Agriculture Reference
In-Depth Information
managed directly at the scale of the farm
and the catchment because local inhabitants
(farmers, nature conservationists) under-
take the soil management. Hence, the main-
tenance of soil fertility and soil health at the
field/farm level is inherently linked to the
maintenance of SOC at that level. However,
different priorities for soil management pre-
vail at the two different scales. While at farm
scale the individual profit and subsistence
assurance of farmers drive soil management
actions, at catchment scale overarching soil
functions such as filter and buffering func-
tions move into the focus of societal de-
mands, and issues such as large-scale ero-
sion protection, provision of clean drinking
water, protection from desertification and
extreme events will drive decision making.
Such soil functions are useful in a meaning-
ful way only at this larger scale. At the
catchment level, processes such as deforest-
ation, desertification and extreme climate
events have a direct impact on SOC through
the reduction of C input and the increase of
C output from the soil. Furthermore, ero-
sion is increased by these processes and in
turn affects the quantity, quality and distri-
bution of SOC across the catchment (Lal,
2005; Doetterl
et al
., 2013).
Most actions which benefit SOC at the
local scale provide benefits at the national
and global scales and can simply be aggre-
gated. If all single farms are prosperous, the
catchment and the nation are also prosper-
ous, and vice versa. However, some soil
ecosystem functions only become meaning-
ful at a larger scale; for example, climate
change mitigation by avoiding SOC losses,
reducing greenhouse gas (GHG) emissions
and sequestration of SOC. Such ecosystem
functions can only be realized when prac-
tices are implemented on many farms sim-
ultaneously.
All of the SOC management strategies
mentioned above also need to be dealt with
at the national level, as this is often the ad-
ministrative unit at which political deci-
sions are made. This can be done in an ag-
gregated way if there are no properties
emerging at the national level that are not
already addressed at the catchment or farm
level. At the global level, climate change is
a major issue. At the local level, however,
with respect to SOC management, climate
change is considered much less important
than land use and land-use change.
At the catchment level (or administra-
tive 'region'), SOC stocks are influenced by
land-use planning including the preserva-
tion of aesthetic values, urbanization linked
to rural urban migration and the need for
transportation corridors. Such regional topics
are often addressed by local actors such as
local-level public agencies (e.g. planning
agencies), conservation and development
NGOs and local business. A region is usu-
ally made up of a matrix of farms, forests,
urban and infrastructure areas. The regional
level is key, as it is at this spatial scale where
farmers' behaviour and national policy interact.
The main issues at the national scale re-
late to improving trade balances: for ex-
ample, through developing export-oriented
agricultural incentives; national security,
involving the need to produce sufficient
cheap food to feed increasingly urban popu-
lations; and securing the provision of suffi-
cient energy and water sources. All these
objectives are linked to how SOC is man-
aged at the lower scales. It is at the national
scale where regulations are designed and
implemented that affect directly the con-
straints and opportunities for alternative
SOC management strategies at the farm and
catchment level. Of course, such policy de-
cisions are influenced by higher-order topics
at the global level. For instance, migration
and land acquisition processes can both
constrain or enable national policy.
Crucially, the socio-economic issues
cut across all scales in a nested way. What
may be a prime concern for a farmer (e.g.
livelihood vulnerability) may be influenced
by rural urban migration processes at the
catchment level or by a higher-order food
security objective at the national level. The
latter may, in turn, be affected by global
issues, such as climate change policies and
economic globalization. Likewise, farmers'
land-use options are determined by global
institutions feeding through national pol-
icies and regional land-use planning.
On the temporal scale, the main object-
ives of land use on different spatial scales
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