Comparaison des bilans azoté, des émissions atmopshériques et des rayons de gene olfactive d'exploitations productrices de porc biologique, fermier et conventionnel en Région wallonne.

The pig production in walloon region exists in different forms. The conventional production
exists side by side with some productions of “differentiated qualities” that are encouraged
as much by the European Union as by the Walloon Region. At the same time, the EU and
the Walloon Region are imposing environmental limitations concerning the management of
nitrogen, the respect to the residents… Differentiated quality and the respect of the
environment seem to be linked implicitly, but no demonstration of this exists for the pig
production. The object of the present survey was to compare the nitrogen balances, the
atmospheric emissions and the distance of odour diffusion for the conventional production,
organic production and the production "fermier". This is taking into account the real
process performances of the farms, existing legislation, the opinion of a jury of experts on
the relative importance of the atmospheric emissions of pig production and the political
objectives of the Region they are situated in.
This survey is based on 21 farms, which are organised into three categories. These farms
have been audited with the software “Ecoferme”. The nitrogen fluxes and the nitrogen
balance within these exploitations were simulated. The atmospheric emissions and the
distance of odour diffusion were estimated as well.
A jury of 16 experts was formed, which was composed of four poles: a scientific pole, a
pole of public proxies and administrations, a pole of producers and a pole of the third party
(citizens, neighbours, … ). This jury was questioned according to a Delphi method
(individually and repetitively) to assign a relative importance to the emissions of ammonia,
greenhouse gases, molecular nitrogen and odour. The most important weighting was
assigned to the odour diffusion, the emission of ammonia came next, then the emissions of
greenhouse gas and finally the emission of molecular nitrogen got a weak weighting.
Some criteria have been constructed to characterize the performances of the farms, which
take into account of the spreading of organic nitrogen and the commitment taken by the
Region to follow the protocols of Kyoto and Gothenburg.
The comparison of the process performances was achieved by means of the method of
multicriteria analysis Electre III, which was applied to the global averages. The relative
ordering obtained was: organic production, production “fermier” and conventional
production. However within every sample an important variability of the performances was
observed. The same method applied within every sample enables the creation of subgroups,
working according to the same specifications but with weak, middle and good
performances.
The application of the ordering method to the nine subgroups shows that the most effective
exploitations of every system of production are classified as top of the class.
Thus, on average, the production of differentiated qualities are more environmentally
effective than the conventional production but the variability of the performances within a
system of production is important and it is quite possible for the conventional exploitations
to reach some results comparable to those of the best organic and “fermier” exploitations.