The effect of rejuvenation of Aspen Parkland ecoregion grass-legume pastures on botanical composition

A 3-yr study was conducted at five different sites in the Aspen Parkland of Saskatchewan to determine the effect of spiking, burning, mowing, deep-ban ding (Trt) and applications of N, P, K and S liquid and granular fertilizer s (Fert) on changes in botanical composition of predominantly smooth bromeg rass (Bromus inermis Leyss.) and alfalfa (Medicago sativa L.) pastures esta blished on Black Chemozemic and Gray Luvisolic soils in central Saskatchewa n. Fertilizer application was in a liquid form blended to provide 100 kg N ha(-1), 45 kg P2O5 ha-1, 23 kg K2O ha(-1) and 12 kg S ha(-1) in 350 kg of f ertilizer ha(-1). The experimental design at each site was a randomized com plete block in a split-plot arrangement. Main plots were spike, burn, mow, deep-band, deep-band liquid fertilizer and control. The split-plot treatmen t was granular fertilizer broadcast at 0 and 350 kg ha(-1) (providing 100 k g N ha-1, 45 kg P2O5 ha(-1), 23 kg K2O ha(-1) and 12 kg S ha(-1)). All trea tments were applied in the spring of 1994. Interaction effects of Trt x Yr and Fert x Yr were significant (P < 0.05), indicating a wide range of respo nse to the rejuvenation methods among years. Spiking reduced grass and legu me composition, and increased (P < 0.05) the presence of annual weeds and b are ground. Burning increased (P < 0.05) alfalfa composition in years 2 and 3 at three sites and tended to decrease (P > 0.05) bluegrass composition i n all 3 yr. Broadcast and liquid fertilizer, at 200 kg N ha(-1) decreased ( P < 0.05) the alfalfa component in years 2 at four sites and increased (P < 0.05) the smooth bromegrass component at two sites in year 1 and all sites in years 2 and 3. Fertilizer (granular or liquid) alone or combined with m echanical treatments (deep-band, mow, spike or burn) increased (P < 0.05) t he composition of smooth bromegrass and decreased (P < 0.05) the compositio n of bluegrass, weeds and bare ground variably over 3 yr. Mowing and deep-b anding had minimal effects on botanical composition.