Establishment of Kura clover no-tilled into grass pastures with herbicide sod suppression and nitrogen fertilization

Sod-seeding legumes into grass-dominated pastures improve forage productivity and quality. Identical field experiments were established in May 2001-2002 at two sites in Québec and three in Minnesota. Our objective was to compare the establishment in perennial cool-season grass sods of two sod-seeded cultivars ('Cossack' and 'Endura') of Kura clover (Trifolium ambiguum M.B.) against that of red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) using different herbicide sod suppression intensities {paraquat, 1,1′-dimethyl-4,4′-bipyridinium (0.9 kg a.i. ha ^-1) and glyphosate [N-(phosphonomethyl) glycine] (0.8 or 3.3 kg a.i. ha^-1)}, without or with N fertilization (110 kg N ha^-1). Establishment year plant density and dry matter (DM) production of both Kura clover cultivars were similar (avg. 90 plants m^-2, 390 kg DM ha ^-1), but were generally inferior to white clover (avg. 110 plants m^-2, 740 kg DM ha^-1) and red clover (avg. 170 plants m^-2, 1450 kg DM ha^-1). Paraquat did not sufficiently suppress the sod, resulting in lower legume populations and yields than glyphosate. Sod suppression using glyphosate, however, led to heavy seeding-year weed infestation at two of three sites in Minnesota (avg. 2.2 Mg weed DM ha^-1). Sod-seeded Kura clover successfully established with glyphosate; however, its contribution to forage production in the sod-seeding year remained minimal (<0.5 Mg ha^-1 at four of five sites). Effects of N fertilization varied with species and herbicides; effects on Kura clover were inconsistent but rarely detrimental, while increasing total forage yields by an average of 40%. It is thus possible to establish Kura clover via sod-seeding; however, its productivity in the seeding year remains minimal.