This article discusses biochar in regard to its increasing significance, its disadvantages, the use of thermogravimetric analysis in relation to it, and any new developments in the field.
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In recent years, there have been continuous developments in the agricultural industry to improve crop productivity, with a focus on improving soil capabilities. Amongst a host of techniques, biochar has been found to be effective in improving soil capabilities.
What is Biochar?
Biochar is an organic material that is produced by a carbonization process at high temperatures (around 300-1000 degrees Celsius) without any presence of oxygen. The process is called ‘pyrolysis’ and the products include bio-oils, gases, and eighty percent carbon in its elemental form (biochar).
Biochar use arose after observing the ‘Terra Preta’ soils in the Amazon. These are highly fertile man-made soils that were found in the Amazon basin. These soils were found to be so fertile that their compositions became the basis for today’s agricultural soils.
Biochar improves soil health while locking the carbon into the ground so that harmful gases like CO2 are not released. A positive aspect of biochar is that any organic material can be converted using the pyrolysis technique. Some common organic materials used include manures, wood, and plant tissues.
Why is it Increasingly Significant?
Over the years, biochar has been found to be extremely effective in CO2 removal from the atmosphere. Adding biochar to soil improves soil health by regulating the acidity, improving water and nutrient retention capabilities, and improving the overall percolation and aeration of the soil. Due to this, the soil becomes a natural habitat for microbes to thrive.
Further, the plants grown in this soil are more naturally resistant to infections, and thus fertilization costs are significantly reduced. Many studies have shown that using biochar has increased crop yeilds by up to four times.
Research by the American Chemical Society has shown that using biochar and chemical fertilizer has increased the yield of winter wheat by twenty-five to thirty percent, instead of using chemical fertilization alone. Other research by the Soil Science Society of America has found that biochar outperforms other fertilizers by sixty percent when replaced.
Disadvantages of Biochar
Despite the host of benefits biochar offers, there are certain disadvantages it also has. As using biochar increases the pH value of the soil, having biochar with a high pH in situations where this is not desirable can lead to detrimental effects on the soil.
Another factor that affects the functionality of biochar is the quality of the material used to develop it. It is advised that any biochar must be FSC (Forest Stewardship Council) certified.
The type of material used to prepare biochar is also important since different materials produce biochar of different chemical compositions. Therefore, it is important to have a set of materials that provide a sustainable amount of pH and nutrient retention capabilities.
What is Thermogravimetric Analysis?
In chemistry terminologies, thermogravimetric analysis (TGA) is an analysis technique that is used to check any material’s thermal stability. The process involves heating a sample of the material at high temperatures at a constant rate and then monitoring the change in weight. This weight is observed after removing the gaseous by-products.
Dynamic TGA is a process where the temperature is made to increase continuously over time and the mass of the substance is recorded.
Static TGA involves keeping the temperature constant and measuring the mass. This process is performed to check whether a material can withstand a specific temperature over time.
Why is Analysis Necessary?
Through scientific studies, it has been found that changes in temperature have a great impact on the surface temperature and thermal stability of biochar. Therefore, performing TGA testing provides knowledge of the thermal stability of biochar.
In recent research that involved determining whether the arhar crop had the potential to be converted into biochar, TGA analysis was performed. This research was published in the volume Innovative Product Design and Intelligent Manufacturing Systems. From the experimental results, it was determined that the porosity of the biochar material created from arhar crops had high porosity values when there was an increase in the pyrolysis temperature.
This study concluded from TGA analysis that having biochar materials prepared at high temperatures provided high thermal stability. It was also found that arhar fiber could be used to prepare activated carbon. Further, preparing biochar at a higher pyrolysis temperature had higher thermal resistance.
Due to the host of benefits biochar is offering, there have been large-scale biochar field trials where the effect of biochar on soil amendment is being observed over different crop yield variations.
There is a specific UK biochar research center, established in 2009, that supports multidisciplinary research in the field with collaboration from the University of Edinburgh. According to a recent economic analysis, it was determined that using biochar in the southeast region of the United States would increase crop yields in these areas.
Therefore, with these benefits, biochar is poised to gain relevance in the soil enrichment process and thermogravimetric analysis plays an important role in its use and development.
References and Further Reading
Amonette, J.E., Blanco-Canqui, H., Hassebrook, C., Laird, D.A., Lal, R., Lehmann, J. and Page-Dumroese, D. (2021). Integrated biochar research: A roadmap. Journal of Soil and Water Conservation, [online] 76(1), pp.24A29A. Available at: https://www.jswconline.org/content/76/1/24A [Accessed 9 Feb. 2022].
Cybulak, M., Sokołowska, Z. and Boguta, P. (2021). The influence of biochar on the content of carbon and the chemical transformations of fallow and grassland humic acids. Scientific Reports, [online] 11(1), p.5698. Available at: https://www.nature.com/articles/s41598-021-85239-w [Accessed 9 Feb. 2022].
Om Prakash, M., Raghavendra, G., Panchal, M. and Ojha, S. (2020). Thermogravimetric Analysis of Biochar from Arhar Fiber Powder Prepared at Different Pyrolysis Temperatures. Lecture Notes in Mechanical Engineering, pp.429–437.
biochar-us.org. (n.d.). Soil & Water Benefits of Biochar | US Biochar Initiative. [online] Available at: https://biochar-us.org/soil-water-benefits-biochar#:~:text=Enhanced%20Crop%20Yields%E2%80%94%20When%20added.
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