Attributes of 15 Tasmanian dermosols were assessed using field and laboratory
techniques to determine changes associated with 3 typical forms of
agricultural management: long-term pasture, cropping with shallow tillage
using discs and tines, and cropping (including potatoes) with more rigorous
and deeper tillage including deep ripping and powered implements. Soil organic
carbon in the surface 75 mm was 7.0% under long-term pasture compared
with 4.3% and 4.2% in cropped paddocks. Microbial biomass carbon
concentrations were 217 mg/kg, 161 mg/kg, and 139 mg/kg,
respectively. These differences were negatively correlated with the number of
years cropped. Greater bulk densities were found in the surface layer of
cropped paddocks but these were not associated with increased penetration
resistance or decreased infiltration rate and are unlikely to impede root
growth. Long-term pasture paddocks showed stronger structural development and
had smaller clods than cropped paddocks. Vane shear strength and penetration
resistance were lower in cropped paddocks than under long-term pasture. Many
soil attributes showed no significant differences associated with management.
Including potatoes in the rotation did not appear to affect these dermosols,
which indicates a degree of robustness in these soils.
clay loams, organic carbon, soil strength, aggregate stability, land
management, cropping.
No long-term trends in p
CO2
despite increasing organic carbon concentrations in boreal lakes, streams, and rivers
