Cool-Season Annual Forage Mixtures Reduce Spring Growth of Tifton 85 Bermudagrass.

Annual cool-season grasses and legumes can contribute considerable forage dry matter (DM) to a perennial warm-season cropping system, but may also interfere with subsequent grass development. Inter-specific interactions of three cool-season annual grasses and two annual legumes, over-seeded in a Tifton 85 bermudagrass (Cynodon dactylon (L.) Pers.) stand, were evaluated in north-central Texas for DM yield and their effects on spring bermudagrass yields. Ryegrass (Lolium multiflorum Lam.), barley (Hordeum vulgare L.), and rye (Secale cereale L.) were no-till drilled into 2 X 2 m plots in early autumn of 2005 and 2006 in a strip plot design. Four treatments, including hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), nitrogen (56 kg ha-1) in mid February, and a control plot were established in a strip plot design perpendicular to grass strips. Species were harvested in the late spring when cool-season grasses were in boot stage and the legumes flowered. Rainfall totals from October through May were 359 mm yr 1 (2005-2006) and 675 mm yr 2 (2006-2007). Dry matter yields of cool-season grasses over-seeded in bermudagrass were affected by species interaction (P < 0.01) and legumes were affected by a grass x species interaction (P < 0.01). Early spring bermudagrass production was reduced by 21 to 60% as a result of over-seeding grass (P < 0.01) but was not affected by over-seeding legumes (P = 0.66). Legume DM yields were reduced when over-seeded with cool-season grass (P < 0.01). Cool-season forage mixtures can contribute additional forage production (2200 to 3200 kg ha-1 yr-1) but can result in a loss of Tifton 85 bermudagrass spring yield.