Sorghum Stature and Mixing Ratio Effects on Sorghum-Legume Intercropping Forage Quality.

Forage sorghum is an alternative to corn in the Southern Great Plains, where declining Ogallala Aquifer is not able to support traditional water requiring forage crops like corn or alfalfa. Sorghum is expected to perform better under stressful conditions and can support large dairy and beef industry in the region. However, forage quality of sorghum is considered lower compared to corn. Adding a legume to sorghum has shown to increase nutritive value of mixture and increased proportion of legumes in the mixture has shown to improve forage quality. Wide row planting of sorghum is amenable for planting an intercrop of legume in between. But, the taller growing conventional forage sorghum cultivars seems to over compete with legume in producing biomass. Recently developed Brown Mid Rib (BMR) sorghum cultivars are planted at much lower population than conventional cultivars. In addition, short-statured Brachytic Dwarf BMR cultivars have been developed recently. Both reduced population and reduced plant height may alter competition dynamics in sorghum and legume intercropping. Therefore, a two year field study was conducted to assess effect of mixing two sorghum types, a conventional height Brown Mid Rib cv. Dairy Master BMR and a new short-statured Brachytic Dwarf BMR cv. 26837, with a legume (Lablab cv. Rongai) at different proportions (six population mixtures) on the forage quality.  Intercropping of lablab bean with sorghum increased forage crude protein (CP) concentration with maximum values occurring at high bean and low sorghum densities. An overall greater benefit in nutritive value of the mixture was observed when Lablab was seeded from 25% to 50% of the total mixture. Pre-ensiled and ensiled forage qualities will be discussed.