Plants rely on the ability of soil to provide secure environments for their development. The suitability of soil for the growth of plants relies upon on its structure, texture, ability to provide vitamins (fertility), and water holding capacity. Additionally, it should grant optimum conditions for the survival of microbes. There exists a huge range of techniques that are treasured in improving soil fertility, structure, water retention, and other bodily and chemical properties. One approach is the use of soil amendments. Soil amendments are valuable compounds for enhancing physical qualities such as fertility and conduct of soils. They help in the proper increase of plant roots. Active development of roots prevents degradation of soil, especially during windy seasons or torrential rains. One of the most effective soil amendment available for agriculturalists is biochar. It improves soil fertility and other properties. Besides, regular application of biochar facilitates the growth of soil microorganisms and increases soil organic carbon content. Further, the use of biochar is a possible technique for climate change mitigation.
Biochar and Its Use in Agriculture
Biochar is a charcoal that is applicable for agricultural purposes (Downie 13). Like most charcoals, it is a product of pyrolysis (or gasification) of organic matter. The technique of pyrolysis involves thermal degradation of organic compounds in the absence (or reduced supply) of oxygen. The procedure results in the formation of three major products: solid biochar, liquid bio-oil, and syngas. An alternative production method is the use of thermo-catalytic depolymerization (Downie 15). This technique employs the use of microwaves to decompose organic materials. Regardless of the process, the biochar that results is a stable compound rich in carbon. Biochar is increasingly becoming popular and gaining a broad range of application. At present, it is most famous for its use as a soil amendment. Many studies propose the addition of biochar to soil improves its fertility. Other studies have associated application of biochar with high crop yields in soils with low nutrient concentration and those that have suffered degradation. As an amendment, it provides several health benefits. First, because of its high porosity, biochar is highly effective in retaining soil water and water-soluble nutrients. Therefore, it is very useful in minimizing leaching.
The ability of biochar to hold nutrients depends on several factors such as the rate of application, soil texture, soil moisture content, and pyrolysis temperature. Whatever the case, regular application of biochar to the soil improves its health and makes it suitable for crop production. Further benefits that the use of biochar provide to soils include improvement of water quality, reducing the ability of soil to emit greenhouse gasses, increasing soil pH, and minimizing the need for fertilizers and irrigation. It also enhances the capacity of plants to fight against pathogens. Nevertheless, biochar has high adsorption capability (Downie 15). Hence, it may reduce the effective of pesticides and similar chemicals. Therefore, it presents problems when it comes to pests and weed control. Biochar with a large surface area may be particularly problematic in pest and disease control. In addition to enhancing soil fertility, biochar provides a suitable habitat for soil microorganisms and improves the soil organic carbon.
The Role of Biochar in Microbial Growth and Soil Organic Carbon
The application of biochar to soil facilitates the growth of microbes and increases the soil organic carbon (SOC). It refers to the carbon component of soil (Department of Agriculture and Food). Soil microorganisms and SOC are vital to soil components in agricultural applications. There are myriads of microbes in the ground. They range from bacteria to actinomycetes, to protozoa, to fungi, and nematodes. These organisms play significant roles in the ecosystem. They regulate plant productivity and contribute to the diversity of plant species. They also help in ecological systems such as nitrogen and carbon cycles. Moreover, soil microbes aid in the formation and improvement of soil structure (Van Der et al. 296-297). These creatures require a constant supply of soil organic matter (SOM) for their survival. Hence, SOM is an essential component of soil in agricultural production and environmental conservation. The decomposition of SOM provides the energy and nutrients that these organisms need for growth.
Carbon is necessary for the growth of microorganisms. Specifically, the carbon present in the SOM is essential for microbe growth. For instance, in the presence of suitable conditions, the growth of spore-forming bacteria goes through three stages: vegetative cell (VC), heat-liable spore (HLS), and heat-stable spore (HSS). For successful sporulation, carbon or nitrogen must be present at either of the stages (Singh 131). Due to its high carbon content, regular application of biochar contributes positively to microbe growth. A 2014 study showed that consistent use of biochar increases the microbial biomass carbon (MBC) significantly (Zhang et al.). Therefore, the existence of these organisms is contingent on the availability and mass of carbon in the soil.
