One of the four cornerstones of biochar,* in terms of the ecosystem services that it provides, is water retention. When I started using biochar as a soil amendment, in 2016, this was the first benefit that I noticed. Immediately, our irrigation requirements dropped 25 percent.
Any sort of organic matter boosts moisture retention, making water more available to plants, but biochar does it semi-permanently. Our garden soil became a bigger reservoir. We didn’t realize how much of our water was evaporating or escaping through the ground until biochar started preventing it.
Consider what would happen if biochar-making became widespread, in place of chipping and burning. Added together, many small reservoirs can change the availability of water throughout an entire region, increasing its resiliency to drought. Compacted soil from logging or urbanization are in need of such restoration, and this can be done by just flinging biochar around as a top dressing. The result would be a cumulative augmentation of the water table, raising all biological boats.
It turns out that this is no small thing, in terms of the global water situation. A recent article in ProPublica describes increasing depletion everywhere, mainly through pumping from aquifers for agriculture and commercial enterprises. Two decades ago, Jay Famiglietti at UC Irvine began using data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites, which measure changes in the mass of the earth, to estimate its water content. Terrestrial (v. oceanic) water depletion is accelerating. Surprisingly, pumping from aquifers is not just causing land subsidence but is a major contributor to sea level rise.
So while locally enhancing soil health by making biochar, know that your contribution is also to the aquifers in your region. And as our personal pyrolysis practices gain recognition by our neighbors and they pick up the biochar baton, let’s be sure to cite the additional benefit of increased groundwater and the biological resiliency that it provides.
*biochar holds water, holds nutrients, provides microbial habitat, and sequesters carbon