Studies on the Use of Fly Ash and Crop Residue Biochar in Soil Amelioration and Nutrient Uptake in Wheat
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Date
2018, 2018
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Central University of Punjab
Abstract
Catalytic pyrolysis of rice straw using fly ash as catalyst was studied in various gravimetric proportions of 1:3, 1:1 and 3:1 (fly ash : rice straw, w/w). The thermogravimetric analysis (TGA ) of the thermal degradation of rice straw in presence of fly ash and its subsequent kinetic analysis by Coats-Redfern equation showed a decrease in the activation energy. The pyrolysis was conducted in a laboratory scale batch reactor maintained at 400, 500 and 600 oC pyrolysis temperatures under slow pyrolysis conditions (10 oC/min). The pyrolysis furnishes three components namely biochar/biochar-fly ash composites (35-90%), bio-oil (4-22%) and syn-gas (6-48%) characteristic of slow pyrolysis conditions. The syn-gas obtained from catalytic pyrolysis were analysed and characterized using GC-TCD analysis to reveal CO2, CH4 and H2 as the major constituents with no traces of CO observed is accounted to fly ash metal oxide catalysed CO to CO2 conversion. The bio-oil obtained from catalytic pyrolysis upon GC-MS analysis, showed an increase in depolymerization of lignin and fragmentation and dehydration of the carbohydrate residues as the major processes operative in presence of fly ash. The results were further affirmed by the Ultimate (CHNO) analysis, 1H-NMR and HSQC 2D-NMR analysis for the catalytic pyrolysis biooil. The biochar and biochar-fly ash composites were characterized for their Ultimate analysis, Functional groups (FTIR and Boehm Titration), SEM-EDS, physico-chemical properties (pH, EC, alkalinity, total phosphate), surface area, micronutrients and its leaching characteristics and Cu(II) adsorption. The O/C and H/C atomic ratios for biochar and biochar fly ash composites decreased with increase in the pyrolysis Name of student Shilpa Nag Registration Number CUP/MPh-PhD/SEES/EVS/2010-11/07 Degree for which submitted Doctor of Philosophy Supervisor Prof. (Dr.) V. K. Garg Co-Supervisor Name Dr. J. Nagendra Babu Department Centre for Environmental Science and Technology School of Studies School of Environment and Earth Sciences Key words Crop residue, Biochar, Fly ash, Soil, Wheat iv temperature. Functional group analysis further reiterated the results with oxygenated functional groups like lactone and carboxylic acids present at lower temperature biochar whereas only phenols were present in case of high temperature biochar. Biochar were alkaline and with increase in the fly ash content the pH of the composites tend to be less basic. Cu(II) adsorption was characteristically observed to increase with increase in the fly ash content in the biochar obtained from catalytic pyrolysis at 500 oC. The biochar and biochar-fly ash composites were ameliorated to soil and changes in the physicochemical properties namely pH, EC, CEC, water holding capacity, total Phosphorus and available Phosphorus, of soil were characterized. The biochar-fly ash composite also prepared externally using biochar obtained at various pyrolysis temperatures with fly ash, mixed in proportion as calculated for the catalytic pyrolysis biochar obtained. The soil ameliorated with biochar-fly ash composite prepared from catalytic pyrolysis were compared with the soil ameliorated with externally mixed biochar-fly ash composite for various soil physicochemical properties. The plant growth of Triticum aestivum was studied for the full crop cycle. The plant growth parameters namely – root length, shoot length, photosynthetic pigments, cellular respiration, antioxidant enzymes, crop height were studied. The results of the study were compared statistically using one way and two way ANOVA. The ANOVA analysis revealed that all the plant growth parameters tend to show a significant change with the biochar/biochar-fly ash composites obtained at various pyrolysis temperatures and their composition. Regression analysis revealed the significant change with all the chemical and biological properties measured at different stages of Triticum aestivum and biochar/biochar-fly ash composite ameliorated soil physicochemical properties. The parameters indicate oxidative stress in case of the plants grown on the biochar and biochar-fly ash ameliorated soils.
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Keywords
Crop residue, Biochar, Fly ash, Soil, Wheat
Citation
NAG, SHILPA, Garg, V.K. and Babu, J. Nagendra (2018) Studies on the Use of Fly Ash and Crop Residue Biochar in Soil Amelioration and Nutrient Uptake in Wheat