Environment of the earth demands a sustainable development with a view to designing a greener threshold. The green framework is fueled by the enviable equilibrium in the field of agriculture. Biochar has the congruence to conserve the stability of agro-ecosystems gleaning the goal for improving environmental quality. The pivotal potential of biochar sustains the quality to generate renewable energy in an agreement with the environment providing a significant soil amendment to strengthen the potentiality of sustainable agriculture. Biochar is the product of pyrolysis where the biomass turns into biofuel pertaining to the purpose of adding it to the productive field of agriculture. The production and application of biochar to soil would not only improve soil and increase crop production, but also design an aspiring approach to structure a significant, long-term sink for atmospheric carbon dioxide to be sequestered reducing greenhouse gas emissions and bioavailability of environmental contaminants.
According to International Biochar Initiative Scientific Advisory Committee, biochar is a fine-grained charcoal, high in organic carbon (residue) and largely resistant to decomposition. It is produced from pyrolysis (direct thermal decomposition of materials at elevated temperature in the absence of oxygen to prevent combustion) of biomass i.e. plant and waste feedstocks (e.g. sawdust, nut shells, agricultural waste, grain crops etc.). It produces a mixture of solids (the biochar proper), liquid (bio-oil), and gas (syngas) products. As a soil amendment, biochar creates a recalcitrant soil carbon pool (nearly pure carbon in soils, in the form of amorphous graphite, not the carbon of living organisms, coal, or natural gas) that is carbon-negative, serving as a net withdrawal of atmospheric carbon dioxide while producing consumable bioenergy, sustaining enhanced nutrients, microbial activity, and moisture retention capacity, and reducing the requirements of irrigation and fertilizers.
Pre-Columbian Amazonians are believed to have used biochar to enhance soil productivity. They seem to have produced it by smoldering agricultural waste (i.e. covering burning biomass with soil) in pits or trenches. Wim Sombroek, a renowned Dutch soil scientist, catalyzed this idea by including several pages on the “terra preta” (black soil) and “terra mulata” (brown soil) in his influential book on Amazon soils. The dark colour of terra preta and terra mulata is caused by the incorporation, by humans, of black carbon (also called biochar). The soils were created by Amerindian populations 500-2,500 years ago and some of the carbon in terra preta soils dates back to 450 B.C. Terra preta is limited to Amazonia - they are not used to grow crop or rice but they represent technology predating modern agriculture. This ancient indigenous technology renders the solutions to the existing problems so that experiences can be extracted to escalate the earth towards an agricultural and environmental equilibrium.
A vast array of fertilizers and synthetic chemicals are applied on the agricultural fields by the farmers. If the systems focus only on the product intensification, then the soil and environment will always be deprived of necessary nutrients. Optimum amount of carbon is needed for sustaining the positive productivity of soil. Biochar is organic in nature (nearly pure carbon) which has the necessary efficacy to nurture maintaining the environmental, physical and chemical structure of soil. The extremely porous structure and high surface area are found to be very effective for being habitat for many beneficial soil microorganisms and at retaining both water and water-soluble nutrients for plant health. Biochar can increase fertility of acidic soils (low pH soils), provide protection against some foliar and soil-borne diseases, and so increase agricultural productivity. Plants, therefore, grow to be healthier as less fertilizer leaches into surface or groundwater. Thermal degradation (pyrolysis) of cellulose results in a rigid amorphous carbon matrix. The matrix is efficient enough to bind with the heavy metals immobilizing the pollutants and improving water quality.
The agricultural waste and other waste from different feedstocks are converted by biochar into a soil enhancer that can receive and conceive the internal cycle of sequestered carbon. In this way, biochar catalyzes climate change mitigation as it allows carbon input into soils and reduce the formation of GHGs (Greenhouse Gases) e.g. methane, carbon monoxide, nitrogen oxides which are responsible for global warming.
If biochar is used for the production of energy rather than as a soil amendment, it can be directly substituted for any application that uses coal. Pyrolysis also may be the most cost-effective way of electricity generation from biomaterial. The pyrolysis of biomass residue generates a biofuel without posing any threat to crop production.
Biochar has potential to be introduced in market and utilized extensively by the farmers. When biochar is exposed to steam and high-pressure oxygen at high temperatures, the co-product is to be transformed into activated carbon, which can absorb infected elements of gas decontamination, gold refinement, metal mining, water refinement, medicine, sewage management, and air filtration. If carbon offset markets develop, biochar can provide income for farmers and ranchers who use it to sequester carbon in soil.
Meanwhile biochar can play a vital role in the areas where soils deplete highly due to lack of sufficient organic resources and scarcity of water. Thus, biochar impact may depend on regional conditions including soil type, soil condition (depleted or healthy), temperature, and humidity. Studies have reported positive effects from biochar on crop production in degraded and nutrient-poor soils. Biochar of high surface area may be particularly problematic in this regard and so more research into the long-term effects of biochar’s addition to soil is needed.
To conclude, biochar can be the way forward to sustainable agriculture. The research on many complex issues related to biochar production systems is perpetually going on and will be needed to fully understand the implications for agricultural food systems, environment and bio-energy production. A proper framework in consideration of the financial, social, and technical aspects along with the environment and public safety can help formulate innovative mechanisms for the adept adoption of biochar technology.
(The writer is a chemical engineer.)