From Chris Deane
I was not reassured by P. J. Loveland and J. Webb’s letter about research
showing “small” changes in the organic carbon content of topsoil
(19 August, p 51).
A loss of 0.1 per cent at arable sites in 15 years extrapolates to the
complete disappearance of organic carbon in 345 years. A loss of 0.5 per cent on
managed grassland would lead to the disappearance of organic carbon at these
sites by the year 2106, on average.
My guess is that there might be problems in soil stability and/or plant
growth before these dates. In addition, not all sites are average, and I
strongly suspect that some might be severely depleted well before these
dates.
Oxford
