ICRISAT study unveils low-cost biochar production system for farm-level sustainability

New Delhi: As global concerns over sustainable agriculture and climate change intensify, the use of biochar for soil amendment is increasingly gaining popularity because of its inherent properties that enrich the soil with nutrients and sequester carbon dioxide. These properties position biochar as a key player in agriculture’s shift towards net-zero emissions and in preventing soil degradation.

A recent study by ICRISAT scientists explores the design of an affordable, farm-level operable kiln for biochar production aimed at supporting smallholder farmers. The research paper also examines the properties of the biochar produced to better understand its applicability.

In her congratulatory remarks to the study’s authors, Director General of ICRISAT, Dr Jacqueline Hughes, underscored the significance of integrated solutions in accelerating our collective journey towards attaining the Sustainable Development Goals (SDGs).

“Biochar production not only solves the issue of managing crop residues, but its application in soil health, wastewater treatment and carbon farming opens up enormous opportunities to move towards a cleaner and greener future,” Dr Hughes shared.

According to the Ministry of New and Renewable Energy, Government of India, India produces over 500 million tons of agricultural residues annually, with about one fourth being burned (2017-2018). The incineration of these residues causes several health and environmental concerns. However, converting these residues into biochar presents a viable alternative, offering not just a method for managing this waste, but also the potential for additional revenue or cost savings for farmers.

Dr ML Jat, Director, Global Research Program – Resilient Farm and Food Systems, ICRISAT emphasized the importance of adopting a decentralized approach to ensure that the process benefits the farmers.

“This low-cost, decentralized biochar production technology will be an affordable and viable option for farmers and Self-Help Groups (SHGs) to solve the issues around crop residues in a sustainable manner. Moreover, this technology also aligns well with government incentives for voluntary carbon markets and environmental initiatives like the ‘Mission Life-Lifestyle for the Environment program,'” Dr Jat noted.

Biochar derived from maize spindles after pyrolysis in the portable kiln at 400°C

The characteristics of biochar significantly depend on the type of crop residue used. In this study, two types of feedstocks—pigeonpea and maize stalk—were used to draw a comparison between the ICRISAT-designed pyrolysis kiln and a lab-scale muffle furnace.

The study also examined the physical and chemical attributes of biochar derived from the two feedstocks, using high-end imaging and analytical technologies such as Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analyzer (TGA).

Research reveals that biochar created in the portable kiln at 400°C exhibits a quality comparable to that produced in the muffle furnace. Further analysis shows that the biochar derived from pigeonpea and maize stalks contains total carbon percentages of 48.9% and 41.9%, respectively. Within these totals, the proportion of stable carbon stands at approximately 98.6% for pigeonpea stalk biochar and 94.4% for maize stalk biochar.

“Organic waste management methods like composting and mulching are efficient, yet thermochemical techniques, such as pyrolysis, offer distinct advantages, including quicker processing times and higher efficiency, particularly with dry residues,” Dr Gajanan Sawargaonkar, Senior Scientist, ICRISAT, and one of the study’s authors, remarked.

Dr Sawargaonkar also highlighted that the data produced in the study will significantly contribute to the development of a holistic set of practices aimed at advancing sustainable agriculture.

“While the biochar for soil amendment is well documented, it is crucial to comprehensively study and gather evidence on how biochar affects soil microbial diversity and plant health. Additionally, understanding the broader societal implications and farmers’ field-level demonstrations are essential for the effective adoption of this technology,” Dr Rajesh Pasumarthi, the lead author of the study, shared.

ICRISAT is advancing its initial biochar research into a broader, strategic long-term study. This expansion aims to explore biochar production from various crop residues and to standardize its use across different cropping systems and soil types. The goal is to create a well-rounded set of practices that will deliver tangible benefits to farmers.