Carbon sequestration is the latest favoured quick fix in the world of business for the snowballing problems of global warming, and there are plenty of reasons to be skeptical of this. Pumping smog into giant underground resevoirs seems destined to hold as many unexpected costs and complications as it prevents. However, exciting new research into soil structure is offering up new opportunities, simple enough to be put into practice in your own back yard, but holding the potential to remove very large portions of our atmospheric carbon.

 

Basically, any carbon that isn’t in the air is sequestered. This is why using as many natural products as possible is important, because as long as wood is in the form of a chair, for instance, the carbon it contains is not changing the climate. Leave it to rot, and much of it will be released (especially in the form of methane, which traps much more heat than carbon dioxide). This is also why it makes sense, as people like George Monbiot remind us, to simply leave carbon in the ground, in the form of coal, oil and natural gas, instead of burning it then trying to catch the smoke.

But there are even simpler solutions which can take us much farther in the ground under our feet. Healthy soil contains a large amount of carbon in forms such as hummus, fungal webs and decaying organic matter. In fact, soils hold three times as much carbon as the atmosphere. Carbon in soil plays crucial roles such as holding nutrients and water (one unit of carbon can hold four units of water). This can be done in a variety of easy ways – carbon-conscious farming techniques (such as no-till farming or covercropping), returning plant wastes to the land or through the state-of-the-art ancient Inca technique of biochar. Estimates suggest that our planet has lost half or more of the soil carbon in its farmlands, and through unwise farming techniques (such as tilling a field and leaving it bare in the off season) we lose more every year, contributing significantly to global climate change. By correcting this we could not only but a large dent in climate change and start reversing the horrendous damage done to our planet’s soil structure, but also boost crop yields and reduce waste.

Worldwatch Report

Here are some of the ways you can practice this on a purely local level in your own backyard – all of the following will help you dispose of your organic waste without having to rely on the city’s green cart program or any costly home-depot economy-sized garbage bags, all while creating enormous potential for sustainable, high-yielding food production at home. Since these methods literally build soil, and because they can rely on any number of resources our city produces in abundance (leaves, grass clippings, paper waste, food scraps, straw, manure etc), the massive potential is clear. Even a few people could quickly create massive, rich, planting surfaces in and about our neighborhoods for little or no cost, with few tools beyond a pitchfork and shovel, and with no more work than at current goes into closely manicured lawns and tacky flower arrangements, we could be producing a safe, healthy and secure local food supply.

 

Composting:

Composting is nature’s basic recycling project. Food scraps and yard waste in a bin or pile will turn back into rich black soil. This happens through a variety of biological and chemical processes, from the smallest microbes up to framilliar creatures like earthworms.

 

Backyard Magic – The Composting Handbook

Composting Guide

Microbiology of Compost

 

Mulching:
Mulching spreads plant matter such as wood chips, leaf litter or straw over the surface of the soil. This helps your garden in several ways – it shields the soil from the harsh wind, rain and sun, helping it resist erosion and hold moisture. It also keeps down competition from weeds and feeds the beneficial organisms which build soil for you.

 

Mulching is good for your garden

Mulching 101

Sheet Mulching

 

No-till gardening:

Tilling is one of the major causes of carbon loss from soil, sending it right up into the atmosphere. By tilling the ground (or even compacting it) you tear apart the delicate networks of soil microbes and fungi and expose them to the elements. It’s bad for soil structure, it’s bad for almost all of the life forms we rely on to work the soil for us, it leads to erosion and nutrient loss, and it’s rather labour-intensive (a fancy way of saying “big pain in the ass”). No-till methods use other means to control weeds and add nutrients to the soil. By layering leaves, cardboard, manure, compost, straw, wood chips and other organic matter, you can stop weeds from getting through at all, while building a rich and healthy layer of topsoil. This is how natural soils are built in forests and grasslands – as leaf litter and straw falls, it biodegrades and the nutrients are “tilled” into the lower layers of soil by worms and insects. And nature’s soils remain fertile for eons without NPK fertilizer or roto-tillers.

 

No-Till Gardening: Sustainable Alternatives to the Rototiller

No-Till.org – No till on the plains

 

Covercropping:

Covercropping, or “green mulching/manuring” uses living plants to shield soil from the elements, as well as keep down weed pressure and help it maintain it’s carbon levels. Depending on the plants used, it can also help with levels of other nutrients (such as nitrogen, by using clover) or even yield an additional food or fodder crop.

 

Overview of Cover Crops and Green Manures

 

Hugelkultur:

A German term which is pretty self-explanatory. Hugelkultur uses buried wood to trap carbon in the soil and release nutrients as it decays, as well as holding water like a sponge. It can be practiced with smaller branches (around an inch wide and a few feet long at maximum), or with larger logs, and offers lots of possibilities for those constructing large planting areas like raised beds, ridges, mounds or terraces.

 

Gaiacraft – Great interactive Hugelkultur Lesson

Hugelkultur – Using Woody Waste in Composting

Step by step with pictures

Hugelkultur compared

 

Biochar:

An idea which dates back to the jungles of ancient Peru, where very thin Amazon topsoils made farming nearly impossible, biochar uses activated carbon (charcoal) to add carbon directly to soil in a very stable form which can persist for up to a thousand years or more. The terra preata (black earth) they found had rich soil many feet deep, still fertile from ancient times. Biochar fulfills carbon’s role in soil by holding water and nutrients, and has been shown to lead to impressive boosts in crop yields. Though traditionally charcoal was made by smoldering large bonfires, modern techniques are far more efficient, using the volatile gases driven off as the wood or other biomass is heated to fuel the process itself and then some, making the whole process effectively carbon-negative since the bulk of the carbon is being sequestered.

 

Video – The Promise of Biochar

Biochar.ca’s research articles

Wikipedia article

 

For my own gardening purposes I grew in a rather shady raised bed, which I dug out and filled with a small mountain of sticks and twigs which had been rotting in my compost heap for a year or two (pretty much making it impossible to add anything else. On top of them I dumped a couple of bags of manure then dumped the earth back on (it’d been fallow for about a decade, completely shaded out by a tree above it which I cut back). The shade took its toll, it was on the north side of a two-story garage, but I still managed a months-long bumper crop of radishes, as well as some hearty kale which is still going, and plenty of salad greens. For next year I’m preparing a strip right outside my kitchen in an otherwise concrete backyard with some of the worst earth I’ve ever seen (the only thing which grows well is a smart-car-sized zebra mallow coming out of a cinder-block-hole) by layering it with kitchen scraps, straw, and garden waste (I picked up some green-bin-bags on garbage night), and manure on an ongoing basis, as a sort of green-bin alternative, and I’ll keep y’all posted on how that goes into the winter and next planting season.

 

 

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