Potential of new summer grasses in Northland

Abstract

Abstract The warm‐season yield of a number of subtropical C 4 ‐pathway grasses was measured over two seasons in small‐plot trials near Kaitaia. Forage yields under dryland conditions ranged from approximately 4500 to 17 000 kg/ha DM for the various grasses over the 5‐month (mid November‐mid April) harvest period during the trial. Setaria splendida produced high yields similar to maize or green‐feed sorghum crops in the area and should be further evaluated as a specialist perennial crop. Cynodon dactylon seemed to be one of the more drought hardy grasses because it was the highest yielding during the driest period of summer. Stoloniferous Digitaria spp. and Hemarthria altissima yielded poorly during periods (January‐February) when rainfall was lowest. Production of most of the grasses was lowest in late summer, with a substantial recovery during autumn, although species of Eragrostis had almost no autumn production. Chloris gayana overwintered poorly on this coastal site, but the other grasses persisted well. Irrigation increased the early summer production of all grasses, but depressed the early autumn production of some species, particularly the high‐yielding grasses ( S. splendida, Panicum maximum ), and this is ascribed to problems of mineral‐nutrient availability. The cool‐season (mid April‐mid November) production of these grasses and a further group of C 4 and C 3 species was measured during 1975. The temperate C 3 species produced over 10 000 kg DM/ha during the cool period, but production of the subtropical C 4 species varied from 2000 to 9000 kg/ha. Cool‐season production of subtropical grasses was highest during spring.