Animal and pasture productivity of ‘coastal’ and ‘tifton 44’ bermudagrass at three nitrogen rates and associated soil nitrogen status
Coastal’ and ‘Tifton 44’ (T44) bermudagrass [Cynodon dactylon (L.) Pers.] are well adapted across the lower southern United States, but the grazing response of (T44) to N application in the Piedmont of the upper South warrants further evaluation. This 3-yr experiment compared animal and pasture productivity of Coastal and T44 with three annual N rates of 101, 202, and 303 kg of N ha–1 on a Cecil clay loam (fine, kaolinitic thermic Typic Kanhapludult) soil typical of the Piedmont. Herbage mass differed for Coastal and T44 (3.5 and 3.0 Mg ha–1 respectively, P < 0.01), but not among N rates. The canopy of T44 was leafier (20.6 vs. 14.5% of dry matter) than Coastal and greater for in vitro true organic matter disappearance (IVTOD) (522 vs. 498 g kg–1) and CP (107 vs. 84 g kg–1) and lesser in NDF (596 vs. 605 g kg–1). The diet selected from T44 was greater in IVTOD (764 vs. 743 g kg–1) and lesser in NDF (596 vs. 605 g kg–1) giving greater steer average daily gain (0.63 kg vs. 0.57 kg; P < 0.01) which increased (P = 0.05) with N rate. Weight gain ha–1 (884 kg) and effective feed units (EFU) (4735 kg ha–1) were similar, and N rate linearly increased gain from 723 to 1073 kg ha–1 and EFU from 3978 to 5523 kg ha–1. Soil inorganic N was similar between cultivars but differed among soil depths. Tifton 44 pasture was greater in nutritive value, hence steer performance, and as productive as Coastal in the Piedmont.