Interseeding kura clover and birdsfoot trefoil into existing cool-season grass pastures

Legumes in cool-season grass pastures can improve productivity and quality. In May of 1997 and 1998, a split-split plot field experiment with six replications was planted in Morris, MN to evaluate the effect of sod suppression, planting method, and legume species on establishment of legumes into existing cool-season grass pastures and to evaluate kura clover (Trifolium ambiguum Bieb.) and birdsfoot trefoil (Lotus corniculatus L.) as potential species for interseeding in the North Central region. Whole-plot sod suppression treatments were (i) 0.62 kg a.i. ha^-1 glyphosate [isopropylamine of N-(phosphonomethyl) glycine] or (ii) no glyphosate. Subplot planting methods were (i) no-till drilling, (ii) broadcasting seed on the soil, (iii) broadcasting seed followed by harrowing, and (iv) broadcasting seed followed by a light disking. Legume species sub-subplots were (i) alfalfa (Medicago sativa L.), (ii) red clover (Trifolium pratense L.), (iii) kura clover, and (iv) birdsfoot trefoil. Stand data were collected in the fall of the planting year and in the spring of the second growing season. Averaged across planting methods and species, legume stands were 38% where glyphosate was used and 3% where it was not. No differences or interactions were detected for planting method (P > 0.12). In this study, if competing vegetation was suppressed, stands were >31% regardless of planting method. When sod was suppressed, alfalfa established better stands than the other legume species. The overriding factor in the ability to establish legumes in this study was the suppression of existing vegetation during establishment.