Submitted to: Trifolium Conference Abstract & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2006
Publication Date: N/A
Technical Abstract: In addition to reducing nitrate and soil losses from cropland, greater use of companion crops (cover crops and living mulches) could enhance yields of corn-silage based production systems. In a replicated multi-year study in southern Wisconsin, Roundup-Ready corn was grown for silage with Kura-clover living mulch or with a cover crop of June-interseeded red clover followed by one year of clover production. These corn-clover rotations were compared to continuous corn silage grown with cover crops of June-interseeded Italian ryegrass, September-seeded winter rye, or no cover crop. Cover crops were seeded with a no-till drill. Each year, manure slurry was surface applied on a phosphorus basis to plots in early November or mid April. No additional nitrogen was applied to the corn-clover rotations but continuous corn plots received additional fertilizer at planting in early May to supply 180 kg/ha of available nitrogen. In 2003 (dry summer), dry matter yields of corn silage were greatest with red clover (23.0 Mg/ha), intermediate with kura clover, winter rye and no cover (20.6 to 21.4 Mg/ha), and lowest with Italian ryegrass (18.4 Mg/ha). In 2004 (wet spring, cool summer), corn silage yields were greatest with red clover and kura clover (19.3 to 20 Mg/ha), intermediate with rye and no cover (17.7 to 18.8 Mg/ha), and lowest with Italian ryegrass (16.6 Mg/ha). In 2005 (dry spring and early summer), corn silage yields with red clover (22.1 Mg/ha) far exceeded yields with kura-clover living mulch and other cover crop systems (14.1 to 16.3 Mg/ha). By late October, growth of companion crops was greatest for Italian ryegrass (0.9 to 1.5 Mg/ha) but biomass was insufficient to justify a harvest. In early May, growth of winter rye (2.9 to 3.5 Mg/ha) exceeded other companion crops, possibly justifying a harvest before corn planting, but this could leave inadequate residue for limiting soil erosion. In the year following corn, total 3-cut yields of red clover were greater than kura clover in 2003 (11.4 vs. 8.6 Mg/ha) and in 2005 (12.7 vs. 7.9 Mg/ha). Production year yields of red clover established in corn were comparable to conventionally established stands grown in adjacent small plot trials. Herbicide suppression and in-row killing of kura clover during corn production depressed yields of kura clover the following year, especially in the 1st cutting, but rhizome growth thickened stands and improved yields as the growing season progressed. Yields of both clovers were similar in 2004 (8.3 Mg/ha) even though red clover was reseeded in April due to drought-induced failure of interseedings the previous summer. Timing of manure application generally had little affect on yields but fall application enhanced spring growth of winter rye. Thus far, interseedings of red clover with corn have yielded the most forage but additional work is needed to make this system more practical and reliable.