Diversifier les rotations céréalières notamment avec du pois et du colza – Données récentes d’expérimentations et d’études

Simplification has been a clear trend in the composition of French crop rotations in the past decades, whereas agronomic knowledge proves the interest of diversification in order to benefit from the so called “preceding effects” and “cumulative effects”. It is needed to study the possible input of crops such as rape seed or pea for the cereal-based rotations in agronomic terms but also in economic and environmental terms. The first step is to quantify the impacts specifically due to the change in crop succession composition, and afterwards to allocate an objective economic value to them so that they are easy to integrate into comparisons of production systems. The regional case studies of a current multi-partner project enable to illustrate the economic and environmental evaluation of alternatives to the rotation “Oilseed rape – Wheat – Barley”. In addition, the recent field experiment data of this project (farm tests or experimental trials) provide technical and scientific elements on technical feasibility and the economic performance of the innovative succession “pea before rape seed”, but also on the interest of the introduction of symbiotically fixed nitrogen in crop rotations in order to decrease the negative environmental impacts of mineral fertilisers-based systems. Diversification of crops and nitrogen fixation appear to be two key elements for (i) competitiveness, when at least the agronomic effects are taken into account, and (ii) sustainable systems, when one considers the preservation of farm potential and of the environment.