Switchgrasses: Forage Yield, Forage Quality and Water-use Efficiency

Abstract

The purpose of the study was to evaluate 3 strains of switchgrass (Panicum virgatum L.) under 3 water and 3 harvest regimes. Dry matter yields, under natural rainfall and full irrigation, averaged 2.0 and 6.7 metric tons/ha, respectively. Productivity of the 3 strains ranked G 300>HV-341>Blackwell. Yields of HV-341 and Blackwell were similar under 1, 2, or 3 harvests per year but those of G-300 were reduced by 2 or 3 harvests. Switchgrass forage contained about 10.8% crude protein (CP) and 0.23% P in late June. In November, previously unclipped forage contained 4.3% CP and 0.12% P, while that clipped twice contained 5.5% CP and 0.15% P. Maximum production was obtained with 116.5 cm of water use but maximum water use efficiency was obtained with about 85.5 cm of water use (rainfall + irrigation + soil water). The switchgrasses are adapted for use both without irrigation and when varying amounts of irrigation water are available. G-300 yielded more and produced earlier and later than the other two strains thus it may be the best choice for use for range improvement or for irrigated pastures. However, it requires careful management because it is more susceptible to overuse than the other two strains.