Long‐term conservation agriculture effects on corn profitability in West Tennessee.

Crop rotations, cover crops, and poultry litter (PL) under no tillage (NT) may improve soil health and crop yields. However, farmers' adoption depends on whether they can generate extra profits. This study evaluated profitability of NT corn (Zea mays L.) in monoculture versus rotations with soybean (Glycine max L.) and cotton (Gossypium hirsutum L.) with or without winter covers from 2002 to 2017. Whole‐block treatments were cropping rotations with monoculture (control) versus nine, 4‐yr cropping sequences (phases) repeated four times (I, II, III, and IV). Split‐block treatments were no cover versus winter covers of PL, hairy vetch (Vicia villosa L.), and wheat (Triticum aestivum L.). Different phases influenced yields and net returns (NRs; p <.05), with the greatest NRs in Phase IV, and the lowest in Phase III. Rotation interacted with phase to influence corn yield and NRs (p <.01), with positive rotation effects occurring in Phase IV. Covers influenced yields and NRs over 16 yr (p <.01). Vetch cover resulted in the highest corn yields, whereas wheat cover was the lowest. However, no cover plots produced NRs greater than any other cover. Enhanced yields or cost savings due to reduced fertilizer from covers did not offset cover costs. Lowering costs of PL, hairy vetch, and wheat by 70, 68, and 100%, respectively, from their base values produced equivalent NRs to no cover. Thus, farmers may need subsidies to adopt conservation agriculture‐based practices. Core Ideas: Rotation, cover crop, and poultry litter affected corn yields and net returns.Rotation effect was positive in the last 4 yr of the 16‐yr experiment.Corn yields were greater after vetch than no cover, wheat, and poultry litter.No cover corn had more net returns than any cover crop or poultry litter. [ABSTRACT FROM AUTHOR]