Plant and soil responses to nitrogen and phosphorus fertilization of bromegrass-dominated haylands in Saskatchewan, Canada

Field experiments were conducted at three different sites in Saskatchewan, Canada (Colonsay, Vanscoy and Rosthern) over two years (2005 and 2006) to determine the effects of dribble-banded and coulter-injected liquid fertilizer applied in the spring of 2005 at 56, 112 and 224 kg N ha(-1) with and without P at 28 kg P2O5 ha(-1). The three sites were unfertilized, 7- to 8-year old stands of mainly meadow bromegrass (Bromus riparius)-dominated haylands. All fertilization treatments produced significantly (P <= 0.05) higher dry matter yield than the control in the year of application at the three Saskatchewan sites. There was no significant difference between the two application methods (surface dribble band vs. coulter injected) for any fertilizer treatments. The addition of 28 kg P2O5 ha(-1) P fertilizer along with the N fertilizer did not have a significant effect on yield in most cases. In the year of application, increasing N rates above 56 kg N ha(-1) did not significantly increase yield over the 56 kg N ha(-1) rate in most cases, but did increase N concentration, N uptake and protein concentration. A significant residual effect was found in the high N-rate treatments in 2006, with significantly higher yield and N uptake. In 2005, the forage N and P uptake in the fertilized treatments were significantly higher than the control in all cases. The N uptake at the three Saskatchewan sites increased with increasing N rate up to the high rate of 224 kg N ha(-1), although the percent recovery of applied N decreased with increasing rate. The P fertilization with 28 kg P2O5 ha(-1) also increased P uptake. Overall, rates of fertilizer of approximately 56 kg N ha(-1) appear to be sufficient to produce nearly maximum forage yield and protein concentration of the grass in the year of application.