Yield and Yield Components of Corn Interseeded with Cover Crops

The rising costs of pesticides, soil erosion, and environmental pollution associated with corn (Zea mays L.) production have led to consideration of alternative production methods. Growing cover crops with corn could address these problems. Field experiments were conducted in 1993 and 1994 at L'Assomption and Macdonald in Quebec to determine the effects of interseeding 12 cover crops on corn yield and yield components. Fall rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), a mixture of red clover (Trifolium pratense L.) and ryegrass (Lolium multiflorum Lam.), a mixture of white clover (T. repens L.) and ryegrass, subterranean clover (T. subterraneum L.), yellow sweetclover (Melilotus officinalis Lam.), black medic (Medicago lupulina L.), Persian clover (T. resupinatum L.), strawberry clover (T. fragiferum L.), crimson clover (T. incarnatum L.), alfalfa (Med. sativa L.), and berseem clover (T. alexandrinum L.) were seeded 10 and 20 d after corn emergence. The experimental design was a splitplot, randomized complete block with four replications at each site. The mainplots were the cover crop planting dates; the subplots were the 12 cover crop treatments and 3 controls (hand weeding, chemical weeding, and no weeding). Seeding the cover crops either 10 or 20 d after corn planting did not affect corn grain yield. Chlorophyll fluorescence measurements (F,/Fm) indicated that corn plants were stressed when interseeded with crimson clover (P < 0.05). When there was competition for moisture, crimson clover was found to be too competitive with corn at the seeding rates used in this experiment. Corn yield was less affected by the interseeded cover crops under conditions of adequate rainfall. No consistent differences in corn grain yield components were found for cover crop treatments.