Interseeding cover crops into soybean and subsequent corn yields

Organic producers in the northeastern USA have difficulty establishing cover crops after soybean [Glycine Mar (L.) Merr.] harvest. We interseeded species into soybean on an organic farm without livestock; to identify cover crops that do not interfere with soybean harvest, provide significant ground cover, and increase subsequent corn (Zea mn)is L. yields. Foenugreek (Trigonella foenum-graceum L.), rye (Secale cereale L.), wheat (Triticum aestivum L.); strawberry clever (Trifolium fragiferum L.), and Austrian winter pea (Dolichos lignosus L.) did not meet establishment and height requirements at the time of harvest. White clover (Trifolium repens L.), red clover (Trifolium pratense L.), barrel medic (Medicago lupulina L.), alfalfa (Medicago sativa: L.), annual ryegrass (Lolium multiflorum L.), and creeping red fescue (Festuca rubra L.) met these requirements and generally provided >30% ground cover. Interseeded grasses provided the most biomass (0.5-1.1 Mg ha(-1)) at spring plowdown. Interseeded legumes did not establish well in 1996-1997 and produced only 0.1 to 0.2 Mg ha(-1) biomass in 1997. Corn yielded more following Dutch white clover (7.2 Mg ha(-1)) and medium red clover (6.7 Mg ha(-1)) than following no cover (5.7 Mg ha(-1)) in 1996 but yielded the same in 1997 (5.7, 6.3, and 6.2 Mg ha(-1): respectively); Corn yielded less following annual ryegrass (5.3 Mg ha(-1)) and creeping red fescue (5.1 Mg ha(-1)) than following no cover in 1997. More research is needed to identify conditions that would reduce the risk of poor establishment of interseeded legumes or reduced corn yields following interseeded grasses.