Sheet Mulch: where the Princess meets permaculture

There are three stages to the life cycle of corrugated cardboard: it arrives as a shipping container, becomes an enchanted fairy princess castle, is put to use restoring the soil.  Each has its purpose, but the last pays dividends for a long, long time.

During our renovation, new appliances arrived packed in lots of cardboard.  I was as excited for the packaging as for the appliances.  The cardboard was repurposed quickly, as a fairy princess castle was ordered.  I was up to that challenge.  Many years back, I transformed, for my Nephew, some boxes into an underwater cave surrounded with schools of fish.  

These days my ambitions are less grand and a few cuts with a sharp knife sufficed here.  The rest was left to our daughter’s imagination.  Of which she has plenty.

Eventually that castle became part of the clutter in her room, and I was beginning to plan a large sheet mulch project.  I carefully broached the topic that her castle would become a part of the garden.  To my relief, she said, “That would be fine, Daddy.”

The corrugated cardboard became a key layer of the 12-inch sheet mulch for the 600 sf vegetable garden that we are preparing for next season.  We layered the materials in October to allow them to decompose over the winter.  

I first learned about sheet mulch from David Homa, of Post Carbon Maine.  He is a local maven of permaculture and gave me this list of ingredients: lawn, stone dust, crushed shells, seaweed, leaves, finished compost, newspaper, straw.

Toby Hemenway, author of Gaia’s Garden, has an excellent discussion of sheet mulch.  His material list for “the perfect sheet mulch” is:

1. newspaper, corrugated box cardboard without staples or tape. cloth, old clothing, or wool carpet, provided they contain no synthetic fabric, but these take far longer to decay than paper.
2. Soil amendments: lime, rock phosphate, bonemeal, rock dust, kelp meal, blood meal, and so on.
3. Bulk organic matter: straw, spoiled hay, yard waste, leaves, seaweed, finely ground bark, stable sweepings, wood shavings, or any mixture of these, ideally resulting in an overall C:N ratio of 100/1 to 30/1 about 4 to 8 cubic yards of loosely piled mulch for 100-200 square feet
4. Compost, about 1⁄4 to 1⁄2 cubic yard (6 to 12 cubic feet).
5. Manure: 1⁄4 to 1 cubic yard,
6. A top layer of seed-free material, such as straw, leaves, wood shavings, bark, sawdust, pine needles, grain hulls, nut husks, or seagrass. You will need roughly 1 cubic yard

There is a wealth of information available on the web, including this site with photos showing each step in the process:

http://permaculturenews.org/2012/07/20/gorgeous-gardens-from-garbage-how-to-build-a-sheet-mulch/

My own recipe was based on the materials on hand.  My first layer was about three inches of horse manure applied directly on top of the lawn.

I scattered stone dust and then layered the corrugated box cardboard.   The cardboard was placed above the manure to create a barrier preventing hayseeds from sprouting.  Newspaper was used to fill in the gaps between the pieces of cardboard.

Wood chips were spread thickly on top of the cardboard, and then, for bulk organic matter, we put maple leaves, grass clippings, end-of-season cuttings of comfrey, hosta and other perennials.  The brown – carbon – side seemed to be dominant, so to boost the nitrogen side, I mowed my neighbors lawn (with fallen maple leaves) and added that into the mix.  My neighbor was thrilled – and a bit incredulous – at my generosity, but I still think I got the better side of that trade.

I would have liked to add seaweed into the mix, but I never found the time to get down to the shore.  Our final layer was loam, primarily as a weight to keep the leaves and clippings from blowing during late autumn storms.

I would have liked to top dress everything with a layer of finished compost, but that can wait until spring.

Gone are the days of “double dig” garden beds, and whether the rationale is carbon sequestration or protecting the soil structure, my back definitely was better off for following the sheet mulch approach.  We are building the beds directly on top of the existing lawn.  I have no idea what our final C:N ratio was but I remain steadfast in my belief that nature is forgiving.  We were close enough, and will continue to add layers of rich organic mulch annually.

We have made a big step forward toward our sun-loving vegetable garden.

In My Backyard

The tar sands debate – dark and dismal – always seemed focused on someplace far away: the Province of Alberta, Nebraska, West Texas.  But en sotto voce, plans have been taking shape right out my back door.

The Casco Bay is the maritime port for Eastern Canada.  Into this year round deep-water port, oil tankers arrive daily to unload their crude and then ship it by pipeline 236 miles north to Canada.  Since 1941 – for almost three generations – over 4 billion barrels of crude oil have been pumped northward along the Portland-Montreal Pipeline.

It is no engineering feat to realize that a pipeline can flow in either direction.  And as the Keystone XL pipeline became embroiled, rumors began to surface for shipping the tar sands oil east, from Alberta to Quebec then into Vermont and New Hampshire for export through the Gulf of Maine.

