Chapter three – Biochar Application to Soil: Agronomic and Environmental Benefits and Unintended Consequences
There are significant organizational and institutional obstacles to the use of biochar in soil. Since biochar could be used on a large scale and cannot be removed from soil once applied, there is a need to carefully assess the potentially negative impacts on occupational health, environmental pollution, water quality, and food safety. This requires a concerted effort to evaluate potential products, and ideally define product standards. Support for the use of biochar in meeting policy objectives will draw upon life-cycle analysis with full greenhouse accounting, backed by a body of experimental data. Where biochar is designated as a regulated waste material, pending defined standards land users in many countries may be subject to a complex and expensive approval process.
The lack of mechanistic understanding as to the function of biochar, and its interaction with already complex soil processes, means predicting the return to an investment in biochar between locations in terms of extent, predictability, and durability of benefits does not yet exist. Providing a measure of certainty to the many possible benefits is a key challenge to be addressed by further research.