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Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 7/1/2012 Publication Date: 10/15/2012 Citation: Anderson, W.F., Cheek, D.F. 2012. Fertilization effects on Tifton 85 bermudagrass quantity and quality. ASA-CSSA-SSSA Internation Meetings, Cincinnati, OH, October 21-24, 2012. CD-Rom p. 1. Interpretive Summary: not required Technical Abstract: Most fertilization recommendations for forage bermudagrass (Cynodon dactylon L.) are based on extensive research with ‘Coastal’ bermudagrass which is grown throughout the Southeastern United States since its release in 1943. Tifton 85, having higher yields and better forage quality, was released in 1993. The biochemical make-up of Tifton 85 has been documented to be different than Coastal, resulting in higher ruminal digestibility. A 4-year study was concluded in 2007 at two sites for Tifton 85 to determine the effects of six nitrogen rates and three phosphorus/potassium levels on mineral uptake, dry matter yields, and soil mineral composition. Coastal with two nitrogen and three P-K levels was also tested at one location. N rates ranged from 200 to 700 lbs/acre. The three sub-plot treatments were P-K applications at 50%, 100%, and 150% of plant uptake. Core soil samples were analyzed at the beginning of the study and after four years. Dry matter yields responded to nitrogen levels significantly in all years up to 400 lbs/acre, predominantly in the first and last of five clippings. Yield differences among P-K treatments were observed in the third and fourth year of the study. Preliminary economic analysis indicates that only N rates at or below 400 lbs/acre result in a net return due to high input costs. N uptake generally correlated with nitrogen applications and resulted in higher rumen digestibility. There were no significant effects among N-P-K treatments on soil nitrogen or carbon; however, there were location effects on the upper 12 inches of soil which caused differential responses to nitrogen application between locations of Tifton 85. Excess applications of K resulted in higher levels after four years in the lower root zone. Forage quality and mineral cycling aspects are also being explored |
