Winter Pea and Lentil Cover Crops Affect On Subsequent Winter Wheat Yield and System Net Return.

Winter (fall-seeded) pea (Pisum sativum L.) and lentil (Lens culinaris Medik) have been developed for hay, green manure, or grain, yet the rotational benefits and economic returns by incorporating these crops into wheat (Triticum aestivum L.)-based cropping systems in the Northern Great Plains have not been well understood. Two two-year crop rotation studies were conducted in central Montana to investigate winter pea and lentil hay, green manure, or grain affecting on the subsequent winter wheat yield and protein and the economic returns of the systems under no-till. Experiment I: winter pea hay-winter wheat (WP(h)-WW) was compared to fallow-winter wheat (FW-WW) and spring wheat-winter wheat (SW-WW) systems. Experiment II: winter lentil green manure-winter wheat (WL(m)-WW) was compared to winter lentil grain-winter wheat system (WL(g)-WW). Four varying rates of nitrogen (N) were applied to the winter and spring wheat only. Winter wheat yield in the WP(h)-WW was 2193 kg ha^-1, which was equivalent to the FW-WW (2136 kg ha^-1) but was much greater than the SW-WW system (1155 kg ha^-1) . The WP(h)-WW system the greatest net returns, followed by the FW-WW, and the SW-WW had the least net returns. In experiment II, winter wheat following WL(m) produced greater grain yield and protein content, especially at lower N input levels, indicating a greater N benefit. Nevertheless, the WL(g)-WW generated 3 times more net returns than the WL(m)-WW system. Pea and lentil cover crops can improve NRG in the subsequent winter wheat, even though NRG decreased as the N input level increased.