The three experiments described in this study were carried out in the Agricultural Experimental Station of INTA, Anguil, La Pampa, Argentina (36°31′S/64°01′W), during different cutting dates and seasons between 2006 and 2008. The average annual rainfall in the Anguil area is distributed with peaks in spring and autumn, with dry summer and some precipitation in the form of snow in winter. The annual average mean, minimum and maximum annual temperatures are 15·6, 7·8 and 22·6°C, respectively, and the average mean precipitation is 759·5 mm (Casagrande et al., 2012). No soil fertilization was used.