Model for quantifying the synergies between farmland biodiversity conservation and water protection at catchment scale

•Efficiency gain is achieved by the spatial allocation and type of vegetation cover.•Favourable locations for joint water and biodiversity protection are identified.•Farmland diversity benefits can be gained by including meadow nectar plants.

This paper studies joint provision of two environmental non-market commodities related to agriculture: biodiversity conservation and water protection. We provide an optimising tool for analysing spatial dependencies of multifunctional agriculture at catchment scale. We show that efficiency gains can be achieved by spatial allocation and choice of the type of vegetation. In particular, inclusion of meadow nectar plants in the founding grass seed mixture of set-asides was found out to be an economically efficient measure to promote biodiversity and water protection on warm, steep slopes.