Optimum cropping pattern is as follows :
| Crop | cropping pattern (ha) |
| Rotation 1 : sugar beet/Soft wheat/Barley/Rapeseed/Soft wheat/Durum wheat |
0 |
| Rotation 2 : Rapeseed/Soft wheat/Barley/Potato/Soft wheat/Durum wheat |
110 |
| Rotation 3 : Rapeseed/Soft wheat/Barley/Rapeseed/Soft wheat/Durum wheat |
0 |
The income is as follows : 141 680€.
The model opts for rotation 2. The agronomic rules imposed in the previous model (cereal crops for two years in a row at the most, etc) are being followed. But the income obtained is lower than the one obtained with the rotation1.gms model. This can be explained by the fact that a diversity of cereal crops is included here whereas in the previous model the only crop to be cultivated was the most profitable crop, durum wheat. Several assumptions may be put forward concerning this difference between the observed practices and the previous model : the reduction in the margins obtained for durum wheat which were perhaps the result of this succession of several years of durum wheat has not been taken into account (decrease in yields and/or increase in the use of phytosanitary products).
Other reasons : risk management, the organisation of labour may also encourage farmers not to choose to grow durum wheat 4 years out of 6 and to opt for a more diversified cropping pattern approach.
This method makes it possible to take into account the practices carried out by the farmers and the effects of previous crops which are not always easy to model. But the advantage of the previous method is that it encourages us to consider the reasons for the differences between our model and the observed reality.
The model solution is : modelEco_rotation2.gms
