TITLE:
Shifts in Carbon Stocks through Soil Profiles Following Management Change in Intensive Agricultural Systems
AUTHORS:
Baokun Lei, Yongbo Xu, Yanfen Tang, Konrad Hauptfleisch
KEYWORDS:
Carbon Sequestration, Intensive Agricultural Systems, Fertilization, Soil Profiles
JOURNAL NAME:
Agricultural Sciences,
Vol.6 No.3,
March
10,
2015
ABSTRACT: Soil carbon content
is an important ecosystem property, especially under the ongoing climate
change. The stability of soil organic matter (SOM) is controlled by
environmental and biological factors including anthropogenic-induced
agricultural management change. However, understanding the effects of
anthropogenic activities (e.g., intensive agricultural practices) on carbon
stability of soil profiles remains a challenge. The objective of this study was
to determine the changes in carbon stocks through soil profiles following
agricultural management change from grain fields to greenhouse vegetable
fields. The sampling sites were located in an intensive vegetable production
area in northernChina.
A total of 20 pairs of grain fields (GF) and adjacent vegetable fields (VF)
within a distance of50 mwere selected. The results showed that soil organic carbon (SOC) storage
increased by 10.6 mg C ha-1 in upper soil layers but decreased by
5.3 mg C hm2 indeeper soil layers due to large input of organic manure and chemical fertilizer
following the conversion from GF to VF. Conversion to VF also led to increased
dissolved organic carbon (DOC) and dissolved organic nitrogen (DON)
concentrations. Extremely higher input of chemical N fertilizer in the VF led to
the soil C:N ratio decreased by 2.02 times and the -N leached to deeper soils increased by 3.7
times compared to that in the GF. The pH value and microbial biomass carbon
(MBC) content were lower in the VF than in the GF. These results indicate that
excessive nitrogen application as fertilizers might lead to deeper soil carbon
depletion. Reducing nitrogen addition in intensive agricultural systems is thus
necessary to reduce soil carbon loss and to maintain a relatively sustainable
soil system.