Carbon balance of cultivated
soil (loamy Phaeozems) under fallow was compared with that of soils abandoned
1, 5, 10, and 25 years converted naturally to permanent grassland (Moscow
region, Russia). Carbon inflow or net primary production (NPP) was calculated
as the sum of the above and below ground productivity of grassland ecosystems.
The total C outflow was equal to the annual CO2 fluxes from the
soils and was estimated as CO2 emission measured by the closed
chamber method. Carbon balance (CB) was defined as the difference between
respiration of heterotrophs and NPP. Botanical survey clearly showed that the
vegetation of abandoned agricultural lands changed to permanent grasslands
after 5 years of abandonment. Carbon inflow increased from 97 g C·m-2·yr-1 in the
arable soils to 1100 g C·m-2·yr-1 in the 10-yr grassland. Total
annual carbon losses from soils as CO2 amounted to 347-845 g
C·m-2·yr-1. Heterotrophic respiration varied from 272 g C·m-2·yr-1
in cultivated soil to 411 g C·m-2·yr-1 in 25-yr grassland. Our
estimations showed that 5, 10, and 25 yr grasslands act as carbon sink and
their C balance constituted -217 g C·m-2·yr-1, -778 g C·m-2·yr-1
and -473 g C·m-2·y-1, respectively. Arable soils under the fallow
act as CO2 source (CB = +175 g C·m-2·yr-1). Carbon
balance of the one-year grassland was close to zero. Hence, after 5 years
abandonment former arable lands converted to permanent grasslands become a
stable C sink.
Author: I. N. Kurganova, A.M. Yermolaev, et al (ikurg at issp dot psn dot ru)
Filesize: 46.55 Kb