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Emily Saeger
Emily Saeger

The Buzz about Biochar

Field-testing a new Soil Amendment

There’s a new hip product on the agricultural block that’s generating a lot of buzz: biochar.  Proponents point to a number of environmental benefits including: carbon sequestration, increased soil fertility, improved water quality due to reduced runoff, and increased agricultural yields.  Sound too good to be true?  It could be.  But it also has the potential to be a useful, sustainable soil amendment for small-scale organic farmers – like Farmscape!

Being the cutting-edge urban farmers that we are, we’re throwing our hats in the game and giving biochar a shot at Faithful Farm, our rooftop farm at Levi’s stadium.  

The ability to enhance soil fertility through traditional means – adding soil and compost – is limited at Levi’s due to the weight-bearing capacity of the roof.  This makes biochar a promising soil amendment for us because it is so light-weight.

So what is Biochar? It’s a fine charcoal made from biomass (green waste) burned in the absence of oxygen, a process called pyrolysis.

The concept for biochar came from studying rich Amazonian soils produced by the regenerative agricultural practices of indigenous peoples there.  This included burning biomass in trenches that were then covered with soil.  The charcoal created through this process was slowly incorporated into the soil with the help of decomposers (like worms).  Over time this lead to dark, fertile soils that reportedly retained their nutrient content for many years.

As awareness of Biochar grows, so too does its commercial availability. We have been using “Cool Terra” from Cool Planet, but there are a number of different brands available. It can be purchased and worked into garden soil, much like any other amendment.

We will continue to incorporate biochar at Faithful Farm as we turn over beds for next season’s plantings.  Check back this summer for our results!

Emily Saeger is the project lead at Faithful Farm at Levi’s Stadium, the largest rooftop farm in Silicon Valley.