The pipeline can move 600,000 gallons per day.  Its terminus is South Portland.  The oil tank farm lies across the street.  Tar sands would come here.  Not without a fight.

The Portland-Montreal Pipeline Company has made no announcement of plans to reverse the pipeline.  None, officially, but a strong grass roots coalition – raising voice from Vermont to South Portland – has been preemptive in resisting the possibility.

In South Portland, it is a zoning issue.  On 5 November there is a referendum up for a vote.  The citizen initiated Waterfront Protection Ordinance states that within the Shipyard District, the permitted use would include “facilities for the unloading of petroleum products from ships docking in South Portland” but “there shall be no enlargement or expansion of existing petroleum storage tank farms and accessory piers, pumping and distribution facilities….”

If you ask any of the activists in favor of Waterfront Protection, they make plain that the existing crude oil business is fine – the inbound unloading of tankers – but there should be no expansion that allows the outbound loading of tankers.  Tar sands is the issue, and the related toxic fumes, emissions, and the very real risk of an oil spill.  The high bitumen content of tar sands makes clean up difficult by an order of magnitude.

In debate, plain language is anything but, and big oil is funding the movement against Waterfront Protection. The Portland-Montreal Pipeline Company, which operates quietly out of a small red brick building over on Hill Street, and does have a sterling record of safety, is a subsidiary of Exxon-Mobil Corporation.

“It’s the Economy, Stupid,” is a slogan proven to win elections, and that is the crux of their argument.  Upon a faulty premise, they have built a case carefully, and are broadcasting misinformation widely in glossy mass mailings, that arrive weekly.  They are spending a reported $275,000 in their campaign against the ordinance.

They paid Charles Lawton, a local economist, $15,000 to quantify the impact of the ordinance shutting down all oil-related business.  (Bear in mind, the ordinance clearly states that the status quo is fine, and only the expansion is restricted.)  Given the premise of all operations ceasing, the economist logically projected over the next decade 5,600 jobs would be lost and $252 million dollars in earnings would vanish; the “economic multiplier” would impact the wider community to the amount of $26.6 million annually, eliminating about 250 jobs, $12 million in income, and $9.4 million in tax revenues.

In the 16 October edition of the Portland Press Herald, a columnist called this report, “a scare tactic masquerading as a fact.  Pretty slick, huh? One minute Lawton is talking hypothetically about a waterfront sans workers – and the next his gloomy forecast is attached, as sure as tomorrow’s sunrise, to a “yes” vote on the Waterfront Protection Ordinance.”  http://www.pressherald.com/news/Oil_guys_pollute_South_Portland_ordinance_issue.html

You have to wonder how Lawton regards this distortion, and what to make of his quote from the article : “I’m not uncomfortable with what I delivered…[but] I can’t say how it’s been represented in ads or handouts or fliers or whatever.”   Is the public nothing more than a bunch of rats being lead through a dirty maze?  Independent thought and fact checking are crucial.

Fear is an easy message to sell.  Whether it is true or not seems hardly the issue.  Big Oil has reportedly hired youths to go door to door, telling people they also want to protect the waterfront but the language is too restrictive.  “It’s just the wording is wrong.”

Now firefighters statewide have raised their voices against the Waterfront Protection Ordinance.  Their union also says the wording is wrong, and would restrict companies from upgrading for safety requirements.  Really?

Bill McKibben, a bright light and outspoken environmental activist has said, “The Portland pipeline isn’t some obscure local issue — it’s a fuse leading straight to one of the most dangerous carbon bombs on the planet.”

A description of this “carbon bomb” – referred to as the most destructive project on earth – can be found at the web site http://allagainstthehaul.org/the-haul/the-heavy-haul/the-alberta-tar-sands/ :

The Alberta Boreal Forest, under which the oil is embedded, is equivalent to the size of England; the deforestation is so vast it can be seen from outer space.

The industrial process is massively consumptive of resources: four barrels of water, four tons of earth, and energy equal to three barrels of oil are required to extract one barrel of oil. 

Ninety percent of water used in tar sands extraction cannot be returned to the Athabasca River due to quality issues.

The Tar Sands contain 17% more carbon than other types of crude oil, and the extraction process emits as much as four times more carbon dioxide than conventional drilling.

First Nations communities living close to the oil sands or downstream on the Athabasca River are suffering from higher-than-normal cancer levels and illness.

The facts of the tar sands are nightmarish, and its scale is overwhelming.  This is an important moment for the members of our community to take a stand.  The question before us, at its most basic, might be framed as whether, as a community, we want to remain dependent upon the fossil fuel economy, or shall we pursue a future that is restorative, that is abundant rather than austere, that embraces creativity as a means to discovery, and that teaches our children to think for themselves and neither follow blindly nor let fear fuel their decisions.