Due to its porosity and intricate structure, charcoal –which is an amorphous form of pure carbon— retains the water and nutrients present in the soil (like a “sponge”), in turn providing an ideal habitat for micro-organisms such as mycorrhizae fungi, well-recognized already in agriculture for their beneficial properties.

Consequently, biochar-amended soils have a higher CEC (Cation Exchange Capacity) which is traditionally used as a measure of fertility, nutrient retention capacity and therefore of the capacity to protect groundwater from nutrient contamination. Many analysis of biochar amended soils also reveal that they typically contain 3 times more phosphorous and nitrogen than other (untreated) soils.