Introduction:
Biochar is a stable solid, rich in carbon, that is made from organic waste material or biomass that is partially combusted in the presence of limited oxygen. The primary purposes of biochar in soils are to improve aeration, decrease greenhouse gas emissions, decrease nutrient leaching, lower acidity, and raise soil water content in coarse soils. Applying biochar could improve agricultural production and soil fertility. Best known as charcoal (when made from woody biomass), biochar is a solid byproduct of biomass pyrolysis that has been produced and used for thousands of years (Weber & Quicker 2018). The potential use of biochar in mitigating the effects of climate change is receiving more attention. Biochar has the ability to remain in soils and other settings for thousands of years because of its refractory stability. It is anticipated that adding biochar to soil will increase its overall ability for absorbing anthropogenic organic pollutants (Verheijen et al; 2010). Additionally, biochar is being investigated for its potential to restore ecosystems, minimize the mobility of pollutants in polluted soils, and lessen the change of hazardous elements in agronomic crops (Ayaz et al; 2021).
Preparation of biochar:
Biochar, a high-carbon, fine-grained residue known, is created through pyrolysis, which is the direct thermal breakdown of biomass without oxygen to prevent combustion. The process yields a mixture of solids (biochar), liquids (bio-oil), and gases (syngas). It is described in short below:
Select a good feedstock, such as wood debris, animal dung, or agricultural waste (such as rice husks or maize stalks). For consistent heating during pyrolysis, prepare the biomass by shredding, chipping, or pelletizing. An essential step in the creation of biochar is pyrolysis. It entails heating biomass without oxygen, which causes it to thermally decompose and produce biochar at the
temperature of 300°C to 700°C is the usual temperature range for pyrolysis. The biomass passes through intricate chemical processes during pyrolysis, producing three primary products: Biochar, Bio oils and Syngas (Lehmann et al; 2006),
Properties of Biochar:
∙ Biochar is formed from polycyclic aromatic hydrocarbons in which 6 carbon atoms are bonded together in a ring. The presence of such an aromatic structure makes Biochar stable against biological and chemical changes (Abed Hussein et al; 2021)
∙ Biochar typically exhibits a high surface area and a porous structure, providing numerous sites for adsorption of nutrients, water, and contaminants.
∙ The pH of biochar can vary depending on the feedstock and pyrolysis conditions. It can range from acidic to alkaline.
∙ Biochar can exhibit a varying degree of CEC, which influences its ability to retain nutrients and interact with soil (Mohan et al; 2014).
∙ Biochar may contain varying levels of plant-available nutrients such as nitrogen, phosphorus, and potassium (Mohan et al; 2014).
Impact of Biochar:
With all the abovementioned properties it has multifaceted impacts in agriculture, examining its benefits for soil health, crop yields, carbon sequestration, and environmental remediation.
∙ Biochar production and use are part of the modern agenda to recycle wastes, and to retain nutrients, pollutants, and heavy metals in the soil and to offset some greenhouse gas emissions (Domingues et al; 2017).
∙ Soil amendment by improving water retention, nutrient availability, and soil structure, leading to enhanced crop yields and reduced fertilizer use while sequestering carbon in the soil.
∙ Biochar applied can contribute to the modifications of physical soil properties such as texture, structure, porosity and bulk density(Muñoz et al ; 2016).
∙ Biochar application promotes phosphate solubilizing bacteria, altering the carbon flux in the soil to increase the abundance of bacteria families such as Streptosporangineae. ∙ Biochar application can condition associations between plants and microorganisms. For example, (Koltan; 2011) found that BC incorporation in the soil enhanced bacterial communities (Flavioibacterium) associated with the root of mature sweet pepper (Capsicum annuum L.) plants.
∙ The improved nutrient retention capacity of biochar can reduce the need for synthetic fertilizers, leading to lower input costs for farmers and reduced environmental impact. ∙ Biochar can increase soil aggregation, which helps to stabilize the soil and reduce erosion. This is particularly beneficial in areas prone to wind and water erosion.
Conclusion
Biochar is useful and may be applied to soils as a way to reduce pollution in the environment. It also acts as a carbon sink, enhances the soil’s physical and chemical properties, and has demonstrated great promise for usage in agriculture, boosting the quantity and caliber of plants that are grown (Sanchez-Reinoso; 2020). Adding biochar to the soil decreases its mineralization and strengthens the soil organic carbon’s resistance to environmental influences. As a result, carbon dioxide emissions are greatly decreased. Hence the use of biochar from agricultural or industrial wastes is a promising substitute that improves soil quality by positively influencing the soil’s chemical and physical characteristics. Using biochar as a soil supplement is also thought to be a suitable method for sequestering carbon and an alternate way to enhance certain soil characteristics.
Refrences
1. Weber, K., & Quicker, P. (2018). Properties of biochar. Fuel, 217, 240-261.
2. Verheijen, F., Jeffery, S., Bastos, A. C., Van der Velde, M., & Diafas, I. (2010). Biochar application to soils. A critical scientific review of effects on soil properties, processes, and functions. EUR, 24099(162), 2183-2207.
3. Ayaz, M., Feizienė, D., Tilvikienė, V., Akhtar, K., Stulpinaitė, U., & Iqbal, R. (2021). Biochar role in the sustainability of agriculture and environment sustainability, 13(3), 1330.
4. Lehmann, J., Joseph, S., & Masiello, C. A. (2006). Biochar for environmental management: An assessment. Mitigation and Adaptation Strategies for Global Change.
5. Abed Hussein, B., Mahdi, A. B., Emad Izzat, S., Acwin Dwijendra, N. K., Romero Parra, R. M., Barboza Arenas, L. A., … & Thaeer Hammid, A. (2022). Production, structural properties nano biochar and effects nano biochar in soil: a review. Egyptian Journal of Chemistry, 65(12), 607-618.
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8. Muñoz, C., Góngora, S., & Zagal, E. (2016). Use of biochar as a soil amendment: a brief review. Chilean Journal of Agricultural & Animal Sciences, 32(SPECIAL ISSUE Nº 1), 37-47.
9. Kolton, M., Harel, Y. M., Pasternak, Z., Graber, E. R., Elad, Y., & Cytryn, E. (2011). Impact of biochar application to soil on the root-associated bacterial community structure of fully developed greenhouse pepper plants. Journal of Applied and Environmental Microbiology, 77(14), 4924-4930.
10. Sanchez-Reinoso, A. D., Ávila-Pedraza, E. A., & Restrepo-Díaz, H. (2020). Use of biochar in agriculture. Acta Biológica Colombiana, 25(2), 327-338.
