Tuesday, 8 November 2005 - 9:00 AM
179-3

Nitrogen Rate Effects on Yield and Quality of Bermudagrass under Pivot Irrigation.

Gregory J. Sohm1, Curtis Thompson1, Ron Hale1, Alan Schlegel2, and John Fritz3. (1) Southwest Area Extension, Kansas State University, 4500 E. Mary, Garden City, KS 67846, (2) Southwest Research Extension Center, Kansas State University, Route 1, Box 148, Tribune, KS 67879, (3) Agronomy Department, Throckmorton Hall, Kansas State Univ., Manhattan, KS 66506

Little research has been done with variable nitrogen (N) rates on irrigated bermudagrass (Cynodon sp.), especially in areas north of where it is normally grown. The objectives of this experiment were to determine the N rate required for optimum economical production, and to evaluate the effect of N rate on forage quality and stand longevity. The effects of different N rates on bermudagrass forage yield and quality were investigated near Rolla, KS, on a Richfield silt loam soil. Individual plots were 2.4 x 4.8 m and all treatments were replicated four times in a randomized complete block design. N rates were 0, 133, 268, 535, and 1070 kg/ha. A nitrate soil test was taken from each plot to a depth of 0.61m. The soil nitrate test value was subtracted from the treatment N rate and the balance was applied to each plot. N was applied in five equal increments, with the first application applied on April 14 and the remaining N was applied after each cutting. Bermudagrass forage was harvested from a 1.8 m2 area on June 8, July 6, August 8, August 31, and September 28. In 2004, a cooler than normal growing season, bermudagrass forage yield and quality increased as the N rate increased. Total season dry matter yields for the 0, 133, 267, 535, and 1070 N treatments were 9.3, 12.6, 14.6, 16.6 and 18.1 tons/ha, respectively. The crude proteins were 12.5, 12.9, 16.2, 17.8, and 18.5 percent, respectfully. Bermudagrass treated with at least 268 kg N had higher yield and protein than the untreated. N rate from 268 to 535 kg/ha is the optimum range to maximize bermudagrass yield and crude protein under irrigation in southwest Kansas.

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