Chernozem under different agricultural land use were compared in a suburban area:
three on cropland with
different land use histories; one in an area of complex cultivation; one fallow; and
one under grassland,
considered to be in close to natural state, as a control. Soil profiles at each site
were described and classified, and
chemical characteristics analyzed in detail. Topsoil (0-40 cm) bulk density (BD),
total organic carbon (TOC), total
nitrogen (TN), ammonium lactate-extractable P, K, Ca and Mg were measured, and microbiological
communities
were characterized by phospholipid-fatty acid (PLFA) markers. We found significantly
increased BD but
decreased TOC and TN in the cultivated sites compared to the control. Values of ammonium
lactate-extractable P
(P-AL) were higher at the natural site, but Ca-AL, Mg-AL and K-AL content of the cultivated
and mineral-fertilized
agricultural sites were higher than or equal to the grassland site. Total microbiological
activity correlates
significantly positively with TOC and TN and negatively with the BD. Sites with perennial
vegetation cover and
higher biodiversity showed greater microbiological activity and, in case of the arbuscular
mycorrhizal fungi,
actinobacteria and anaerobe bacteria, the differences are significant. Despite the
nutrient depletion and lesser
microbiological activity, cropland sites preserved their taxonomic status as Chernozem.
Sites that have under
gone more extreme human impacts before the recent land use had lost their diagnostic
features (aggregation,
color, secondary carbonate accumulation) and now key out as Kastanozem, Phaeozem or
Regosol.
