Our objective was to evaluate the long-term impact of management systems combining rotation types [barley in monoculture (M) vs. barley in rotation with forage (R)], tillage practices [chisel plow (CP) vs. moldboard plow (MP)], and nutrient sources [mineral fertilizer (MIN) vs. liquid dairy manure (LDM)] on forage and barley grain production in the Lac-Saint-Jean region of Quebec, Canada. Barley grain yields were significantly higher in MP (14%) than in CP during the first 10 yr of the experiment only. In R, grain yields were comparable between the two fertilizer sources, but in M, LDM resulted in 17%–20% lower yields compared with MIN. In contrast, forage yields reached 5000 kg ha^-1 under LDM, which was 11% more than under MIN. Nutrient uptake was significantly higher under R than under M. In forage production, nutrient uptake was higher under LDM than under MIN. In the long term, perennial forages and barley can be sustainably produced in rotation without productivity loss using LDM and either MP or CP. Residual N effects and non-N benefits from manure and rotation are identified as important factors contributing to cereal and forage productivity.