Winter Population Response of Two Native Grasses to Nitrogen Fertilization and Herbage Allowance

Abstract

The research was conducted at the School of Agronomy, located in Paysandú, Uruguay (32º 23’57,86" South and 58º 02' 42,48" West 61 msnm). The aim was to study the response in winter production of a native pasture to different levels of nitrogen fertilization and herbage allowance. The experiment was led in an experimental central compound rotational design of uniform precision, with two factors with five levels each: nitrogen (N) (0, 44, 150, 256, 300 kg/ha of N) and herbage allowance (HA) (4,0; 5,5; 9,0; 12,5 and 14,0 kg MS/100 kg of live weight LW), distributed in two blocks. The results obtained show a clear interaction between the nitrogen fertilization, grazing intensity and pasture botanical composition, determining distinct results depending on the levels of each factor used. There was a strong response in the number of tillers of Bromus auleticus when increasing the HA regardless of the level of N, suggesting their low tolerance to increased grazing intensity. It highlights the pioneering capacity to colonize poor environments Stipa setigera presented, that would allow early recovery of highly disturbed environments, enabling increased system productivity.