Barley (Hordeum vulgare L.) and oat (Avena sativa L.) have been intercropped with field pea [Pisum sativum subsp. sativum var. arvense (L.) Poir.] to increase forage yield and quality. Our objective was to evaluate the effects of two barley and two oat cultivars and seeding rates of cereal—pea intercrop on forage production, crude protein (CP) concentration, and N yield. A field experiment was conducted in 1993 and 1994 under dryland management in both fallowed and continuously cropped, no‐tillage environments. ‘Bowman’ and ‘Horsford’ barley, and ‘Dumont’ and ‘Magnum’ oat, were each sown at 93, 185, and 278 kernels m−2 with ‘Trapper’ pea at 40, 80, and 120 seeds m−2, in all possible rate combinations. The cereal cultivars also were sown alone at 185 kernels m−2. Cultivars developed for forage production (Horsford, Magnum) produced as much or more forage than cultivars developed for grain production (Bowman, Dumont) across sole‐crop and intercrop plots (P ≤ 0.05). Forage yield was unaffected by intercropping when the cereal crop was sown at the sole‐crop or greater rate. Less forage was produced by intercrops when the cereal component was sown at half the sole‐crop rate. Forage yield was not affected by the pea seeding rate, but CP concentration increased with increasing seeding rate of pea in three of four environment‐years. Forage N yield was unaffected by intercropping. These data indicate that the cereal component in barley—pea and oat—pea mixtures should be sown at a sole‐crop or greater seeding rate for maximum forage production. Forage CP concentration can be increased as the relative proportion of pea seed to cereal kernels sown in a mixture is increased, but forage N yield may not be affected, since the cereal component contributes more to yield than the pea component.

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Conservation tillage and crop diversification are increasing in the northern Great Plains. Few regional studies have determined if tillage influences crop rotation effects. Our objective was to determine if reductions in tillage affect grain yield of spring wheat (Triticum aestivum L. emend. Thell.) similarly in a rotation with field pea (Pisum sativum L.) and in a continuous spring wheat monoculture. Wheat grain yield under no‐till averaged 40% higher compared with clean‐till and 30% higher compared with reduced‐till, regardless of cropping strategy (wheat‐pea rotation and continuous wheat monoculture). An additional inch of stored soil water occurred under no‐till compared with clean‐till and probably explains much of the yield enhancement that resulted when tillage was eliminated. Better crop stand establishment under no‐till also contributed to superior wheat grain yield in some years. Results of this research demonstrate that the beneficial effects of eliminating tillage on wheat grain yield apply across contrasting cropping strategies and support the continued replacement of clean‐till with no‐till systems in the northern Great Plains.

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