Stubble burning, the controlled setting of fire on farmland, is a common and long-employed practice that efficiently helps farmers remove crop residues after harvest. Indecomposable agricultural wastes such as wheat straws can be easily broken down through stubble burning into essential nutrients for future crops. Despite its great conveniences, however, this practice has also pitfalls. In Esat Mumbai, India, the burning of rice fields contributes to a huge increase in air pollution, and in early fall its air quality index peak at over 300 (“Maharashtra Air Pollution in 2017”), about six times the healthy level. This has negative effects on farmers’ health and crop growth. Biochar, charcoal made from organic material, thus appears as a valuable alternative. Instead of releasing the carbon substances and dust into the air by burning on open fields, they can be stored in biochar and used as a soil amendment. It is produced through pyrolysis, possibly through cheap basic ovens. It also holds monetary value in the global market, which can be a help to farmers who have access to the market. Yet this alternative is significantly less efficient, and using the biochar without sufficient fertilization can in the long run cause decreased productivity. This paper analyzes the effects of both stubble burning and biochar with case studies and concludes on the extent to which making and using biochar have value to farmers as an alternative to stubble burning.

            Biochar is introduced just recently to most modern farmers, but it can be dated back to as early as 450 BCE. In the Amazon Basin, an Amazonian civilization has long been adding charcoals, made from burned materials in the kitchen, to acres of their soil. Sixty years ago, scientist Wim Sombroek discovered this area, and to his surprise, both the appearance and the contents of the soil in farmland are vastly different from adjacent soil. It contained about seventy times more carbon than the adjacent soil. (Bruno Glaser, Ludwig Haumaier, Georg Guggenberger, Wolfgang Zech) Because of the dark color, it was called Terra Preta, meaning “Amazonian dark earth”. Plants, especially crops like wheat and cotton, can increase up to 200% in yield.

This ancient soil amendment is the earliest form of biochar and is now found to be of great importance to today’s world. One biggest environmental problem nowadays is global warming, which increases global temperature slightly, but significant enough to disrupt the climate cycles, raise sea levels, and in such ways destroy wildlife habitats and cause a detrimental domino effect on the food chain. The primary cause of global warming is increased carbon emissions. In a normal carbon cycle, microbes and plants absorb carbon in the air, and the absorbed carbon is later returned to the air in the form of carbon dioxide either by burning organic matters or through respiration. Yet humans’ ability to release carbon far exceeds plants' and microbes’ ability to absorb it, which gradually increases Earth’s atmospheric carbon concentration and contributes to global warming. Biochar provides a new solution to the problem. Instead of releasing the carbon into the air, biochar reverses part of the carbon cycle by storing and restoring it to the soil. Using biochar, in the long run, can thus mitigate global warming and even has the potential to reduce up to 10% of the world’s total greenhouse gas emissions (Jyoti Rawat, Jyoti Saxena, Pankaj Sanwal).

However, the most essential part of spreading biochar and implementing this technique is to evaluate its benefits and drawbacks for the subjects, who are the individual farmers. Global warming and its effects would not act disastrously to farmers momentarily, but a huge change in traditional farming has the potential to. Besides, the people and the world’s economy depend on agricultural production, and a slight change, for good or for bad, can influence people around the world, much like global warming. Stubble burning is, although harmful to the environment, an effective means to reduce labor when clearing out fields, which makes it hard to incentivize for using biochar, which requires a relatively cumbersome production process, just for its environmental effects. The purpose of this research, therefore, is to evaluate the benefits of biochar and identify some of its limitations, with comparison to stubble burning, in a specific context. Most of the research is a case study on current issues in Mumbai, India, and how biochar may help, which does not conclude on using biochar elsewhere but can still provide valuable insights for the value of this invention, pertinent to the entire world.

            This research is designed to investigate whether biochar should be employed in place of stubble burning, so it is important to look from the perspective of farmers. In East Mumbai, most of the farms are scattered and family-run, producing on average a net income of 71 US$ per household per week, according to a 2013 survey. (Vazhacharickal, Prem & Predotova) Other farms are larger plantations, owned by organizations, like the Indian Railway Company—it introduced the “Grow More Food” scheme and owned 8859 acres of land purposed for farming—, or by wealthy families. Plantation workers in Mumbai under the Indian Railway Company earn from 1.8 to 5.6 US$ per day and are provided housing and food. ((Vazhacharickal, Prem & Predotova) For small family farms, the primary concern is their income. As most families have virtually no savings, a single season of drought or infestation can cause a long time of starvation and severer poverty. According to the 2013 survey, 42% of the families cannot afford any education, and about 90% do not actually own real estate. (Vazhacharickal, Prem & Predotova) The second-largest issue is health, damaged by the world’s worst air pollution. During May in West Mumbai, which is next to the Arabian Ocean, the air quality index, or the AQI, ranges from 80 to 140, and in August, when stubble burning begins, the AQI can peak at over 300, beyond the benchmark for “hazardous”. About the same times of the year, the AQI in Rhode Island, U.S., which is next to the Atlantic Ocean, ranges only from 26 to 49. High air pollution has long-term effects on vital organs, especially on brain and lung, and can induce cancer. One other side effect of air pollution is bad haze visibility, which blurs over the sun and the streets, causing more car accidents. Worse, most of East Mumbai, where most farming and burning take place, is located at low sea level and surrounded by mountains. This particular geography acts as a cage that traps much of the air pollutants inside the area, making the pollutant concentration higher and more lasting.

