Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2005
Publication Date: 6/11/2005
Citation: Armstrong, K., Albrecht, K., Lauer, J., Riday, H. 2005. Intercropping climbing beans with corn for silage. American Forage and Grassland Council Conference Proceedings. 2005 CDROM.
Technical Abstract: Corn silage is an important source of forage for dairy cattle in the USA because of its relatively consistent nutritive value, high yield, and high energy density compared to other forage crops. Low crude protein (CP) concentration in corn silage is its major limitation in dairy rations. Climbing beans are grown with corn for grain in the tropics and subtropics, and similar intercropping in the northern USA could result in silage with greater CP concentration than corn alone. In this experiment corn was intercropped with three climbing beans: lablab bean [Lablab purpureus (L.) Sweet], velvet bean [Mucuna pruriens (L.) D.C.], and scarlet runner bean (Phaseolus coccineus L.), or grown in monoculture near Arlington and Lancaster, WI. Corn was sown at 33,000 (high density) or 22,000 (low density) plants/acre in early May. Beans were sown in rows six inches beside corn rows at 33,000 plants/acre 2 or 4 weeks after corn planting. Effects of corn density, bean planting date, and bean species on the yield and nutritive value of these mixtures were evaluated and mixture yield and nutritive value were compared to monoculture corn. Averaged over locations and management treatments the lablab bean-corn mixture produced 8.9 tons/acre of whole plant dry matter compared to 8.7 tons/acre in monoculture corn with no detectable differences (P=0.1373) among mixture treatments. Early bean planting decreased total mixture yield 0.22 tons/acre (P=0.0065) while the high density corn treatment was 2.1 tons/acre higher than the low corn density treatment. Mean percentages of beans in the mixtures were: lablab bean 8.8%, scarlet runner bean 5%, and velvet bean 3.4%. Although addition of bean had no effect on total yield there was an effect on yield of the corn component of mixtures. Whole plant corn yield was 0.45 tons/acre less in mixture with lablab bean compared to when it was grown alone. This shift in species composition of mixtures was great enough to alter laboratory measures of forage nutritive value. Addition of lablab bean increased neutral detergent fiber concentration from 37.9 to 39.2% (P=0.0072) and acid detergent fiber concentration from 19.6 to 21.2% (P<0.0001) in mixtures. Bean planting date had no significant effect on mixture CP concentrations however mixtures with lower corn density contained a half percentage unit more CP (P<.0001) than the high density corn treatment. Beans increased (P<0.0001) the CP concentration of all mixtures, with lablab bean-corn mixtures containing 7.4% CP compared to 6.5 in monoculture corn. This experiment showed that lablab bean has the greatest potential of the three beans to increase CP concentration without compromising silage yield.