Presentation on theme: "Some 50 – 80% of the organic carbon that was once in the topsoil has been lost to the atmosphere over the last 150 years or so, due to inappropriate management."— Presentation transcript:
Some 50 – 80% of the organic carbon that was once in the topsoil has been lost to the atmosphere over the last 150 years or so, due to inappropriate management. By inference, degraded soils have the potential to store up to five (5) times more organic carbon in their surface layers than they currently hold. But only under changed management.
What Carbon looks like in nature We can tell, just by looking, that there is more carbon in one area than the next area. The amount of vegetation - both trees and grasses tells us about carbon levels
This cattle ranch in Sonora, Mexico, is typical of hundreds of millions of hectares of grazing land in arid and seasonally dry areas worldwide.
This is the neighboring ranch, La Inmaculada.
Same area Same rainfall Same soils Same plant species Same season (pictures taken on the same day) La Inmaculada actually has more cattle than the drier ranch The only difference is management
Same area Same rainfall Same soils Same plant species Same season (pictures taken on the same day) The area above actually has more livestock It also has far more wildlife, including buffalo, elephant, and lion The only difference is management
When properly managed, grass plants store large amounts of carbon material below the soil surface Improper management (common in most of the world) leads to poor carbon storage - LH pots Proper management (RH pot) means plants hold very large amounts of carbon out of sight, below the soil surface
Carbon is black. When properly managed soils become darker
The simple maths behind Soil Carbon One hectare = 10,000 sq. metres Soil 33.5 cm deep (1 foot approx) Bulk density = 1.4 tonnes per cubic metre Soil mass per hectare = about 4,700 tonnes 1% change in soil organic matter = 47 tonnes Which gives about 27 tonnes Soil Carbon This captured 100 tonnes of atmospheric CO 2
Soil carbon potential change and CO2 consumption per annum in Australia Prof. Peter Grace - QUT (personal communication)
Prof. Keith Paustian - University of Colorado (personal communication)