In the age of climate change water is becoming ever more valuable. Water is not only a limited resource, it also costs increasingly higher amounts to access. The physical characteristics of charcoal absorbs water and disperses it slowly into the soil, reducing evaporation.
The San Juan Islands studies found increased water holding capacity of 5% - 20% in the biochar plots, and 13% - 18% in the charged biochar plots. As you can see, seasonal variation influenced the water holding capacity of the charcoal.