In the journal Biochar, authors Md Shafiqul Islam and Shangwen Xia provide a comprehensive review of how biochar-soil-tea interactions can revolutionize sustainable agriculture. Tea cultivation is a cornerstone of global agriculture, supporting millions of livelihoods across Asia, Africa, and Latin America. However, the intensive farming practices required to meet rising global demand have led to significant environmental challenges. Most tea plants grow in naturally acidic, nutrient-poor soils that are easily degraded by the long-term use of synthetic fertilizers. This degradation leads to soil acidification, the buildup of toxic heavy metals, and a decline in the beneficial microscopic life that keeps the soil healthy. Biochar offers a powerful solution to these growing problems by restoring the ecological balance of these sensitive agroecosystems.

The primary benefit of biochar in tea gardens is its ability to act as a powerful soil conditioner. When mixed into the earth, it works like a sponge to hold onto essential nutrients and water that would otherwise wash away during heavy rains. Because biochar is naturally alkaline, it neutralizes the excessive acidity common in tea plantations, which in turn prevents toxic aluminum from damaging delicate tea roots. The porous structure of the biochar also creates a perfect habitat for beneficial bacteria and fungi to thrive. These microbes help break down nutrients into forms the plants can easily absorb, leading to much stronger root systems and more vigorous shoot growth. Field studies have shown that these improvements to the soil’s physical and chemical makeup can lead to a ten to forty percent increase in the final tea harvest.

Beyond just increasing the quantity of the harvest, biochar significantly enhances the quality and safety of the tea produced. It regulates the supply of nutrients in a way that encourages the plant to produce more amino acids, polyphenols, and soluble sugars, which are the chemical compounds responsible for the flavor, aroma, and health benefits of high-quality tea. Simultaneously, biochar acts as a protective barrier against pollution. Its high surface area and chemical groups bind tightly to heavy metals like lead, cadmium, and arsenic, locking them in the soil so they cannot be taken up by the tea roots. This process can reduce the amount of lead found in tea leaves by more than sixty percent, ensuring that the final product is safer for human consumption.

The environmental impact of switching to biochar-based management is equally impressive, particularly regarding climate change. Biochar is a highly stable form of carbon that can remain in the soil for hundreds or even thousands of years, effectively acting as a permanent carbon sink. By using biochar, farmers can turn agricultural waste into a tool for sequestering carbon dioxide from the atmosphere. Furthermore, the presence of biochar in the soil changes how nitrogen moves through the system, often reducing the release of nitrous oxide, a greenhouse gas that is hundreds of times more potent than carbon dioxide. In some controlled trials, biochar applications have slashed these harmful emissions by as much as ninety-four percent, making it a critical component of modern climate-smart agriculture.

While the benefits are clear, the researchers emphasize that there is no one-size-fits-all approach to using biochar in tea farming. The best results usually come from moderate application rates of approximately twenty tons per hectare. If too much biochar is added, it can occasionally make the soil too alkaline or temporarily lock away nitrogen, which can hinder plant growth in the short term. The effectiveness also depends on what the biochar was made from, with materials like tea pruning waste, rice husks, and bamboo all offering slightly different advantages. By carefully tailoring the type and amount of biochar to the specific needs of a region’s soil and climate, the tea industry can move toward a future that is more productive, more profitable, and far more environmentally responsible.

Source: Islam, M. S., & Xia, S. (2026). Biochar-soil-tea nexus: a review of soil health, microbial interactions, and sustainable Camellia sinensis cultivation. Biochar, 8(71).