| In recent years,biochar has proven to be an effective method for the treatment and reuse of biomass waste,and the preparation of different types of biomass waste into biochar has become a hot topic of research.Biochar can be used as a soil conditioner to improve soil physicochemical properties,however,the majority of current studies assessing the effects of biochar on soil properties and plant growth have focused on agricultural soils,with limited attention to applications in forest environments.Therefore,in order to explore the similarities and differences in the properties of biochar prepared by pyrolysis of different raw materials at different temperatures and their effects on soil improvement,sewage sludge and sugarcane bagasse were selected as raw materials for this study to investigate the differences in the characterization properties and chemical composition of biochar at different pyrolysis temperatures.The differences in soil amelioration effects between sewage sludge biochar,sugarcane bagasse biochar and a 1:1 mixture of the two were further analysed by potting experiments,and the feasibility of sludge and sugarcane bagasse biochar in forest sandy soil remediation was further demonstrated.In this study,the sludge and bagasse raw materials and their sludge biochar(SB400,SB550,SB700)and bagasse biochar(GB400,GB550,GB700)prepared by pyrolysis at 400°C,550°C and 700°C were subjected to yield analysis,X-ray fluorescence spectroscopy(XRF),infrared spectroscopy(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM)tests to investigate the differences in yield,surface morphological characteristics,elemental composition,heavy metal content,functional group species and crystal species of the two biochars pyrolysed at different temperatures.The results showed that the pyrolysis process significantly reduced the volume and mass of sludge and bagasse waste biomass,producing biochar products with porous structures and rich surface functional groups,but also increased the concentration of trace elements per unit biochar weight,with bagasse biochar having rich C reserves and sludge biochar rich in N and P elements,which have potential as soil conditioners.A greenhouse pot trial was conducted by taking a sandy loam soil from a woodland in Xinmin City,Shenyang,and applying SB550,GB550 and a 1:1 mixture of both with biochar MB550 at 2%,4%,6% and 8% by mass,and planting ryegrass.The soil p H,total carbon,total N and total P were measured in an artificial climate chamber for 15 days,and the fresh weight and leaf length of ryegrass leaves were also measured.The results showed that the addition of SB550,GB550 and MB550 to sandy soils in woodlands with low nutrient content all increased soil p H and nutrient content.Due to differences in the composition of the feedstock,the effect of bagasse biochar on the organic carbon content of the soil was greater than that of sludge biochar,which had a more significant effect on the nitrogen and phosphorus content of the soil,while the mixed biochar was more even.Both sludge biochar and sugarcane bagasse biochar had a boosting effect on ryegrass growth,but the boosting effect of sludge biochar was poorer and tended to decrease when added at too high a concentration.This may be due to the high concentration of metal elements in sludge biochar,or to its high ash content,which led to soil caking or reduced the effective level of nutrients when too much was added.Mixing sludge biochar with bagasse biochar changed the material composition of the single type of biochar,increasing the total carbon and decreasing the concentration of nutrients and heavy metal elements in MB550 compared to SB550.The mixed biochar proved to be more effective in promoting the growth of ryegrass. |
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