Nitrogen Management for Production of Hybrid Bermudagrass Hay In Tennessee.

A nitrogen fertility study with Vaughn’s hybrid bermudagrass conducted on a Crider silt loam soil (fine, silty, mixed, active, mesic Typic Paleudalfs) over three (3) years (2008-2011) at the Highland Rim Research and Education Center near Springfield, Tennessee is evaluated in this manuscript.  Nitrogen applications are evaluated in both irrigated and non-irrigated plots at five (5) different application rates: 0, 56, 112, 168, and 224 kg N ha^-1.  These rates are applied beginning in late April, and three (3) additional times upon harvests occurring in June, July, and August.  Irrigation plots receive enough water to bring total weekly water up to 2.24 cm/plot whenever rainfall is less than that amount. The results of the study show irrigation has no effect on yields during the period of this study.  There is a significant effect resulting from the interaction between month and nitrogen application on yield.   Investigation of this interaction reveals two (2) distinct periods of production potential during the growing season.  A low to medium yielding period (occurring during June and September) produces an average harvest yield maximum of 3.14 Mg ha^-1.  A medium to high yield period (occurring during July and August) produces an average harvest yield maximum of 5.4 Mg ha^-1.  Based on an analysis of variance and mean separation, a nitrogen rate of 56 kg N ha^-1 rate is recommended for harvests occurring during the low to medium yielding period, and a nitrogen rate of 113 kg N ha^-1 is recommended for those occurring during the high to medium yielding period. The savings from this analysis result in an annual decreased use of nitrogen by as much as 25 percent compared to current University of Tennessee annual recommendations.