Biochar: Best for soil vs. Last 1000 years

This article is suggesting that biochar burned at a higher temperature, like 700 degrees, will last longer, about 1000 years.  Therefore it's great for carbon sequestration.  However, they said that biochar burned at a lower temperature, like 300-500 degrees, is more productive for soil fertility.

John S
PDX OR

https://biochartoday.com/news/high-temperature-biochar-offers-thousand-year-stability-while-low-temperature-varieties-maximize-soil-benefits/