  Decision making in the Agriculture domain can be a complex task. The land
area allocated to each crop should be fixed every season according to several
parameters: prices, demand, harvesting periods, seeds, ground, season etc...
The decision to make becomes more difficult when a group of farmers must fix
the price and all parameters all together. Generally, optimization models are
useful for farmers to find no dominated solutions, but it remains difficult if
the farmers have to agree on one solution. We combine two approaches in order
to support a group of farmers engaged in this kind of decision making process.
We firstly generate a set of no dominated solutions thanks to a centralized
optimization model. Based on this set of solution we then used a Group Decision
Support System called GRUS for choosing the best solution for the group of
farmers. The combined approach allows us to determine the best solution for the
group in a consensual way. This combination of approaches is very innovative
for the Agriculture. This approach has been tested in laboratory in a previous
work. In the current work the same experiment has been conducted with real
business (farmers) in order to benefit from their expertise. The two
experiments are compared.
