Soil erosion in Italy could be reduced by 43% if Good Agriclutural and Environmental Conditions (GAEC) were fully adopted, a recent study has found. Reducing soil erosion would also increase soil organic carbon stocks, particularly on cultivated sloping land.
Source: Science for Environmental Policy, March 2016
Protecting European soils from erosion is therefore a priority
under the European Commission’s soil protection thematic strategy 1 . To encourage
environmentally sound agriculture, actions to protect soil are included in the
cross compliance mechanism attached to pillar 1 farm subsidies under the Common
Agricultural Policy (CAP). Under the CAP Good Agricultural and Environmental
Condition (GAEC) requirements, Member States are obliged to prevent soil
erosion and maintain soil organic matter through national or regional standards,
such as minimal soil cover maintenance (GAEC 4); minimum land management reflecting
site specific conditions to soil loss (GAEC 5); and maintenance of soil organic
matter level (GAEC 6). Should farmers not comply with these requirements, they
are liable to a small penalty (approx. 5%) on their subsidy.
The concept of GAEC includes protecting soils against erosion
and maintaining soil organic matter and soil structure (other GAECs are aimed
at protecting water, biodiversity and animal health). It is up to Member States
to establish standards which are appropriate to their conditions. Example
actions include minimising the area of bare soil (e.g. by leaving vegetable matter on soil surfaces); limiting
soil loss through methods such as growing crops across or perpendicular to a
slope; and maintaining soil organic carbon stocks (e.g. by residues management
including restrictions on burning crop residues).
Although Member States must notify the commission on how
they implement the GAECs, little is known about the effect GAEC standards have
had on reducing soil erosion and increasing soil carbon stocks in Europe. In
the first study of its kind, researchers, including from the European
Commission’s Institute for Environment and Sustainability, have assessed the
impact of the GAECs at the national level. They chose Italy as a case study because
arable land there often has steep slopes with soil that is particularly
susceptible to being eroded by heavy rainstorms.
The researchers linked an erosion model with an agro-ecosystem
model to calculate the impact of GAEC practices on soil losses and soil organic
carbon stocks. Average annual soil erosion losses due to changes in climate,
land cover, soil properties, landscape features and agricultural practices were
assessed using data from climate, land cover and agricultural databases, as
well as satellite images.
The researchers looked at three scenarios. The first,
‘baseline’, represented the absence of any specific national policy on erosion
prevention and carbon conservation and was based on conditions prior to the
GAECs on soil being included in the cross compliance mechanism. The ‘current’
scenario is based on the implementation of compulsory GAEC standards, beginning
in 2005. As a result of changes to practice, this scenario had different soil
erosion rates to the baseline. Finally, the ‘technical potential’ scenario
reflects the avoided erosion and the amount of soil organic carbon that could
be stored by 2050, if GAEC standards were to be implemented across all arable
In short, the three scenarios represent: no GAECs; current
GAEC implementation; and application of GAECs to the entire surface of arable
land in Italy.
For the baseline, the researchers estimated that soil is
being lost at 8.33 tonnes per hectare per year (t/ha/yr) across all arable land
in Italy. Around 29% of the arable land had losses
greater than 10 t/ha/yr, which is the water erosion threshold
indicator for tolerable soil losses in Mediterranean environments, at which
point the rate of soil erosion becomes unsustainable.
estimate that approximately 73% of soil erosion is occurring in 25% of the
Italian cropland. Farms located on slopes (greater than 10%) experience around
64% of the total annual soil loss, as they are the most exposed to soil erosion.
For the current scenario, soil loss was estimated to be 7.43
t/ha/yr. Approximately 25% of the arable
land has losses greater than 10 t/ha/yr, which is around an 11% decrease compared
with the baseline scenario. The ‘technical potential’ scenario could
significantly reduce soil losses to 4.1 t/ha/yr, a 51% reduction compared with
the baseline scenario and approximately 43% compared with the current scenario.
Top-soil organic carbon stock varied in the three scenarios
depending on the location of arable land and land management practices. The
study suggests that current GAEC practices have led to an overall 17% carbon
accumulation through avoided soil erosion, compared with the baseline scenario.
If these standards were fully implemented on all arable land, the soil organic
carbon stock in Italy may increase by up to 11% in the long-term.
As monitoring soil erosion and carbon levels across all
farms is not viable, the researchers suggest their modelling approach could
help policymakers to assess the effectiveness of soil conservation measures at
national, regional and even global levels. Research is also being conducted to
assess sediment and carbon budgets, including transport and depositional