SOIL CARBON STORAGE FROM USING ORGANIC RESOURCES ON LAND
*B. J. Chambers1, A. Bhogal1, P. Gibbs1, A. P. Whitmore2, D. S. Powlson2
1ADAS Gleadthorpe, 2Rothamsted Research,
(free)
The extent to which organic material returns could increase the organic carbon content of
arable soils in the UK is reviewed in this paper. Increases in soil organic carbon (SOC)
following the addition of a range of organic materials were estimated from a number of longterm experiments in the UK. Carbon retention was greatest from biosolids cake, green
compost and paper crumble additions, and least from farm manure additions, with an
estimated 630 -1800 kg/ha C retained in the topsoil at application rates of 250 kg/ha total N.
This equates to a 0.7-2.0% increase in the typical carbon content of an arable topsoil.
However, it is debatable whether these increases in SOC can be counted as genuine
additional carbon storage (against a present/recent day baseline), as with the probable
exceptions of compost and paper crumble applications (which are largely a result of recent
diversions away from landfill), almost all other organic materials considered were already
being applied to land. The predominant justification for returning organic materials to soil
should therefore be for maintaining and enhancing existing SOC levels, and completing
natural nutrient and carbon cycles, not carbon storage for climate change mitigation per se.
KEYWORDS
Soil organic carbon, carbon storage, organic materials, climate change