Biochar is also helpful in improving soil organic carbon (SOC). By proportion, it SOM constitutes between 2% and 10% of the mass of soil. It is a vital component and plays an essential role in the biological, chemical, and physical properties of soil. One of the primary components of SOM is carbon. About 58% of SOM exists in the form of carbon (the percentage varies with individual soils and locations) (Department of Agriculture and Food). Another constituent of SOM is hydrogen. Additionally, SOM has small amounts of nutrients that provide nourishment for soil microbes. Besides, organic matter improves soil structure, moisture availability and retention capacity, soil buffering, greenhouse gas emissions, and degradation of environmental pollutants. Further, SOM enhances the cation exchange capacity of soils.
Climate Change Mitigation
A lot of research is currently underway on the possible applications of biochar aside from agricultural applications. One possible use of biochar is climate change mitigation. Climate change mitigation using biochar is possible in two ways: carbon sequestration and displacement of fossil fuels (Matovic). Carbon sequestration involves the trapping and long-term storage of atmospheric (or other forms) carbon. It is a useful process of minimizing or deferring global warming. Environmental experts have proposed it as a potential mechanism for slowing down the accumulation of greenhouse gasses from fossil fuels. The process of trapping atmospheric carbon (IV) oxide occurs naturally through chemical, biological (Bio-sequestration) and physical, mechanisms.
Bio-sequestration processes include peat production, forestry, agriculture, enhancing carbon (IV) oxide removal through cover crops or rotational grazing, ocean-related processes, and many other mechanisms. Examples of chemical methods are mineral carbonation, chemical scrubbers, or industrial processes. Physical techniques include geological sequestration, ocean storage, and biomass-related processes. The burial of biochar in the soil can be a potential biomass-related carbon sequestration. Biochar has a high percentage of carbon and is stable. Therefore, it can store carbon for an extended period. The carbon component resists soil degradation and is capable of holding soil carbon for many years. Consequently, it is under investigation as a carbon sequestration substance. If found viable, it will be useful in mitigating climate change. Additionally, sustainable use of biochar is capable of producing gasses and oil as byproducts. These byproducts are potential sources of clean and renewable forms of energy. Therefore, it has the potential of reducing the rate of emission of carbon (IV) oxide without jeopardizing food security, soil conservation, or habitat preservation. Accordingly, biochar can be an efficient replacement of fossil fuels that have a high potential of environment degradation.
Biochar is a form of charcoal. Due to its high carbon content, it finds many applications in agricultural use and environmental conservation. In agriculture, biochar is an essential soil amendment that enriches the soil with nutrients. It also improves the water retention capacity of soils and, thus, minimizes leaching and improves soil moisture content. The addition of biochar increases the soil organic carbon. Carbon is an essential element for the growth of soil microorganisms. Therefore, regular application of biochar enhances soil microbe growth. Soil microbes are useful in improving soil texture and aerating the soil. In addition to agricultural use, biochar has the potential to mitigate climate change and environmental degradation. Biochar can help minimize climate change in at least two ways. First, it can be a valuable carbon sequestration agent. Because it has a high carbon content, biochar is stable. Therefore, it can hold soil carbon for an extended period. Carbon resists environmental degradation. Therefore, biochar can be highly valuable in sequestration. The second way in which it contributes to environmental conservation is by using it as a source of fuel. Biochar is capable of producing a clean and renewable energy. Therefore, it can replace fossil fuels that have a high capacity to degrade the environment.
Downie, Adriana, Alan Crosky, and Paul Munroe. “Physical Properties of Biochar.” Biochar for environmental management: Science and technology (2009): 13-32.
Matovic, Darko. “Biochar as a Viable Carbon Sequestration Option: Global and Canadian Perspective.” Energy 36.4 (2011).
Singh, Raizada. “The Role of Carbon and Nitrogen Sources in Bacterial Growth and Sporulation.” American Society of Microbiology 22.1 (1971): 131-132.
Van Der Heijden, Richard D. Bardgett, Marcel G. A., and Nico M. Van Straalen. “The Unseen Majority: Soil Microbes as Drivers of Plant Diversity and Productivity in Terrestrial Ecosystems.” Ecology Letters 11.3 (2008): 296-310.
“What Is Soil Organic Carbon?” Department of Agriculture and Food. The Government of Western Australia, November 18, 2016. Web. March 9, 2017.
Zhang, Qing-Zhong, Dijkstra, Feike, Liu, Xing-ren, Wang, Yi-Ding, Huang, Jian, Lu, Ning. “Effects of Biochar on Soil Microbial Biomass.” PLoS. 9.7 (2014). Quant Seq. Web. March 9, 2017.