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MMWD Blog: Think Blue Marin

Welcome to our blog! Written by staff at MMWD, “Think Blue Marin” explores all things water in south and central Marin—water supplies, conservation, new projects, watershed management, and more.

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Aug 17

The Sponge

Posted on August 17, 2018 at 7:35 AM by Ann Vallee

by Charlene Burgi

Recently, for the third year I found my way to our Canadian friends’ choice location to do some amazing hikes and throw a fly into pristine lakes for the chance of catching the famed Kamloops trout. Before leaving on vacation, I promised to share with you my plant experiences while north of Kamloops, BC. 

wild blueberries
 Wild blueberries

 product of living soil
 Product of living soil
Mornings found a few arduous fishermen on the narrow trails leading through the heavily forested lands to pristine lakes. The vegetation surrounding us consisted of tall timber and lush green growth. Various colors and shapes of mushrooms appeared all around us. Tucked among the trees were bushes covered with huckleberries and blueberries ripe for the picking, which seemed to lighten the load of our gear as we hiked on. 

But it was the sponge-like soil underfoot that particularly captured my attention. It seemed as if it was alive. Years of built-up duff from fallen, decomposed plant material fed this soil teeming with microorganisms. I couldn’t help but think of it as the quintessence of what we strive to achieve in our gardens. Only layers of well-rotted compost could duplicate the perfection of this soil.

I chatted about the wealth of the soil with the owner of the lodge where my oldest grandson Steve and I stayed. She made a comment that surprised me. She said there were only about three inches of this fertile, sponge-like soil covering the hardpan clay underneath. Her statement left me speechless and wondering what this rich environment would be like without the interface layer of the two elements. Of course, the thought of double-digging a landmass of that scope is absurd, but in a home garden? The idea struck home that I could do a lot more with the rotting manure from my chickens, horses and donkeys to enrich my own garden. That living sponge is doable for all of us!

Not all of us have equine or chickens in our backyards, but we can compost. We can add organic layers of thick mulch over cardboard or any material that will decompose in time. The duff build-up from the forest did not occur overnight, and it will take time in our backyards, too. But our commitment to feeding our soil will pay off in a multitude of ways if we stay the course. Our plants will thrive, and our vegetables, fruit trees and shrubs will out-produce. Our gardens will need less irrigation thanks to the moisture-retaining properties of those layers of organic material, and weed seeds will have difficulty germinating—or at the very least plucking them out will be much easier if they do manage to set down a root.

Are you up for the challenge? Visit a local dairy or equine center and ask what they do with their manure. They might be willing to share several truckloads on an ongoing basis. (Just be certain it is well-rotted and weathered to leach out any existing salts.) Then join me in creating a living sponge in our gardens.


Anonymous User
August 17, 2018 at 8:01 AM
In China they have a national effort to create "Sponge Cities" as a way to reduce flooding and improve storm water quality. I want to encourage MMWD to join with the citie and the county to copy the ideas being tried in China. Kathleen Schafer @kathyq100lady
David Kessell
August 17, 2018 at 8:12 AM
In my back yard had probably 1/3 acre of eucalyptus with years of "duff". But removed much of it and the brush around and above it and the scotch broom and the "small" eucalyptus to reduce fire load and firestorm exposure. What is your recommendation for maintaining and building soil in such an area? I didn't remove duff to bare dirt, but did remove much of the loose stuff. What is your recommendation for balance of reduced fire danger, controlling erosion, and healthy soil given the towering eucalyptus trees and not enough money to remove and start from "ground up"
Anonymous User
August 20, 2018 at 9:53 AM
David. Eucalyptus presents a different scenario encompassing oils that typically prevent under story growth as well as fire fuel. Additionally, the breakdown is extremely slow with that type of duff. I think you are doing the right thing by removing the loose vegetation and leaving a thicker layer of compacted material on the ground for both erosion control as well as a thicker mat of duff missing the oxygen that feeds fires. In your case, I would recommend you talk to someone from Fire Safe Marin for other suggestions. Good luck!
Anonymous User
August 20, 2018 at 10:02 AM
Kathleen, Thank you for sharing this information. I had not heard the term "sponge cities" before. I am familiar with the concept that is employed here in the USA but using different terminology. With the use of pavers, popcorn asphalt, and soil improvements we are absorbing the water instead of sending it into storm drains. Bioswales, rain gardens and specific types of grading will slow water down, spread it out and sink it in to again prevent flooding our storm systems. It is encouraging to hear this type of water management is going world wide now. Thanks for sharing!

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