Agriculture Reference
In-Depth Information
Table 5.
Characteristics of the Analyzed Model Regions in Bavaria
Permanent
Average
Model Agricultural Agricultural Maize
Crops and
Field
share
1)
Region Area in Use Crop Land
Pasture Land
Size
ha
ha
percent
percent
ha
I
30,812
20,900
44
32
2.17
II
47,572
31,511
19
34
1.89
Source:
Reitmeier and Menrad, 2006.
that have agricultural areas in use (AAU) of between 30,800 ha in model
region I and nearly 50,000 ha in model region II (Table 5). Agricultural
crop land (ACL) is between 20,000 and 30,000 ha with high shares of
maize in model region I (44 percent of ACL) and low maize cultivation
in model region II (19 percent of ACL) (Table 5).
So far, there are no definite rules concerning the width of the isola-
tion distances between Bt maize and conventional maize fields to comply
with the legal threshold of 0.9 percent in Germany. Therefore, a vari-
ety of buffer zones around Bt maize fields are considered in the analysis
ranging from 20 m to 100 m. A buffer zone of 20 m is in line with the
results of the German field trial experiments (so-called “Erprobungsan-
bau”) where out-crossing rates of Bt maize were analyzed under German
conditions in 2005. According to this experience, an isolation distance
of 20 m for maize is sufficient to comply with the threshold of 0.9 per-
cent GM adventitious presence (Weber et al., 2005a, b). Furthermore,
the effects of adoption rates of 10 percent, 30 percent, and 50 percent Bt
maize were analyzed in both model regions.
In an initial scenario with 10 percent Bt maize adoption in the region
I, it can be observed that between 1 percent and 7 percent of the conven-
tional maize area is affected by neighboring Bt maize fields depending
on the isolation distance required. With increasing adoption rates of Bt
maize the proportion of the affected conventional maize area increases
up to 31 percent (Table 6). With respect to potential conflicts among
