Stand decline in older hybrid bermudagrass varieties has been attributed to deficiency of K. We initiated this study to evaluate Tifton 85 bermudagrass response to increasing rates of K, Cl, and S applied as KCl, KCl + S, and K2SO4 at two rates of N. Annual K rates were 0, 125, 250, and 375 kg ha-1 split in three applications during the growing season. Initial N rates were 67 and 134 kg ha-1 for each regrowth of bermudagrass, and in year four, N rates were increased to 90 and 180 kg ha-1. Strip-applied N rates were main plots and K rates and sources were split plots in a four-replication, randomized-block, split-plot design. Dry matter yields were increased to 15.5 Mg ha-1 at the 180 kg ha-1 N rate compared to 13.1 Mg ha-1 at the 90 kg N ha-1 rate the fourth year. Yield response increased with increasing rates of applied K over time. In year four, significantly increased dry matter yields occurred in the order KCl + S > K2SO4 > KCl. This study includes nutrient analyses in soil and plant samples and will continue through 2006.
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