以猪、鸡、牛和羊骨为原材料厌氧热解制备成生物质炭(骨炭)作为改良剂，探究骨炭最佳制备条件及其对酸性土壤改良效果，并从土壤固相和液相二个角度探究骨炭对酸性土壤铝(Al)形态的影响。结果表明:高温厌氧热解制备的骨炭富含CaO、CaCO3和Ca5(PO4)3(OH)，同时含有NaO、MgO等碱性物质及-OH等多种官能团。但骨炭碱含量受热解温度影响较大，鸡骨和牛骨在800℃、猪骨和羊骨在900℃时其炭碱含量接近峰值并保持稳定，约为生石灰的90%，是最佳制备温度。此温度下制备的四种骨炭均可有效地提高 pH<6。0 的酸性红黏土、红砂土和砖红壤 pH。骨炭中的碱性物质主要以H+缓冲剂的形式存在，从而导致其提高土壤pH的幅度与初始土壤pH成反比。pH=4。40的红黏土中添加5 g·kg-1猪、鸡、羊和牛骨炭后土壤溶液Al浓度分别较对照降低 33%、34%、47%和 41%，固相有机结合态Al含量无显著变化(P>0。05)。骨炭增加了酸性土壤阳离子交换量，并通过促进活性 Al 向土壤固相吸附态羟基 Al 和更稳定态 Al 转化从而降低土壤溶液 Al及交换态Al含量。骨炭富含植物生长所需营养元素，具备无机和有机改良剂的双重特性，是可替代传统石灰作为酸性农田土壤改良剂的优质材料。
Alleviating Effects of Bone Meal Biochars on Acidic Soil
[Objective]The purpose of this study was to explore the optimum preparation conditions of bone biochars,their improvement effects on acid soil,and the influence on Al forms from the perspective of soil solid phase and liquid phase.[Method]The anaerobic pyrolysis of pig,chicken,ox,and sheep bone meals were used as raw materials to produce biochars(bone biochars)as ameliorants and three typical acid soils were used.[Result]The results showed that the bone biochars prepared by high-temperature anaerobic pyrolysis were rich in CaO,CaCO3,and Ca5(PO4)3(OH),contained alkaline substances such as NaO and MgO and characterized by many functional groups including-OH.Nevertheless,the alkali content of bone biochar was greatly affected by the pyrolysis temperature.The alkali content was close to the peak value and remained stable at 800℃for chicken and cow bones,and the same at 900℃for pig and sheep bones.Interestingly,the alkali content of these bone biochars was about 90%of the quicklime,which is the best preparation temperature.Also,the biochars effectively increased the pH of acidic red soils from Anhui,Jiangxi,and Guangdong with an original pH of lower than 6.The alkaline substances in bone biochars mainly existed in the form of H+buffers and the magnitude of the increase in soil pH was inversely proportional to the initial soil pH.After adding 5 g·kg-1 pig,chicken,sheep,and ox bone biochars to the red soils with pH=4.40,the Al concentration in soil solution decreased by 33%,34%,47%,and 41%,respectively,compared with the control,and the content of organically bound Al in solid phase had no significant change(P>0.05).Bone biochars increased the cation exchange capacity of acidic soil and reduced the content of soil solution Al and exchange Al by promoting the conversion of active Al to adsorbed hydroxyl Al and more stable Al in the soil solid phase.[Conclusion]Bone biochars are rich in nutrients required for plant growth,has the dual characteristics of inorganic and organic amendments,and are high-quality materials that can replace traditional lime as soil amendments for acidic farmlands.
Animal bone meal biocharsPyrolysis temperatureAcid soilAluminum toxicitySoil aluminum species
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