Abstract: This study determined the efficacy of liquid dairy manure and inorganic fertilizers on hayfields. Thirteen combinations of treatments were tested, based on the nutrient source (liquid dairy manure and / or inorganic fertilizer), the time of application (fall, spring, and / or summer) and manure application rates based on manure N or P contents. The details of treatments applied were as follows: 1/ No fertilizer applied, 2/ conventional N, P, and K in spring + inorganic N after the first cut, 3/ inorganic P and K applied in the previous fall + spring inorganic N, 4/ spring inorganic N + inorganic N, P, and K after first cut, 5/ fall based-N manure application + spring inorganic P and K (as required), 6/ fall based-P manure application + spring inorganic N; 7/ inorganic N, P, and K applied after the first cut, 8/ spring N-based manure application, 9/ spring N-based manure application + summer N-based manure application, 10/ spring N-based manure + inorganic P and K, 11/ spring P-based manure + inorganic N and K, 12/ summer N-based manure + inorganic P and K, and 13/ summer P-based manure + inorganic N and K. The application rate was based on current inorganic fertilizer recommendations on forage hays. Prior to fertilizer application in spring and after the first cut, soil samples were taken from the plots for soil quality monitoring. For many plots, additional inorganic fertilizers were not needed since the soil contained very high P and moderately high K levels. The treatments did not have any significant effects on the feed yields of the first and second cuts, and the sum of the two cut yields. The total forage yields varied from 7.6 to 8.2 tonnes ha^-1 under the zero fertilizer treatment and the treatment 7 (inorganic N, P, and K applied after the first cut). In particular, the average yields from the second cut (4.5 tonnes ha^-1) were higher than those of the first cut (3.2 tonnes ha^-1). Based on currently recommended fertilizer application rates, the results show that manure applications did not increase soil phosphorus. They also tend to indicate that shifting fertilizer application from spring to summer may result in a better nutrient management in hayfields; this may, however, be season or year-dependent.