Francisco E. Contreras-Govea1, Richard E. Muck2, and Kenneth A. Albrecht1. (1) Agronomy Department UW-Madison, 1575 Linden Drive, 1575 Linden Drive, Madison, WI 53706-1597, (2) USDA Dairy Forage Research Center, 1925 Linden Drive, Madison, WI 53706
Growing climbing beans in mixture with corn (Zea mays L.) has been proposed as a means to improve protein concentration of silage. The aim of this study was to determine the silage characteristics of mixtures of corn with each of three climbing beans. The crops were grown in 2004 and 2005 at Arlington and Lancaster, WI. Corn was grown in two densities (82 and 55 thousand plants/ha) alone or with lablab bean [Lablab purpureus (L.) Sweet], scarlet runner bean (Phaseolus coccineus L.), and velvet bean [Mucuna pruriens (L.) D.C.] sown at a single density (82.5 thousand plants/ha). Sole corn and mixtures were harvested when corn was at the 2/3 milk line stage. Eight glass jars per treatment of chopped sole corn or mixture with bean were ensiled and allowed to ferment for a minimum of 30 days at room temperature (~ 25oC). The silos were opened and pH, organic acids, and fiber characteristics were measured. The pH of silage ranged from 3.8 to 4.07 and was always lower for sole corn than corn-bean mixtures. In 2004, the addition of bean increased crude protein concentration by 7.5% compared to sole corn at the normal density and by 13.4% compared to corn at the low density, but also increased the NDF concentration by 3.6 to 17 %. Lactic acid concentration was not different among bean treatments (P > 0.05), but was 7.3% greater in corn-bean mixtures than in sole corn. This indicates greater buffering capacity in corn-bean mixtures compared to sole corn silage.