            Biochar is a potential solution to both problems aforementioned. It is quite versatile, used in farming, gardening, and even odor control. This versatility caused it to have a much higher value than pure conventional soil amendments. In 2013, biochar has an average purchasing price of 1.29 US$ per pound, or 2580 US$ per ton, in contrast with conventional soil amendments, which are 40 US$ per ton. (Anna Austin) In 2020, 300,000 tons of biochar are traded costing in total 572.3 million US$, which means an average price of 1907 US$ per ton. (“Global Biochar Market”) The unit prices are proven to be relatively stable, considering that production has increased by 300% from 2013 to 2020. Using this market can significantly add to families’ income. Take corn farming as an example: corn stalk residue weighs about 4.2 tons per acre (Douglas Jose, Lance Brown); produced biochar weighs around 35% to 50% of the biomass before production (Pamela Porter, David Laird); corn can only be harvested once every year; if a family owns an acre of land, ideally, they can sell all the produced biochar for a total of 4000 US$, which is already more than the average family’s yearly income. The initial investment is very costly. One of the more expensive biochar-making machines found on Alibaba costs 5,250 US$ and can process 1000kg per five to six hours. The cheapest machine costs 800.0 US$ but has only a quarter of the above efficiency. But still, producing and selling biochar can over a few years accumulate to a large fortune for farming families.

            Also, using biochar has the potential for increasing crop production. First, it has a pH of around 8. When added to the soil, which tends to be quite acidic, biochar can bring down the acidity. Most staple crops, such as wheat, grow better in slightly acidic soil at a pH of 6.5, acidic enough for a good amount of nutrients to become available but not too much for the crop to be poisoned. (Lee Reich) Moreover, biochar has a microscopically porous structure, even when after grinding it. This has two primary effects. First, water can be trapped by the soil longer, instead of escaping deeper into the earth or through evaporation. This would thus enhance the effect of irrigation and provide the plants more consistent moist than previously available. Likewise, nutrients like nitrogen will have a higher chance to stay in the soil after fertilization. Experiments have reported a 30% increase in corn production with biochar, applying 5 tons per hectare. (“Jyoti Rawat, Jyoti Saxena, Pankaj Sanwal”)

            The biggest drawback for stubble burning is the high air pollution it causes. In the year 2017, 2311 cases of severe disease or death are found to be associated with local air pollution. (“Maharashtra Air Pollution in 2017”) Children are reported to have lung deformities because of air pollution. On the foggiest days, dozens of car accidents occur just in West Mumbai, causing more casualties. Biochar, on the other hand, is made by burning biomass in a closed anaerobic environment, which stores most of the carbon and dust instead of releasing them into the air. It is predicted to drop air pollution by 30% if it is implemented nationwide.

            Nevertheless, stubble burning still has two great advantages over biochar. First is its ability to quickly and effortlessly clear out the field. On a typical dry, un-windy day in Mumbai, an acre of rice field can be cleared out in less than 5 minutes. In comparison, picking the rice stalk tirelessly by hand can take 5 to 10 hours. A weeding machine can be maneuvered to cut stalk much more efficiently, but it would still require a lot of time and manpower, and most family-run farms cannot even afford to purchase one. Secondly, burned residues can increase microorganic activities, which produces nitrogen for the crops to feed on. Burning biomass into biochar however will not have this effect. In fact, applying biochar attracts more pests to the crops, which increases the need for pesticides, which are harmful to the soil.

