Crop diversification across scales : implications for resource use and cropping systems sustainability

The industrialization of agriculture and efforts to maximize yields of commodity crops are major drivers of biodiversity loss and disruption of ecosystems balance. To become more sustainable, agriculture needs to be aligned with the delivery of multiple ecosystem services, and reduce its dependency on external inputs and its negative environmental impacts. Increasing crop diversity may be a key strategy to promote multiple benefits and enhance the sustainable development of agroecosystems. More specifically, introducing crop diversification practices such as intercropping, cover crops, or diversified crop rotations may allow for efficient use of resources and enable the synergies of ecosystems processes and functions. In this thesis, I combined theoretical approaches and scientific methods along several scales to assess the sustainability of diversified cropping systems and increase the knowledge of complex cropping systems. The studies include a systematic review, field experiments, farmer interviews, sustainability assessments, and landscape analysis. I found that increasing crop diversity at field, farm, and landscape scales may enable synergies in these agroecosystems without causing yield reductions. Further, crop diversification showed promising effects on nutrient-use efficiency, reduced risk of nutrient losses and promoting associated biodiversity, thereby ensuring environmental sustainability and increasing the resilience of these diversified cropping systems. However, there are still several socio-economic factors that cause disadvantages in these diversified systems, demonstrating the need for increasing policy support or higher market demand for food produced in diversified cropping systems. The findings of this thesis support that increased crop diversity across spatial and temporal scales can contribute to resource-efficient production and enhance the delivery of ecosystem services, thus contributing to more sustainable cropping systems