Irrigating Tifton 85 Bermudagrass for Forage Production In the Humid Southeast.

Although total acreage and total hay production in South Carolina have increased substantially over the last 30 years, average forage yield has changed little. Nearly all of the production is under rainfed conditions. This research was conducted to investigate how irrigation affects yield and quality of Tifton 85 hybrid bermudagrass (Cynodon dactylon Pers. × C. nlemfuensis Vanderyst) grown for forage. The experiment was conducted in 2008 and 2009. Treatments were cutting schedule (4 or 8 wks), N fertilizer rate (224, 448, or 672 kg ha^-1), and irrigation level (0, 33, 66, or 100 % of ET). Irrigation was initiated when tensiometers installed at 30 cm below the soil surface were at -30 kPa. Because of adequate precipitation, irrigation was not applied during much of the growing season in either year. When precipitation was lacking, yield increased linearly with irrigation level (twice in 2008 and once in 2009 for forage cut every four wks and once in both 2008 and 2009 for forage cut every eight wks). No interactions for yield occurred between irrigation level and N rate at any harvest in either year. Yield increased linearly with N rate at most harvests. Even though yield was higher with irrigation at some harvests in both years, total season forage production did not significantly differ among irrigation levels in either year (mean yield across all treatments was 9702 kg ha^-1 in 2008 and 14724 kg ha^-1 in 2009).