Agriculture Reference
In-Depth Information
be biophysical limits to how much carbon a
soil can store naturally. However, the know-
ledge on a soil's inherent capacity to seques-
ter carbon is absent, as natural reference
soils are missing as a result of intensive land
use. The biophysical limits are further con-
strained by land-use routines, which often
have a strong historical/traditional bearing
and are slow to change.
Economic drivers, in contrast, may change
the cultivated crop or the land-use type
(e.g. forest to grassland) rapidly, with pos-
sibly grave consequences for the soil carbon
balance. Examples of the latter are changing
market demands for food, fodder and energy
crops. Changes in policies with implication
for land use from one cultivation period to
the next occur quickly and can lead to rapid
and severe losses of soil carbon, as illustrated
by governmental biofuel and bioenergy sub-
sidies that stimulate the ploughing of grass-
land for maize cultivation or the drainage
of peatlands. In view of the various con-
straints, a research management plan must
be implemented along with management
actions to monitor and adapt practices and
goals according to site-specific conditions
at different spatial and temporal scales.
We propose to create a global research pro-
gramme that focuses on developing robust
SOC management and policies for multiple
benefits across terrestrial ecosystems.
Despite current knowledge on SOC pro-
cesses, there are still multiple uncertainties
and challenges for the management of SOC
that call for a research action programme.
Uncertainties include, but are not limited
to: the quantification of synergies between
the different benefits of SOC, defining critical
thresholds for achieving gains by individual
and multiple benefits, and establishing the
time frame needed to reach the level re-
quired for significant impact on an environ-
mental service. In addition, the significance
of change in SOC towards a social benefit is
not well understood. Research is needed to
measure and assess better the supplies and
benefits of SOC for agricultural productiv-
ity, water, biodiversity, bioenergy and cli-
mate regulation. Other uncertainties of im-
portance include the precise rates of change
in SOC, especially across the full rooting
zone of the soil system, and the quantifica-
tion of the impact of future land conver-
sions to agriculture, the abandonment of de-
graded land and deforestation on SOC.
Finally, the lack of methodologies for quan-
tifying the effects of land management and
SOC on multiple benefits is a handicap for
promoting initiatives towards enhancing
SOC stocks. However, these uncertainties
should not stand in the way of the critical
need to increase SOC and of research that
runs across terrestrial ecosystems (Seastedt
et al ., 2008).
The research community is exploring a
wide range of technologies to reduce uncer-
tainty on the benefits of SOC. A variety of
geographic information system (GIS) tools
and ecosystem models are being used to
explore the spatial interactions between
services from fields and across landscapes
(Hayes et al ., 2012; Aide et al ., 2013). These
tools and models can be used to identify
where one service negates the ability to
have other services (in the past, agriculture
and biodiversity conservation). Such tools
could be expanded to include SOC. The key
limitations here are effective representation
of soil carbon-services relationships, suffi-
cient data to represent these services over
space and the capacity to predict changes to
interactions over time. While there is evi-
dence of the positive impact of management
practices for enhancing SOC on some ser-
vices such as food production and water
quality at local (plot) and catchment level,
other services such as climate regulation occur
at a larger scale (subnational, regional or
global) and are even more difficult to quan-
tify. Despite these uncertainties, failing to
act towards increasing SOC on the basis of
limited current scientific evidence is much
more dangerous than the risks associated
with continuous decline in SOC stocks.
Finally, an overriding challenge is the
communication between scientists, policy
makers and the public. Educating the public
about the critical importance of SOC to
food, water, bioenergy and climate requires
a revolution in communication, specifically
about the multiple benefits of SOC for daily
life. Translating knowledge of the management
and benefits of SOC into communications
 
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