Assessing the consequences of policy measures on long-term agricultural productivity - Quantification for Flanders

Policy can influence the long-term agricultural resource productivity by stimulating/discouraging farmers to apply certain land use practices (LUP), as LUPs may affect the soil organic carbon (SOC) stock, hence influencing crop productivity. We introduce six policy strategies, each characterized by its own mix of LUPs, for the Flemish agricultural sector. Three strategies reveal the impact of the Common Agricultural Policy (CAP) in the past, while others reflect the potential of the CAP and the application of compost. We use the life cycle impact assessment indicators ‘SOC change’ and ‘biomass productivity loss’, which account for the impact of LUPs on SOC and yield, to assess the effects on long-term productivity. To avoid burden shifting, also the resource footprint is calculated. Several farm management systems (FMS) are distinguished, each characterized by a specific combination of farm type, agricultural region, rotation system and manure type. The results highlight that policies such as the CAP significantly contribute to a better SOC stock and (to a lesser extent) productivity. Furthermore, applying extra compost seems to be promising: it can result in an increasing resource productivity and reduced resource footprint. It is important to consider the resource footprint as only for one strategy the resource consumption outweighs the benefit (i.e. reduction in N fertilizer) in the short or medium term, while also being beneficial in terms of resource productivity. As the results differ per FMS, a differentiated approach is advisable when specific LUPs are stimulated in the context of sustainable farming.