The provisioning Ecosystem Services (ES) of organically managed grasslands could be compromised, compared to grasslands under non-organic management, due to restrictions regarding mineral fertilization. We investigated this by measuring forage yield increase per day and feed value in 25 pairs of organic and non-organic fertilized meadows (mown) and pastures (grazed) in the canton of Solothurn (Switzerland). Lower forage yield and feed value in organic pastures were related to lower phosphorus (P) in topsoil compared to non-organic pastures. However, in meadows, organic management had no effect on forage yield and feed value as soil P was hardly affected by organic management. From these findings we conclude that forage provision does not considerably differ between organic and non-organic meadows, but in pastures we see potential indications of nutrient limitation under organic management. Future research should thus assess organic pasture management in more detail to close this production gap.