            Biochar also appears to have huge limitations as well. First, biochar made from different biomasses varies drastically. Biochar made from residues of citric fruit can be 100 times finer particles than that from corn stalk. Many other farm wastes such as rice leaves are even unfit to produce usable biochar, because of moisture and other factors. In dry seasons, biochar-rich soils will trap water components too much and make them unavailable for crops. Also, applying biochar on slightly acidic soil can bring the soil to almost neutral, which is adverse to plant growth. (Jyoti Rawat, Jyoti Saxena, Pankaj Sanwal)

            Biochar certainly has value to farmers as an alternative to stubble burning. It can increase soil fertility and water absorption, decrease soil acidity, enhance fertilizer effectiveness, and mitigate air pollution. It is also marketable, which makes it a profitable source of income for farmer families. However, biochar production and usage can be highly inconsistent and might decrease crop production without careful management of the type and amount of biochar applied. Also, manually removing farm wastes of crops, especially of stubble crops, and burning them in a kiln, is much less efficient and more arduous than simply burning in the open field. But in Mumbai, the air pollution has impacted so many lives and damaged the city economically, and if it continues to worsen, which it will without governmental restrictions on burning, an estimated 113.08 million US$ would be lost per 50 μg/m3 increase in PM10 concentration (Patankar, Trivedi). Although picking up biochar is costly at first and certainly unconventional, farmers will be able to have better living condition and improved economic status, with careful management of biochar.

Bibliography

Anna Austin. “Beyond the Hype.” Biomass Magazine.  biomassmagazine.com/articles/4080/beyond--the--hype#:~:text=Although%20researchers%20are%20currently%20willing,%24100%20per%20ton%2C%20Twombly%20says.

“Global Biochar Market is Expected to Reach 300 Kilo Tons and USD 572.3 Million by 2020 in Terms of Volume and Revenue Respectively: Transparency Market Research.” PRNewswire. 2014, August 11. prnewswire.com/news-releases/global-biochar-market-is-expected-to-reach-300-kilo-tons-and-usd-5723-million-by-2020-in-terms-of-voume-and-revenue-respectively-transparency-market-research-270770061.html

Pamela Porter, David Laird. “Biochar: Prospects of Commercializing.” Farm Energy. 2019, April 3. farm-energy.extension.org/biochar-prospects-of-commercialization/

Douglas Jose, Lance Brown. “NF96-310 Costs of Harvesting and Hauling Corn Stalks in Large Round Bales.” 1996. digitalcommons.unl.edu/cgi/viewcontent.cgi?referer=google.com/&httpsredir=1&article=1404&context=extensionhist#:~:text=The%20weight%20of%20stalks%20available,2%2C000%20%3D%204.2%20tons%20per%20acre.

“Production.” Biochar Farms: resources for sustainable use of biochar in agriculture. biocharfarms.org/biochar_production_energy/#:~:text=Slow%20pyrolysis%2C%20for%20instance%2C%20is,yields%20of%2010%20to%2030%25.

Vazhacharickal, Prem & Predotova, M. & Chandrasekharam, Dornadula & Bhowmik, S. & Buerkert, Andreas. “Urban and Periurban agricultural production along railway tracks: A case study from the Mumbai metropolitan region.” Journal of Agriculture and Rural Development in the Tropics and Subtropics. 114. 145-157. 2013. researchgate.net/publication/287237523_Urban_and_Periurban_agricultural_production_along_railway_tracks_A_case_study_from_the_Mumbai_metropolitan_region

Lee Reich. “The Four Things You Need to Know About Soil pH.” How to.  finegardening.com/article/the-four-things-you-need-to-know-about-soil-ph#:~:text=Most%20plants%20thrive%20in%20slightly,good%20access%20to%20all%20nutrients.&text=A%20pH%20level%20that%20is,a%20plant's%20uptake%20of%20nutrients.

Jyoti Rawat, Jyoti Saxena, Pankaj Sanwal. “Biochar: A Sustainable Approach for Improving Plant Growth and Soil Properties, Biochar - An Imperative Amendment for Soil and the Environment.” Vikas Abrol, Peeyush Sharma, IntechOpen, DOI: 10.5772/intechopen.82151. intechopen.com/books/biochar-an-imperative-amendment-for-soil-and-the-environment/biochar-a-sustainable-approach-for-improving-plant-growth-and-soil-properties#B72

Sadaguru Pandit. “Maharashtra doesn’t breathe easy, air pollution killed 1.08 lakh in 2017.” Mumbai News. 2018, December 7. hindustantimes.com/mumbai-news/maharashtra-doesn-t-breathe-easy-air-pollution-killed-1-08-lakh-in-2017/story-fT45OgiR5CFmTEMqbcUi4L.html

Patankar, A M, and P L Trivedi. “Monetary burden of health impacts of air pollution in Mumbai, India: implications for public health policy.” Public health vol. 125,3 (2011): 157-64. DOI: 10.1016/j.puhe.2010.11.009. 2011, March. pubmed.ncbi.nlm.nih.gov/21334032/#affiliation-1