Biochar, a product of biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, is recognized for its potential to combat climate change by storing carbon (C) and regulating nitrogen (N) in soils. While its effects on soil C and N cycles are well-documented, the precise origins and transformations of these elements in the soil remain less clear. Traditional studies often measure changes in total soil C and N following biochar addition but fall short in distinguishing between native and biochar-derived elements.

The use of C and N isotopes offers a promising solution, enabling researchers to track the specific sources and transformations of these elements in soil. Isotope technology can identify the contribution of biochar to soil C and N cycles, differentiate it from native soil matter, and assess the persistence and mineralization rates of biochar-derived C and N. However, current research using these isotopes is inconsistent and fragmented.

A recent review highlights the advantages and challenges of using C and N isotopes in biochar research. It points out that while isotopes can precisely track changes in greenhouse gas emissions and soil nutrient cycles, there is a need for long-term, field-based studies to provide more comprehensive insights. The review also calls for improved methods to quantify small changes in soil C and N, which are often undetectable with conventional techniques.

By summarizing existing studies and identifying gaps in the research, this review aims to pave the way for more accurate and detailed evaluations of biochar’s role in soil C and N cycles. Such understanding is crucial for maximizing biochar’s potential as a soil amendmentA soil amendment is any material added to the soil to enhance its physical or chemical properties, improving its suitability for plant growth. Biochar is considered a soil amendment as it can improve soil structure, water retention, nutrient availability, and microbial activity.   More and climate change mitigation tool.