantly increased by different particle sizes of biochar treatment.CMPI increased with the decrease of biochar particle size,and T1-T3 treatment was at the same significant level,T4 treatment was significantly higher than other treatments.?.Effects of Biochar with Different Particle Sizes on the Growth of Flue-cured Tobacco1.Biochar with different particle sizes could improve the agronomic characters of tobacco plants in the field.The plant height of tobacco increased with the decrease of biochar particle size during the whole growth period,and the increase of plant height could reach 42.29%under T4 treatment.The application of biochar could increase the maximum leaf area of tobacco leaves,and the increase rate increased with the decrease of biochar particle size,and the increase rate of T4 could reach 44.69%.2.The effect on dry matter accumulation.The smaller the particle size of biochar,the more obvious the promotion of dry matter accumulation in the early growth stage of Flue-cured tobacco.At 30,45 and 75 days after transplantation,T4 treatment significantly increased the dry matter accumulation of tobacco stem,and promoted the biomass growth of tobacco stem.For tobacco leaf dry matter accumulation,T2 showed the best performance in the whole growth period,and T4 treatment could significantly increase leaf dry matter accumulation 30 and 45 days after transplantation.3.Effects on root growth.Biochar with different particle sizes could significantly increase root activity at different stages of tobacco plant growth;T2 treatment had the greatest effect on root activity at 30-60 days after transplantation;T1 treatment had the best effect at 75-90 days after transplantation.Different particle sizes of biochar could significantly increase the total and active absorption area of root system at different stages of tobacco plant growth.There was no clear relationship between the total and active absorption area of root system and the particle size of biochar.The particle size of biochar might not be the decisive factor affecting the root growth of Flue-cured tobacco.?.Effect of Biochar with Different Size on Quality of Flue-cured TobaccoThe Sugar-alkali ratio and sugar-sugar ratio of tobacco leaves could be effectively improved by the treatment of biochar particle size.Micron-scale biochar made the K/CI ratio of tobacco leaves reach the level of high-quality tobacco leaves.The ratio of total nitrogen,nicotine,reducing sugar and sugar to alkali was less affected by the particle size of biochar,and the ratio of reducing sugar and sugar to alkali increased with the decrease of the particle size of biochar.The degraded products of new phytadiene,carotene and Anhui-like cypress increased after the application of biochar,but had no clear relationship with the particle size of biochar.In summary,all particle sizes of biochar can improve soil bulk density,field water holding capacity,soil aggregate structure and carbon pool.The smaller the particle size of biochar,the more obvious the effect of soil improvement.Reducing the particle size of bio-carbon promoted the growth of tobacco plants more obviously in the early stage,but had a certain negative impact on root activity,total root absorption area and active root absorption area.Micrometer-scale biochar less than 20 micron could significantly improve soil carbon pool management index,and had the best performance in soil physical properties,soil carbon pool,tobacco plant growth and flue-cured tobacco quality.