This is a huge article. Quite sciency, it's written as an academic paper. Lots of useful information. Covers some things not frequently talked about here, such as
biochar's role in limiting negative impacts of heavy metal toxins. Covers many research papers over many years in many places using many different methods.
John S
PDX OR
https://onlinelibrary.wiley.com/doi/full/10.1111/gcbb.12885