BERMUDA GRASS RESPONSE TO NITROGEN-FERTILIZATION AND REGROWTH AGE .9.RESIDUAL NITROGEN

In a split plot design with 4 replications, the residual N effect on y ield and quality of Coast cross 1 bermuda grass was studied when ferti lized with 0, 200 and 400 kg N/ha/year and cutting from the second to the eleventh week of regrowth. For DM yield there was interaction (P < 0.05) between treatments and from the sixth week more than 1 t DM/ha was obtained when the greatest N dosage was applied and it did not sur pass the 4.5 t/ha at 11 weeks. Cell content was increased (P < 0.05) w ith N and varied significantly with age. The protein content increased (P < 0.05) with N and decreased (P < 0.05) with age ranging between 1 3 and 2%. For structural carbohydrates the increase of residual N redu ced (P < 0.05) these indicators and the effect of age was variable. Th ere was interaction (P < 0.05) between treatments for the digestibilit y which varied between 20 and 55% and quadratic regression equations w ere adjusted between this indicator and age whose lowest coefficient o f determination was of 0.62. It is suggested that after 12 weeks of N application, the residual effect does not allow to obtain high yields nor adequate pasture quality.