Intercropping Corn with Lablab Bean, Velvet Bean, and Scarlet Runner Bean for Forage
Journal - Crop Science
This experiment was designed to determine if intercropping corn(Zea mays L.) with climbing beans is a viable option to increasecrude protein (CP) concentration in forage rather than purchasingcostly protein supplements for livestock rations. In these experiments,corn was intercropped with three beans—lablab bean [Lablabpurpureus (L.) Sweet], velvet bean [Mucuna pruriens (L.) D.C.],and scarlet runner bean (Phaseolus coccineus L.)—or grownin monoculture near Arlington and Lancaster, WI. Corn was sownin early May and late April in 2004 and 2005, respectively,and later thinned to 55,000 (low density) or 82,500 (normaldensity) plants ha–1. Beans were sown in rows 8 cm onone side of the corn rows at 82,500 plants ha–1 2 or 4wk after corn planting. Averaged over four environments, mixtureforage dry matter (DM) yields were similar. However the velvetbean and scarlet runner bean mixtures produced significantlyhigher forage DM yield, 1.2 Mg ha–1 and 0.89 Mg ha–1more, respectively, in the late bean planting treatment. Beans,except scarlet runner bean, which was damaged by mold and insects,increased the CP concentration of all mixtures, with the greatestincreases from the lablab bean (13%) and velvet bean (16%).The experiments show that lablab bean grown with corn has thegreatest potential of the three beans to increase CP concentrationabove monoculture corn, without compromising forage yield orcalculated milk ha–1 and increasing forage nutrient value.Abbreviations: CP, crude protein • DIP, degradable intake protein • DM, dry matter • IVTD, in vitro true digestibility • NDF, neutral detergent fiber • NDFd, neutral detergent fiber digestibility • NIRS, near infrared reflectance spectroscopy • SECV, standard error of cross validation • UIP, undegradable intake protein
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ROOT SEGREGATION OF C3 AND C4 SPECIES USING CARBON ISOTOPE COMPOSITION
Journal - Crop Science
Partitioning roots for studying cropping systems containingmore than one species is important since root growth interactioncould influence system performance. The study objective wasto test a method for segregating plant species roots from soilsamples taken in a mixed stand of corn (Zea mays L.), a C4,and kura clover (Trifolium ambiguum M. Bieb.), a C3 plant. Soilcores containing both corn and kura clover roots were obtainedat three distances from the corn row and at two depths in aRozetta silt loam soil (moderately well drained, fine-silty,mixed, superactive, mesic Typic Hapludalf). Root compositionof these C4 and C3 species was based on 13C/12C ratios expressedas 13C. A significant linear relationship (r2 = 0.99) was foundbetween the 13C and the percentage of corn roots in samplescontaining known ratios of corn and kura clover roots. Thisrelationship was used to determine corn and kura clover rootpercentages in field samples. Ratios of 13C/12C effectivelysegregated corn and kura clover root materials obtained fromsoil samples and seem to be a powerful tool for partitioningroots of C3 and C4 plants in similar studies.