Saturday, February 12, 2011

Green Roof Sprouts!

The rabbit hutch green roof expansion was completed only a few days ago.

Constantly using new materials to see how they preform in the field, I am always surprised - usually pleasantly, with the results.

The green roof plant seeds sown on the expansion green roof had already sprouted!

Future C3 and C4 Green Roof Plants
Green Roof Rabbit Hutch Expansion
Existing Green Roof on Rabbit Hutch - C3 and C4 Plants
The Green Roof is 50MM thick at its maximum depth.

One of the exciting aspects of this field trial is the use of Bio-Char material in the green roof soil media.

Bio-Char is a highly stable charcoal type compound with properties including high efficiencies at sequestering additional Carbon, Nitrogen and Phosphorous.

Wikipedia's bio-char description is as follows:

Biochar is a way for carbon to be drawn from the atmosphere and is a solution to reducing the global impact of farming (and in reducing the impact from all agricultural waste). Since biochar can sequester carbon in the soil for hundreds to thousands of years[2], it has received considerable interest as a potential tool to slow global warming. The burning and natural decomposition of trees and agricultural matter contributes a large amount of CO2 released to the atmosphere. Biochar can store this carbon in the ground, potentially making a significant reduction in atmospheric GHG levels; at the same time its presence in the earth can improve water quality, increase soil fertility, raise agricultural productivity and reduce pressure on old-growth forests.

The plants appear to like the bio-char material so far, and we will continue to update their progress.

As a lawyer trained educationally in environmental tort law, I am constantly looking at issues associated with new technologies as relating to green roofs.   As a botanist I love to see how plants adapt.

Anyone can find issues with new materials.  From a legal perspective there is nothing easier than bringing an action against someone for negligence or products liability when the product is not appropriately tested.  Therein lies a great fear we must overcome in our quest for sustainability.

Fear keeps us thinking within the boundaries of safe and proven technologies, usually averting liability issues.  However fear based approaches can lead to technology becoming stale and outdated, a 'backwards' type of thinking.

Bio-char materials will need to be thoroughly tested for many qualities, flammability being one.  As soon as I mention bio-char, the first reaction many times is 'charcoal and fire!'.  Research bio-char's flammability ratings though and you may be surprised at how stable it is.

Revisiting the rabbit hutch though, the 50mm thick soil and drainage layer will soon be thick with vegetables and wildflowers, cleaning stormwater, feeding rabbits, giving nectar to pollinators and providing beauty.

As always, your comments are appreciated.

Happy Green Roofing!


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