Abstract: | Many mine spoils present at the surface of reclamation sites in the Lower Lusatian mining district are carboniferous substrates,
i.e. contain geogenic organic matter. Depending on its susceptibility to microbial degradation, geogenic organic matter might
influence the establishment of a carbon requiring microflora in mine spoils. As geogenic organic matter contains substantial
amounts of organic nitrogen it is also a potential source for plant available N. The objective of the present study was to
quantify C and N mineralisation and microbial biomass in geogenic organic matter present at reclamation sites in Lower Lusatia.
We also studied, whether these properties can be influenced by raising the originally low pH to near neutral conditions. In
laboratory incubation studies, the rates of CO2 evolution and net N mineralisation were determined in geogenic organic matter and carboniferous mine spoil with and without
addition of lime. At the same time, microbial biomass carbon was estimated. As a reference, soil organic matter originating
from the humus layer of a 60-year-old Pinus sylvestris stand was used. As indicated by the initial rates of C mineralisation,
geogenic carbon was microbially available but to a lower extent than soil organic carbon. During incubation, C mineralisation
remained constant or tended to increase with time, depending on the origin of the sample, while it decreased in soil organic
matter. Unlike in soil organic matter, in geogenic organic matter and carboniferous mine spoil, C mineralisation was not consistently
promoted by lime addition. Prior to incubation, microbial biomass in geogenic organic matter and carboniferous mine spoil
was about 10-fold lower than in soil organic matter and tended to increase with incubation time while it decreased in soil
organic matter. Similar to C mineralisation, microbial biomass in geogenic organic matter increased after liming, while it
declined in carboniferous mine spoil immediately after lime addition. Rates of net N mineralisation were very low in geogenic
organic matter and carboniferous mine spoil regardless of the length of incubation and could not be enhanced by raising the
pH. It was concluded, that in mine spoils where accumulation of soil organic matter has not yet occurred, geogenic organic
matter can be favourable for the establishment of a heterotrophic microflora. However, in the short term, geogenic matter
is no source for plant available N in mine spoils.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. |