Performance of alfalfa strains grown in mixture with smooth bromegrass as affected by management

This study was conducted to evaluate the yield and persistence of seven contrasting alfalfa (Medicago sativa L. sensu lato) strains growing in binary mixture with smooth bromegrass (Bromus inermis Leyss.) under different fertilizer and cutting managements. The alfalfa strains were seeded in mixtures with smooth bromegrass in 1980 in northeast Saskatchewan and harvested each year, 1982 through 1987. Two fertilizer treatments (0 and 18 kg ha−1 P) and two cutting managements (2 and 3-4 cuts) were imposed annually. The application of P fertilizer increased the total yield (6-yr average) from 1.47 t ha−1 in control plots to 2.52 t ha−1 in the fertilized plots. Frequent cutting reduced average total yield from 2.59 t ha−1 (2-cut system) to 1.4 t ha−1. Fertility and cutting management did not affect the proportion of alfalfa or weeds in the harvested herbage. The alfalfa strain significantly affected total yield and the proportion of alfalfa and weeds throughout the years of this study. The strain ScMf3713, a M. sativa subsp. falcata (L.) Arcang. type, outyielded all entries during the last 3 yr of this study. The study suggests that alfalfa strains of the falcata subspecies germplasm showed superior long-term performance when the alfalfa was grown in a binary mixture with bromegrass. Key words: Medicago sativa L., falcata, Bromus inermis Leyss., phosphorus, simulated grazing