Study finds multiple benefits from using biochar in agriculture
A group of researchers from the University of Connecticut in the US have synthesised global data from 592 peer-reviewed papers on biochar. From their findings, they concluded that, while biochar application is context dependent, it generally improves the soil quality. The study highlights the potential for the use of biochar as a viable climate-smart agricultural practice and thereby partially contributing towards a number of the United Nations Sustainable Development Goals.
Climate-smart agriculture (CSA) is an integrated approach that helps guide actions to transform agri-food systems towards more sustainable and climate-resilient practices. CSA aims to tackle three objectives: sustainably increasing agricultural productivity and incomes; adapting and building resilience to climate change; and reducing and/or removing greenhouse gas emissions, where possible. Current examples of CSA practices include cover crops, practicing no-till or reduced till and integrated nutrient management.
Biochar is a charcoal-like substance made from any organic material (such as crop residues or wood waste) that has been carbonised under very high temperatures (300-1000°C) in the absence of oxygen. It is a traditional agricultural practice that has been used by humans for centuries.
Biochar takes a long time to break down, therefore increasing the soils carbon content. If the same material was incorporated into the soil directly, rather than being converted into biochar, it would decompose much quicker, releasing greenhouse gases such as methane and carbon dioxide in the process. This would also be the case if the material was burned. However, by turning it into biochar, the carbon is sequestered and remains in the soil. In addition, biochar can improve the soil’s capacity to hold water and nutrients, by acting like a sponge. This can help make the soil more nutrient-dense and resilient to droughts, while maintaining crop yields.
"Through the global data synthesis, you can see that across different soil and climate conditions, biochar, together with other practices, can help farmers to sustain food production. It can also reduce greenhouse gas emissions, reduce nitrogen leaching, and save soil water," said study co-author Yawen Huang.
The team found that some of the laboratory experiments used in some studies may have overstated the capability of biochar and they are planning to perform more field experiments to understand exactly when and where to use the biochar to maximise its benefits.
"We still need to consider biochar together with other traditional sustainable practices for nutrient management and irrigation treatments in different locations considering different climate conditions," said study lead Wei Ren. "We can achieve the goal of climate-smart agriculture, and in the case of biochar, Connecticut is an ideal place for exploring and applying biochar as a CSA approach. We have so many trees and natural resources here. Studies show that biochar made from trees can largely reduce nitrous oxide emissions, which is almost 300 times more potent than CO2 in its global warming potential."
One important aspect of sustainable and climate smart practices is that waste can often be repurposed. The researchers have a vision to use waste from trees to make biochar to be used by farmers in Connecticut.
"We would just use waste materials; it is the sustainability cycle," said Ren. "The forest owners have the potential to make the biochar from their own resources to benefit cropland or farmland. You can use the crop residues or other non-agricultural organic wastes and return them back to the soil too. I want to expand the concept of climate-smart agriculture and forestry to create a climate-smart landscape. Let's think about if we can manage the natural resources, farmland, wetlands, and other natural systems together. Can we use these climate-smart practices for linking forest and agriculture?”
The team are planning to push the project forward by connecting with local biochar producers in order to keep the production local and save energy from transportation.
"With the pandemic, customers tended to shift their food habits towards more locally grown products. This transition calls for more resilient and sustainable food systems. Climate-smart agriculture is an important concept to guide us to achieving sustainable agriculture. It also serves as a natural-based climate solution for building a climate-resilient future."
Journal Reference
Yawen Huang, Bo Tao, Rattan Lal, Klaus Lorenz, Pierre-Andre Jacinthe, Raj K. Shrestha, Xiongxiong Bai, Maninder P. Singh, Laura E. Lindsey, Wei Ren. A global synthesis of biochar's sustainability in climate-smart agriculture - Evidence from field and laboratory experiments. Renewable and Sustainable Energy Reviews, 2023; 172: 113042 DOI: 10.1016/j.rser.2022.113042
Further information
FAO – Climate-Smart Agriculture
United Nations Sustainable Development Goals
The World Bank - Climate Smart Agriculture
Further reading on this topic is also available to subscribers of Environmental Impact. For example, by using the search string charcoal AND "climate change" AND "carbon sequestration" yields over 325 records. A selection of these is provided in the further reading section below.