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Definition of the study system
Before changing anything on the farm, it was necessary to understand in details the way the farm works precisely, in order to determine the perimeter of our work and the relationships of the system to its environment.
1. Understanding the way the farm works
A fundamental phase of the project consisted in learning to know and understand the way the Grignon farm works. To do so, it was necessary to describe the flows of inputs (seeds, fertilizers, phytosanitary products for crops, animal feed, additives and packaging for transformed products), of outputs (crops, milk, transformed products etc.) and of water and energy (electricity, fuel, gaz, ...), for all the subdivisions of the farm (cowshed, sheep pen, dairy, shop ...). The items needing transportation (of material or persons) were also pinned out.
- Schéma de fonctionnement de la ferme de Grignon
2. Defining the perimeter of the work
Once the way the farm works was understood, a delimitation of the scope of the study was necessary. This step consisted in the exclusion of some activities from the analysis of the environmental impacts of the farm. And indeed, it can be tricky to determine what impacts can be directly imputable to the farm, especially in a farm as diversified as Grignon.
| For example : Grignon’s shop stores and sells products made in the farm but also other products coming from farms belonging to the same GIE (Groupement d’Intérêt Economique - Group of economic interest, a union of different farms which sell products together). As Grignon farm doesn’t decide anything about the production processes of all the products of the GIE, we decided to exclude the shop of the analysis of the environmental impacts of Grignon farm. |
Consequently, only the quantitative data on net exchanges (excluding stock variations) in the perimeter of the study were taken into account. They were then used to make the environmental diagnosis of the farm.
3. Defining the set of constraints
The work perimeter goes under different economic, geographical, technical and demographical constraints, which are also those of Grignon farm as a whole.
The farm has to maintain its economic performances and the number of workers.
It is constrained by the urban pressure and the dispersion of its fields. Crop cultivation has to take into account the presence of pests, especially rabbits, on some fields. The soil characteristics (hydromorphy) of some fields make it necessary to coordinate cultivation practices according to humidity periods.
The evolution of bovine production needs to be done according to milk quotas, and within the limits of 2 UGB (Unité Gros Bovin - Big Bovine Unit) per hectare and the spreading of 170 organic nitrogen units per hectare and per year on the authorized fields.
Finally, a part of the farm income comes from experiments made on animals or crops, which thus limit the system’s evolution possibilities.
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