Living mulch forage yield and botanical composition in a corn-soybean-forage rotation
Managing forages as living mulches during row crop production requires suppressing the forages to produce economical crop yields. The objective of this research was to identify forage plants with varied growth habit, persistence, and yield potential to provide desirable ecosystem functions in a multifunctional cropping system. Alfalfa (Medicago sativa L.), kura clover (Trifolium ambiguum Bieb.), and birdsfoot trefoil (Lotus corniculatus L.) were evaluated in sole seedings, binary mixtures, and reed canarygrass (Phalaris arundinacea L.) and orchardgrass (Dactylis glomerata L.) were included in three-way mixtures in a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.]–forage rotation. The forages functioned as cover crops in corn and soybean and were suppressed using a 25-cm glyphosate band over the row. In the forage year, treatments containing alfalfa produced the highest yields (7824 kg ha–1 average dry matter 2005–2007). Three-way mixtures provided greater weed suppression in the interrow than sole seedings or binary mixtures in 2 of 3 yr (80 vs. 127 weeds m–2, 2005–2006 average). Kura clover provided greater weed suppression than alfalfa in the former row (108 vs. 186 weeds m–2). Reed canarygrass exhibited better stability in sward composition (20% in 2005 and 22% in 2007) than orchardgrass (58% in 2005 and 16% in 2007). Consequently, the best combination of species to use as living mulches to provide high forage yields and lower weed densities includes alfalfa, kura clover, and reed canarygrass. Seeding a nondormant alfalfa in the spring of the forage year will supplement yield and suppress weeds in the former crop row.