The response of the nitrogen content in ryegrass (Lolium multiflorum cv. Midmar) to a variation in applied nitrogen (0kg N ha-1, 150kg N ha-1, 300kg N ha-1 and 450kg N ha-1) and defoliation intervals (every 2, 4, 6 and 8 weeks, as well as twice a season) was determined. In a field trial, the four nitrogen levels were combined with the five defoliation intervals. The quality of the dry matter (DM) was determined by Near Infrared Spectroscopy (NIRS). Total nitrogen, non-protein nitrogen and true protein were significantly (P≤0.01) influenced by nitrogen level, defoliation interval and the interaction between these two factors. The total nitrogen content varied from 0.68% to 3.38%, the true protein from 0.57% to 2.74% and the non-protein nitrogen from 0.11% to 0.65%. Nitrogen assimilated in the aboveground material ranged from 9.8kg N ha-1 to 423.0kg N ha-1. Linear relationships (P≤0.01) between total nitrogen, true protein and non-protein nitrogen (NPN) respectively were found.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.