Effects of clipping frequency, row spacing and nitrogen fertilization in Digitaria eriantha cv. Irene

Abstract

During the yearly cycles 2000-2001 and 2001-2002 an experiment was conducted with the perennial grass, Digitaria eriantha cv. Irene, at Bahía Blanca (Argentina). In randomized blocks-design with three replications and a 2 x 2 x 3 factorial arrangement of treatments, the factors studied were: 1) cutting frequency: continuous, whenever the plants reached a height of 26-28 cm; and seasonal, with one cutting at the end of spring and of summer; 2) row spacing: 30 and 50 cm; and 3) levels of nitrogen fertilization: 0, 50, and 100 kg/ha. Forage harvested in spring and summer was weighed to determine dry matter yields per season and annual total (MS, kg/ha). Crude protein content (% PC), CP yield (kg/ha), efficiency of N utilization (ENU, kg MS/kg N) and N recovery in forage (% NR) were also determined. Fertilization was the most influential factor in addition to rainfall. Mean total yields of DM with 0, 50, and 100 kg N/ha were, in drier 2000-2001: 1632, 2122, and 2539 kg/ha, and in rainier 2001-2002: 2564, 4474, and 4708 kg/ha, respectively. Mean of CP of both years for the same N levels, were 6.8, 9.0, and 10.7, respectively. Yields of CP were also highest with 100 kg N/ha, but ENU and NR were better with the lower level of N application. These results suggest that N fertilization at a level close to 50 kg/ha is recommendable. Continuous cutting reduced forage yields (P<.05), but gave higher % CP relative to seasonal cutting (P<.05). Row spacing had no consistent effect on these variables, but 30 cm is favored to reduce soil erosion.