Agriculture Reference
In-Depth Information
There are moderate opportunity costs of increasing isolation dis-
tances in maize crop production due to the small differences in the gross
margins of alternative crops whereas the changing of flowering times
causes substantial income losses for farmers active in maize crop produc-
tion. The opportunity costs of discard widths on the non-GM field (which
is separately harvested) differ significantly depending on the width of the
discard width as well as the size of the non-GM field (Table 2). High dif-
ferences in the per-hectare costs can also be observed for non-GM buffer
zones around GM fields mainly depending on the GM adoption rate in a
region and the estimated economic performance of GM maize.
The comparison of our results with the results of other studies dealing
with coexistence issues is complicated by the fact that other regions with
other cropping systems are analyzed as well as due to differing method-
ological approaches. Tolstrup and colleagues (2003) assumed that for
silage/feed maize production in Denmark it might be sufficient to fulfill
the required threshold of 0.9 percent by cleaning machinery what results
in significantly lower per-hectare coexistence costs compared to the sug-
gested measures for the French region of Poitou-Charantes. Bock and
colleagues (2002) analyzed coexistence costs in maize crop production
for feed purposes in France and Italy. For a farm producing in an inten-
sive maize cultivating region that is comparable to the analyzed region
of Poitou-Charantes, costs of changing agricultural practices were esti-
matedto45.4
/ha due to changing flowering time of the cultivated vari-
eties (Bock et al., 2002). This result is in line with the time isolation costs
of changing from late to mid-early varieties (Table 2).
To identify the effects of different coexistence measures in a land-
scape, several scenarios of GM adoption were simulated with the
MAPOD
R
model in the region of Poitou-Charantes (France). The costs
of an existing farm in this region were calculated for this purpose assum-
ing that non-GM buffer zones are used as coexistence measure because
they seem to be a cost-effective measure to reach the defined thresh-
old of 0.9 percent GM adventitious presence in maize crop production.
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