Although much of the manure in Canada is surface-applied to forages, little research exists evaluating time of year (Time) and rate (Rate) of application on forage yield and nutrient uptake. Field trials (10 yr) on two soils (sandy loam upland and silty clay loam dykeland) investigated this. Experimental arrangement was a factorial [Time (spring, summer, early, and late fall manure applications)] plus a control [spring-applied ammonium nitrate fertilizer (ANF)] in a Latinized split plot. ANF at 0, 25, 50, 100 and 200 kg N·ha⁻¹; 0, 75, 150, and 300 as semi-solid beef (SSM) and 150 kg N·ha⁻¹ as liquid dairy manure (LDM), constituted respective splits. The Time × Rate interaction, later in the trial on the upland soil, showed higher yields and nutrient uptakes with fall manure application. There was little interaction on the dykeland soil; summer application resulted in higher yields at times. For both soils, the optimal long-term application rate of SSM was approximately 150 kg N·ha⁻¹ while that of ANF was approximately 100 kg N·ha⁻¹. Inherent fertility of dykelands resulted in lesser responses to manure addition. Negligible and significant residual N occurred with fertilizer and manure, respectively. Nitrogen, phosphorus, potassium, calcium, magnesium, manganese, copper, zinc, and boron uptakes were due to amendment impact on yield. The recommended rate is 150 kg N·ha⁻¹ of SSM or LDM applied in fall and summer to Maritime grasslands grown on upland and dykeland soils, respectively. Yield differences may not warrant producers adjusting timing of in-season manure application.