Soils

     "There is hope right beneath our feet. There is a technology for massive planetary geo-engineering that is tried and tested, and available for widespread dissemination right now.  It costs little and is adaptable to local contexts the world over.  It can be rolled out tomorrow, providing multiple benefits beyond climate stabilization.  The solution is farming.  Not just business-as-usual industrial farming, but farming like the Earth matters.  Farming like water and soil and land matter.  Farming like clean air matters.  Farming like human health, animal health and ecosystem health matters.  Farming in a way that restores and even improves on soil’s natural ability to hold carbon.  This kind of farming is called regenerative organic agriculture, and it is the short-term solution to climate change we need to implement today.”

     Field trials in the U.S., Egypt, Iran, and Thailand show carbon seqestration of 2.4 to 6.4 tonnes per hectare [0.87 to 2.34 tons per acre] per year.  "Even if modest assumptions about soil’s carbon sequestration potential are made, regenerative agriculture can easily keep annual emissions to within the desirable lower end of the 41-47 GT CO2e range by 2020.”

     Elements of regenerative organic farming include cover crops, residue mulching, composting, crop rotation, and conservation tillage.  Plants so treated sequester carbon in soils at depths to at least 80 cm, for decades to millennia.  Clay helps.  Mycorrhizal fungi are key players in the process, producing glomalin in which carbon is stored.  Yields of organic crop systems exceed those in artificial fertilized systems in times of drought, and they are more resilient in the face of greater weather variability.

     Rodlae's Farming Systems Trial, for 23 years since 1981, has shown that soil, under organic agriculture management, can accumulate about 1,000 pounds of carbon per acre foot of soil each year.  This accumulation is equal to about 3,500 pounds of carbon dioxide per acre, taken from the air and sequestered into soil organic matter.  When multiplied over the 160 million acres of corn and soybeans grown nationally, a potential for 580 billion pounds of excess carbon dioxide per year can be sequestered, when farmers transition to organic grain systems.
    Organic grain production systems increase soil carbon 15 to 28%.  Moreover, soil nitrogen in the organic systems increased 8 to 15%.  Decay rates differ for soil organic matter under different management systems.  In the conventional system, the application of soluble nitrogen fertilizers stimulates more rapid and complete decay of organic matter, sending carbon into the atmosphere instead of retaining it in the soil as the organic systems do.
    Soil microbial activity, specifically the work of mychorrhiza fungi, plays an important role in helping conserve and slow down the decay of organic matter.  Mychorriza fungi are more prevalent in the organic farm systems. These fungi work to conserve organic matter by aggregating organic matter with clay and minerals. In soil aggregates, carbon is more resistant to degradation than in free form and therefore more likely to be conserved.
    In conventional and organic farming systems, yields of corn and soybean were not different, except in drought years.  Then, organic systems yielded 25 to 75% more than the conventional system.  The organic yield advantage in drought years is specifically related to the ability of higher-carbon organic soils to capture and deliver more water to crop plants.

This may be our most important way to reduce CO2 levels in the air.