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Effect Of Biochar On Acid Soil Improvement And Enhancement Of Silicon/phosphorus Transformation In Soybean

Posted on:2020-04-14Degree:MasterType:Thesis
Country:ChinaCandidate:J H DengFull Text:PDF
GTID:2480306182451074Subject:Ecology
Abstract/Summary:PDF Full Text Request
Acid soils(usually p H<6.5)account for about 40%of farming land in the world.Soil acidification is becoming more and more serious due to irrational human activities,which severely restricts crop production and reduces soil phosphorus availability.Traditional acid soil amendments,such as lime and fly ash have limitations.Biochar is widely used for acid soil improvement due to its high p H and large pore structure as well as strong adsorption performance.Rice residues are ideal materials for preparing biochar due to their large amount and high silicon content.In this study,Biochar was firstly prepared from different raw materials(rice straw and rice husk),and then pot experiments were conducted to study the effects of phosphorus and biochar application(0,1,2,4%)on acid soil improvement,Si and P absorption and transportation in soybean plants were also investigated.The main results are as follows:Biochar application significantly increased soil p H(by 0.21-2.16 units)and EC value,and dramatically reduced soil exchangeable acid(by 25.92%-95.96%)and exchangeable aluminum(Al)content(by 23.95%-95.24%);biochar treatment can increase soil total C and N as well as P,exchangeable base ions in soil,so as to improve soil fertility.In general,rice straw biochar has better effects than rice husk biochar in soil improvement,while the effect of phosphorus treatment is not obvious.The addition of biochar significantly increased plant height and stem diameter of soybean,and plant biomass were also increased significantly by 0.87-1.47 times.At the same time,biochar application increased root length,root surface area and root volume,but reduced average root diameter.Biochar treatments(4%)significantly increased silicon content by 48.39%in roots and42.15%in leaves of soybean.Biochar application also increased the content of soil available Si by 4.13%-42.15%and reduced the proportion of amorphous silicon.The content of available silicon in rice straw biochar is up to 790.7 mg·kg-1,which provides sufficient silicon source for the soil.As a result,the expression of Si transporter Gm NIP2-1and Gm NIP2-2 in root tips were down-regulated,after the application of biochar.Biochar promoted the uptake of phosphorus in soybean root and transferred to the aboveground part,and the phosphorus content in stem,leaf and pod were increased by17.05,1.54 and 0.77 times respectively,which showed more effective than the phosphorus treatment.The availability of soil phosphorus increased significantly under the addition of biochar.Biochar application significantly increased the content of soil available P and active phosphorus component(NH4Cl-Pi+Na HCO3-Pi(NH4F-Pi)+Na HCO3-Po)by0.91%-12.58%,and decreased the proportion of residual phosphorus by 0.32-17.86%,which converted the soil phosphorus into available forms.After the application of biochar into soil,the contents of organic acid such as the tartaric acid and fumaric acid secreted by soybean root tips were increased by 5.74 and 1.78 times,respectively,soil microbial P increased by 29.86%-67.24%,so as to accelerate the mineralization of organic phosphorus and improve the content of active phosphorus in soil.According to the analysis of soil bacterial microbial community through 16S r DNA quenching,biochar application significantly increased microbial diversity of soil bacteria and influence microbial community structure at phylum level.The relative abundance of Gemmatimonadetes and Bacteroidetes were significantly increased,the relative abundance of Gemmatimonas,Flavisolibacter and Bacillus were also increased significantly by18.63-20.94 times,9.78-15.91 times and 26.45-27.88 times,respectively under biochar treatments.
Keywords/Search Tags:Biochar, acid soil, soybean, silicon, phosphorus
PDF Full Text Request
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