Establishment and growth of self-seeded winter cereal cover crops in a soybean–corn rotation
Perpetuating cereal cover crops through self-seeding may increase adoption by reducing risk and cost. Winter rye (Secale cereale L.), wheat (Triticum aestivum L.), and triticale (x Triticosecale Wittmack) were used to develop self-seeding cover crop systems in a soybean [Glycine max (L.) Merr.]–corn (Zea mays L.) rotation. Cereals were planted and managed chemically and mechanically in varying configurations. The objectives were to (i) quantify temporal establishment patterns after one cycle of self-seeding, (ii) quantify shoot biomass, N uptake, and seed production growing concurrently with corn, and (iii) quantify cover crop establishment after two cycles of self-seeding. Final plant densities for most species by treatment combinations were fully established within 1 wk after soybean (Cycle 1) harvest. Fall green ground cover after soybean was consistently higher with wheat and ranged from 16 to 61%. Straw biomass the following July ranged from 50.4 to 79.1 g m–2 in wheat, 20.1 to 39.3 g m–2 in triticale, and 0.0 to 52.7 g m–2 in rye. Combined spring and maturity maximum N uptake was 20.7, 21.2, and 35.0 kg ha–1 for triticale, wheat, and rye. Cycle two cover crop seed production was greatest in wheat and ranged from 559 to 1280 seeds m–2. Wheat also consistently had greater self-seeding plant establishment after two cycles than rye and triticale, which ranged from 5 to 21% of the original plant densities and 19 to 64% of the cycle one plant densities. Future research on self-seeding cereal cover crops should focus on efficient technologies for seed dispersal.