‘Bellis’, Brisbane’s sustainable house and garden, produces 4 metric tonnes of compost a year. Using low till, ecologically sustainable gardening techniques enables this property to sequester 0.638 metric tonnes of atmospheric CO2 gas each year. Doesn’t sound much, does it?
In the USA, a thirty year study by the Rodale Institute discovered that ecologically sustainable farming, where compost is central to food production, each 1 hectare of composted land sequesters 7.845 metric tonnes of atmospheric CO2 gas a year.
Andre Leu, the chairman of the Organic Federation of Australia, said “The important point about this ground breaking research is that the amount of CO2 sequestered is based on what has been achieved through current organic farming practices. This is not a theoretical estimate as in some of the tree plantation models, or unproven like the millions of dollars being spent on clean coal or mechanical geosequestration trials.”
By contrast, organic farming and gardening rely on using the natural carbon cycle to increase the amount of carbon stored in the soil. They achieve this by stimulating soil microorganisms to increase soil fertility, defend plants against disease and to improve plant nutrition and soil health. Commonly referred to by organic farmers as “black gold”, humus is a stable form of organic matter that remains in soil after prolonged microbial decomposition, and is an ultimate indicator of healthy soil. Carbon can be contained in stable humus fractions for more than 1,000 years.
Dr Andrew Monk, BFA Standards Committee Chair, says humus also helped farmers remain viable in dry times. “Humus is well-known for its moisture retention and resilient nature in extreme weather conditions. Strong soil has been a saving factor for many producers during recent droughts.”
Organic growers know that mycorrhizal fungi are a critical group of soil microorganisms to cultivate. These special fungi conserve soil carbon by secreting glomalin, a powerful glue, and using it to bind humus with clay and minerals to form aggregates. Natural carbon sequestration by this mechanism allows organic carbon to steadily accumulate in organically farmed soil, rather than being lost as an inorganic Greenhouse Gas to the atmosphere.
Sequestration starts in the first year of change. According to Australia’s CSIRO there is approximately 50 M ha of farmland in Australia, roughly 6 per cent of the land area. Using Rodale’s results this represents potential for at least 390 million tonnes of captured carbon per year.
Why have our representatives been ignoring a simple, cheap and effective means of reducing our carbon footprint? Perhaps it’s easier to throw money and resources at one big, headline project that promises ‘business as usual’ instead of looking at how we need change our damaging ways. The hard facts of Global Warming and Peak Oil mean that ‘business as usual’ is not an option.
According to the Australian Greenhouse Inventory in 2005, net Greenhouse gas emissions were 559,074,490. Therefore Australian farmers using compost could naturally sequester almost 70% (69.76%) of our emissions.
This extract comes from my article ‘Carbon Farming’ first published in the ABC’s ‘Organic Gardener’ magazine, 2008.
How will you celebrate International Compost Awareness Week?
9th May 2014