Diversifying crop rotations with temporary grasslands - Université de ...

Table 3: Four strategies for combining agricultural production and biodiversity conservation.
The four strategies lie on a gradient between separation and integration, as illustrated in Fig. 5.
What is preserved?
Fragmentatio
n of habitats
Use of ecosystem
services?
Problems
Crop yield
risk of weed,
pest, disease
invasions
‘Spatial separation’
‘Wildlife friendly farming’
(no spatial separation)
1) Large-scale 2) Small-scale 3) Temporal
4) Complete
spatial separation: spatial separation: separation:
integration:
Large ‘untouched’
nature reserves and
regions of intensive
production
Static mosaic of
productive fields and
‘unproductive’ zones
Dynamic mosaic of high
productive crops and
less productive periods
on crop rotation scale
Productive and
unproductive organisms
coexist at the same place
and time
Separation Integration
Natural areas with
associated ‘wild’
organisms
Some organisms typical for farmed landscapes (and
some ‘wild’ organisms
Organisms typical for
farmed landscapes, no
space for ‘wild’ species
Large-scale Medium scale Low
No
No ‘untouched’ nature
and no space for huge
reserves in Europe
Some (needing spatial
migration of organisms)
small size of protected
areas
Maximum on productive parts? But no production
on ‘spared’ land
High? (no mechanisms
of auto-regulation)
A.III.8 Crop rotation
18
Some (needing spatial
migration of org. or
temporal outlast of
positive effects)
Spatio-temporal mosaic
of high and low yield
fields
Immediate,
without spatial or
temporal restrictions
No optimal weed
infestation level, no steady
balance possible
Permanently reduced
yield?
? ? Low?
The main benefits of rotating different crops on a given field are (1) the maintenance of soil
fertility and (2) the regulation of weeds, pests and diseases. Both may contribute to increase
crop yields and reduce the need of inputs compared to monocultures (Smith et al., 2008).
Historically, the soil fertility has often been restored by letting the field lie fallow for about
one year after 1-3 years of wheat, barley, oats or other cereal crops. In central and northern
Europe, such ‘food-feed-fallow’ rotations were probably introduced by the Romans about
2000 years ago. Between about 1700 and 1800, European farmers gradually replaced the
fallow phase by sown grass or legume forage crops that were grazed by livestock. They
adopted four-year rotations including e.g. cereal grain crops, root crops and forage crops
(Freyer, 2003). Fields were thus always planted for food or feed increasing the overall