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Ulrich Köpkea1 and Thomas Nemecekb2
Faba bean enables diversification of the agroecosystem, i.e. planned biodiversity in time via diversified crop rotations and in space via intercrops, indirectly enhancing associated diversity of wild flora, wild fauna and soil microbes that may affect the sustainability of agricultural systems. Nevertheless, most effects are indirect effects on soil fertility, productivity, and system stability, as well as resilience of the entire agroecosystems, effects that can seldom be attributed solely to this crop.
The environmental impacts of grain legumes have been studied at different
levels by means of life cycle assessment (LCA). Considering the individual
crops, it can be shown that faba bean enables savings of energy and
reductions of greenhouse gas emissions, but it is difficult to assess
all precrop effects at the individual crop level. First, comparisons
of whole crop rotations with and without grain legumes show reductions
of energy consumption, global warming, ozone formation, and acidification
and ecotoxicity in intensive cereal-rich crop rotations. Eutrophication
was at a similar level, with a tendency for increased nitrate leaching
and a decrease of other N emissions. Replacement of imported soybean
meal by locally produced pulses could have a favourable effect, particularly
for pulses produced and used on-farm. However, depending on the raw
materials used to replace soybean meal, the effects can also be unfavourable.
Finally, shifting the human diet toward less reliance on meat has the
potential to reduce environmental burdens, but care must be taken that
the plant products are not too highly processed.
© 2012, Organic Agriculture Centre of Canada (OACC)