EFFECT OF NITROGEN AND POTASSIUM ON THE MACRONUTRIENT CONTENT OF 15 BERMUDAGRASS CULTIVARS

Information concerning the mineral nutrient composition of various tur fgrass species and cultivars is limited. The concentration of nutrient s in the turfgrass plant provides an indication of the overall nutrien t status and quality of the turf stand. Bermudagrass [Cynodon dactylon (L.) Pers.] is an important turfgrass utilized throughout the Southea stern and Southwestern states and the transition zone of the United St ates. A study was conducted to determine the effects of different rate s of nitrogen (N) and potassium (K) on the macronutrient content of fi fteen bermudagrass cultivars. The cultivars utilized were: 'Ormond' 'T exturf 10','Tiflawn', 'Tufcote', and 'U-3'; : 'Pee Dee', 'Santa Ana', 'Tifdwarf', 'Tifgreen', 'Everglades', 'Midiron 'Midway 'Tifway', and ' Tifway II' [Cynodon dactylon (L.) Pers. x Cynodon transvaalensis Burtt -Davey]; and 'Sunturf' [Cynodon magennisii Hurcombe]. Cultivar plots w ere replicated three times and were divided into four sub-plots for th e application of N and K monthly from July to October, 1996 at rates o f 227 g N and K 93 m(-2) (low rates) and 454 g N and K 93 m-2 (high ra tes). The four N:K treatments were: (i) high N:high K; (ii) high N:low K; (iii) low N:high K; and (iv) low N:low K. Plant tissue samples wer e collected in late August and analyzed for N, K, phosphorus (P), calc ium (Ca), magnesium (Mg), and sulfur(S). The high N:low K treatment wa s the only one to result in differences of N content among the cultiva rs. There were differences in P, K, Ca, Mg, and S content among the cu ltivars under each of the four treatments. The N, P, and S contents fo r all cultivars under all treatments were within the sufficiency range s for these elements while K, Ca, and Mg contents were less than the l ower value of the sufficiency range for these three elements for some cultivars under certain treatments. The content of K for most cultivar s was toward or below the low end of the sufficiency range regardless of the high or low K rates.