Composting and Climate Change

Consumption of fossil fuels is far from the only cause of GHG emissions.  Carbon released from soil exploitation has been a significant contributor to climate change.  Recognizing the connection between soil and climate is key to reestablishing sustainable soil management practices.

Impact of Soil Exploitation

  • More than twice as much carbon is stored in the Earth’s soil as is stored in all living vegetation and the atmosphere combined
  • Over approximately 20 years, most agricultural soils loose 50% of their organic carbon because of the reliance of industrial agriculture on chemical fertilizers and intensive farming practices
  • Soil exploitation has been responsible for approximately one-third of the increase in atmospheric CO2 over the last 150 years, mainly through the loss of soil organic carbon
  • More carbon entered the atmosphere from soils than from fossil fuel consumption from the 1860s until the 1970s

Compost and Carbon Sequestration

  • Harvesting crops removes carbon from the soil that would otherwise return to the soil when the plant dies and decomposes
  • Compost returns organic matter to the soil
  • The nitrogen in compost can increase soil productivity, which can lead to increased crop residues and an increased return of carbon to the soil
  • Composting increases the formation of stable carbon that remains bound in the soil for long periods of time
  • Applying organic matter to soils is one of the most effective ways to divert CO2 from the atmosphere and convert it into organic carbon in soils

Organics Diversion and Methane Avoidance

  • Organic “green” waste in the conventional waste stream is either landfilled where it decomposes in anaerobic conditions producing methane – a GHG 72 times more powerful than CO2 over a 20 year period – or it is incinerated and its useful components obliterated
  • One ton of food waste in a landfill generates 0.25 tons of methane (or 6 tons of CO2) in the first 120 days
  • Organic waste can be separated at the source and diverted from the conventional waste stream
  • Composting source separate organic waste allows the organic materials to decompose aerobically thereby avoiding the production and release of methane into the environment
  • The US sent 31 million tons of food waste to landfills in 2007
  • Composting this waste would be the equivalent of taking 8.4 million passengers cars off the road