Seed size variability has implications for achieving cover cropping goals

It is common to use mass-based units (e.g., kg ha^–1) to describe cover crop seeding rates. However, this convention obscures important information about seed size and resulting plant density in the field, which may be linked to cover crop performance and ecosystem services. Seed counts of 27 lots of commercially available winter rye (Secale cereale L.) spanned a wide range from 28,000 to 50,000 seeds kg^–1. If the lots with the lowest and highest seed counts were seeded at a common mass-based seeding rate of 125 kg ha^–1, it would result in a nearly twofold difference in density-based seeding rate, or 3.0 and 5.6 million live seeds ha^–1. Including density-based metrics such as live seeds per area and resulting in-field plant density in research will help advance our understanding of cover crop management, and these efforts will make it easier for farmers and policymakers to tailor cover cropping practices for specific goals.