Forage yields and quality of common vetch and oat sown at varying seeding ratios and seeding rates of vetch

Abstract

In the Mediterranean area, most annual legumes, such as common vetch ( Vicia sativa L.) that have a scrambling habit, are sown with oat ( Avena sativa L.) to improve growing conditions and forage harvesting. Although some studies have examined the effects of varying seeding ratios, the optimum seeding rates for those combinations are not well-defined. The objective of this study was to compare the yields from mixed stands of vetch (principal species) and oat (secondary species) obtained when several seeding rates of vetch were combined with various seeding ratios of the two species. A field study was conducted at two locations near Madrid in the 1981–1982 and 1982–1983 growing seasons. Both species were planted as monocrops and in mixtures. Ratios of the number of vetch to oat seed were 100:0; 90:10; 80:20; 70:30 and 60:40. Within each mixture, seeding rates of vetch were 60, 80, 100 and 120 kg ha −1. The oat monocrop was seeded at 140 kg ha −1. Plants were harvested at the pod-setting stage of vetch. Relative yield total (RYT) calculated as the sum of the relative dry matter yields of both species was used as the criterion for mixed stand advantage. Mixtures produced 34% more dry matter than the monocrop of vetch, but 57% less than the oat monocrop. Dry matter yields of mixtures were not affected by seeding ratio or seeding rate of vetch but proportions of vetch dry matter decreased linearly as the percentage of oat seed in the mixture increased. The net effect of oat in the mixture was a linear increase in competition as oat density increased. Relative yield totals of mixtures with 90:10 or 80:20 ratios of vetch:oat seed exceeded unity.