Influence of nitrogen rates on the persistence of ryegrass (Lolium multiflorum L.) forage production

This work aimed at evaluating the influence of nitrogen rates on the persistence of ryegrass forage production during four agricultural years. The experiment was performed in the experimental area of the University of Cruz Alta, Brazil. The experimental design was complete randomized blocks, with four agricultural years (2013, 2014, 2015 and 2016) × four harvesting times (first, second, third and fourth) × seven nitrogen doses (0, 50, 100, 150, 200, 250 and 300 kg ha-1), arranged in four replicates. The application of nitrogen on natural re-sowing ryegrass promotes the increase in dry biomass production across agricultural years. The use of nitrogen as topdressing showed little effect on the persistence of ryegrass plants in the four years of study. The efficiency of nitrogen utilization was inversely proportional to the increment of the nitrogen doses used. It is fundamental to understand the behavior of nitrogen fertilization in pastures with natural re-sowing and its effects on the persistence of the plants throughout agricultural years, as well as their participation in the sustainability of agricultural activity. Keywords: biomass production, Lolium multiflorum, urea, Brazil.