ROW SPACING AND NITROGEN - EFFECT ON ALFALFA-BERMUDAGRASS QUALITY COMPONENTS

Interseeding legumes into grass sods increases herbage quality, Inters eeding alfalfa (Medicago sativa L.) into bermudagrass [Cynodon dactylo n (L.) Pers.] has given yields comparable to grass fertilized with hig h rates of N. Our objective was to compare forage quality attributes o f N-fertilized bermudagrass with alfalfa-bermudagrass mixtures. N rate s of 0, 112, 224, and 448 kg ha(-1) were applied to bermudagrass monoc ulture and to alfalfa interseeded into bermudagrass at 20-, 40-, and 6 0-cm row spacings. Experiments were conducted on a Cecil sandy clay lo am (clayey, kaolinitic, thermic Typic Kanhapludult) and a Norfolk sand y loam (fine-loamy, siliceous, thermic Typic Kandiudult) site. Hand-ha rvested herbage samples were separated into botanical components. Crud e protein, acid-detergent fiber and neutral-detergent fiber were measu red using a combination of wet-lab and near infrared reflectance spect roscopy (NIRS) procedures. Nitrogen increased the crude protein in ber mudagrass monoculture by 11 to 61 g kg(-1). The crude protein response of bermudagrass in mixtures to N was slight to nonsignificant. Increa sing row spacing of alfalfa reduced grass crude protein by 9 to 23 g k g(-1) and had no effect on alfalfa crude protein, Fiber fractions decr eased slightly in grass with added N, but fiber in alfalfa was not inf luenced by any treatment. Yield of crude protein increased with N, par ticularly in bermudagrass monoculture, but interseeding alfalfa withou t N produced crude protein yields that usually exceeded those of bermu dagrass monoculture at the 448 kg ha(-1) N rate, Interseeded alfalfa, even at wide row spacings, appears to produce enough biological N to r eplace 448 kg fertilizer N ha(-1) or more in the production of herbage protein in bermudagrass.