Interseeding cover crops into soybean and subsequent corn yields

Organic producers in the northeastern USA have difficulty establishing cove r crops after soybean [Glycine Mar (L.) Merr.] harvest. We interseeded spec ies into soybean on an organic farm without livestock; to identify cover cr ops that do not interfere with soybean harvest, provide significant ground cover, and increase subsequent corn (Zea mn)is L. yields. Foenugreek (Trigo nella 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 a t the time of harvest. White clover (Trifolium repens L.), red clover (Trif olium pratense L.), barrel medic (Medicago lupulina L.), alfalfa (Medicago sativa: L.), annual ryegrass (Lolium multiflorum L.), and creeping red fesc ue (Festuca rubra L.) met these requirements and generally provided >30% gr ound cover. Interseeded grasses provided the most biomass (0.5-1.1 Mg ha(-1 )) at spring plowdown. Interseeded legumes did not establish well in 1996-1 997 and produced only 0.1 to 0.2 Mg ha(-1) biomass in 1997. Corn yielded mo re 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 identif y conditions that would reduce the risk of poor establishment of interseede d legumes or reduced corn yields following interseeded grasses.