This article was originally published in ThePrint India.
India is no stranger to farmers woes. Agricultural workers are affected by monsoon, by crop quality, by disappearing yields, and soil fertility. Piling on to it is of course the practice of crop burning that causes a spike in air pollution every year for extended periods of time.
A potential solution to several of these problems comes in the form of burned organic matter, called biochar.
Biochar is a concept that has gained scientific importance in recent times, although its usage has been recorded in history through the ages. It is essentially organic matter that is burned without oxygen such that it produces a black residue which can then be used to enhance soil fertility.
Ancient cultures like settlers along the Amazon river and Native American tribes have used it successfully for improving soil fertility, by burning organic matter inside covered pits.
Of late, more evidence is coming to light that the process also helps store or sequester carbon, thus helping reduce pollution. Research worldwide into biochar has increased drastically over the past decade, and in India specifically, the number of studies on biochar have gone up in the past five years.
Working on how biochar solutions can be effectively used in India is a lab in the heart of the land of Alps, in University of Zurich. In UZH’s department of soil science and biogeochemistry, researchers work on understanding the impact of biochar and improving its production process to enable both soil fertility and carbon sequestration, aided by field trials spanning over a decade in India.
The carbon cycle
Samuel Abiven, a biogeochemist is the group leader for the soil science research group at UZH.
“As a biogeochemist,” Abiven says,” I study the carbon cycle, starting with how carbon enters plants through photosynthesis and how it moves into the soil, to the life cycles of related compounds responsible for soil health such as nitrogen and phosphorus.”
Abiven’s research students also study about carbon that’s released by fire and the link between carbon and other cycles like those of nitrogen and phosphorus.
According to Abiven, biochar is a “custom made” organic matter produced from fire or heat which can be applied in agriculture or industrial applications. It is similar to charcoal but is produced artificially with intention for specific use. Organic waste (called ‘feedstock’ when it’s raw material) is transformed through heating without oxygen — to prevent combustion, in a process called pyrolisis — into charcoal-like material producing heat and energy, as well as byproducts like bio oil and fuel gases, which are sources of clean energy.
And biochar lasts in the soil for a very long time, which is what makes it an effective form of carbon storage.
Globally, we have a finite amount of carbon.
“To prevent excessive build up of methane and carbon dioxide in the atmosphere, there are ways to store carbon on earth,” Abiven explained.
And this is what occurs naturally: fossil fuel is stored carbon collected over millions of years and buried deep under the ground. Much higher though, it is stored in sediments and soil. Carbon, in the form of organic matter, is the backbone of soil health. It works with nitrogen and gives fertiliser to the plants, its porosity helps retains water thus helping soil hold more moisture, and a soil is generally healthier and more fertile if there’s more organic matter in it.
But there are exceptions, of course. Permafrost — permanently frozen ground that is today thawing because of our climate crisis and global heating — contains a lot of frozen carbon but isn’t really fertile land for farming.
“What is interesting about soil is that you can act on it,” explained Abiven. “You can change it and allow for it to absorb more carbon to be stored.”
And studies have shown that biochar is a double whammy winner: it can increase fertility, mitigate pollution, and store carbon. It is especially efficient on the last front because it lasts a very long time in the soil and microbes don’t break it down as fast as they do regular organic matter.
It can be made of any organic matter, including wood, animal excreta, plant waste, household organic waste, and crop remains that would otherwise be burned, and the process produces up to 50% in volume of biochar as the raw material.
Pyrolisis can also be performed in many ways. Digging a pit into the ground, dumping the feedstock in it, covering it, and lighting it is the easiest and has been practiced for thousands for years. But kilns are used today.
Biochar’s quality depends not just on the method, but also the quality of raw materials, the amount of oxygen that seeps into the process, and the temperature. In fact, the higher the temperature, in the 400 deg C to 1000 deg C range, the longer the biochar lasts in the soil.
However, there is a delicate balance needed when applying and creating biochar: since it absorbs water, it also tends to absorb nutrients. So the type of biochar that is produced and its retention potential needs to be adjusted for the site of use.
“Woody biochar, for example, absorbs a lot more nutrients,” explains Abiven. “But if the nutrients aren’t tightly packed into the biochar structure, plants can still tap into it for their benefit.”
Abiven’s research into biochar systems has also led to surprising discoveries. A field trial conducted in Zambia showed that one of the reasons there’s increased crop yield upon using biochar is that a plant’s root system’s architecture changes, leading to increased and more extensive root systems.
The UZH and Abiven’s team has conducted field trials in Germany, Spain, Italy, Norway, Nepal, North America, Indonesia, Madagascar, Zambia, and of course India.
Biochar in India
A big factor in the use of biochar in India is the socio economic situations of farmers. In India, UZH collaborates with GKVK College of Agriculture and Indian Institute of Science (IISc) in Bengaluru, and has been doing so for over 12 years.
In India, Abiven’s team’s most recent field trial, still ongoing, is in the town of Mandya, Karnataka. The team also collects samples from biochar use in the outskirts of Mysore, and Godavari watersheds ranging from Pune to Mumbai.
Before applying biochar to a farmer’s soil, Abiven obtains consent by explaining how biochar works, understanding how composting is implemented, what their investment capacities are, whether they can obtain subsidies, and evaluate the farm area for its needs. Farmers are then recommended to test in a corner to first see how it affects the new yield.
The kind of biochar produced for use here will depend on all of these factors.
“Instead of seeking out wood, the more popular material in biochar, we want Indian farmers to use their own crops’ waste material,” says Abiven.
Of course, just as with manure, biochar rich in a plant’s remains will provide more nutrition for the same plant.
And biochar doesn’t need to act independently, it also works in conjunction with existing compost material and can be applied mixed into it.
“What is surprising is that most of the times, Indian farmers don’t need technical information,” explains Abiven. “Does it work? That’s all they want to know before they adopt it.”
And it has worked well for most farmers, who have seen an increase in yield that has been noticeable enough for them to continue using biochar more. However, things don’t always go as planned. Sometimes, inexplicably, there is negative yield in the crop which can prove to be a huge disadvantage.
“One suspect is ’sodic soil’, where there’s a high salt content in the soil,” elaborates Abiven. “In general, soil with pH tends to be unfavourable for biochar. Also soil with high amounts of organic matter do not react well.”
More research would be needed to understand the efficiency of biochar in India, adds Abiven. “And when done right, it can provide a big solution for both crop yields as well as carbon sequestration.”