What does humus have to do with the carbon cycle ?
• Why is carbon storage in soils important? The global carbon cycle transforms carbon from one form into another, using energy supplied by the sun. The primordial atmosphere, before plants and photosynthesis, contain much more carbon dioxide than today and the mean Earth temperature was correspondingly much higher. Plants use the energy in solar radiation to transform carbon dioxide 3 and water into biomass, releasing oxygen into the atmosphere. The carbon in biomass, residue, humus 1 and fossil fuels is “reduced” carbon 1. If all of the “reduced” carbon (biomass, residue, humus and fossil fuels) was combusted the oxygen in the atmosphere would be consumed and carbon dioxide produced, returning both the oxygen and carbon dioxide contents in the atmosphere to their original primordial levels. Humus is important because there is twice as much “reduced” carbon stored as humus than is stored in biomass. Anything that would increase the rate humus is oxidized will increase atmospheric carbo
