How to reconcile short-term and long-term objectives in mixed farms? A dynamic model application to mixed fruit tree - vegetable systems

Mixed fruit tree and vegetable (MFV) farms correspond to the joint production of fruit trees and vegetable crops. In temperate regions, this emerging farming system is a potentially attractive land use to foster the diversification of agricultural systems. However, these systems combine two productive and labor-intensive enterprises (orchard and market gardening) and in practice, the system feasibility depends on the availability and need for labor. Long-term yield predictions are needed to assess the economic profitability of such innovative farming systems. A dynamic bio-economic model of MFV systems was developed to assess its main properties over time. This simple state-control model is based on yields, biological dynamics, workload requirements and economic profitability of each farming enterprise. Due to the lack of data from long-term experiments, the model was parametrized on data from specialized systems and calibrated with expert knowledge. The implementation of the model made it possible to simulate management strategies for vegetable crops and fruit trees, and to assess their impact on the long-term system dynamics. Results show that specialized market gardening enterprise has an overall higher profitability per hectare than specialized fruit trees. Nevertheless, mixed systems composed of roughly equivalent shares of fruit trees and vegetable crops make it possible to decrease workload constraints while maintaining a high level of profitability. In addition, intermediate shares of fruit trees and vegetable crops can lead to higher profitability in the long term, but require addressing both short- and long-term objectives, and the ability for farmers to cope with several consecutive years of lower income. Further research is now needed to better understand the biological processes underlying MFV systems and their evolution in different management configurations.