Performance of rose clover and hairy vetch interseeded into Old World bluestem.

Abstract

Old World bluestems (Bothriochloa spp.) are extensively used throughout the Southern Plains. Interseeding these stands with persistent nitrogen-fixing legumes could reduce N fertilizer input, extend the grazing season, and enhance diet quality. The objective of this study was to evaluate production and persistence of 'Overton R18' and TXR20 rose clover (Trifolium hirtum All.) and hairy vetch (Vicia villosa Roth) when interseeded into Old World bluestem. Treatments included these interseeded annual legumes and bluestem + 100 kg/ha N fertilizer. Both rose clover and vetch produced a measurable quantity of forage by early spring before bluestem began to grow. Crude protein and in vitro dry matter digestibility were higher in legume treatments when legumes were actively growing. Total season forage production was similar (6,460 kg/ha; P > 0.05) between rose clover and bluestem + N treatments except during 1991 when production under the Overton R18 treatment was less than bluestem + N or TXR20 rose clover. Average rose clover seed production (26 kg/ha) was greater than vetch (2 kg/ha; P < 0.05) resulting in greater rose clover forage compared to vetch during natural reseeding years. Rose clover plant counts 4 years after the original seeding showed an average of 22 plants/m2. Both rose clover entries appear to have excellent potential over previously available germplasm because of improved cold tolerance and the ability to produce substantial quantities of seed for natural reseeding even after close defoliation.